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Health differences between the elderly in Japan and the United States

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Health differences between the elderly in Japan and the United States

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Content 1"
HEALTH"DIFFERENCES"BETWEEN"THE"ELDERLY"IN"JAPAN"AND"THE"UNITED"
STATES"
"
by"
"
"
Shieva"Davarian"
"
________________________________________________________________________"
"
"
A"Dissertation"Presented"to"the"
FACULTY"OF"THE"USC"GRADUATE"SCHOOL"
UNIVERSITY"OF"SOUTHERN"CALIFORNIA"
In"Partial"Fulfillment"of"the"
Requirements"for"the"Degree"
DOCTOR"OF"PHILOSOPHY"
(GERONTOLOGY)"
"
"
"
"
December"2013"
"
"
"
"
"
"
"
"
"
Copyright"2013" " " " " " " """""Shieva"Davarian"
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TABLE!OF!CONTENTS!
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CHAPTER(1:(INTRODUCTION.(..................................................................................(3(
Specific!Aims.!................................................................................................................................!4!
Dissertation!Format.!..................................................................................................................!4!
References.!.....................................................................................................................................!7!
!
CHAPTER(2:(HYPERTENSION(................................................................................(10(
Methods!.........................................................................................................................................!13!
Results!...........................................................................................................................................!18!
Discussion!....................................................................................................................................!22!
References!....................................................................................................................................!26!
Tables!and!Figures!...................................................................................................................!31!
Appendix!.......................................................................................................................................!36!
!
CHAPTER(3:(COGNITIVE(PERFORMANCE(..........................................................(40!
Methods!.........................................................................................................................................!43!
Results!...........................................................................................................................................!48!
Discussion!....................................................................................................................................!53!
References!....................................................................................................................................!56!
Tables!and!Figures!...................................................................................................................!61!
Appendix!A:!Supplemental!Tables!and!Data!.................................................................!68!
Appendix!B:!Imputations!.......................................................................................................!73!
!
CHAPTER(4:!MORTALITY(.......................................................................................(79!
Methods!.........................................................................................................................................!84!
Results!...........................................................................................................................................!91!
Discussion!....................................................................................................................................!95!
References!....................................................................................................................................!98!
Tables!and!Figures!................................................................................................................!105!
Appendix!....................................................................................................................................!112!
!
CHAPTER(5:(CONCLUSION(..................................................................................(120!
Summary.!...................................................................................................................................!120!
Findings!......................................................................................................................................!120!
Implications!..............................................................................................................................!123!
Limitations!and!Future!Directions!.................................................................................!125!
References!.................................................................................................................................!128!
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! !
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3"
Chapter"1:"Introduction"
" Japan"and"the"United"States"(US)"are"unique"models"for"studying"health"and"
aging."While"it"is"well"established"that"the"Japanese"experience"lower"levels"of"most"
chronic"conditions"and"longer"lifeXexpectancy"compared"to"Americans"(Crimmins,"
Preston,"&"Cohen,"2011;"WHO"2011),"there"are"several"characteristics"associated"
with"health"and"longevity"that"don’t"seem"to"explain"the"differences"we"observe"
between"countries.""In"fact,"compared"to"the"Japanese,"Americans"have"higher"levels"
of"education,"which"is"ordinarily"associated"with"better"health"outcomes"(Crimmins"
et"al.,"2010).""Additionally,"Americans"have"lower"rates"of"smoking"(among"men)"
(WHO,"2012),"which"should"give"Americans"an"advantage"given"that"smoking"has"
been"shown"to"reduce"lifeXexpectancy"by"at"least"1.6X3.9"years"among"those"65"
yearsXorXolder,"controlling"for"other"lifeXstyle"factors"(Ferrucci"et"al.,"1999),"but"at"
the"individual"level,"there"is"a"larger"effect"of"smoking"in"the"US"than"in"the"Japan"
(Crimmins"et"al.,"2011)."
" Given"the"multiple"characteristics"for"which"Americans"should"have"a"health"
advantage,"it"is"surprising"that"Americans"are"overall"in"worse"health.""If"Americans"
have"several"factors"working"in"their"favor"leading"to"better"health"in"old"age,"the"
question"remains"what"leads"to"Americans"having"overall"worse"health"than"their"
Japanese"counterparts.""Can"JapanXUS"differences"in"health"be"explained"by"
differences"in"the"level"of"risk"factors"for"a"given"health"outcome"or"by"differences"in"
the"effect"of"the"risk"factors?""Is"the"direction"and/or"size"of"the"relative"risk"similar"
between"countries?""Also,"do"Americans"perform"better"on"health"outcomes"that"
"
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4"
play"to"their"strengths,"such"as"cognitive"performance,"which"is"typically"heavily"
influenced"by"education?"
" This"dissertation"examines"country"differences"between"Japan"and"the"US"in"
the"level"and"the"size"and"direction"of"associations"of"risk"factors"with"three"health"
outcomes:"hypertension"(chapter"2),"cognitive"performance"(chapter"3),"and"
mortality"(chapter"4).""A"comparative"study"between"a"relatively"healthy"and"longX
lived"population,"like"Japan,"and"a"relatively"unhealthy"population,"like"the"US,"helps"
us"better"understand"aging"through"the"examination"of"the"similarities"and"
differences"in"risk"factors"and"outcomes.""Findings"could"help"us"better"clarify"how"
the"aging"process"can"differ"based"on"health"and"environment"and"background"
circumstances.!!
Specific!Aims!
" The"aims"of"this"study"are"twoXfold:"
1) To"establish"comparisons"of"levels"of"hypertension,"and"comparable"measures"
of"cognitive"performance,"and"the"frequency"of"mortality"by"age"for"older"
persons"in"Japan"and"the"US."
2) To"determine"whether"differences"exist"by"country"in"the"association"of"
known"risk"factors"for"hypertension,"as"well"as"factors"associated"with"
cognitive"performance"and"mortality.""
Dissertation!Format!
" This"dissertation"determines"country"differences"in"the"level"and"the"
association"between"risk"factors"and"hypertension"(chapter"2),"cognitive"
performance"(chapter"3),"and"mortality"(chapter"4)"in"the"elderly"populations"of"the"
US"and"Japan.""Each"chapter"is"designed"as"its"own"independent"article"with"an"
"
"
5"
introduction"and"review"of"the"literature,"methods,"results,"discussion,"and"
references."
" Chapter"two"examines"country"differences"in"the"prevalence"of"risk"factors"
versus"the"size"of"their"effect"on"hypertension.""Hypertension"is"a"risk"factor"for"
heart"attacks,"heart"failure,"stroke,"and"kidney"disease,"as"well"as"other"health"
problems"(DiGiovanna,"1999).""The"association"between"hypertension"and"increased"
risk"of"cardiovascular"diseases"has"been"well"documented"in"various"nationally"
representative"studies"(Benetos"et"al.,"1997;"Franklin"et"al.,"2001;"MacMahon"et"al.,"
1990)."""
" The"third"chapter"determines"country"differences"in"cognitive"performance"
and"investigates"risk"factors"associated"with"cognition."Cognitive"performance"has"
been"associated"with"chronic"conditions"such"as"diabetes,"heart"disease,"
hypertension"(Dik"et"al.,"2007;"Dodge"et"al.,"2005;"Dodge"et"al.,"2008),"and"metabolic"
syndrome"(Dik"et"al.,"2007;"Katsumata"et"al.,"2012;"Van"den"Berg"et"al.,"2007;"Yaffe"
2007).""Increases"in"life"expectancy"affect"cognitive"performance"in"three"ways:"1)"
increased"age,"itself,"is"a"risk"factor"for"declines"in"cognitive"performance,"as"well"as"
increased"risk"for"chronic"conditions"and"2)"more"individuals"are"living"with"chronic"
conditions"for"longer"(Crimmins"2004;"Crimmins"&"BeltranXSanchez,"2010)."
" The"fourth"chapter"determines"country"differences"in"the"frequency"of"
mortality"by"age"and"health"condition,"as"well"as"differences"in"the"association"
between"comparable"mortality"risk"factors.""The"health"outcomes"in"the"previous"
two"chapters"have"both"been"associated"with"mortality"(Benetos"et"al.,"1997;"Dewey"
&"Saz,"2001;"DiGiovanna,"1999;"Franklin"et"al.,"2001;"MacMahon"et"al.,"1990),"as"
"
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6"
have"their"risk"factors"(i.e."diabetes,"cardiovascular"disease,"and"obesity)"
(DiGiovanna,"1999)."""
" The"fifth,"and"final,"chapter"summarizes"the"results"and"their"implications"as"
well"as"gives"suggestions"for"future"research."" "
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7"
References"
Benetos"A,"Safar"M,"Rudnichi"A,"Smulyan"H,"Richard"JL,"Ducimetière"P,"Guize"L."Pulse"
Pressure:"A"predictor"of"longXterm"cardiovascular"mortality"in"a"French"male"
population."Hypertension"1997;"30:"1410X1415."
Crimmins"EM."Trend"in"the"health"of"the"elderly."Annu!Rev!Public!Health"2004;"
25:79X98."
Crimmins"EM,"BeltranXSanchez"H."Mortality"and"morbidity"trends:"is"there"
compression"of"morbidity?."Journal!of!Gerontology:!Social!Sciences"2010;"
66B(1):75X86."
Crimmins"EM,"Preston"SH,"Cohen"B."Explaining"divergent"levels"of"longevity"in"highX
income"countries."2011."Washington,"D."C.:"The"National"Academies"Press."
Crimmins"EM,"Garcia"K,"Kim"JK."Are"international"differences"in"health"similar"to"
international"differences"in"life"expectancy?."In"E."M."Crimmins,"S."H."Preston,"&"B."
Cohen"(Eds.),"International!difference!in!mortality!at!older!ages:!dimensions!and!
sources"2010a;!64X104."Washington,"D."C.:"The"National"Academies"Press."
Dewey"ME,"Saz"P."Dementia,"cognitive"impairment"and"mortality"in"persons"aged"65"
and"over"living"in"the"community:"a"systematic"review"of"the"literature."
International!Journal!of!Geriatric!Psychiatry"2001;16(8):751X761."
DiGiovanna"AG"(eds)."Human!Aging:!Biological!Perspectives"2
nd
"edn."McGrawXHill,"
San"Francisco,"1999."
Dik"MG,"Jonker"C,"Comijs"HC,"Deeg"DJH,"Kok"A,"Yaffe"K,"Penninx"BW."Contribution"of"
Metabolic"Syndrome"Components"to"Cognition"in"Older"Individuals."Diabetes!
Care"2007;"30(10):"2655X2660."
"
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Dodge"HH,"Kadowaki"T,"Hayakawa"T,"Yamakawa"M,"Sekikawa"A,"Ueshima"H."
Cognitive"Impairment"as"a"Strong"Predictor"of"Incident"Disability"in"Specific"
ADL–IADL"Tasks"Among"CommunityXDwelling"Elders:"The"Azuchi"Study."The!
Gerontologist"2005;"45(2):"222X230"
Dodge"HH,"Yoshikuni"K,"Takechi"H,"Hayakawa"T,"Ganguli"M,"Ueshima"H."Healthy"
Cognitive"Aging"and"Leisure"Activities"Among"the"Oldest"Old"in"Japan:"Takashima"
Study."J!Gerontol!A!Biol!Sci!Med!Sci"2008;"63(11):"1193X1200."
Ferrucci"L,"Izmirlian"G,"Leveille"S,"Phillips"CL,"Corti"MC,"Brock"DB,"Guralnik"JM."
Smoking,"physical"activity,"and"active"life"expectancy."American!Journal!of!
Epidemiology"1999;149(7):645X653."
Franklin"SS,"Larson"MG,"Khan"SA,"Wong"ND,"Leip"EP,"Kannel"WB,"Levy"D."Does"the"
relation"of"blood"pressure"to"coronary"heart"disease"risk"change"with"aging?:"The"
Framingham"heart"study."Circulation"2001;"103:"1245X1249."
Katsumata"Y,"Todoriki"H,"Higashiuesato"Y,"Yasura"S,"Willcox"DC,"Ohya"Y,"Willcox"BJ,""
Dodge"H."Metabolic"Syndrome"and"Cognitive"Decline"Among"the"Oldest"Old"in"
Okinawa:"In"Search"of"a"Mechanism."The"KOCOA"Project."J!Gerontol!A!Biol!Sci!Med!
Sc!2012;!67A(2):!126N134."
MacMahon"S,"Peto"R,"Cutler"J,"Collins"R,"Sorlie"P,"Neaton"J,"Abbott"R,"Godwin"J,"Dyer"
A,"Stamler"J."Blood"pressure,"stroke,"and"coronary"heart"disease."Part"I,"
Prolonged"differences"in"blood"pressure:"prospective"observational"studies"
corrected"for"the"regression"dilution"bias."Lancet"1990;"335:765X774."
"
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9"
Van"den"Berg"E,"Biessels"GJ,"de"Craen"AJM,"Gussekloo"J,"Westendrop"RGJ."The"
metabolic"syndrome"is"associated"with"decelerated"cognitive"decline"in"the"
oldest"old."Neurology"2007;"69(10):"979X985."
World"Health"Organization"(WHO)."Global"Health"Observatory"Data"Repository:"Life"
Expectancy"Tables."2011."Retrieved"from"http://apps.who.int/ghodata"""
World"Health"Organization"(WHO)."Prevalence"of"tobacco"use"among"adults"and"
adolescents."2012."Retrieved"from:"
http://gamapserver.who.int/gho/interactive_charts/tobacco/use/atlas.html?filt
er=filter4,AMRO"
Yaffe"K."Metabolic"Syndrome"and"Cognitive"Disorders:"Is"the"Sum"Greater"Than"Its"
Parts?"Alzheimer’s!Disease!and!Associated!Disorders"2007;"21(2):"167X171."
"
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Chapter"2:"Hypertension"
Introduction"
Prior"to"the"introduction"of"blood"pressure"control"medication,"Japan"has"
traditionally"had"high"levels"of"blood"pressure"(Marmot"et"al.,"1975);"consequently,"
reducing"hypertension"has"been"a"major"focus"of"Japanese"health"policy"(Crimmins"
et"al.,"2010;"Ikeda"et"al.,"2008;"Imai"et"al.,"2003).""Population"based"interventions"to"
reduce"salt"intake"and"increases"in"antihypertensive"medication"usage"have"
contributed"to"declines"in"the"prevalence"of"hypertension"(Ikeda"et"al.,"2008;"Ikeda"
et"al.,"2011;"Mori"et"al.,"2006).""Despite"these"gains"in"hypertension"control,"
prevalence"rates"still"remain"relatively"high"in"Japan"(Hozawa"et"al.,"2002;"Ohkubo"et"
al.,"2004;"Tanaka"et"al.,"2007)."Whereas"Japan"has"high"prevalence"of"hypertension,"
the"United"States"(US)"has"lower"levels"of"hypertension,"compared"to"Japan,"
although"risk"factors"associated"with"hypertension"(i.e."overweight/obesity)"and"
associated"chronic"conditions"(i.e."diabetes"and"heart"disease)"are"higher"in"the"US"
(Crimmins"et"al."2010)."""
One"explanation"for"the"varying"levels"of"hypertension"prevalence"between"
the"US"and"Japan"can"be"high/low"levels"of"risk"factors"in"the"population"versus"
stronger/weaker"effects"of"specific"factors"related"to"hypertension."This"study"
utilizes"comparable,"nationally"representative"measures"to"determine"if"differences"
in"hypertension"prevalence"between"the"US"and"Japan"can"be"explained"by"
differences"in"the"distribution"of"risk"factors"or"in"the"level/direction"of"their"
association"with"hypertension.""Since"levels"of"hypertension"risk"factors"are"known"
to"be"relatively"low"in"Japan"and"high"in"the"US,"it"is"hypothesized"that"the"effects"of"
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the"associations"will"be"relatively"stronger"in"Japan"and"lower"in"the"US.""Factors"
that"influence"hypertension,"and"therefore"are"examined"in"this"study,"include"
related"chronic"conditions,"health"behaviors,"and"sociodemographic"status"
(Crimmins"et"al.,"2008a;"Digiovanna,"1999;"Kim"et"al.,"2006;"Matsumura"et"al.,"2001;"
Ohkubo"et"al.,"2002;"Sleight,"1993).""
Background"
JapanNUS!Differences!in!the!Association!between!Hypertension!and!Health!Behaviors!
On"one"hand,"the"US"is"a"country"with"high"rates"of"obesity"(Crimmins"et"al.,"
2010),"comparatively"low"rates"of"current"smoking"(among"men)"(WHO,"2012b),"
and"prevalence"of"hypertension"(Crimmins"et"al."2010).""On"the"other"hand,"Japan"is"
a"country"with"low"BMI"(Crimmins"et"al."2010),"high"rates"of"smoking"(among"men)"
(Yoshiike"et"al.,"2002;"WHO"2012b),"and"traditionally"high"prevalence"of"
hypertension"(Marmot"et"al.,"1975).""Hypertension,"as"defined"by"systolic"(SBP)"and"
diastolic"(DBP)"blood"pressure"(WHO,"2012a),"shows"varying"associations"with"BMI"
and"smoking"in"the"US"and"Japan."
Associations"between"hypertension"and"BMI"and"smoking"are"relatively"clear"
in"the"US"and"other"Western"countries"but"are"inconsistent"in"Japan.""In"the"US"and"
many"Western"countries"hypertension"is"positively"associated"with"BMI,"particularly"
in"the"obese"range"(≥30"kg/m
2
),"and"smoking"(Digiovanna,"1999;"Sleight,"1993).""
Whereas,"in"Japan,"some"researchers"have"found"positive"associations"between"BMI"
and"hypertension"(Matsumura"et"al.,"2001)"and"others"have"found"the"association"is"
weaker"at"older"ages"(Wakabayashi,"2012).""Similarly,"the"acute"and"longXterm"
effects"of"smoking"on"hypertension"are"not"consistent"across"studies"in"Japan;"some"
"
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12"
researchers"have"found"that"blood"pressure"was"significantly"lower"among"Japanese"
men"who"were"current"smokers,"compared"to"nonX"and"exXsmokers"(Ohkubo"et"al.,"
2002),"whereas"others"have"found"smoking"is"associated"with"hypertension"in"
Japanese"men"(Dochi"et"al.,"2009)."
JapanNUS!Differences!in!the!Association!between!Hypertension!and!Sociodemographic!
Characteristics!
The"association"between"hypertension"and"sociodemographic"characteristics,"
such"as"age,"gender,"and"education,"varies"between"the"US"and"Japan.""Clear"negative"
associations"between"education"and"hypertension"have"been"documented"in"the"
American"literature"(HDFPCG,"1977;"Pincus,"Callahn,"&"Burkhauser,"1987)"but"not"in"
the"Japanese"(Yong"&"Saito,"2012).""However,"hypertension"is"associated"with"age"
and"gender"in"a"less"consistent"manner;"increases"in"hypertension"have"been"linked"
with"age"when"the"entire"age"range"is"examined,"but"when"studies"are"limited"to"
older"age"groups,"this"relationship"is"not"found"(Satish"et"al.,"2001).""Lastly,"varying"
degrees"of"gender"differences"in"hypertension"prevalence"and"onset"exist"between"
the"US"and"Japan.""Male"gender"has"been"shown"to"be"associated"with"a"higher"risk"of"
hypertension"at"some"ages"in"the"US,"with"men"typically"experiencing"earlier"onset"
but"women"having"higher"prevalence"at"older"ages"(Crimmins"et"al.,"2008a;"Fried"et"
al.,"1998;"Kim"et"al.,"2006).""Gender"differences"in"hypertension"among"the"older"
population"in"Japan"are"much"smaller"than"in"the"US"(Crimmins"et"al.,"2008b)."
"
This"paper"examines"country"differences"in"the"association"and"effect"of"
health"behavior,"chronic"conditions,"and"sociodemographic"characteristics"on"
"
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13"
hypertension.""Knowing"crossXnational"differences"in"associations"and"effects"of"risk"
factors"and"comorbidities"on"hypertension"will"allow"us"to"quantify"the"effects"of"
risk"factors"on"the"level"of"hypertension"and"test"whether"effects"are"country"
specific."
Methods"
Data!Sources!
The"addition"of"measured"blood"pressure"in"2006"to"the"Nihon"University"
Japanese"Longitudinal"Study"of"Aging"(NUJLSOA),"a"nationally"representative"sample"
of"older"persons"in"Japan,"provides"a"source"of"data"on"elevated"blood"pressure"
among"individual"older"persons"in"Japan"in"a"publicly"available"data"set.""The"
inclusion"of"blood"pressure"measurements,"that"were"previously"unavailable"at"the"
individual"level"for"the"Japanese"elderly"population,"allows"for"a"direct"comparison"
to"the"Health"and"Retirement"Study"(HRS)"of"the"US.""This"study"utilizes"measured"
blood"pressure,"as"well"as"information"on"antihypertensive"medication"usage,"
allowing"for"identification"of"participants"with"undiagnosed"hypertension.""Both"the"
HRS"and"the"NUJLSOA"additionally"include"selfXreports"of"antihypertensive"
medication"usage,"allowing"for"identification"of"participants"with"controlled"
hypertension.""The"combination"of"these"measures"provides"the"opportunity"for"a"
more"comprehensive"examination"of"Japan’s"hypertension"profile,"allowing"for"
better"analysis"and"comparison"between"countries."
NUJLSOA."This"study"examines"data"collected"in"2006"during"the"fourth"wave"
of"the"NUJLSOA,"a"nationally"representative"sample"of"the"Japanese"population"aged"
65"and"older"at"baseline"collected"by"the"Nihon"University"Tokyo,"Japan.""The"first"
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wave"of"data"was"collected"in"1999"and"subsequent"waves"were"conducted"in"2001,"
2003,"and"2006.""Younger"participants"were"added"at"the"second"and"third"waves"so"
as"to"remain"nationally"representative"of"the"65"and"older"population.""New"
participants"were"not"added"at"the"fourth"wave"in"2006,"therefore"the"fourth"wave"
contains"data"from"participants"aged"68"years"and"older.""Complete"information"on"
the"design"and"methods"of"the"study"can"be"found"on"the"website"of"the"Nihon"
University"Center"for"Information"Networking"(NUJLSOA,"2004)."
The"fourth"wave"of"the"survey"includes"3,395"participants"age"68"yearsXorX
older"of"whom"2,357"participated"in"blood"pressure"measurements"and"2,305"had"
both"a"blood"pressure"measurement"and"information"on"antihypertensive"
medication"usage."A"flowchart"indicating"the"reasons"for"loss"of"sample"can"be"found"
in"Figure"A1"of"the"Appendix.""The"analytic"sample"was"59.8%"of"the"eligible"sample"
or"2031."In"the"analytic"sample"53.7%"were"female"and"the"average"age"of"the"
participants"was"75.79"years"(Table"1)."""
TwoXtailed"tXtests"and"chiXsquare"tests"revealed"that"the"participants"who"
were"excluded"from"the"analysis"(n=1364),"due"to"missing"values"on"one"or"more"
variables,"were"significantly"different"from"those"who"were"included"(n=2031)"
(Table"A2b"in"the"Appendix)."Those"with"missing"data"were"3.55"years"older"
(p<.001),"had"0.84"fewer"years"of"education"(p<.001),"8.6%"higher"prevalence"of"
never"smoking,"7.1%"lower"prevalence"of"former"smoking,"and"7.8%"higher"
prevalence"of"stroke.""An"adjusted"sample"weight"was"created"to"account"for"having"
missing"data"on"measured"blood"pressure.""The"adjustment"was"created"by"
multiplying"the"normalized"weight"of"the"sample"by"the"inverse"of"the"predicted"
"
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probability"that"an"individual"participant"would"have"a"blood"pressure"
measurement.""The"predicted"probability"was"based"on"age,"sex,"and"level"of"
education."The"adjusted"weight"was"used"in"all"analyses."
HRS."The"HRS"surveys"more"than"22,000"Americans"over"the"age"of"50"every"
two"years.""Data"for"the"eighth"wave"of"HRS"used"in"this"study"were"collected"in"2006"
(n=15,722)"and"was"chosen"to"correspond"to"the"timing"of"the"fourth"wave"of"
NUJSLOA.""In"2006,"9,262"participants"were"68"yearsXorXolder"and"were"chosen"to"
match"the"age"of"the"Japanese"sample.""Half"of"the"HRS"2006"sample"(n=4,734)"was"
randomly"selected"at"the"household"level"to"participate"in"an"enhanced"faceXtoXface"
interview"where"blood"pressure,"height,"and"weight"were"measured"along"with"the"
collection"of"other"physical"and"biological"measures.""Respondents"who"used"a"
proxy,"were"residing"in"a"nursing"home,"or"who"participated"via"a"phone"interview"
were"not"considered"for"the"enhanced"faceXtoXface"interview."
The"data"used"for"this"study"are"a"subset"of"all"2006"participants"who"were"
68"yearsXorXolder"and"who"had"participated"in"the"enhanced"faceXtoXface"interview"
(n=4,734);"3,543"participants"agreed"to"having"their"blood"pressure"measured"and"
3,516"participants"had"both"a"blood"pressure"measurement"and"information"on"
antihypertensive"medication"usage;"a"flowchart"indicating"the"reasons"for"loss"of"
sample"can"be"found"in"Figure"A2"of"the"Appendix.""The"analytic"sample"was"74.3%"
of"the"eligible"faceXtoXface"sample."The"analytic"sample"was"58.9%"female"and"the"
average"age"of"the"sample"was"76.74"years"(Table"1).""TwoXtailed"tXtests"and"chiX
square"tests"revealed"that"the"participants"who"were"excluded"from"analysis"
(n=1287)"due"to"being"missing"on"one"or"more"measurements"were"significantly"
"
"
16"
different"from"those"included"(n=3447)"(Table"A2b"in"the"Appendix)"by"age"(1.14"
years"older"than"analytic"sample,"p<.001),"years"of"education"(about"0.78"years"less"
educated"than"nonXmissing,"p<.001),"and"overweight/obese"BMI"(10.1%"higher"
prevalence"than"nonXmissing,"p<.001),"never"smoking"(5.2%"lower"prevalence"than"
nonXmissing),"former"smoking"(4%"higher"prevalence"than"nonXmissing),"stroke"
(6.1%"higher"prevalence"than"nonXmissing),"and"antihypertensive"medication"usage"
(31.2%"higher"prevalence"than"nonXmissing).""A"sample"weight"was"provided"by"the"
HRS"and"was"used"in"all"analyses"to"account"for"those"who"did"participate"in"the"
biomarker"sampling.""
Measurements"
Blood"Pressure"Collection"
Blood"pressure"in"NUJLSOA"and"HRS"was"measured"using"the"digital"OMRON"
HEMX762"and"OMRON"HEMX780N,"respectively.""Measurement"methods"were"
comparable"between"studies;"the"participant"was"typically"in"a"seated"position"and"
the"recording"was"performed"on"the"left"arm"by"the"interviewer."Blood"pressure"was"
measured"three"times"with"approximately"one"minute"between"measurements"and"
the"average"of"the"three"readings"was"used"for"analysis."""
Hypertension"
" Measured"Hypertension.""The"universally"accepted"cutoffs"for"systolic"blood"
pressure"(SBP)"and"diastolic"blood"pressures"(DBP)"are"140"mmHg"and"90mmHg,"
respectively,"and"were"used"to"create"the"measured"hypertension"variable;"defined"
as"either"high"SBP"or"high"DBP.""
"
"
17"
Overall"Hypertension.""Overall"hypertension"was"indicated"by"either"having"
measured"hypertension"or"selfXreported"antihypertensive"medication"usage."The"
question"of"whether"or"not"participants"had"been"prescribed"antihypertensive"
medication"was"asked"of"those"participants"who"responded"affirmatively"to"ever"
having"experienced"or"been"diagnosed"with"hypertension."
Table"1"provides"descriptive"statistics"on"the"blood"pressure"and"
hypertension"variables.""
Health"Behavior"and"Chronic"Conditions"
" Body"Mass"Index"(BMI)"was"coded"as"a"dichotomous"variable"where"1"
indicated"being"overweight"or"obese"(BMI"≥"25"kg/m
2
)"and"0"indicated"BMI"<"25"
kg/m
2
.""Smoking"was"separated"into"three"dichotomous"variables;"never"smoked,"
former"smoker,"and"current"smoker;"never"smoked"was"used"as"the"referent"
category."
" Stroke,"heart"disease,"and"diabetes"were"coded"as"dichotomous"measures"
where"1"indicated"having"ever"had"the"condition."
Sociodemographic"measures"
Age"and"education"were"coded"as"continuous"variables.""In"coding"gender,"
female"was"coded"as"a"1"and"male"was"coded"as"a"0."
Medication"
" Antihypertensive"medication"usage"was"included"in"order"to"control"for"its"
effect"on"measured"hypertension.""Medication"usage"was"coded"as"a"dichotomous"
variable,"where"1"indicated"being"prescribed"antihypertensive"medication"and"0"
indicated"not"having"been"prescribed"antihypertensive"medication.""The"question"of"
"
"
18"
whether"or"not"a"participant"had"been"prescribed"medication"was"asked"only"of"
those"who"reported"having"ever"experienced"or"been"told"by"a"doctor"that"they"have"
hypertension.""
Statistical!Methods!
" All"analyses"were"conducted"on"Statistical"Analysis"System"(SAS)"9.2"(SAS"
Institute,"Inc,"Cary,"NC).""Hypertension"analyzes"were"performed"using"logistic"
regressions"on"pooled"data"across"the"two"countries"and"include"a"variable"
indicating"the"country"and"country*predictor"interactions"in"order"to"see"if"there"are"
differences"in"the"effects"in"the"two"countries"(Tables"2"and"3aXb).""The"series"of"
regressions"begins"with"a"model"that"includes"only"age,"sex,"and"country."This"
indicates"the"effect"of"country"when"age"and"sex"are"essentially"the"same.""The"
addition"of"variables"in"subsequent"models"indicates"the"effect"of"the"variable"and"
whether"the"effect"of"country"changes"with"controls"for"those"variables."
The"final"n"using"the"pooled"data"is"5,478.""Significant"country"differences"for"
descriptive"statistics"are"indicated"by"pXvalues"obtained"from"twoXsided"tXtests"and"
chiXsquare"tests"(Table"1).""
Results"
Descriptive!Statistics"
Table"1"shows"the"descriptive"statistics"for"blood"pressure,"hypertension,"
health"behavior,"chronic"conditions,"and"sociodemographic"characteristics"for"Japan"
and"the"US.""Differences"in"measures"of"hypertension"and"predictors"were"tested"
using"a"twoXtailed"tXtest"or"chiXsquare.""SBP"(155.05"vs."135.22"mmHg)"and"DBP"
(82.14"vs."78.03"mmHg)"were"significantly"(p<.001)"higher"in"Japan"compared"to"the"
"
"
19"
US.""Almost"threeXfourths"(73.61%)"of"the"Japanese"sample"had"measured"
hypertension"compared"to"only"39.98%"of"the"American"population"(p<.001).""
Overall"hypertension"was"significantly"higher"in"Japan"(81.14%)"than"in"the"US"
(74.07),"p<.001,"whereas"antihypertensive"medication"usage"was"higher"in"the"US"
(59.73%"vs."34.17,"p<.001)."
This"table"also"clarifies"that"older"Americans"are"more"likely"to"report"having"
each"of"the"health"conditions"listed.""Americans"are"also"more"likely"to"be"
overweight"or"obese"(US:"70.35%,"Japan:"20.61%).""Japanese"older"persons"are"more"
likely"to"be"current"smokers"(US:"7.4%,"Japan:"12.21%)"and"less"likely"to"be"former"
smokers"(US:"47.74,"Japan:"50.25)."
Country!Interactions"
In"order"to"examine"differences"across"countries"in"the"associations"of"
individual"variables"with"hypertension,"we"examine"interactions"with"individual"
variables"before"adding"only"the"significant"ones"to"the"equation."This"enables"us"to"
reduce"the"number"of"interaction"terms"and"make"the"estimation"more"tractable.""
Table"2"summarizes"the"country*predictor"variable"interactions"for"measured"and"
overall"hypertension"outcomes.""Each"interaction"term"was"included"in"a"separate"
logistic"regression,"which"simultaneously"controlled"for"health"behaviors,"chronic"
conditions,"sociodemographic"characteristics,"and"country.""The"odds"ratios"and"
95%"CI"for"measured"hypertension"revealed"stronger"relative"effects"in"Japan"for"
overweight/obese"BMI"(1.46,"CI:1.13X1.89),"former"smoking"(1.29,"CI:"1.04X1.59),"
and"diabetes"(1.56,"CI:"1.12X2.16),"whereas"a"weaker"effect"was"found"for"age"(0.97,"
CI:"0.96X0.99).""Results"for"overall"hypertension"revealed"a"stronger"relative"effect"in"
"
"
20"
Japan"for"overweight/obese"BMI"(1.55,"CI:"1.14X2.12)"and"current"smoking"(1.56,"CI:"
1.07X2.26),"whereas"a"weaker"effect"of"female"gender"was"found"in"Japan"(0.75,"CI:"
0.59X0.95)."
Estimation!of!Measured!and!Overall!Hypertension!"
Tables"3aXb"show"four"logistic"regression"models"for"measured"hypertension"
(a)"and"overall"hypertension"(b).""Model"I"controls"for"age,"gender,"and"country,"
Model"II"controls"for"health"behavior,"chronic"conditions,"sociodemographic"
characteristics,"and"country"and"does"not"include"any"interaction"terms.""Model"III"
adds"the"significant"interactions"from"Table"2.""The"final"model,"Model"IV"includes"
only"those"interactions"that"remain"significant"in"Model"III."
Measured"Hypertension."Model"I"demonstrates"that"as"expected,"the"Japanese"
have"higher"risk"of"hypertension,"in"fact,"the"relative"likelihood"is"about"4"fold"
greater."""Across"the"remaining"models,"the"effect"of"being"Japanese"remains"
relatively"consistent,"(with"the"exception"of"the"third"model"which"obviously"has"too"
many"interaction"terms"in"the"model).""The"final"model"indicates"that"the"relative"
risk"of"measured"hypertension,"when"all"of"the"risk"factors"are"controlled,"remains"
about"four"times"higher"in"Japan"than"in"the"US"(3.93,"CI:"3.32X4.64)."""This"means"
that"the"differential"presence"of"health"conditions"and"health"behaviors"are"not"a"
cause"of"the"difference"in"the"presence"of"hypertension"in"Japan"and"the"US"older"
persons.""In"fact,"none"of"the"diseases"are"related"to"a"greater"likelihood"of"having"
hypertension"in"the"US.""
When"the"significant"country"interactions"from"Table"2"(overweight/obese"
BMI,"former"smoking,"diabetes,"and"age)"are"included"in"Model"III"of"Table"3a,"the"
"
"
21"
interactions"with"former"smoking"and"age"are"no"longer"significant;"country"
interactions"with"overweight/obese"BMI"and"diabetes"remain"significant"and"
indicate"the"odds"of"measured"hypertension"for"overweight/obese"are"2.50"times"
higher"in"Japan"(main"effect"+"interaction=1.14+1.36).;"there"was"no"significant"
effect"in"the"US.""In"Japan,"those"who"have"diabetes"are"2.46"times"more"likely"to"
have"hypertension;"there"was"no"effect"in"the"US.""The"odds"ratio"for"the"country"
variable"indicates"that"adding"four"interactions"to"Model"III"stretches"the"data.""For"
these"reasons,"the"only"country"interactions"included"in"Model"IV"are"
overweight/obese"BMI"(1.43,"CI:"1.10X1.85)"and"diabetes"(1.51,"CI:"1.09X2.10),"which"
increases"the"odds"of"measured"hypertension"by"2.54"times"and"the"odds"of"diabetes"
by"2.48"times"in"Japan;"the"effect"was"not"significant"in"the"US."
Increasing"age"is"linked"to"a"higher"risk"of"measured"hypertension,"whereas"
being"female"reduces"the"risk"in"both"countries.""Heart"disease"is"also"linked"to"lower"
levels"of"hypertension"in"both"countries,"a"somewhat"surprising"result."""
Overall"Hypertension.""Being"Japanese"is"also"related"to"a"greater"likelihood"
of"having"overall"hypertension;"however,"the"differences"between"the"US"and"Japan"
are"not"as"great"in"this"measure."The"Japanese"are"1.5"to"2"times"as"likely"to"have"
overall"hypertension."""Across"the"three"models,"being"overweight/obese,"having"
diabetes,"stroke,"or"higher"age"are"associated"with"an"increase"in"the"risk"of"overall"
hypertension.""Current"smoking,"however,"is"associated"with"a"reduced"risk.""When"
the"presence"of"diseases"and"weight"is"controlled"for,"meaning"that"if"the"Japanese"
and"Americans"had"the"same"level"of"disease,"the"difference"between"the"two"
countries"would"be"somewhat"greater.""When"the"interaction"effects"are"added,"the"
"
"
22"
size"of"the"country"difference"is"closer"to"the"original"level.""When"the"significant"
country"interactions"from"Table"2"(overweight/obese"BMI,"current"smoking,"and"
female)"are"included"in"Model"III"of"Table"3b,"the"interaction"with"female"is"no"
longer"significant;"country"interactions"with"overweight/obese"BMI"(1.56,"CI:"1.14X
2.13)"and"current"smoking"(1.53,"CI:"1.05X2.24)"remain"significant"and"indicate"the"
risk"of"overall"hypertension"increases"by"2.99"times"in"Japan"and"1.43"times"in"the"
US"for"overweight/obese"and"2.10"times"in"Japan,"while"risk"decreases"by"almost"
half"(0.57)""in"the"US"for"current"smoking.""The"final"model,"Model"IV,"does"not"
include"the"country*female"interaction.""The"results"from"Model"IV"indicate"an"effect"
of"2.99"in"Japan"and"1.41"in"the"US"for"overweight/obese"BMI"and"an"effect"of"2.18"in"
Japan"and"0.57"in"the"US"for"current"smoking."In"the"case"of"overall"hypertension,"
Americans"who"are"overweight/obese"or"are"current"smokers"are"47%"and"51%"
less"likely"to"have"overall"hypertension,"respectively."
Discussion"
The"intent"of"this"paper"was"to"examine"potential"differences"in"hypertension"
between"the"US"and"Japan"and"the"role"played"by"differences"in"levels"of"risk"factors"
and"comorbidities"and"the"effects"of"risk"factors"and"comorbidities"on"the"presence"
of"hypertension.""Logistic"regression"models"using"a"pooled"dataset"across"the"two"
countries"found"evidence"of"significant"differences"between"the"two"countries"in"the"
levels"of"hypertension"using"both"measures"of"hypertension.""The"Japanese"older"
persons"had"higher"levels"of"hypertension.""The"fact"that"the"relative"difference"in"
measured"hypertension"was"twice"as"great"as"that"in"overall"hypertension"indicates"
the"effect"of"control"of"hypertension"in"the"US"in"reducing"the"differential"between"
"
"
23"
the"US"and"Japan.""There"was"a"marked"difference"in"the"presence"of"risk"factors"and"
comorbidities"across"the"two"countries.""People"in"the"US"have"substantially"more"
diseases"and"adverse"health"conditions;"however,"these"conditions"played"little"role"
in"determining"the"differences"in"the"two"countries"in"hypertension.""
Overweight/obese"BMI"and"diabetes"had"an"effect"in"Japan"but"not"in"the"US.""It"is"
possible"that"these"conditions,"which"are"relatively"rare"in"Japan,"are"not"as"wellX
handled"medically"in"Japan.""We"have"evidence"that"hypertension"does"not"appear"to"
be"as"well"managed"in"japan"and"other"conditions"may"be"similar."
It"is"important"to"note"that"these"data"reflect"only"those"who"selfXreported"
diabetes,"therefore"there"could"be"a"discrepancy"in"disease"awareness"that"could"
explain"this"observation"relative"to"diabetes.""While"severe"diabetes"is"more"
recognizable,"impaired"glucose"tolerance"is"less"obvious,"particularly"if"the"healthier"
Japanese"diet"masks"some"of"the"more"obvious"symptoms"of"impaired"glucose"
tolerance,"compared"to"an"American"diet."
The"significant"interaction"between"current"smoking"and"country"in"overall"
hypertension"suggests"that"smoking"might"play"a"different"role"in"hypertension"risk"
between"Japan"and"the"US,"particularly"for"men.""It"should"be"noted"that"the"
prevalence"of"current"smoking"among"Japanese"men"is"more"than"twice"that"of"
American"men,"and"the"interaction"between"current"smoking"and"country"reflects"
the"different"adoption"of"smoking"habits"and"their"relation"to"hypertension.""
Smoking"interacts"with"hypertension"in"complex"ways;"the"effects"are"not"always"
consistent.""In"Western"countries,"smoking"is"generally"associated"with"increased"
rates"of"hypertension"(Sleight,"1993)."Our"finding"using"the"HRS"data"suggests"this"
"
"
24"
relationship"may"no"longer"be"true,"and"in"fact"we"find"38%"lower"hypertension"
among"current"smokers,"though,"since"the"effects"of"smoking"are"cumulative,"this"
may"also"be"related"to"the"number"of"years"spent"smoking,"which"could"not"be"
determined"in"the"NUJLSOA.""Access"to"antihypertensive"medications"has"changed"
dramatically"since"the"1990s,"and"thus"the"link"to"previously"known"risk"factors"may"
no"longer"be"as"apparent."""
The"literature"on"smoking"and"hypertension"in"Japan"is"inconsistent.""One"
study"focusing"on"workingXage"men"in"Japan"found"smoking"was"associated"with"
higher"risk"of"hypertension"(Dochi"et"al.,"2009),"while"another"study"(Ohkubo"et"al.,"
2002)"that"looked"at"older"people"of"both"genders"found"smokers"had"lower"levels"
of"blood"pressure.""The"findings"from"this"study"are"mixed"and"show"no"main"effect"
of"smoking"but"indicate"a"weaker"effect"of"smoking"on"hypertension"in"the"US"and"a"
stronger"effect"in"Japan."""
The"Japanese"are"1.5"times"more"likely"to"have"overall"hypertension"than"
Americans.""Some"of"the"difference"in"overall"hypertension"level"can"be"accounted"
for"by"the"stronger"effect"of"overweight/obese"and"diabetes"in"Japan,"as"well"as"
smoking,"which"is"more"common"in"Japan."""""
This"paper"confirmed"the"levels"of"hypertension"and"its"risk"factors"and"
associated"conditions"in"two"comparable"and"nationally"representative"surveys.""
Additionally,"this"paper"identified"some"key"differences"in"the"way"hypertension"is"
associated"with"risk"factors"in"the"US"and"Japan.""There"are"differences"linked"to"
diabetes"(in"measured"hypertension),"overweight/obese"BMI,"and"current"smokers"
(in"overall"hypertension).""Diabetes"and"overweight/obese"BMI"have"weaker"
"
"
25"
associations"with"hypertension"in"the"US;"explanations"for"this"difference"were"
suggested"and"included"differences"in"diet"(Hu"et"al.,"2001),"body"size"(Reynolds"et"
al.,"2008),"and"education"(Yong"&"Saito,"2012).""Additional"explanations"for"the"
observed"country"differences"might"include"physical"activity"(Hu"et"al.,"2001),"access"
to"care"(Chin"et"al.,"2001),"support"networks"(Zhang"et"al.,"2007),"and"use"of"
alternative"versus"Western"medicine"(Chang,"Wallis,"&"Tiralongo,"2007)."""
Now"that"country"differences"have"been"established"for"the"effect"of"health"
behaviors"(overweight/obese"BMI"and"smoking)"and"diabetes"as"they"relate"to"
hypertension,"future"studies"could"use"multiple"waves"of"data.""A"longitudinal"
analysis"will"allow"for"comparisons"between"Japan"and"the"US"in"how"the"predictor"
variables"are"associated"with"changes"in"hypertension.""Longitudinal"analysis"would"
also"enable"us"to"determine"how"the"effect"of"the"predictor"variables"influences"
change"in"hypertension.""Lastly,"it"is"important"to"note"that"this"study"was"limited"to"
people"68"years"of"age"or"older,"those"with"higher"blood"pressure"and"worse"health"
outcomes"could"have"experienced"higher"mortality"before"this"age,"thus"creating"a"
survivor"effect."
" "
"
"
26"
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"
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28"
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Japan.!Hypertens!Res"2006;"29:143X151.""
Nihon"University"Japanese"Longitudinal"Study"of"Aging"2004;"Home"page."Retrieved"
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http://www.nihonXu.ac.jp/affiliate/institute/information_networking/"
(Japanese).""
Ohkubo"T,"Obara"T,"Funahashi"J,"Kikuya"M,"Asayama"K,"Metoki"H,"Oikawa"T,"
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Pincus"T,"Callahan"LF,"Burkhauser"RV."Most"chronic"diseases"are"reported"more"
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18–64"United"States"population."Journal!of!Chronic!Diseases"1987;"40(9):865X
874."
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29"
countries—the"United"States"and"Japan:"Are"differences"in"health"due"to"
differences"in"overweight?."Journal!of!epidemiology"2008;"18(6):"280X290."
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Tanaka"T,"Okamura"T,"Yamagata"Z,"Takebashi"T,"Tamura"U,"Kusaka"Y,"Urano"S,"
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World"Health"Organization"(WHO)."Prevalence"of"tobacco"use"among"adults"and"
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transitions"and"active"life"expectancy"among"Japanese"older"adults?"Findings"
from"a"10Xyearprospective"cohort"study."Journals!of!Gerontology,!Series!B:!
"
"
30"
Psychological!Sciences!and!Social!Sciences"2012;"67:343X353."
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persons"with"diabetes."The!Diabetes!Educator"2007;"33(2):"273X281." "
"
"
31"
Table"1."Descriptive"statistics"for"NUJLSOA"and"HRS"samples."
!! Japan!(n=2031)! US!(n=3447)!
!!
Mean/!
percent! SD!
Mean/!
percent! SD!
Systolic!blood!pressure!(mmHg)***!
155.05! 28.49! 135.22! 21.96!
Diastolic!blood!pressure!(mmHg)***!
82.14! 15.50! 78.03! 12.20!
Measured!hypertension!(%)***!
73.61! KKK! 39.98! KKK!
Overall!hypertension!(%)***!
81.14! KKK! 74.07! KKK!
Antihypertensive!medication!usage!(%)***!
34.17! KKK! 59.73! KKK!
Overweight/obese!BMI!(%)***!
20.61! KKK! 70.35! KKK!
Never!smoked!(%)***!
37.54! KKK! 44.86! KKK!
Former!smoker!(%)!
50.25! KKK! 47.74! KKK!
Current!smoker!(%)***!
12.21! KKK! 7.40! KKK!
Diabetes!(%)***!
10.70! KKK! 20.00! KKK!
Stroke!(%)***!
5.11! KKK! 10.19! KKK!
Heart!disease!(%)***!
7.70! KKK! 32.26! KKK!
Female!(%)***!
53.67! KKK! 58.93! KKK!
Age!(years)***!
75.79! 7.55! 76.74! 6.43!
Education!(years)***!
10.05! 3.35! 12.41! 3.15!
***p<.001"
"
" "
"
"
32"
Table"2."Summary"table"of"interaction"effects"of"country*predictor"interactions.""
Each"interaction"was"included"separately"in"a"regression"that"controlled"for"health"
behavior,"chronic"conditions,"sociodemographic"characteristics,"and"one"country"
interaction
#
,"(Japan=1)."
Measured Hypertension Overall Hypertension
OR 95% CI OR 95% CI
Country*Overweight/obese
BMI
1.46 1.13 1.89 1.55 1.14 2.12
Country*Former smoker 1.29 1.04 1.59 0.99 0.78 1.25
Country*Current smoker 1.06 0.74 1.51 1.56 1.07 2.26
Country*Diabetes 1.56 1.12 2.16 0.75 0.51 1.10
Country*Stroke 1.06 0.68 1.64 0.66 0.39 1.12
Country*Heart disease 0.92 0.67 1.27 0.82 0.57 1.19
Country*Age 0.97 0.96 0.99 1.00 0.98 1.02
Country*Female 0.88 0.71 1.09 0.75 0.59 0.95
Country*Education 1.01 0.97 1.05 1.03 0.99 1.08
Country*Antihypertensive
medication
1.05 0.84 1.31 --- --- ---

n 5478 5478
#
Each"regression"controlled"for"BMI,"former"smoking,"current"smoking,"diabetes,"
stroke,"heart"disease,"age,"gender,"education,"country,"and"one"country*risk"factor"
interaction.""Antihypertensive"medication"usage"was"additionally"controlled"for"
when"measured"hypertension"was"regressed"on"the"predictor"variables."
"
!
!
33!
Tables!3a)b.!Odds!ratios!and!95%!confidence!intervals!from!logistic!regressions!of!measured!hypertension!(a)!and!overall!
hypertension!(b)!regressed!on!age,!gender,!and!country!(Model!I);!health!behavior,!chronic!conditions,!sociodemographic!
characteristics,!antihypertensive!medication!(for!measured!hypertension),!country!(Model!II);!and!country!interactions!
(Models!III!and!IV)!(n=5478).!
Table!3a.!Measured!Hypertension!
Measured Hypertension (n=5478)
Model I Model II Model III Model IV
OR 95% CI
OR 95% CI OR 95% CI OR 95% CI
Overweight/obese BMI
1
--- --- --- 1.25 1.10 1.41 1.14 0.98 1.32 1.11 0.95 1.29
Former smoker
2
--- --- --- 1.05 0.93 1.18 0.95 0.83 1.10 1.04 0.93 1.17
Current smoker
2
--- --- --- 1.03 0.85 1.25 1.02 0.84 1.24 1.02 0.84 1.24
Diabetes --- --- --- 1.07 0.93 1.24 0.97 0.82 1.15 0.97 0.82 1.15
Stroke --- --- --- 1.16 0.95 1.40 1.15 0.94 1.39 1.16 0.96 1.40
Heart disease --- --- --- 0.75 0.65 0.85 0.74 0.65 0.85 0.75 0.65 0.85
Age (years) 1.02 1.01 1.03 1.02 1.01 1.03 1.03 1.02 1.04 1.02 1.01 1.03
Female 0.84 0.76 0.93 0.82 0.74 0.92 0.81 0.72 0.91 0.82 0.73 0.91
Education (years) --- --- --- 0.97 0.96 0.99 0.97 0.95 0.99 0.97 0.96 0.99
Antihypertensive medication --- --- --- 1.32 1.19 1.48 1.34 1.20 1.49 1.33 1.19 1.48
Country (Japan=1) 4.27 3.85 4.73 4.69 4.09 5.37 17.33 4.22 71.23 3.93 3.32 4.64
Country*Overweight/ obese --- --- --- --- --- --- 1.36 1.05 1.77 1.43 1.10 1.85
Country*Former smoker --- --- --- --- --- --- 1.19 0.95 1.47 --- --- ---
Country*Diabetes --- --- --- --- --- --- 1.49 1.08 2.08 1.51 1.09 2.10
Country*Age --- --- --- --- --- --- 0.98 0.96 1.00 --- --- ---
Chi-square 844.37 945.22 956.47 947.45
df 3 11 15 13
BIC -850.2 -965.5 -983.9 -971.4

pseudo-R2 0.14 0.16 0.16 0.16
!
!
34!
1
BMI!2
!was!used!as!the!referent!category.!
2
Never!smoked!was!used!as!the!referent!category.!
Significant!associations!indicated!in!bold!font.!
! !
!
!
35!
Table!3b.!Overall!Hypertension!
Overall Hypertension (n=5478)
Model I Model II Model III Model IV
OR 95% CI
OR 95% CI OR 95% CI OR 95% CI
Overweight/obese BMI --- --- --- 1.62 1.41 1.85 1.43 1.21 1.68 1.41 1.20 1.66
Former smoker --- --- --- 0.95 0.84 1.09 0.95 0.83 1.08 0.96 0.84 1.09
Current smoker --- --- --- 0.73 0.59 0.89 0.57 0.43 0.74 0.57 0.43 0.75
Diabetes --- --- --- 1.67 1.40 2.00 1.69 1.41 2.02 1.70 1.42 2.03
Stroke --- --- --- 1.63 1.27 2.08 1.62 1.27 2.07 1.63 1.27 2.08
Heart disease --- --- --- 1.04 0.89 1.21 1.04 0.89 1.21 1.03 0.89 1.20
Age (years) 1.02 1.01 1.03 1.02 1.01 1.03 1.02 1.01 1.03 1.02 1.01 1.03
Female 0.98 0.87 1.10 1.00 0.89 1.13 1.11 0.95 1.30 1.01 0.89 1.14
Education (years) --- --- --- 0.98 0.96 1.00 0.98 0.96 1.00 0.98 0.96 1.00
Country (Japan=1) 1.54 1.37 1.73 2.04 1.75 2.37 1.94 1.53 2.47 1.67 1.39 2.01
Country*Overweight/
obese
--- --- --- --- --- --- 1.56 1.14 2.13 1.58 1.16 2.16
Country*Current smoker --- --- --- --- --- --- 1.53 1.05 2.24 1.61 1.10 2.34
Country*Female --- --- --- --- --- --- 0.79 0.62 1.00 --- --- ---

Chi-square 70.21 251.85 224.05 220.28
df 3 11 13 12
BIC -83.3 -286.0 -265.9 -259.1

pseudo-R2 0.01 0.04 0.04 0.04
1
BMI!2
!was!used!as!the!referent!category.!
2
Never!smoked!was!used!as!the!referent!category.!
Significant!associations!indicated!in!bold!font.!
!
!
36!
Appendix!
Figure!A1.!Reasons!for!loss!of!sample!for!NUJLSOA!
!
! !
68+years!
and!in!2006!data!
3395!
Measured!BP!
2357!
Measured!BP!and!
medication!
2305!
Smoking,!heart!
disease,!diabetes,!
stroke,!BMI!
2031!
!
!
37!
Figure!A2.!Reasons!for!los s!of!sample!for!HRS !
!
! !
68+years!and!in!
2006!data!
9262!
Eligible!for!faceRtoR
face!
4734!
!!
Measured!BP!
3543!
Measured!BP!and!
medication!
3516!
Smoking,!heart!
disease,!diabetes,!
stroke,!BMI!
3447!
!
!
38!
Tables!A1aRb.!Characteristics!of!participants!who!are!missing/not!missing!on!
measured!hypertension!(a)!and!who!are!included/excluded!in!the!analytic!sample!
(b).!
Table!A1a.!Missing/not!missing!on!measured!hypertension!
!! Japan! United!States!
!!
Not!missing!!
(n=2357)!
Missing!
(n=1038)! !!
Not!missing!!
(n=3543)!
Missing!
(n=5719)! !!
!!
Mean/!
%! SD!
Mean/!
%! SD! !!
Mean/!
%! SD!
Mean/!
%! SD! !!
BMI!(kg/m
2
)!
22.60! 4.05! 22.17! 4.38! **! 28.26! 5.68! 26.77! 5.27! ***!
Never!smoked!
(%)!
39.1! III! 44.18! III! **! 44.9! III! 42.5! III! *!
Former!smoker!
(%)!
48.9! III! 44.85! III! *! 47.7! III! 49.0! III! !!
Current!smoker!
(%)!
12.0! III! 11.0! III! !! 7.4! III! 8.7! III! *!
Diabetes!(%)!
10.8! III! 11.00! III! !! 20.0! III! 19.9! III! !!
Stroke!(%)!
5.4! III! 13.23! III! ***! 10.2! III! 13.1! III! ***!
Heart!disease!
(%)!
8.0! III! 7.1! III! !! 32.2! III! 34.2! III! !!
Age!(years)!
76.13! 7.80! 79.31! 9.33! ***! 76.75! 6.43! 77.09! 6.61! *!
Female!(%)!
54.70! III! 55.10! III! !! 58.9! III! 57.7! III! !!
Education!
(years)!
9.92! 3.37! 9.33! 3.57! ***! 12.40! 3.15! 12.04! 3.24! ***!
Antihypertensive!
medication!(%)!
36.0! III! 31.7! III! *! 59.7! III! 93.2! III! ***!
!
!
! !
!
!
39!
Table!A1b.!Included/excluded!in!analystic!sample!
!! Japan! United!States!
!!
Not!missing!!
(n=2031)!
Missing!
(n=1364)! !!
Not!missing!!
(n=3447)!
Missing!
(n=1287)! !!
!!
Mean/!
%! SD!
Mean/!
%! SD! !!
Mean/!
%! SD!
Mean/!
%! SD! !!
Overweight/!
obese!BMI!(%)!
20.61! III! 17.9! III! !! 70.35! III! 60.2! III! ***!
Never!smoked!
(%)!
37.5! III! 46.1! III! ***! 44.9! III! 39.7! III! **!
Former!smoker!
(%)!
50.3! III! 43.2! III! ***! 47.7! III! 51.7! III! *!
Current!smoker!
(%)!
12.2! III! 10.7! III! !! 7.4! III! 8.6! III! !!
Diabetes!(%)!
10.7! III! 11.5! III! !! 20.0! III! 20.6! III! !!
Stroke!(%)!
5.1! III! 12.9! III! ***! 10.2! III! 16.1! III! ***!
Heart!disease!(%)!
7.7! III! 7.9! III! !! 32.3! III! 33.5! III! !!
Age!(years)!
75.79! 7.55! 79.34! 9.23! ***! 76.74! 6.43! 77.88! 6.68! ***!
Female!(%)!
53.67! III! 57.0! III! !! 58.9! III! 57.4! III! !!
Education!(years)!
10.05! 3.35! 9.21! 3.50! ***! 12.41! 3.15! 11.63! 3.32! ***!
Antihypertensive!
medication!(%)!
34.2! III! 36.0! III! !! 59.7! III! 90.9! III! ***!
!
!
! !
!
!
40!
Chapter!3:!Cognitive!Performance !
Introduction!
! !Older!age!is!strongly!related!to!the!onset!of!problems!in!cognitive!
functioning.!!With!increased!life!expectancy!and!the!aging!of!the!Baby!Boomers,!the!
effects!of!ageCassociated!declines!in!cognitive!functioning!will!become!a!serious!
problem!for!increasing!numbers!of!people!in!the!US!and!globally.!!While!people!
across!the!world!all!experience!some!form!of!decline!with!age!in!performance!on!
cognitive!tests,!it!is!unclear!how!countries!differ!in!cognitive!performance.!!!!
This!study!establishes!differences!in!cognitive!performance!of!older!Japanese!
and!older!Americans.!!It!also!determines!whether!differences!can!be!explained!by!
differences!in!the!distribution!of!risk!factors!for!low!cognitive!functioning!or!in!the!
associations!of!risk!factors!with!cognitive!performance.!!On!the!one!hand,!we!would!
expect!that!Japanese!elderly!would!have!better!cognitive!functioning!because!they!
have!a!lower!prevalence!of!diabetes,!obesity,!heart!disease,!and!frailty,!which!are!
associated!with!worse!cognitive!performance!(Dik!et!al.,!2007;!Crimmins!et!al.,!
2010;!Zelinski!et!al.!1998).!!On!the!other!hand,!education!is!a!major!factor!related!to!
cognitive!performance!in!the!elderly!in!the!US!and!other!Western!countries!(Alley,!
Suthers,!&!Crimmins,!2007;!Inouye!et!al.,!1993;!Lynch,!Gold,!&!Shema,!1997;!
Skirbekk,!Loichinger,!&!Weber,!2012),!and!elderly!Japanese!have!lower!levels!of!
education,!compared!to!Americans!(Skirbekk!et!al.,!2012).!!It!is!hypothesized!that!
despite!higher!levels!of!education,!American!elderly!will!have!lower!cognitive!
performance!scores!than!the!Japanese!because!Americans!experience!more!health!
problems!and!because!education!is!typically!not!associated!with!health!in!Japan.!
!
!
41!
Background!
Risk%Factors%for%Cognitive%Impairment!
Chronic!conditions!are!among!some!of!the!risk!factors!for!impaired!cognitive!
performance!in!old!age.!!Risk!factors!include!cardiovascular!disease,!diabetes,!
stroke,!and!metabolic!syndrome,!etc.!(Dik!et!al.,!2007;!Zelinski!et!al.!1998).!!
Americans!are!more!likely!than!the!Japanese!to!have!higher!prevalence!of!all!of!the!
chronic!conditions!mentioned!above,!with!the!exception!of!stroke!(Crimmins!et!al.,!
2008;!Crimmins!et!al.,!2010).!
In!addition!to!chronic!health!conditions!at!older!ages,!education!and!earlyR
life!environment!are!also!risk!factors!related!to!impaired!cognitive!performance!in!
old!age.!!Researchers!have !found!that!earlyRlife!nutritional!deprivation!and!lower!
socioeconomic!environment!throughout!life,!particularly!in!earlyRlife,!increase!risk!
of!cognitive!impairment!in!Chinese!elderly!(Zhang,!Gu,!&!Haywayrd,!2008;!Zhang,!
Gu,!&!Haywayrd,!2010).!!Additionally,!in!a!multi!country!comparison,!Skirbekk!et!al.!
(2012)!found!that!the!elderly!in!countries!with!earlier!improvements!to!earlyRlife!
environment!and!higher!levels!of!education!consistently!performed!better!on!
cognitive!tasks!than!those!with!later!improvements!in!earlyRlife!environment!and!
lower!levels!of!education.!
Differences%in%Effects%of%Risk%Factors!
Although!the!associations!between!lower!socioeconomic!environment!in!
earlyRlife!and!cognitive!impairment!in!old!age!seem!to!exist!across!countries,!
associations!between!chronic!conditions!and!cognitive!impairment!in!the!elderly!are!
not!as!consistent.!!For!example,!the!presence!of!diabetes!and!heart!disease!has!been!
!
!
42!
associated!with!reduced!cognitive!functioning!in!the!US!and!other!Western!
countries!(Dik!et!al.,!2007;!Elias!et!al.,!2004;!Fontbonne!et!al.,!2001;!McKhann!et!al.,!
1997;!Selnes!&!McKhann,!2001)!and!in!Japan!(Mogi!et!al.,!2004).!!However,!
metabolic!syndrome,!which!includes!hypertension,!lipid!and!glucose!dysregulation,!
and!obesity,!has!been!associated!with!lower!cognitive!scores!in!the!US!(Dik!et!al.,!
2007;!Yaffe!2007)!but!associations!are!not!always!found!among!the!oldest!old!in!
other!Western!countries!(Van!den!Berg!et!al.,!2007)!and!Japan!(Katsumata!et!al.,!
2012).!!Similarly,!hypertension!has!been!associated!with!impaired!cognitive!
performance!in!Western!countries!(Harrington!et!al.,!2000;!Zelinski!et!al.!1998)!but!
associations!in!Japan!and!other!Asian!countries!have!not!been!found!(Huang!et!al.,!
2009).!
! Physical!frailty!has!also!been!associated!with!cognitive!impairments!in!older!
persons;!associations!have!been!found!in!both!the!US!and!Japan!(Blaum,!Ofstedal,!&!
Liang,!2002;!Buchman!et!al.,!2007;!Dodge!et!al.,!2005;!Dodge!et!al.,!2008).!!
Americans!experience!higher!levels!of!physical!frailty!compared!to!the!Japanese!
(Crimmins!et!al.,!2010).!!In!the!biological!literature,!it!is!hypothesized!that!increases!
in!frailty!and!declines!in!cognitive!performance!share!similar!etiologies!(Bergman!et!
al.,!2007;!Buchman!et!al.,!2007).!!!
! While!Americans!clearly!have!worse!health!by!many!indicators,!older!
Americans!have!higher!education!levels!than!the!Japanese,!and!they!have!had!
relatively!more!affluent!lives!(Skirbekk!et!al.,!2012).!!Studies!of!the!association!
between!cognitive!performance!and!educational!attainment!among!the!elderly!in!
Japan!are!lacking;!though!research!has!shown!little!effect!of!education!on!other!
!
!
43!
Japan!are!lacking;!though!research!has!shown!little!effect!of!education!on!other!
aspects!of!health!in!Japan!(Yong!&!Saito,!2012).!!!
Methods!
Data$Sources$
! Studies!of!cognitive!performance!in!Japan!have!generally!been!conducted!in!
localized!populations!using!variable!diagnostic!criteria!and!therefore,!cannot!be!
generalized!to!the!national!population!(Ogura!et!al.,!1995;!Ueda!et!al.,!1992).!!Using!
the!Nihon!University!Japanese!Longitudinal!Study!of!Aging!(NUJLSOA)!and!the!US!
Health!and!Retirement!Study!(HRS)!for!crossQnational!cognitive!comparisons!
provides!us!three!advantages.!!First,!they!are!comparable!by!design.!!Second,!they!
are!both!nationally!representative.!!Third,!each!data!set!contains!comparable!
assessments!of!cognitive!function!and!information!on!health!behaviors,!chronic!
health!conditions,!physical!functioning,!and!sociodemographic!characteristics.!!
These!datasets!provide!us!with!the!opportunity!to!study!differences!in!cognitive!
performance!at!older!ages!at!the!national!level!and!determine!whether!the!
association!of!risk!factors!for!low!cognitive!performance!is!similar!in!the!two!
countries.!
NUJLSOA.!This!study!uses!data!collected!in!2006!during!the!fourth!wave!of!
the!Nihon!University!Japanese!Longitudinal!Study!of!Aging!(NUJLSOA),!a!nationally!
representative!sample!of!the!Japanese!population!aged!65!and!older.!!Data!were!
collected!in!47!provinces.!!
The!first!wave!of!data!was!collected!in!1999!and!subsequent!waves!were!
conducted!in!2001,!2003,!and!2006.!!Younger!participants!were!added!at!the!second!
!
!
44!
and!third!waves!so!as!to!remain!nationally!representative!of!the!65!and!older!
population.!!New!participants!were!not!added!at!the!fourth!wave!in!2006,!so!the!
youngest!participants!are!68!years!of!age!at!that!interview.!!Complete!information!
on!the!design!and!methods!of!the!study!can!be!found!on!the!website!of!the!Nihon!
University!Center!for!Information!Networking
!
(NUJLSOA,!2004).!!
The!fourth!wave!of!the!survey!includes!3,395!participants.!!The!final!analytic!
sample!used!here!is!58.7%!(n=1,993)!of!the!total!sample.!!Details!on!reasons!for!
exclusion!can!be!found!in!Figure!A1!of!Appendix!A.!!Persons!who!were!excluded!
from!the!analytic!sample!had!a!higher!prevalence!of!underweight!BMI!(p<.001),!
more!than!twice!the!prevalence!of!stroke!(p<.001),!1.22!more!functioning!
difficulties!(p<.001),!were!3.56!years!older!(p<.001),!and!had!0.86!years!less!
education!(p<.001)!than!the!analytic!sample!(Table!A2,!Appendix!A).!!Weights!
adjusting!for!participation!in!the!cognitive!section!and!attrition!from!earlier!waves!
were!used!in!all!analyses!to!maintain!the!national!representation!of!the!sample.!!The!
sample!used!in!our!analysis!was!53.6%!female.!The!average!age!of!the!participants!
was!75.8!years!old.!Descriptive!statistics!on!other!variables!used!in!the!analysis!can!
be!found!in!Table!1.!!!
!!HRS.!The!Health!and!Retirement!Study!(HRS)!surveys!more!than!22,000!
Americans!over!the!age!of!50!every!two!years.!!Data!for!the!eighth!wave!of!HRS!used!
in!this!study!were!collected!in!2006!and!were!chosen!to!correspond!to!the!timing!of!
the!fourth!wave!of!NUJSLOA.!!In!2006,!9,262!participants!were!68!yearsQorQolder!
and!were!chosen!to!match!the!age!of!the!Japanese!sample;!51.1%!(n=4,734)!of!
!
!
45!
participants!68!yearsQorQolder!were!eligible!to!participate!in!the!faceQtoQface!
interview.!!!
The!final!analytic!sample!included!about!68.9%!(n=3,263)!of!the!eligible!
sample!(n=4,734);!details!on!sample!size!can!be!found!in!Figure!A2!of!Appendix!A.!!
Those!excluded!from!the!analytic!sample!(Table!A2!Appendix!A)!had!a!higher!
prevalence!of!underweight!(p<.001)!and!normal!BMI!(p<.001);!a!lower!prevalence!
of!overweight/obese!BMI!(p>.001);!higher!prevalence!of!diabetes!(p<.001),!stroke!
(p<.001),!and!heart!disease!(p<.01);!more!functioning!difficulties!(p<.001);!2.09!
years!older!(p<.001);!1.24!years!less!education!(p<.001);!and!a!higher!percentage!of!
females!(p<.001).!!!
The!analytic!sample!included!57.6%!females.!!The!average!age!of!the!analytic!
sample!was!76.6!years!old.!!Descriptive!statistics!on!other!variables!used!in!the!
analysis!can!be!found!in!Table!1.!Sample!weights!provided!by!the!survey!to!adjust!
for!nonresponse!and!sampling!were!used!in!all!analyses.!!!
Measurements!
Cognitive!Performance!
! Cognitive!functioning!is!assessed!using!harmonized!scales!indicating!
performance!in!memory!and!working!memory!for!the!two!countries.!In!both!the!
HRS!and!the!NUJLSOA,!cognitive!performance!was!measured!using!a!ten!item!
immediate!word!recall!and!a!ten!item!delayed!word!recall,!which!measure!shortQ!
and!longerQterm!memory,!and!a!five!item!serial!7s!trial!working!memory!task!
(Ofstedal,!Fisher,!Herzog,!2005).!!The!number!correct!for!each!of!the!tests!was!
added!to!create!three!separate!cognitive!scores.!!A!correct!trial!in!word!recall!was!
!
!
46!
defined!as!any!word!correctly!recalled.!!For!the!serial!7’s,!a!correct!trial!was!defined!
as!any!trial!were!the!difference!between!the!previous!and!current!trial!was!equal!to!
7.!!Summing!the!three!separate!cognitive!scores!created!a!composite!score.!!!The!
total!cognitive!score!ranged!from!0B 25.!
Imputations!were!performed!for!selfB respondents!who!were!missing!a!
portion!of!the!cognitive!items!in!both!Japan!and!the!US!(see!Appendix!B!for!details).!!
The!imputations!for!Japan!were!designed!to!be!similar!to!the!method!used!by!the!
Health!and!Retirement!Study!(HRS)!(Fisher!et!al.!2012).!!In!the!HRS!sample,!212!
cases!were!imputed!for!at!least!parts!of!the!immediate!word!recall!task,!371!for!the!
delayed!word!recall!task,!and!431!for!the!serial!7’s!task!in!2006!(Fisher!et!al.,!2012).!!
In!Japan,!197!cases!were!imputed!for!the!immediate!word!recall!task,!265!for!the!
delayed!word!recall!task,!and!505!for!the!serial!7’s!task.!!Descriptive!statistics!on!the!
imputed!cognitive!performance!measures!in!NUJLSOA!can!be!found!in!Tables!B1B B3!
of!Appendix!B.!!
Chronic!Diseases!and!Health!Behavior!
BMI,!calculated!by!dividing!weight!(kg)!by!the!square!of!height!(m)!
(BMI=kg/m
2
),!was!separated!into!three!dichotomous!categories:!underweight!
(<18.5!kg/m
2!
),!normal!(18.5!kg/m
2
B 25!kg/m
2
),!and!overweight/obese!(≥!25!
kg/m
2
).!!Normal!BMI!was!used!as!the!referent!category.!
Diabetes,!stroke,!and!heart!disease!were!selfB reported!by!respondents!in!
response!to!a!question!about!ever!having!had!a!diagnosis.!!Hypertension!was!based!
on!measured!systolic!(SBP)!and!diastolic!(DBP)!blood!pressure.!!SBP!and!DBP!were!
!
!
47!
calculated!by!averaging!three!measurements!for!each!participant.!Hypertension!was!
defined!as!a!SBP≥140!and/or!a!DBP!≥90!mmHg!(WHO,!2003).!!!
Frailty!
! Two!measures!of!frailty!were!used!in!the!analyses:!1)!total!number!of!ADL!
and!IADL!functioning!difficulties!and!2)!grip!strength.!!The!number!of!ADL!!!
difficulties!(bathing,!dressing,!eating,!walking,!and!going!to!the!bathroom!alone)!and!
IADL!difficulties!(preparing!meals,!shopping,!managing!money,!using!the!phone,!and!
taking!medication)!was!used!to!create!the!total!functioning!difficulties!measure,!
which!was!coded!as!a!continuous!variable.!!Grip!strength!(kg)!was!created!by!taking!
the!highest!grip!strength!measurement!(kg)!between!the!two!hands,!then!norming!
the!measure!on!the!mean!by!country,!and!dividing!by!weight!(kg).!!The!grip!strength!
measurements!were!normed!to!account!for!procedural!differences!in!grip!strength!
measurement!between!the!two!surveys.!!
Sociodemographic!
! Age!and!years!of!education!were!used!as!continuous!measures.!!In!order!to!test!
whether!the!countries!differed!in!the!effect!of!an!independent!variable,!a!country!
variable,!where!Japan=1!and!US=0,!was!created.!
Statistical$Methods$
! All!analyses!were!conducted!on!Statistical!Analysis!System!(SAS)!9.2!(SAS!
Institute,!Inc,!Cary,!NC).!!All!analyses!were!performed!by!gender!to!account!for!
differences!between!genders!in!cognitive!performance!(Oksuzyan!et!al.,!2010;!
Rabbitt!et!al.,!1995);!for!example!in!the!US!women!perform!better!on!word!recall!
tests!and!men!perform!better!on!mathematical!tests!(Hyde!et!al.,!1990).!!Cognitive!
!
!
48!
performance!analyzes!were!performed!using!OLS9regressions!on!pooled!data!across!
the!two!countries!and!include!a!variable!indicating!the!country!and!country!
predictor!interactions!in!order!to!see!if!there!are!differences!in!the!effects!in!the!two!
countries!(Tables!2!and!3a9b).!!The!series!of!regressions!begins!with!a!model!that!
includes!only!age!and!country.!This!indicates!the!effect!of!country!when!age!is!
essentially!the!same.!!The!addition!of!variables!in!subsequent!models!indicates!the!
effect!of!the!new!variables!and!whether!the!effect!of!country!changes!with!controls!
for!those!variables.!!The!final!n!using!the!pooled!data!is!5,256.!!Significant!country!
differences!for!descriptive!statistics!are!indicated!by!p9values!obtained!from!two9
sided!t9tests!and!chi9square!tests!(Table!1).!
Results!
Descriptive*Statistics!
First!we!determine!whether!country!differences!exist!in!cognitive!
performance;!Table!1!shows!average!total!cognitive!score,!immediate!and!delayed!
word!recall,!and!serial!7s!scores!for!men!and!women!in!Japan!and!the!US.!!
Differences!in!measures!of!cognitive!performance!and!predictors!were!tested!using!
a!two9tailed!t9test!or!chi9square.!!Total,!immediate!and!delayed!word!recall!scores!
were!significantly!higher!in!the!US!than!in!Japan!by!0.4!(p<.05),!0.4!(p<.001)!,!and!
0.2!(p<.01)!points,!respectively,!for!women!and!by!0.9!(p<.001),!0.4!(p<.001),!and!
0.3!(p<.001)!points,!respectively,!for!men.!!However,!the!Japanese!sample!scored!
higher!in!serial!7’s!by!0.4!points!(p<.001)!for!women;!serial!7!scores!were!not!
significantly!different!for!men.!!
!
!
49!
This!table!also!clarifies!that!older!Americans!are!more!likely!to!report!having!
each!of!the!health!conditions!listed.!!Americans!are!also!more!likely!to!have!more!
functioning!difficulties!(0.2!more!difficulties)!and!lower!grip!strength!(0.1!kg!).!!
Japanese!older!persons!are!more!likely!to!have!measured!hypertension!and!fewer!
years!of!education.!
Second,!we!determine!whether!country!differences!in!cognitive!performance!
differ!with!age;!figures!1aFd!illustrates!the!average!total!cognitive!(Figure!1a),!
immediate!word!recall!(Figure!1b),!delayed!word!recall!(Figure!1c),!and!serial!7s!
(Figure!1d)!scores,!by!age,!country,!and!gender.!!The!values!used!to!generate!Figures!
1aFd!can!be!found!in!Appendix!A!Tables!A1aFb.!!Figure!1a!reveals!that!American!
women!in!the!70F74,!80F84,!and!90+!age!groups!scored!significantly!higher!than!
Japanese!women!on!total!cognitive!performance,!whereas!American!men!in!the!68F
69!and!70F74!age!groups!scored!higher!than!Japanese!men.!!Figure!1b!shows!that,!at!
every!age!group,!American!women!scored!significantly!higher!than!Japanese!women!
in!immediate!word!recall.!!American!men!scored!significantly!higher!than!Japanese!
men!in!immediate!word!recall!in!the!68F69!and!70F74!age!groups!only.!!American!
women!were!significantly!better!than!Japanese!women!on!delayed!word!recall!
(Figure!1c)!up!to!age!85.!!On!the!other!hand,!only!American!men!in!the!70F74!age!
group!scored!significantly!higher!than!Japanese!men!on!delayed!word!recall.!!The!
last!figure!(Figure!1d)!shows!that!Japanese!women!in!the!68F79!age!range!scored!
significantly!higher!than!American!women!on!serial!7s,!whereas!Japanese!men!in!
the!70F79!age!groups!had!significantly!higher!scores,!compared!to!American!men.!
!
!
50!
Country(Interactions!
In!order!to!examine!differences!across!countries!in!the!effects!of!individual!
differences,!interactions!with!individual!variables!were!examined!before!adding!
only!the!significant!ones!to!the!equation.!!This!allows!for!the!reduction!in!the!
number!of!interaction!terms!and!makes!the!OLS!models!more!tractable.!!Table!2!
summarizes!the!country*predictor!variable!interactions!for!total!cognitive!
performance.!!Each!interaction!term!was!included!in!separate!OLSG regressions,!
which!simultaneously!controlled!for!BMI!category,!chronic!conditions,!frailty,!
sociodemographic!characteristics,!and!country!(Table!2).!!The!coefficients!for!
women!indicate!that!compared!to!the!US,!education!has!a!less!positive!effect!in!
Japan,!whereas!underweight!BMI!is!more!positively!related!to!total!cognitive!
performance.!!Grip!strength,!which!was!almost!significant!at!p<.06,!has!a!stronger!
effect!in!Japan.!!The!coefficients!for!men!indicate!less!positive!effects!of!
overweight/obese!BMI!and!more!positive!effects!of!heart!disease!and!grip!strength!
in!Japan,!compared!to!the!US.!
Estimation(of(Cognitive(Performance(
Tables!3aG b!show!four!logistic!regression!models!for!total!cognitive!
performance!for!women!(a)!and!men!(b).!!Model!I!controls!for!age!and!country,!
Model!II!controls!for!education.!!Model!III!controls!for!health!behavior,!chronic!
conditions,!frailty,!sociodemographic!characteristics,!and!country!and!does!not!
include!any!interaction!terms.!!The!final!model,!Model!IV!adds!the!significant!
interactions!from!Table!2.!
!
!
51!
Model!I!demonstrates!that!Americans!have!higher!total!cognitive!
performance;!in!fact,!Japanese!women!and!men!score!0.64!and!0.97!fewer!points!on!
the!25!point!scale,!respectively,!than!their!American!counterparts!on!tests!of!total!
cognitive!performance.!!Across!the!remaining!models,!the!effect!of!country!changes,!
with!Japanese!women!having!better!scores!than!American!women!and!Japanese!
men!performing!at!similar!levels!as!American!men!when!education!is!controlled!
(see!country!coefficient!in!Model!II,!II!and!IV).!!Model!III!found!that!among!both!
women!and!men,!overweight/obese!and!higher!education!improve!cognitive!
performance,!while!the!main!effect!for!grip!strength!was!significant!for!men.!!
Controlling!for!health!behaviors,!chronic!conditions,!and!frailty!reduces!the!main!
effect!of!education!slightly!for!women!(by!0.07),!but!had!no!appreciable!effect!on!the!
coefficient!for!men.!!!
The!fourth!model!indicates!that!total!cognitive!performance!scores,!when!all!
of!the!risk!factors!are!controlled,!including!the!interactions!of!country!and!education!
and!grip!strength!for!women,!and!overweight/obese!and!heart!disease!for!men,!the!
main!effect!for!country!is!no!longer!significant!for!women,!though!it!is!nearly!
significant!for!men!(p<.06).!!The!effect!of!education!for!Japanese!women!was!0.35!
and!0.54!for!American!women,!whereas!the!interactions!of!country!and!
overweight/obese!and!grip!strength!were!not!significant!in!women!when!
controlling!for!multiple!interactions.!!In!men,!the!effect!of!grip!strength!was!6.23!and!
0.41!for!Japanese!and!American!men,!respectively.!!The!effects!of!overweight/obese!
BMI!and!heart!disease!for!Japanese!was!0.05!and!1.06,!respectively,!and!for!
!
!
52!
American!men!the!effects!were!1.35!and!2.04!for!overweight/obese!BMI!and!heart!
disease,!respectively.!!!
The!findings!show!that!the!differential!presence!of!health!conditions,!health!
behaviors,!and!frailty!are!not!a!cause!of!the!difference!in!cognitive!performance!
scores!between!the!countries,!but!rather,!the!addition!of!education!in!Model!II!
explains!differences!in!cognitive!performance!between!the!countries.!!When!
education!is!added!in!Model!II,!in!women,!the!coefficient!for!country!changes!signs,!
indicating!that!when!years!of!education!is!controlled!between!American!and!
Japanese!women,!Japanese!women!would!score,!on!average,!0.72!points!more!than!
American!women.!!Similarly,!when!education!is!controlled!for!in!Model!II!for!men,!
the!effect!of!country!is!lost,!indicating!that!when!Japanese!men!have!the!same!level!
of!education!as!American!men,!total!cognitive!performance!scores!would!be!similar!
between!the!two!groups.!!!The!findings!suggest!that!cognitive!differences!observed!
between!Japan!and!the!US!are!in!fact!differences!in!years!of!education,!and!Japanese!
women!perform!better!on!cognitive!tests!when!education!is!controlled.!
The!effect!of!education!in!model!IV!of!Table!3a!for!women!is!0.36!in!Japan!
(main!effect!+!interaction)!and!0.54!in!the!US!(main!effect+0*interaction).!!On!
average,!Japanese!women!have!2.6!fewer!years!of!education!than!American!women,!
yet!their!total!cognitive!scores!are!only!0.4!points!lower.!!If!the!effect!of!education!
were!similar!to!what!we!see!in!the!US!we!would!expect!Japanese!women!to!score!
much!lower!on!average.!!This!finding!coincides!with!earlier!research!that!education!
has!little!effect!on!health!in!Japan!(Yong!&!Saito,!2012).!!!
!
!
53!
When!the!significant!country!interactions!for!men!(grip!strength,!
overweight/obese!BMI,!and!heart!disease)!from!Table!2!are!included!in!Model!IV!of!
Table!3b,!all!three!interactions!remain!significant.!!The!interaction!for!grip!strength!
indicates!an!effect!of!6.23!in!Japan!and!2.04!in!the!US.!!The!interaction!for!
overweight/obese!BMI!reveals!an!effect!of!0.04!in!Japan!and!1.35!in!the!US.!!The!
interaction!for!heart!disease!indicates!an!effect!of!1.07!in!Japan!and!G0.50!in!the!US.!
Discussion!
The!intent!of!this!paper!was!to!examine!potential!differences!in!cognitive!
performance!between!the!US!and!Japan!and!the!role!played!by!differences!in!levels!
of!risk!factors!and!comorbidities!and!the!effects!of!risk!factors!and!comorbidities!on!
cognitive!performance!scores.!!OLSGregression!models!using!a!pooled!dataset!across!
the!two!countries!found!evidence!of!significant!differences!between!the!two!
countries!in!cognitive!performance!scores,!particularly!for!women!(Table!3a!Models!
IGIV).!!The!Japanese!older!persons!had!lower!cognitive!performance!scores.!!The!fact!
that!controls!for!education!removed!the!advantage!in!total!cognitive!performance!
that!Americans!had!relative!to!the!Japanese,!indicates!the!effect!of!education!in!
Japan!in!reducing!the!differential!between!the!US!and!Japan.!!This!finding!is!
consistent!with!the!international!findings!of!Skirbekk!et!al.!(2012),!in!which!the!
authors!found!that!higher!cognitive!scores!were!found!in!countries!with!earlier!
improvements!to!childhood!conditions!and!more!years!of!education!(e.g.!US,!UK,!
Northern!Europe,!Continental!Europe,!Southern!Europe,!China,!India,!and!Mexico).!!
It!is!particularly!interesting!that!though!years!of!education!differed!greatly!between!
the!two!countries!(women:!2.6!years;!men:!2.2!years),!differences!in!cognitive!
!
!
54!
performance!scores!were!small!(0.4!for!women!and!0.9!for!men),!providing!support!
for!previous!findings!that!Japan’s!more!egalitarian!society!may!reduce!the!effects!of!
education!on!health!(Yong!&!Saito;!2012).!!!
!!While!education!is!obviously!linked!to!cognitive!performance,!other!factors!
tied!to!cognitive!performance!include!chronic!conditions!(i.e.!diabetes!and!stroke)!
and!measures!of!frailty.!!People!in!the!US!have!substantially!more!diseases!and!
adverse!health!conditions;!however,!these!conditions!played!little!role!in!
determining!the!differences!in!the!two!countries’!cognitive!performance,!
particularly!for!men,!where!there!was!little!change!in!the!effect!of!being!Japanese!
after!controlling!for!chronic!conditions!and!frailty.!!However,!controlling!for!chronic!
conditions!and!frailty!reduced!the!size!and!level!of!significance!of!the!effect!of!being!
Japanese!for!women.!!When!age,!education,!health!behavior,!chronic!conditions,!and!
frailty!are!controlled,!Japanese!women!still!perform!better!than!American!women,!
though!the!effect!of!country!is!reduced!by!0.32!points!and!the!significance!falls!from!
p<.001!to!p<.01.!!!This!finding!suggests!that!American!women’s!high!levels!of!
chronic!conditions!are!overwhelmed!by!Japanese!women’s!worse!grip!strength!and!
hypertension.!!The!very!significant!role!of!education!in!explaining!cognition!is!
indicated!by!the!increase!in!the!predictive!value!of!the!equation!when!it!is!added!to!
the!model.!In!Table!3a,!the!model’s!predictive!value!nearly!doubles!(from!10%!to!
19%,!variance!explained)!compared!to!the!more!slight!increase!(from!19%!to!22%,!
variance!explained)!when!health!behavior,!chronic!conditions,!and!frailty!are!
controlled.!!
!
!
55!
Cognitive!functioning!is!a!critical!skill!for!living!independently!and!avoiding!
other!risk!factors!of!illness!and!injury.!!This!paper!found!surprisingly!small!
differences!in!cognitive!performance!across!these!two!very!different!countries!
despite!larger!differences!in!other!measures!of!health!and!environment.!!This!study!
had!a!crossGsectional!design!and!established!country!differences!in!cognitive!
performance.!!Future!studies!could!use!multiple!waves!of!data!in!order!to!examine!
how!risk!factors!are!associated!with!change!in!performance!in!Japan!and!the!US.!! !
!
!
56!
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!
!
61!
Table!1.!Descriptive!statistics!for!indicators!of!cognitive!functioning,!BMI,!chronic!
conditions,!frailty,!and!sociodemographic!measures!
Women Men
Japan US Japan US

Measure Mean/
%
SD Mean/
%
SD Mean/
%
SD Mean/
%
SD

Cognitive

Total Cognitive (number
correct)
12.0 4.7 12.4 4.5 * 11.5 4.7 12.4 3.9 ***
Immediate word recall
(number correct)
4.7 1.8 5.1 1.7 *** 4.4 1.9 4.8 1.6 ***
Delayed word recall
(number correct)
3.7 2.4 3.9 2.1 ** 3.3 2.4 3.6 1.8 ***
Serial 7's (number correct) 3.8 1.5 3.4 1.8 *** 4.0 1.5 3.9 1.5
Health Behavior and Chronic Conditions
Underweight (<18.5kg/m
2
)
(%)
10.2 --- 2.1 --- *** 8.3 --- 0.2 --- ***
Normal weight (18.5-
<25kg/m
2
) (%)
68.3 --- 32.4 --- *** 71.6 --- 22.2 --- ***
Overweight/obese
(≥25kg/m
2
) (%)
21.5 --- 65.5 --- *** 20.1 --- 77.6 --- ***
Diabetes (%) 8.6 --- 17.5 --- *** 13.4 --- 21.9 --- ***
Stroke (%) 4.3 --- 9.0 --- *** 7.0 --- 10.8 --- **
Heart disease (%) 6.0 --- 26.6 --- *** 9.8 --- 38.3 --- ***
Measured hypertension
(%)
71.7 --- 38.8 --- *** 75.9 --- 41.7 --- ***
Frailty
Total functioning difficulties 0.3 1.3 0.5 1.2 ** 0.4 1.5 0.3 0.9
Grip/kg (kg) 0.4 0.1 0.3 0.1 *** 0.5 0.1 0.4 0.1 ***
Sociodemographic
Age (years) 75.6 6.5 76.9 6.6 *** 75.6 6.3 76.3 6.1 **
Education (years) 9.7 2.5 12.3 2.9 *** 10.5 3.2 12.7 3.3 ***
n 1055 1847 938 1416
*p<.05,!**p<.01,!***p<.001!
!
! !
!
!
62!
Table!2.!Summary!table!of!unstandardized!beta!coefficients!of!country*predictor!
interactions.!Each!interaction!was!included!separately!in!a!regression!that!regressed!
total!cognitive!performance!on!BMI,!chronic!conditions,!frailty,!sociodemographic!
characteristics,!and!one!country!interaction
#
,!(Japan=1).!
Women (n=2902) Men (n=2354)

b p b p
Japan*underweight 1.58 0.03 3.07 0.21
Japan*overweight/obese 0.39 0.26 -1.54 <.0001
Japan*diabetes 0.30 0.53 -0.17 0.68
Japan*stroke 0.22 0.74 -0.21 0.69
Japan*heart disease -0.41 0.44 1.40 0.00
Japan*measured hypertension 0.27 0.40 0.03 0.92
Japan*total functioning difficulties 0.09 0.49 -0.10 0.47
Japan*grip strength/kg 3.08 0.06 5.15 0.00
Japan*age 0.04 0.10 0.04 0.09
Japan*education -0.16 0.01 -0.02 0.69
Significant!interactions!indicated!in!bold!font.!
#
Each!regression!controlled!for!underweight!BMI,!overweight/obese!BMI,!diabetes,!
stroke,!heart!disease,!measured!hypertension,!total!functioning!difficulties,!grip!
strength,!age,!education,!country,!and!one!country*risk!factor!interaction.!
! !
!
!
63!
Tables!3a*b.!Unstandardized!beta!coefficients!from!OLS*regressions!of!total!
cognitive!performance!regressed!on!age!and!country!(Model!I);!age,!country,!and!
education!(Model!II);!!BMI,!chronic!conditions,!failty,!!and!sociodemographic!
measures!(Model!III);!and!BMI,!chronic!conditions,!failty,!!sociodemographic!
measures,!and!country!interactions!(Model!IV)!(Japan=1)!for!women!(a)!and!men!
(b).!!
Table!3a.!Women!
Women (n=2902)
Model I Model II Model III Model IV
B B B B
Intercept 29.00 *** 20.45 *** 18.17 *** 17.03 ***
Underweight --- --- --- --- -0.10 -1.58 *
Overweight/obese --- --- --- --- 0.46 *** 0.54 **
Diabetes --- --- --- --- -0.67 *** -0.92 ***
Stroke --- --- --- --- -0.81 *** -0.23
Heart disease --- --- --- --- -0.17 -0.01
Measured hypertension --- --- --- --- -0.24 * -0.34 *
Total functioning difficulties --- --- --- --- -0.50 *** -0.46 ***
Grip/kg (kg) --- --- --- --- 0.67 1.76
Age (years) -0.22 *** -0.19 *** -0.15 *** -0.15 ***
Education (years) --- --- 0.50 *** 0.43 *** 0.54 ***
Japan -0.64 *** 0.72 *** 0.40 ** 1.39
Japan*underweight --- --- --- --- --- --- 1.37
Japan*education --- --- --- --- --- --- -0.18 **
Japan*grip/kg --- --- --- --- --- --- 3.26

R
2
0.10 0.19
0.22 0.22
*p<.05,!**p<.01,!***p<.001!
! !
!
!
64!
Table!3b.!Men!
Men (n=2354)
Model I Model II Model III Model IV
B B B B
Intercept 27.22 *** 19.39 *** 14.33 *** 14.64 ***
Underweight --- --- --- --- -0.04 -0.37
Overweight/obese --- --- --- --- 0.85 *** 1.35 ***
Diabetes --- --- --- --- -0.19 -0.24
Stroke --- --- --- --- -1.23 *** -1.15 ***
Heart disease --- --- --- --- -0.16 -0.50 *
Measured hypertension --- --- --- --- -0.06 -0.05
Total functioning
difficulties
--- --- --- --- -0.43 *** -0.42 ***
Grip/kg (kg) --- --- --- --- 3.67 *** 2.04 *
Age (years) -0.19 *** -0.16 *** -0.12 *** -0.12 ***
Education (years) --- --- 0.42 *** 0.41 *** 0.41 ***
Japan -0.97 *** -0.04 0.12 -1.59 #
Japan*grip/kg --- --- --- --- --- --- 4.19 **
Japan*overweight/obese --- --- --- --- --- --- -1.31 ***
Japan*heart disease --- --- --- --- --- --- 1.57 ***

R
2
0.09 0.20 0.24 0.25
#
p<.06,!*p<.05,!**p<.01,!***p<.001!
!
!
! !
!
!
65!
Figure!Legend!
Figures!1a*d.!Average!number!of!correct!responses!in!total!cognitive!performance!
(a),!immediate!word!recall!(b),!delayed!word!recall!(c),!and!serial!7s!(d)!by!age,!
country,!and!gender.!
! !
!
!
66!
!
!
!
!
0"
5"
10"
15"
20"
25"
68(69" 70(74" 75(79" 80(84" 85(89" 90+"
Average!number!correct!
Figure!1a.!Total!cognitive!score!by!age,!country,!and!gender!(range:!
0*25)!
F,!Japan! M,!Japan! F,!US! M,!US!
SigniXicant!country!differences!indicated!by!X.!
!!!!!!!!!!!!!!!!!!!68*69 !70*74!!!!!!!!!!75*79!!!!!!!!!!80*84!!!!!!!!!!85*89!!!!!!!!!!90+!
Women !!!!!X"""""""""""""""""""""""""""""""""""""""""X """""""""""""""""""X!
Men!!!!!!!!!!!!!!!X""""""""""""""X!
0"
1"
2"
3"
4"
5"
6"
7"
8"
9"
10"
68(69" 70(74" 75(79" 80(84" 85(89" 90+"
Average!number!correct!
Figure!1b.!Immediate!word!recall!scores!by!age,!country,!and!
gender!(range:!0*10)!
F,!Japan! M,!Japan! F,!US! M,!US!
SigniXicant!country!differences!indicated!by!X.!
!!!!!!!!!!!!!!!!!!68*69 !70*74!!!!!!!!!!75*79!!!!!!!!!!80*84!!!!!!!!!!85*89!!!!!!!!!!90+!
Women!!!!!!!X """""X"""""""""""""""""""X """"""""""""X"""""""""""""""""""X"""""""""""""""""""X!
Men!!!!!!!!!!!!!!X"""""""""""""""X!
!
!
67!
!
!
!
0"
1"
2"
3"
4"
5"
6"
7"
8"
9"
10"
68(69" 70(74" 75(79" 80(84" 85(89" 90+"
Average!number!correct!
Figure!1c.!Delayed!word!recall!scores!by!age,!country,!and!gender!
(range:!0*10)!
F,!Japan! M,!Japan! F,!US! M,!US!
SigniXicant!country!differences!indicated!by!X.!
!!!!!!!!!!!!!!!!!68*69 !70*74!!!!!!!!!!75*79!!!!!!!!!!80*84!!!!!!!!!!85*89!!!!!!!!!!90+!
Women!!!!!!X """""X"""""""""""""""""""X """"""""""""X """"" """""!
Men!!!!!!!!!!!!!X!
0"
1"
2"
3"
4"
5"
68(69" 70(74" 75(79" 80(84" 85(89" 90+"
Average!number!correct!
Figure!1d.!Serial!7s!score!by!age,!country,!and!gender!(range:!0*5)!
F,!Japan! M,!Japan! F,!US! M,!US!
SigniXicant!country!differences!indicated!by!X.!
!!!!!!!!!!!!!!!!!68*69 !70*74!!!!!!!!!!75*79!!!!!!!!!!80*84!!!!!!!!!!85*89!!!!!!!!!!90+!
Women!!!!!!X """""X"""""""""""""""""""X """"" """"" """""!
Men !!!!!X"""""""""""""""""""X!
!
!
68!
Appendix!A:!Supplemental!Tables!and!Figures!
Tables!A1a*b.!Average!number!correct!on!total!cognitive,!immediate!word!recall,!
delayed!word!recall,!and!serial!7s!for!women!(A1a)!and!men!(A1b)!by!age!and!
country.!
Table!A1a.!Women!
!
Japan United!States!
!! Mean!
95%!
Lower!
95%!
Upper! Mean!
95%!
Lower!
95%!
Upper!
Total!Cognitive!
68;69! 13.21! 12.62! 13.80! 13.88! 13.58! 14.18!
70;74! 12.62! 12.23! 13.01! 13.54! 13.32! 13.75!
75;79! 11.49! 10.98! 12.00! 12.19! 11.91! 12.47!
80;84! 9.83! 9.33! 10.32! 10.98! 10.68! 11.28!
85;89! 9.29! 8.61! 9.97! 10.18! 9.82! 10.54!
90+! 6.32! 5.25! 7.40! 8.24! 7.74! 8.75!
Immediate!Word!Recall!
68;69! 5.17! 4.92! 5.41! 5.67! 5.56! 5.79!
70;74! 4.89! 4.74! 5.04! 5.57! 5.49! 5.65!
75;79! 4.54! 4.35! 4.73! 4.99! 4.89! 5.09!
80;84! 4.07! 3.89! 4.26! 4.65! 4.53! 4.76!
85;89! 3.69! 3.42! 3.96! 4.23! 4.10! 4.37!
90+! 2.74! 2.28! 3.20! 3.58! 3.38! 3.78!
Delayed!Word!Recall!
68;69! 4.19! 3.87! 4.51! 4.78! 4.64! 4.92!
70;74! 3.95! 3.74! 4.16! 4.47! 4.37! 4.58!
75;79! 3.35! 3.10! 3.61! 3.92! 3.80! 4.05!
80;84! 2.74! 2.49! 2.99! 3.20! 3.06! 3.35!
85;89! 2.72! 2.40! 3.05! 2.82! 2.66! 2.98!
90+! 1.57! 1.12! 2.02! 2.15! 1.94! 2.36!
Serial!7s!
68;69! 3.96! 3.77! 4.14! 3.43! 3.30! 3.55!
70;74! 3.90! 3.77! 4.03! 3.49! 3.41! 3.58!
75;79! 3.78! 3.60! 3.95! 3.28! 3.17! 3.38!
80;84! 3.30! 3.12! 3.49! 3.13! 3.00! 3.25!
85;89! 3.30! 3.06! 3.54! 3.13! 2.97! 3.28!
90+! 2.73! 2.24! 3.22! 2.51! 2.30! 2.73!
! !
!
!
69!
Table!A1b.!Men!
!
!
Japan United!States!
!! Mean!
95%!
Lower!
95%!
Upper! Mean!
95%!
Lower!
95%!
Upper!
Total!Cognitive!
68;69! 12.56! 11.99! 13.14! 13.59! 13.25! 13.92!
70;74! 11.93! 11.50! 12.35! 12.82! 12.59! 13.04!
75;79! 11.59! 11.11! 12.07! 11.91! 11.64! 12.18!
80;84! 10.27! 9.74! 10.80! 10.73! 10.41! 11.05!
85;89! 9.62! 8.80! 10.45! 10.13! 9.67! 10.59!
90+! 7.60! 5.92! 9.27! 8.83! 8.12! 9.54!
Immediate!Word!Recall!
68;69! 4.72! 4.48! 4.95! 5.37! 5.23! 5.50!
70;74! 4.54! 4.36! 4.71! 5.04! 4.95! 5.13!
75;79! 4.42! 4.22! 4.63! 4.60! 4.50! 4.71!
80;84! 3.83! 3.59! 4.07! 4.19! 4.07! 4.31!
85;89! 3.63! 3.31! 3.94! 3.91! 3.74! 4.09!
90+! 3.24! 2.55! 3.93! 3.44! 3.17! 3.71!
Delayed!Word!Recall!
68;69! 3.84! 3.52! 4.17! 4.29! 4.14! 4.45!
70;74! 3.56! 3.33! 3.78! 3.94! 3.83! 4.04!
75;79! 3.20! 2.94! 3.47! 3.51! 3.39! 3.63!
80;84! 2.77! 2.53! 3.02! 2.95! 2.81! 3.09!
85;89! 2.48! 2.04! 2.93! 2.52! 2.31! 2.72!
90+! 2.26! 1.52! 3.00! 2.05! 1.74! 2.36!
Serial!7s!!
68;69! 4.08! 3.89! 4.26! 3.92! 3.79! 4.05!
70;74! 4.06! 3.94! 4.19! 3.84! 3.76! 3.93!
75;79! 4.15! 4.00! 4.30! 3.80! 3.69! 3.90!
80;84! 3.83! 3.64! 4.02! 3.59! 3.46! 3.73!
85;89! 3.81! 3.52! 4.10! 3.70! 3.51! 3.89!
90+! 2.87! 2.31! 3.43! 3.35! 3.04! 3.66!
!
!
!
!
!
!
70!
Table!A2:!Characteristics!of!participants!are!included/excluded!in!the!analytic!
sample.!
!
!! Japan! United!States!
!!
Not!missing!!
(n=1993)!
Missing!
(n=1402)! !!
Not!missing!!
(n=3263)!
Missing!
(n=1471)! !!
!!
Mean/!
%! SD!
Mean/!
%! SD! !!
Mean/!
%! SD!
Mean/!
%! SD! !!
Underweight!(%)! 9.4! ;;;! 14.7! ;;;! ***! 1.27! ;;;! 4.39! ;;;! ***!
Normal!weight!
(%)! 70.0! ;;;! 67.3! ;;;! !! 28.09! ;;;! 35.95! ;;;! ***!
Overweight/obese!
(%)! 20.6! ;;;! 18.1! ;;;! !! 70.64! ;;;! 59.7! ;;;! ***!
Diabetes!(%)! 10.7! ;;;! 11.1! ;;;! !! 19.39! ;;;! 24.45! ;;;! ***!
Stroke!(%)! 5.2! ;;;! 12.6! ;;;! ***! 9.75! ;;;! 19.85! ;;;! ***!
Heart!disease!(%)! 7.7! ;;;! 7.9! ;;;! !! 31.57! ;;;! 37.76! ;;;! ***!
Measured!
hypertension!(%)! 73.6! ;;;! 78.8! ;;;! !! 40.02! ;;;! 38.89! ;;;! !!
Total!functioning!
difficulties! 0.27! 1.37! 1.49! 3.58! ***! 0.42! 1.09! 1.73! 2.40! ***!
Grip/kg!(kg)! 0.45! 0.14! 0.44! 0.15! !! 0.37! 0.11! NA! NA! NA!
Age!(years)! 75.77! 7.54! 79.33! 9.22! ***! 76.65! 6.36! 78.74! 7.96! ***!
Education!(years)! 10.06! 3.35! 9.20! 3.48! ***! 12.46! 3.11! 11.22! 3.73! ***!
Female!(%)! 53.6! ;;;! 56.9! ;;;! !! 57.59! ;;;! 62.29! ;;;! ***!
!
!
71!
Figure!A1.!Reasons!for!loss!of!sample,!Japan!
! !
Japan:!68+!years!
and!in!2006!data!
3395!
Participated!in!
cognitive!
2869!
BMI!
2691!
Diabetes!
2601!
Stroke!
2589!
Heart!disease!
2583!
Measured!
hypertension!
2103!
Functioning!
difXiculties!
2103!
Grip!strength!
2075!
Education!
1993!
Missing
Missing
28
Missing
0
Missing
480
Missing
526
Missing
178
Missing
90
Missing
12
Missing
6
Missing
82
!
!
72!
Figure!A2.!Reasons!for!loss!of!sample,!United!States
! !
US:!68+!years!
and!in!2006!data!
9262!
Eligible!for!face*
to*face!
4734!
Participated!in!
cognitive!
4319!
BMI!
4282!
Diabetes!
4275!
Stroke!
4270!
Heart!disease!
4266!
Measured!
hypertension!
3521!
Functioning!
difXiculties!
3521!
Grip!strength!
3263!
Education!
3263!
Missing
4528
Missing
415
Missing
37
Missing
7
Missing
5
Missing
4
Missing
745
Missing
0
Missing
258
Missing
0
!
!
73!
Appendix!B:!Imputations!
In!order!to!be!comparable!to!the!Health!and!Retirement!Study!(HRS),!
imputations!for!the!cognitive!measures!of!the!Nihon!University!Japanese!
Longitudinal!Study!of!Aging!(NUJLSOA)!were!performed!according!to!the!steps!
outlined!in!Fisher!et!al.!(2012).!
Measures'
Calculating!imputed!cognitive!values:!
The!following!measures!were!taken!from!the!2006!wave!or!an!earlier!wave!
(if!not!asked!in!2006):!birth!year,!birth!month,!years!of!education,!gender,!age,!heart!
disease,!stroke,!diabetes,!marital!status,!household!income,!self*rated!health,!
hypertension,!activities!of!daily!living!(ADL),!instrumental!activities!of!daily!living!
(IADL).!
HRS!imputation!procedures!for!imputing!the!baseline!cognitive!values!called!
for!using!the!subsequent!wave’s!cognitive!measures.!!!Therefore,!since!2006!was!the!
first!time!cognitive!measures!were!included!in!NUJLSOA,!the!2008!cognitive!values!
were!used!to!impute!the!2006!values.!!The!following!cognitive!measures!are!
therefore!taken!from!the!2008!wave!to!conform!to!HRS!imputation!procedures:!
immediate!word!recall,!delayed!word!recall,!serial!7’s.!
Generating'the'predicted'values!
A!regression!model!containing!the!birth!year,!birth!month,!years!of!
education,!gender,!age,!heart!disease,!stroke,!diabetes,!marital!status,!household!
income,!self*rated!health,!hypertension,!ADL,!and!IADL!measures,!as!well!as!each!of!
the!three!cognitive!measures!(immediate!and!delayed!word!recall!and!serial!7’s)!as!
!
!
74!
the!outcome!measure!was!used!to!calculate!a!predicted!value!for!each!of!the!
outcome!cognitive!measures!for!individuals!missing!a!value!on!the!outcome!
cognitive!measures.!
The!following!is!the!regression!model!for!the!outcome!cognitive!measures!
regressed!on!birth!year,!birth!month,!years!of!education,!gender,!age,!heart!disease,!
stroke,!diabetes,!marital!status,!household!income,!self*rated!health,!hypertension,!
ADL,!IADL,!2008!immediate!word!recall,!2008!delayed!word!recall,!and!2008!serial!
7!used!to!predict!each!of!the!outcome!cognitive!measures:!
Outcome'cognitive'measure=α+β1(birth'year)+'β2(birth'month)+'β3(years'of'
education)+'β4(female)+'β5(age'in'years)+'β6(marital'status)+'β7(household'income)+'
β8(selfGrated'health)+'β9(hypertension)+'β10(heart'disease)+'β11(stroke)+'
β12(diabetes)+'β13(number'of'ADL'difficulties)+'β14(number'of'IADL'difficulties)+'
β15(immediate'word'recall'2008)+'β16(delayed'word'recall'2008)+'β17(serial'7’s'2008)!
Where:'
β1=birth'year'
β2=birth'month'
β3=years'of'education'
β4=female'
β5=age'in'years'
β6=!marital!status'
β7=household'income'
β8=selfGrated'health'
β9=hypertension'
!
!
75!
β10=heart'disease'
β11=stroke'
β12=diabetes'
β13=number'of'ADL'
β14=number'of'IADL'
β15=immediate'word'recall'2008'
β16=delayed'word'recall'2008'
β17=serial'7’s'2008! '
!
!
76!
Table!B1.!Number!of!imputed!cognitive!values!per!measure!(NUJLSOA)!
Immediate!Word!Recall! 197!
Delayed!Word!Recall! 265!
Serial!7's! 505!
!
!
! !
!
!
77!
Table!B2.!Percent!of!respondents!with!at!least!one!imputed!cognition!score!
(NUJLSOA)!
!!
68;69! 70;74! 75;79! 80;84! 85+!
At!least!1!imputed!score!(%)! 3.1! 2.5! 3.2! 5! 7.2!
Immediate!Word!Recall!(%)! 6.28! 18.62! 17.91! 20.97! 36.21!
Delayed!Word!Recall!(%)! 6.17! 18.77! 16.96! 22.21! 35.89!
Serial!7s!(%)! 7.92! 17.49! 19.07! 19.51! 36.02!
!
!
! !
!
!
78!
Table!B3.!Descriptive!statistics!for!unimputed!and!imputed!cognitive!measures!
(NUJLSOA)!
!! Non;imputed!cases! Imputed!cases! Range!
!! N! Mean! Std!Dev! N! Mean! Std!Dev! !!
Immediate!
Word!Recall! 2810! 4.492! 1.778! 197! 4.411! 0.896! 0;10!
Delayed!
Word!Recall! 2726! 3.413! 2.331! 265! 2.950! 1.176! 0;10!
Serial!7's! 2797! 3.858! 1.465! 505! 3.641! 1.018! 0;5!
!
!
! !
!
!
79!
Chapter!4:!Mortality!
Introduction!
! While!the!US!has!the!largest!economy!and!among!the!highest!Gross!Domestic!
Product!per!capita!in!the!world,!life!expectancy!at!birth!and!at!age!50!in!the!US!is!
actually!among!the!lowest!among!developed!countries.!!In!contrast,!Japan!has!one!of!
the!highest!life!expectancies!at!these!ages!(Robine,!Saito,!&!Jagger,!2003;!WHO,!
2011).!!However,!at!around!age!75!the!differential!changes,!with!Americans!having!
mortality!rates!similar!to!the!Japanese!(Arias,!2012;!Ministry!of!Health!Labor!and!
Welfare,!2011);!the!reasons!for!this!dramatic!change!are!not!well!understood.!!It!is!
known!that!levels!of!many!mortality!risk!factors!as!well!as!the!prevalence!of!
diseases!linked!to!mortality!are!higher!in!the!American!population!than!in!the!
Japanese!population!(Crimmins,!Garcia,!&!Kim,!2010;!Ikeda!et!al.,!2011;!Reynolds!et!
al.,!2008)!but!it!is!unclear!if!their!effects!are!also!stronger.!!It!is!hypothesized!that!at!
older!ages!the!effects!of!risk!factors!on!mortality!are!lower!in!the!US!compared!to!
Japan!because!the!Japanese!experience!similar!levels!of!mortality!but!have!lower!
levels!of!risk.!!
Health'Conditions'and'Health'Behaviors!
Many!health!conditions!are!associated!with!higher!mortality;!chronic!
hypertension!indirectly!affects!mortality!as!a!risk!factor!for!stroke!and!can!lead!to!
other!cardiovascular!diseases,!such!as!heart!disease,!and!eventually!death!(Benetos!
et!al.,!1997;!Digiovana,!1999;!Franklin!et!al.,!2001;!MacMahon!et!al.,!1990).!!An!
American!study!suggests!that!the!relationship!between!hypertension!and!mortality!
is!not!as!clear!in!people!85!years\or\older!as!it!is!among!those!65\84!(Satish!et!al.,!
!
!
80!
2001).!!Furthermore,!this!effect!is!seen!only!for!women,!suggesting!a!possible!
gender!effect!(Satish!et!al.,!2001).!!In!Japan,!as!in!the!US,!elevated!blood!pressure!
levels!and!chronic!hypertension!predict!risk!of!mortality!when!the!entire!age!range!
is!considered!(Ikeda!et!al.,!2011);!suggesting!age!of!onset!may!affect!the!impact!
hypertension!has!on!mortality!risk.!
!!Diabetes!is!another!chronic!health!condition!associated!with!mortality!in!
many!populations!(Bertoni!et!al.,!2002);!although!control!of!diabetes!is!low!in!Japan,!
when!elderly!diabetics!in!Japan!controlled!their!disease!they!had!similar!mortality!
rates!to!the!general!population!(Katakura!et!al.,!2003).!
Cancer!is!an!important!cause!of!mortality;!in!general,!cancer!risk!and!cancer!
mortality!increase!with!age!(Yancik,!1997).!!In!Japan,!men!have!almost!twice!the!
mortality!rate!for!overall!cancer!as!women;!differences!are!much!smaller!in!the!US!
(Crimmins!et!al.,!2010a).!!Additionally,!screening!practices!and!informing!patients!of!
cancer!diagnosis!differ!between!Japan!and!the!US;!more!aggressive!screening!
practices!are!seen!in!the!US!(Crimmins!et!al.,!2010a),!whereas!a!cultural!tendency!to!
conceal!cancer!diagnosis!from!elderly!patients!is!seen!in!Japan!(Seo!et!al.,!2000;!
Shahidi!2010).!These!cultural!differences!could!affect!the!links!between!self!
reported!cancer!and!mortality!in!the!two!countries.!
Depression,!as!measured!by!the!CES\D!scale,!has!been!associated!with!
declines!in!overall!health!and!non\suicide!mortality!in!elderly!Americans!(Blazer,!
Hybels,!&!Pieper,!2001;!Schulz,!Drayer,!&!Rollman,!2002)!and!Japanese!(Takeida,!
Nishi,!&!Miyake,!1999)!but!mortality!differentials!between!depressed!and!non\
depressed!elderly!are!large!in!Japan!(Takeida!et!al.,!1999),!suggesting!a!an!effect!of!
!
!
81!
depression!on!mortality!in!Japan.!!In!the!US,!low!cognitive!performance!has!been!
associated!with!worsened!health!outcomes!and!higher!mortality!rates,!particularly!
among!men!80\89!years!old!(Perls!et!al.,!1993).!!A!review!of!the!literature!by!Dewey!
&!Saz!(2001)!showed!consistent!links!between!low!cognitive!performance!and!
higher!mortality!in!the!community!dwelling!elderly!population!of!multiple!
countries,!including!the!US!and!Japan.!
Certain!health!behaviors,!particularly!having!high!or!low!weight!and!
smoking,!have!been!associated!with!mortality!(DiGiovanna,!1999).!!Higher!body!
mass!index!(BMI)!is!associated!with!increased!mortality!in!middle\aged!populations,!
though!the!association!is!not!as!clear!in!the!elderly!(DiGiovanna,!1999);!though!
obese!BMI!(≥30!kg/m
2
)!has!been!shown!to!increase!risk!of!mortality!and!worsen!
health!outcomes!(Reynolds!et!al.,!2008).!!While!BMI!is!low!in!Japan,!relative!to!most!
other!countries,!it!has!been!steadily!increasing
!
(Yoshiike!et!al.,!2002)!and!seems!to!
influence!mortality!in!males!more!strongly!than!in!females!(Ikeda!et!a.,!2011).!!
Similarly,!in!many!countries,!including!the!US!and!Japan,!men!have!traditionally!had!
higher!rates!of!smoking!than!women!(Fukuda,!Nakamura,!&!Takano,!2004;!
Garfinkel,!1997;!Giskes!et!al.,!2005;!Ikeda!et!al.,!2011;!WHO!2012),!exposing!men!to!
the!deleterious!effects!of!first\hand!smoke!on!longevity!at!a!disproportionate!rate!
than!women.!
Indicators'of'Frailty!
! Frailty!has!been!associated!with!increased!risk!of!mortality,!and!with!higher!
levels!of!cardiovascular!disease!in!the!US!and!Japan!(Klein!et!al.,!2005;!Koizumi!et!
al.,!2013)!and!with!other!comorbid!medical!conditions!in!the!US!(Klein!et!al.,!2005).!!
!
!
82!
While!diseases!and!risk!factors!have!been!shown!to!be!better!predictors!of!mortality!
in!the!younger!old\ages,!indicators!of!frailty!are!better!predictors!among!the!oldest!
old!(Crimmins,!Vasunilashorn,!&!Kim.;!2010b).!!In!this!analysis!we!examine!three!
indicators!of!frailty:!an!indicator!of!physical!functioning!ability,!grip!strength,!and!an!
indicator!of!cognitive!ability.!!!
At!age!65,!fewer!Japanese!elderly!experience!difficulties!with!activities!of!
daily!living!(ADL)!and!instrumental!activities!of!daily!living!(IADL)!and!those!that!do!
have!greater!life!expectancy,!compared!to!American!elderly!(Crimmins!et!al.,!
2010a).!!Interestingly,!in!general,!more!women!experience!ADL!and!IADL!
functioning!difficulties!than!do!men!but!women!with!functioning!difficulties!also!
experience!greater!life!expectancy!than!men!(Crimmins!et!al.,!2010a).!!!
Similarly,!grip!strength!is!inversely!associated!with!mortality!in!Americans!
(FitzGerald!et!al.,!2004;!Phillips,!1986;!Ruiz!et!al.,!2008).!!By!contrast,!grip!strength!
is!not!associated!with!mortality!in!elderly!Japanese!women!but!is!associated!with!
mortality!in!men!(Fujita!et!al.,!1995);!researchers!in!other!Western!countries!have!
found!results!similar!to!those!in!Japan!(Gale!et!al.,!2007),!this!points!to!potential!
country!and!gender!differences!in!the!effect!of!grip!strength!on!mortality!!
The!biological!literature!suggests!that!increases!in!frailty!and!declines!in!
cognitive!performance!share!similar!etiologies!(Bergman!et!al.,!2007;!Buchman!et!
al.,!2007).!!Worse!cognitive!performance!has!been!linked!to!higher!mortality!in!
Western!countries!(Berr!et!al.,!1994;!Gale!et!al.,!1996;!Korten!et!al.,!1999),!however!
research!is!lacking!in!Asian!countries.!
!
!
83!
Sociodemographic'measures'
Sociodemographic!characteristics,!such!as!age,!education,!urban/rural!
residence,!living!arrangement,!and!gender,!have!been!strongly!associated!with!
mortality!in!the!US!and!other!Western!countries.!!Studies!on!Western!countries!have!
repeatedly!demonstrated!that!the!better!educated!experience!health!and!longevity!
advantages!across!age!groups!(Lynch,!2003;!Ross!&!Wu,!1996;!von!dem!Knesebeck,!
Verde,!&!Dragano,!2006).!!On!the!other!hand,!education!differentials!in!mortality!do!
not!seem!as!strong!or!sometimes!to!exist!in!Japan!as!they!do!in!the!US!(Yong!&!Saito,!
2012).!!However,!some!research!has!found!that!an!education!cross\over!exists!
among!Japanese!men!80!years\or\older,!so!that!at!advanced!ages,!those!with!less!
education!live!longer!than!those!with!higher!education;!no!effect!of!education!was!
found!on!women’s!mortality!(Liang!et!al.,!2002).!!!
Living!arrangement!(i.e.!living!alone!or!with!others)!has!also!been!linked!
with!mortality,!with!those!living!with!someone!other!than!a!spouse!having!worse!
health!and!higher!rates!of!mortality!in!the!US!(Magaziner!et!al.,!1998)!but!lower!
mortality!in!Japan!(Saito,!Sagawa,!&!Kanagawa,!2005).!!Rural!versus!urban!residence!
is!another!sociodemographic!measure!that!has!been!associated!with!mortality!in!the!
US,!but!the!association!is!not!consistent;!often!times,!gender!and!race!are!mediating!
factors!(Blazer!et!al.,!1995).!!Findings!between!residence!and!mortality!rates!in!
Japan!also!vary!based!on!gender!and!results!are!often!mixed!(Yoshiike!et!al.,!2002).!
Gender,!on!it’s!own,!influences!mortality!in!both!the!US!and!Japan,!with!men!
generally!experiencing!lower!life!expectancy!than!women!(Oksuzyan!et!al.,!2010;!
!
!
84!
WHO,!2011);!in!a!three\country!comparison!between!Japan,!the!US,!and!Denmark,!
the!gender!gap!was!greatest!in!Japan!(Oksuzyan!et!al.,!2010).!
!
Studies!on!mortality!in!the!US!and!Japan!clearly!demonstrate!that!for!many!
health!indicators!Americans!are!at!a!disadvantage!with!regards!to!their!health!
profile.!!However,!the!literature!still!leaves!a!question!about!whether!the!prevalence!
of!risk!factors!for!mortality!simply!occur!at!a!lower!rate!in!Japan!or!whether!they!
have!varying!effects!on!mortality!in!the!two!countries.!It!is!also!unclear!about!how!
true!this!is!at!the!oldest!ages!when!there!has!been!a!narrowing!of!differences!in!
mortality!between!the!US!and!Japan.!This!study!aims!to!examine!whether!the!
prevalence!of!risk!factors!for!mortality!occur!at!a!lower!rate!in!Japan!or!whether!
they!have!varying!effects!on!mortality!at!older!ages.!
Methods!
Data'Sources!
NUJLSOA.!This!study!examines!data!collected!in!2006,!and!uses!vital!status!
data!from!a!mortality!follow\up!survey!completed!in!2008.!!The!Nihon!University!
Japanese!Longitudinal!Study!of!Aging!(NUJLSOA)!is!a!nationally!representative!
sample!of!the!Japanese!population!aged!65!and!older!at!baseline!collected!by!the!
Nihon!University!Tokyo,!Japan.!!The!first!wave!of!data!was!collected!in!1999!and!
subsequent!waves!were!conducted!in!2001,!2003,!and!2006.!!New!participants!were!
added!at!the!second!and!third!waves!so!as!to!remain!nationally!representative!of!the!
65!and!older!population.!!New!participants!were!not!added!at!the!fourth!and!fifth!
waves!in!2006!and!2008!so!that!the!fourth!wave!contains!data!from!participants!
!
!
85!
aged!68!years\or\older.!Complete!information!on!the!design!and!methods!of!the!
study!can!be!found!on!the!website!of!the!Nihon!University!Center!for!Information!
Networking
!
(NUJLSOA!website,!2004).!
The!fourth!wave!of!the!survey!includes!3,395!participants!68!years\or\older;!
84.8%!(n=2,879)!had!a!vital!status!follow\up!in!2008,!with!the!remainder!unknown!
(n=516).!!The!interval!between!the!first!interviews!of!Wave!4!and!the!final!vital!
status!follow\ups!of!Wave!5!is!32!months.!!Of!those!respondents!with!a!2008!follow\
up,!49.2%!(n=1,417)!were!included!in!the!analytic!sample,!1,320!were!found!alive!
and!97!were!known!to!be!dead!(Table!A3!of!the!Appendix);!details!on!sample!size!
can!be!found!in!Figure!A1!of!the!Appendix.!!Of!the!sample!included!for!analysis,!
53.5%!were!female!and!46.5%!were!male.!The!average!age!of!the!participants!used!
in!the!analyses!was!75.7;!details!on!other!descriptive!statistics!can!be!found!in!Table!
1.!!
Participants!who!were!excluded!from!the!2006!analytic!sample!differ!from!
those!in!the!analytic!sample!in!the!following!ways:!the!excluded!sample!has!a!higher!
prevalence!of!underweight!BMI!(p<.001)!and!people!who!have!never!smoked!
(p<.001);!lower!prevalence!of!former!smokers!(p<.001);!more!that!twice!the!
prevalence!of!stroke!(p<.001);!higher!CES\D!(depression)!scores!(p<.001);!worse!
cognitive!performance!(p<.001)!and!grip!strength!(p<.05);!higher!number!of!
functioning!difficulties!(p<.001);!!3.55!years!older!(p<.001);!0.89!years!less!
education!(p<.001);!and!more!females!than!males!(p<.05).!
Sample!weights!specific!to!the!2006!data!were!provided!by!the!survey!to!
adjust!for!nonresponse!and!sampling.!!An!adjusted!weight!was!created!to!account!
!
!
86!
for!having!missing!data!on!health!measurements.!!The!adjustment!was!created!by!
multiplying!the!normalized!weight!of!the!sample!by!the!inverse!of!the!predicted!
probability!that!each!participant!would!have!a!measurement.!!The!adjusted!weight!
was!used!in!all!analyses.!
HRS.!The!Health!and!Retirement!Study!(HRS)!surveys!more!than!22,000!
Americans!over!the!age!of!50!every!two!years.!!Data!for!the!eighth!and!ninth!waves!
of!HRS!used!in!this!study!were!collected!in!2006!and!2008!and!were!chosen!to!
correspond!to!the!timing!of!the!fourth!and!fifth!waves!of!NUJSLOA.!!Half!of!the!HRS!
2006!sample!was!randomly!selected!at!the!household!level!to!participate!in!an!
enhanced!face\to\face!interview!where!blood!pressure,!height,!and!weight!were!
measured!along!with!the!collection!of!other!physical!and!biological!measures.!!
Respondents!who!used!a!proxy,!were!residing!in!a!nursing!home,!or!who!
participated!via!a!phone!interview!were!not!considered!for!the!enhanced!face\to\
face!interview.!
The!data!used!for!this!study!are!a!subset!of!all!2006!participants!who!were!
68!years\or\older!in!2006!(n=9,262),!and!uses!only!vital!status!data!from!survivor!
interviews,!National!Death!Index!(NDI)!tracking,!and!social!security!reports!
completed!by!the!HRS!for!2008;!51.1%!(n=4,734)!of!participants!68!years\or\older!
were!eligible!to!participate!in!the!face\to\face!interview.!!The!interval!between!the!
first!interviews!of!Wave!8!and!the!final!vital!status!follow\ups!of!wave!9!is!36!
months.!!The!final!analytic!sample!included!62.2%!(n=2,947)!of!the!eligible!sample!
(n=4,734),!of!which!2,762!were!known!to!be!alive!and!185!were!known!to!be!dead!
(Table!A3!of!the!Appendix).!!The!resulting!sample!size!included!57.8%!females.!!The!
!
!
87!
average!age!of!the!analytic!sample!was!76.4;!details!on!other!descriptive!statistics!
can!be!found!in!Table!1.!!!
Participants!who!were!excluded!from!analysis!differ!from!the!analytic!sample!
in!the!following!ways!(Table!A1!of!the!Appendix):!the!excluded!sample!has!a!higher!
prevalence!of!underweight!(p<.001)!and!normal!BMI!(p<.001)!and!a!lower!
prevalence!of!overweight/obese!BMI!(p<.001);!higher!prevalence!of!diabetes!
(p<.01),!heart!disease!(p<.01),!and!stroke!(p<.001);!higher!CES\D!(depression)!
scores!(p<.001);!1.62!lower!cognitive!scores!(p<.001);!nearly!one!more!(0.93)!
functioning!difficulty!(p<.001);!1.83!years!older!(p<.001);!1.36!years!less!education!
(p<.001);!and!a!higher!prevalence!of!living!alone!(p<.001).!
Biomarker!sample!weights!for!2006!were!provided!by!the!survey!to!adjust!
for!nonresponse!and!sampling!and!were!used!in!all!analyses.!
Measurements!
Mortality!was!coded!as!a!categorical!variable,!which!included!those!who!died!
between!2006!and!2008,!those!who!survived,!and!those!with!unknown!vital!status!
for!the!2008!follow\up.!!Table!A3!of!the!Appendix!details!the!frequencies!and!
characteristics!of!those!who!died!in!the!two!year!interval!in!the!NUJLSOA!and!the!
HRS!samples.!!Date!of!death!is!not!available!in!this!version!of!the!data,!so!we!assume!
death!happened!at!the!midpoint!of!the!interval.!
Health!Behavior!
BMI,!calculated!by!dividing!weight!(kg)!by!the!square!of!height!(m)!
(BMI=kg/m
2
),!was!separated!into!three!dichotomous!variables,!underweight,!
normal!(referent),!and!overweight/obese.!!Underweight!was!creating!by!coding!a!1!
!
!
88!
for!those!whose!BMI!was!2
!and!0!indicated!not!being!underweight.!!
Normal!(the!referent!category)!was!coded!as!1!for!those!who!had!a!BMI!between!
18.5!kg/m
2
\25!kg/m
2!
(exclusive),!and!0!if!not!within!that!range.!!A!value!of!1!for!
overweight/obese!indicated!having!a!BMI!≥!25!kg/m
2!
and!0!if!less.!!
Smoking!was!coded!as!three!dichotomous!variables;!never!smoked,!former!
smoker,!and!current!smoker.!!Current!smoker!was!created!by!coding!a!1!for!those!
who!reported!smoking!and!a!0!for!those!who!reported!not!currently!smoking.!!
Former!smoker!was!created!by!coding!a!1!for!those!who!reported!having!smoked!in!
the!past!but!who!did!not!report!currently!smoking!and!0!if!they!are!not!former!
smokers.!!Never!smoked!was!created!by!coding!a!1!for!those!who!did!not!report!
ever!smoking!and!who!do!not!currently!smoke!and!a!0!for!those!who!reported!being!
either!former!or!current!smokers.!
Health!Conditions!
The!hypertension!variables!were!dichotomous!and!were!created!in!the!
following!way.!!Respondents!who!answered,!either!“yes”!or!“no”!!to!a!self\report!of!
hypertension!and!had!as!SBP!no!hypertension!or!controlled!hypertension!(referent!category),!while!respondents!
with!a!SBP!≥!140!mmHg!or!DBP!≥!90!mmHg!were!classified!as!
uncontrolled/undiagnosed.!!
Diabetes,!heart!disease,!stroke,!and!cancer!(excluding!skin!cancer)!were!
coded!as!dichotomous!measures,!with!1!indicating!having!had!the!given!condition.!!
The!CES\D!score,!a!measure!of!depression,!is!out!of!5!comparable!questions!between!
!
!
89!
NUJLSOA!and!HRS!(Suthers,!Saito,!&!Crimmins,!2003).!!The!CES\D!score!was!used!as!
a!continuous!measure,!where!a!higher!score!indicated!higher!levels!of!depression.!
! Both!HRS!and!NUJLSOA!measured!cognitive!performance!using!a!series!of!tests!
to!assess!memory!and!working!memory!comprised!of!a!10!item!immediate!and!
delayed!word!recall!and!a!5!item!serial!7!trial.!!The!number!correct!for!each!of!the!
three!tests!was!added!to!create!a!total!cognitive!score,!which!ranged!from!0\25.!!A!
correct!trial!in!word!recall!was!defined!as!any!word!correctly!recalled.!!For!the!serial!
7’s,!a!correct!trial!was!defined!as!any!trial!were!the!difference!between!the!previous!
and!current!trial!was!equal!to!7.!
Frailty!
! Two!measures!of!frailty!were!used!in!the!analyses:!1)!total!number!
functioning!difficulties!and!2)!grip!strength.!!The!sum!of!five!ADL!(bathing,!dressing,!
eating,!walking,!and!going!to!the!bathroom!alone)!and!five!IADL!(preparing!meals,!
shopping,!managing!money,!using!the!phone,!and!taking!medication)!difficulties!was!
used!to!create!the!total!functioning!difficulties!measure,!which!was!coded!as!a!
continuous!variable.!!Grip!strength!(kg)!was!created!by!first!taking!the!highest!
measurement!between!the!two!hands,!then!norming!the!measure!on!the!mean!by!
country,!and!dividing!by!weight!(kg).!!The!grip!strength!measurements!were!
normed!to!account!for!procedural!differences!in!grip!strength!measurement!
between!the!two!surveys.!!The!different!measurement!is!based!on!the!angle!at!which!
the!test!was!done.!!In!the!US,!participants!were!instructed!to!hold!their!hand!at!a!90!
degree!angle!relative!to!the!their!body,!while!in!Japan!participants!were!simply!told!
to!hold!the!dynomometer!at!their!side.!
!
!
90!
Sociodemographic!measures!
! Age!was!used!as!a!categorical!variable!with!six!categories:!68\69!(referent),!
70\74,!75\79,!80\84,!85\89,!and!90!years!or!older.!Education!was!used!as!a!
continuous!measure.!!Childhood!rural!residence!was!coded!as!a!dichotomous!
variable,!where!1!indicated!rural!residence!during!childhood!and!0!indicated!non\
rural!residence.!!Living!alone!was!coded!as!a!dichotomous!variable,!where!1!
indicated!living!alone!and!0!indicated!living!with!at!least!one!other!person.!
Statistical'Methods'
! All!analyses!were!conducted!on!Statistical!Analysis!System!(SAS)!9.2!(SAS!
Institute,!Inc,!Cary,!NC).!!Mortality!analyzes!were!performed!using!multinomial!
logistic!regression!analysis!on!pooled!data!across!the!two!countries.!!The!CATMOD!
command!was!used!to!account!for!those!missing!in!mortality!status;!the!mortality!
results!of!interest!compare!those!known!to!die!and!those!known!to!survive.!!The!
results!showing!the!difference!between!the!missing!and!the!survivors!are!included!
in!Tables!A2a\b!of!the!Appendix.!!!!The!series!of!regressions!begins!with!a!model!
that!includes!only!age!groups!and!country,!followed!by!a!model!that!includes!age!
groups,!country,!and!their!interactions.!This!indicates!the!effect!of!country!when!age!
is!controlled!and!provides!an!indicator!of!the!effect!of!each!age!group!on!mortality!
relative!to!the!youngest.!!The!addition!of!variables!in!subsequent!models!indicates!
the!effect!of!the!added!variables!and!whether!the!effect!of!country!changes!with!
controls!for!those!variables.!The!fifth,!and!final,!regression!model!includes!variables!
indicating!the!country!and!country*predictor!interactions!in!order!to!see!if!there!are!
differences!in!the!effects!in!the!two!countries!(Tables!2!and!3a\b).!
!
!
91!
The!final!n!using!the!pooled!data!is!4,364.!!Significant!country!differences!for!
descriptive!statistics!are!indicated!by!p\values!obtained!from!two\sided!t\tests!and!
chi\square!tests!(Table!1).!!
Results!
Descriptive'Statistics!
Table!1!shows!the!descriptive!statistics!for!mortality,!health!behavior,!health!
condition,!frailty,!and!sociodemographic!characteristics!by!gender!for!the!US!and!
Japan.!!Differences!in!mortality!and!measures!of!predictors!were!tested!using!a!two\
tailed!t\test!or!chi\square.!!Mortality!did!not!significantly!differ!between!men!or!
women!in!the!two!countries!between!2006!and!2008:!among!Japanese!women!5.1%!
died!in!two!years,!this!was!true!for!6.1%!of!American!women.!!Among!Japanese!men!
7.6%!died!in!two!years,!this!was!true!for!7.9%!of!American!men.!
Men!and!women!in!the!US!had!a!higher!percentage!of!overweight/obese!
individuals!than!men!and!women!in!Japan!(p<.001),!who!had!a!higher!prevalence!of!
normal!(p<.001)!and!underweight!(p<.001)!BMI.!!The!opposite!pattern!was!seen!for!
smoking,!where!the!US!had!a!higher!percentage!of!men!who!never!smoked!(p<.001)!
and!Japan!had!a!higher!prevalence!of!men!who!were!current!smokers!(p<.001).!!The!
US!had!a!higher!prevalence!of!women!who!are!former!(p<.001)!and!current!(p<.01)!
smokers,!whereas!Japan!had!a!higher!prevalence!of!women!who!had!never!smoked.!
Compared!to!the!Japanese,!a!greater!percentage!of!Americans!of!both!
genders!had!no!hypertension/controlled!hypertension!(p<.001),!whereas!Japanese!
women!had!a!higher!prevalence!of!undiagnosed/uncontrolled!hypertension!
(p<.001)!compared!to!American!women.!!A!greater!number!of!American!men!and!
!
!
92!
women!reported!having!had!diabetes!(p<.001),!heart!disease!(p<.001),!stroke!
(women:!p<.001;!men:!p<.01),!and!cancer!(p<.001)!compared!to!their!Japanese!
counterparts.!!Since!cancer!was!self\reported,!the!difference!in!cancer!is!likely!
partially!due!to!cultural!differences!in!informing!or!not!informing!elderly!patients!
that!they!have!cancer,!as!well!as!in!screening!practices.!!!
Japanese!men!and!women!had!higher!CES\D!scores!than!Americans!(p<.001),!
whereas!men!and!women!in!the!US!had!higher!total!cognitive!scores!compared!to!
the!Japanese!(p<.001).!!American!women!had!a!higher!number!of!functioning!
difficulties!than!Japanese!women!(p<.001);!there!was!no!significant!difference!in!
number!of!functioning!difficulties!between!Japanese!and!American!men.!!!!The!
average!age!of!Japanese!men!was!older!than!the!average!age!of!American!men!
(p<.01).!!The!American!sample!had!more!years!of!education!(p<.001)!and!a!higher!
percentage!living!alone!(p<.001)!than!the!Japanese!sample,!who!reported!higher!
rates!of!living!in!a!rural!environment!during!childhood!(p<.001).!
Country'Interactions'
In!order!to!examine!differences!across!countries!in!the!associations!of!
individual!variables!with!mortality,!we!examine!interactions!with!individual!
variables!before!adding!only!the!significant!ones!to!the!equation.!This!enables!us!to!
reduce!the!number!of!interaction!terms!and!make!the!estimation!more!tractable.!!
Table!2!summarizes!the!country!and!predictor!variable!interactions!for!mortality!
outcomes.!!Each!interaction!term!was!included!in!a!separate!CATMOD!logistic!
regression,!which!simultaneously!controlled!for!health!behaviors,!chronic!
!
!
93!
conditions,!frailty,!sociodemographic!characteristics,!country,!and!unknown!vital!
status.!!!!
The!odds!ratios!and!95%!CI!for!mortality!revealed!four!significant!country!
interactions!for!women!(70\74!years!old,!80\84!years!old,!heart!disease,!and!living!
alone)!and!men!(75\79!years!old,!80\84!years!old,!current!smoker,!and!cancer,).!!!
The!results!for!age!and!country!interactions!reveal!a!stronger!effect!at!age!
(70\74!years)!on!mortality!in!Japanese!women!than!American!women!(3.04,!CI:!
1.04\8.86)!and!!a!weaker!effect!at!ages!80\84!(0.20,!CI:!0.07\0.54).!!The!results!for!
men!indicate!a!weaker!effect!of!age!(75\79!years!old)!for!Japanese!men!compared!to!
American!men!(0.58,!CI:!0.27\1.28)!and!stronger!effect!at!ages!80\84!years!old!(2.37,!
CI:!1.14\4.96).!!!
The!results!also!revealed!that!reporting!that!one!has!heart!disease!(2.57,!CI:!
1.05\6.29)!and!living!alone!(2.29,!CI:!1.08\4.85)!have!stronger!effects!on!mortality!in!
Japanese!women!than!in!American!women.!!Similarly,!cancer!(2.76,!CI:!1.06\7.18)!
has!a!stronger!effect!on!Japanese!men!than!in!American!men,!however,!current!
smoking!has!a!weaker!effect!on!Japanese!men,!compared!to!American!men!(0.36,!
CI:0.15\0.84).!
Prediction'of'Mortality!
Tables!3a\b!show!four!logistic!regression!models!for!mortality!in!women!(a)!
and!men!(b).!!Model!I!controls!for!only!age!groups!and!country.!!Model!II!controls!
for!age!group,!country,!and!age!and!country!interactions.!!Model!III!controls!for!
health!behavior,!cognitive!performance,!sociodemographic!characteristics,!and!
!
!
94!
country.!!Model!IV!controls!for!chronic!conditions.!!The!final!model,!Model!V!adds!
the!significant!interactions!from!Table!2.!
Model!I!indicates!that!a!country!difference!in!mortality!does!not!exist!when!
controlling!for!age!group!and!country.!!As!expected,!increasing!age!increased!the!
risk!of!mortality.!!Model!II!demonstrates!no!significant!effect!of!country!on!
mortality.!!!Age!increases!risk!of!mortality!across!all!models!but!country!differences!
in!the!effect!of!age!groups!is!seen!only!in!women!and!only!in!the!80\84!age!group,!
where!Japanese!women!experience!an!effect!of!12.17!(main!effect!+!
interaction=12.05+\0.12)!and!American!women!experience!an!effect!of!12.05!
relative!to!the!youngest!age!group.!!The!effect!of!the!interaction!with!the!80\84!age!
group!is!seen!across!all!models.!!!
When!controlling!for!additional!variables!in!Model!III,!an!effect!of!country!
can!be!seen!in!men,!with!Japanese!men!having!lower!risk!of!mortality!than!American!
men.!In!the!final!model,!Model!V,!country!differences!in!the!effects!of!living!alone!
and!heart!disease!remain!for!women;!3.01!for!living!alone!and!an!effect!of!3.76!for!
heart!disease!for!Japanese!women!and!non\significant!effects!of!0.74!and!1.24!for!
American!women!for!living!alone!and!heart!disease,!respectively.!!For!men,!country!
interactions!for!cancer!and!current!smoking!do!not!remain!significant!in!Model!V.!
In!women,!underweight!BMI!(2.95,!CI:!1.63\5.32),!higher!CES\D!scores!(1.20,!
CI:!1.05\1.37),!higher!number!of!functioning!difficulties!(1.13,!CI:!1.01\1.26),!and!a!
rural!childhood!(1.60,!CI:!1.12\2.29)!increase!risk!of!mortality.!!Overweight/obese!
BMI!(0.48,!CI:!0.31\0.72),!higher!cognitive!performance!scores!(0.91,!CI:!0.87\0.95),!
and!higher!grip!strength!(1.13,!CI:!1.01\1.26)!decrease!risk!in!women.!!In!men,!
!
!
95!
underweight!BMI!(2.13,!CI:!1.10\4.12),!former!(1.85,!CI:!1.19\2.89)!and!current!
(6.78,!CI:!3.39\13.56)!smoking,!higher!number!of!functioning!difficulties!(1.30,!CI:!
1.16\1.47),!diabetes!(2.04,!CI:!1.38\3.01),!and!heart!disease!(1.54,!CI:!1.06\2.24)!
increase!risk!of!mortality.!!Overweight/obese!BMI!(0.36,!CI:!0.23\0.56),!higher!
cognitive!performance!scores!(0.91,!CI:!0.87\0.95),!higher!grip!strength!(0.08,!CI:!
0.01\0.48),!and!stroke!(0.52,!CI:!0.29\0.96)!decrease!risk.!
Discussion!
The!intent!of!this!paper!was!to!examine!potential!differences!in!mortality!
between!the!US!and!Japan!and!the!role!played!by!differences!in!levels!of!risk!factors!
and!the!effects!of!risk!factors!on!mortality.!!Logistic!regression!models!using!a!
pooled!dataset!across!the!two!countries!found!little!evidence!of!significant!
differences!between!the!two!countries!in!the!levels!of!mortality,!though!levels!of!
mortality!risk!factors!differed!significantly!between!countries.!!!
Japanese!men!had!more!than!three!times!the!prevalence!of!current!smoking!
than!American!men,!yet!differences!in!mortality!were!not!significant!between!
groups!when!not!controlling!for!risk!factors.!!When!all!but!the!chronic!condition!risk!
factors!were!controlled,!Japanese!men’s!odds!of!mortality!was!0.27!based!on!the!
main!effect!of!country!from!Table!3b!Model!III.!!It!is!also!interesting!to!note!that!
when!chronic!conditions!were!controlled!in!men,!the!main!effect!of!country!was!no!
longer!significant!(Table!3b,!Model!IV),!meaning!that!when!Japanese!and!American!
men!have!the!same!level!of!chronic!conditions,!no!significant!main!effect!of!country!
is!found.!!
!
!
96!
Differences!in!mortality!at!these!ages!between!Japan!and!US!appear!to!be!
relatively!weak.!Being!a!current!smoker!and!having!cancer!appear!to!be!related!to!
mortality!differently!in!Japan,!however!when!controlling!for!multiple!interactions,!
they!no!longer!stand!out!as!different!effects.!!!
Not!surprisingly,!being!underweight!was!linked!to!an!increased!risk!of!death,!
while!being!overweight/obese!significantly!reduced!mortality!rates;!other!studies!
have!found!a!similar!pattern!(Reynolds!et!al.,!2008).!!This!finding,!coupled!with!
Americans!having!higher!levels!of!overweight/obese!BMI!and!Japanese!having!
higher!levels!of!underweight!BMI!(Table!1)!partially!explains!the!finding!in!Table!1!
that!mortality!levels!are!not!significantly!different!between!countries.!!!
As!expected!both!former!and!current!smoking!increased!the!risk!of!death!for!
men!and,!interestingly,!the!effect!grew!stronger!after!controlling!for!chronic!
conditions.!!Japanese!men!have!nearly!three!times!the!rate!of!current!smoking!than!
American!men!(Table!1),!partially!explaining!the!finding!that!even!when!not!
controlling!for!any!risk!factors!in!Table!1,!mortality!rates!are!not!significantly!
different!between!countries.!!The!effect!of!smoking!is!not!seen!for!women!because!
very!few!have!smoked,!compared!to!men.!
Interestingly,!the!effect!of!age!groups!persists!for!women!through!the!various!
models!in!Tables!3a\b,!however!the!effect!of!age!groups!is!lost!in!men!when!
controlling!for!additional!risk!factors.!!This!finding!suggests!that!the!higher!presence!
of!chronic!conditions!and!frailty!at!older!ages!has!a!greater!effect!on!men’s!risk!of!
mortality!than!on!women’s.!!
!
!
97!
Living!alone!was!another!factor!significantly!associated!with!a!significant!
country!interaction!in!women.!!However,!the!main!effect!of!living!alone!was!not!
significantly!associated!with!mortality.!!The!literature!has!shown!country!
differences!in!the!effect!of!living!alone!on!health!and!mortality!(Magaziner!et!al.,!
1998;!Saito!et!al.,!2005),!which!points!to!cultural!differences!in!this!risk!factor,!in!
fact!the!prevalence!of!living!alone!in!the!US!is!about!twice!as!high!as!in!Japan!for!
both!genders!(Table!1).!!It!will!be!interesting!to!see!how!Westernization!and!Japan’s!
low!fertility!rate!will!affect!this!measure.!!!!!!
There!are!obvious!differences!in!disease!prevalence!and!socioeconomic!
characteristics!between!the!US!and!Japan,!however!there!are!no!obvious!
explanations!for!differences!in!mortality!between!the!two!countries.!Some!of!the!
reasons!for!Japan’s!long!life!expectancy!are!linked!to!lower!mortality!before!
reaching!old!age,!but!not!necessarily!lower!after.!! !
!
!
98!
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105!
Table!1.!Descriptive!statistics!of!sample!characteristics.!T7tests!and!chi!square!used!
to!test!significance!between!countries!within!genders.!
!! Women& Men&
&& Japan& US& && Japan& US&
!!
Measure&
Mean/&
Percent&
SD&
Mean/&
Percent&
SD& &&
Mean/&
Percent&
SD&
Mean/&
Percent&
SD&
!!
Mortality!(%)! 5.1! 000 ! 6.1! 000 ! !! 7.6! 000 ! 7.9! 000 ! !!
!!!!!Health!Behavior!
Underweight!
(<18.5kg/m
2
)!(%)!
9.6! 000 ! 2.1! 000 ! ***! 9.0! 000 ! 0.1! 000 ! ***!
Normal!weight!
(18.50<25kg/m
2
)!
(%)!
71.2! 000 ! 32.4! 000 ! ***! 73.2! 000 ! 22.2! 000 ! ***!
Overweight/obes
e!(≥25kg/m
2)
!(%)!
19.1! 000 ! 65.5! 000 ! ***! 17.9! 000 ! 77.8! 000 ! ***!
Never!smoked!
(%)!
70.1! 000 ! 55.6! 000 ! ***! 18.3! 000 ! 30.1! 000 ! ***!
Former!smoker!
(%)!
24.6! 000 ! 36.3! 000 ! ***! 62.1! 000 ! 63.1! 000 ! !!
Current!smoker!
(%)!
5.3! 000 ! 8.2! 000 ! **! 19.6! 000 ! 6.7! 000 ! ***!
!!!!!Chronic!Conditions!and!Cognitive!Performance!
No!hypertension/!
controlled!(%)!
28.9! 000 ! 62.1! 000 ! ***! 23.5! 000 ! 59.1! 000 ! ***!
Uncontrolled/!
undiagnosed!
hypertension!(%)!
71.2! 000 ! 37.9! 000 ! ***! 76.5! 000 ! 40.9! 000 ! ***!
Diabetes!(%)! 8.7! 000 ! 17.7! 000 ! ***! 11.4! 000 ! 21.8! 000 ! ***!
Heart!disease!(%)! 6.2! 000 ! 26.6! 000 ! ***! 10.6! 000 ! 37.1! 000 ! ***!
Stroke!(%)! 4.4! 000 ! 8.9! 000 ! ***! 7.3! 000 ! 10.2! 000 ! *!
Cancer!(excluding!
skin)!(%)!
2.6! 000 ! 18.3! 000 ! ***! 5.5! 000 ! 23.8! 000 ! ***!
CES0D!score! 1.0! 1.3! 0.7! 1.2! ***! 0.9! 1.2! 0.4! 1.0! ***!
Total!cognitive!
score!
11.9! 5.5! 12.6! 4.5! ***! 11.6! 5.2! 12.6! 3.8! ***!
!!!!!Frailty!
Total!functioning!
difficulties!
0.3! 1.3! 0.4! 1.2! ***! 0.3! 1.4! 0.3! 0.9! !!
Grip!strength!(kg)! 0.4! 0.1! 0.3! 0.1! ! 0.5! 0.1! 0.4! 0.1! !
!!!!!Sociodemographic!
Age!(years)! 77.1! 7.7! 76.6! 6.5! !! 76.7! 7.1! 76.0! 6.0! **!
Education!(years)! 9.5! 2.8! 12.5! 2.7! ***! 10.4! 3.6! 12.9! 3.3! ***!
Rural!childhood!
residence!(%)!
54.7! 000 ! 46.1! 000 ! ***! 54.8! 000 ! 47.2! 000 ! ***!
Living!alone!(%)! 22.2! 000 ! 41.3! 000 ! ***! 7.0! 000 ! 15.3! 000 ! ***!
n! 747! 1669! !! 670! 1278! !!
!*p<.05,!**p<.01,!***p<.001
! !
!
!
!
106!
Table!2.!Summary!table!of!interaction!effects!of!country!and!predictor!interactions!
indicating!the!effect!of!the!likelihood!of!dying!relative!to!surviving.!!Each!interaction!
was!included!separately!in!a!CATMOD!logistic !regression!of!mortality!regressed!on!
health!behavior,!chronic!conditions,!frailty,!sociodemographic!characteristics,!
country,!and!country*predictor!variable!interactions!for!women!and!men
#
,!
(Japan=1).!
Women (n=2416) Men (n=1948)
OR 95% CI OR 95% CI
Japan*70-74 years 3.04 1.04 8.86 0.56 0.23 1.37
Japan*75-79 years 0.90 0.39 2.07 0.58 0.27 1.28
Japan*80-84 years 0.20 0.07 0.54 2.37 1.14 4.96
Japan*85-89 years 2.31 0.97 5.49 1.06 0.43 2.62
Japan*90+ years 1.06 0.33 3.37 2.05 0.44 9.54
Japan*underweight BMI 1.10 0.34 3.50 --- --- ---
Japan*overweight/ obese
BMI
0.95 0.34 2.68 0.78 0.26 2.35
Japan*former smoker 1.73 0.75 3.99 1.75 0.86 3.55
Japan*current smoker 0.62 0.08 5.07 0.36 0.15 0.84
Japan*CES-D 1.11 0.82 1.50 1.17 0.86 1.60
Japan*cognitive 1.04 0.96 1.13 1.03 0.94 1.12
Japan*total functioning
difficulties
0.93 0.76 1.14 1.05 0.84 1.30
Japan*grip strength --- --- --- 0.14 0.01 3.68
Japan*education 0.87 0.73 1.03 0.95 0.85 1.07
Japan*rural childhood 0.64 0.33 1.23 1.31 0.76 2.27
Japan*alone 2.29 1.08 4.85 0.94 0.30 2.93
Japan*uncontrolled/
undiagnosed hypertension
0.88 0.41 1.86 1.57 0.75 3.28
Japan*diabetes 0.64 0.21 1.92 0.58 0.24 1.39
Japan*heart disease 2.57 1.05 6.29 0.55 0.21 1.41
Japan*stroke --- --- --- 1.74 0.52 5.79
Japan*cancer 0.65 0.09 4.61 2.76 1.06 7.18
Significant!interactions!indicated!in!bold!font.!
#
Each!regression!controlled!for!underweight!BMI,!overweight/obese!BMI,!former!
smoker,!current!smoker,!uncontrolled!hyerptension,!diabetes,!heart!disease,!stroke,!
cancer,!CESOD!score,!cognitive!score,!total!functioning!difficulties,!grip!strength,!age!
!
!
!
107!
group,!education,!childhood!rural!residence,!living!alone,!country,!and!one!
country*risk!factor!interaction.
!
!
!
108!
Tables!3a,b.!CATMOD!Logistic!regression!of!pooled!data.!!Mortality!regressed!on!age!groups!and!country,!(Model!I);!age!and!
country!interactions!(Model!II);!health!behavior,!cognitive!performance,!frailty,!and!sociodemographic!characteristics!(Model!
III);!chronic!conditions!(Model!IV);!country!interactions!(Model!V).!
Table!3a.!Women!
Women&(n=2416)&
&& Model&I& Model&II& Model&III& Model&IV& Model&V&
&& OR& 95%&CI& OR& 95%&CI& OR& 95%&CI& OR& 95%&CI& OR& 95%&CI&
70;74&years
1&
1.65& 0.65& 4.14& 1.78& 0.47& 6.84& 1.66& 0.43& 6.44& 1.45& 0.37& 5.75& 1.50& 0.38& 5.94&
75;79&years& 3.80% 1.62% 8.91% 5.59% 1.59% 19.69% 3.96% 1.11% 14.19% 3.82% 1.06% 13.72% 4.07% 1.13% 14.64%
80;84&years& 6.06% 2.58% 14.23% 12.05% 3.45% 42.07% 7.23% 2.02% 25.93% 6.93% 1.92% 24.98% 7.54% 2.09% 27.25%
85;89&years& 9.93% 4.17% 23.67% 10.18% 2.78% 37.31% 6.55% 1.72% 24.98% 5.74% 1.49% 22.19% 6.62% 1.70% 25.71%
90+&years& 23.18% 9.22% 58.27% 22.34% 5.74% 86.98% 8.91% 2.15% 36.93% 8.98% 2.15% 37.48% 10.51% 2.50% 44.19%
Country&(Japan=1)& 0.78& 0.56& 1.09& 1.49& 0.30& 7.39& 1.15& 0.22& 5.92& 1.39& 0.27& 7.26& 1.03& 0.20& 5.47&
Country*70;74&
years& && && && 1.08& 0.17& 6.94& 1.14& 0.17& 7.64& 1.31& 0.19& 8.87& 1.27& 0.19& 8.65&
Country*75;79&
years& && && && 0.42& 0.07& 2.38& 0.51& 0.09& 3.02& 0.44& 0.07& 2.68& 0.36& 0.06& 2.23&
Country*80;84&
years& && && && 0.12% 0.02% 0.77% 0.12% 0.02% 0.77% 0.12% 0.02% 0.81% 0.10% 0.02% 0.68%
Country*85;89&
years& && && && 1.02& 0.18& 5.89& 0.75& 0.12& 4.56& 0.88& 0.14& 5.46& 0.75& 0.12& 4.68&
Country*90+&years& && && && 1.27& 0.20& 8.13& 0.57& 0.08& 4.17& 0.55& 0.08& 4.00& 0.34& 0.05& 2.57&
Underweight
2&
&& && && && && && 3.05% 1.73% 5.38% 2.93% 1.62% 5.28% 2.95% 1.63% 5.32%
Overweight/&obese& && && && && && && 0.47% 0.31% 0.71% 0.47% 0.31% 0.71% 0.48% 0.31% 0.72%
Former&smoker
3&
&& && && && && && 1.43& 0.97& 2.08& 1.38& 0.94& 2.03& 1.38& 0.94& 2.04&
Current&smoker& && && && && && && 1.11& 0.52& 2.37& 1.10& 0.51& 2.40& 1.12& 0.52& 2.45&
CES;D& && && && && && && 1.22% 1.07% 1.39% 1.18% 1.04% 1.35% 1.20% 1.05% 1.37%
!
!
!
109!
Total&cognitive&score& && && && && && && 0.91% 0.87% 0.95% 0.91% 0.87% 0.95% 0.91% 0.87% 0.95%
Total&functioning&
difficulties& && && && && && && 1.15% 1.03% 1.27% 1.13% 1.01% 1.26% 1.13% 1.01% 1.26%
Grip&strength&(kg)& && && && && && && 0.02% 0.00% 0.19% 0.02% 0.00% 0.21% 0.02% 0.00% 0.22%
Education&(years)& && && && && && && 1.00& 0.93& 1.08& 0.99& 0.92& 1.06& 0.99& 0.92& 1.06&
Rural&childhood&
residence& && && && && && && 1.62% 1.14% 2.29% 1.53% 1.07% 2.18% 1.60% 1.12% 2.29%
Living&alone& && && && && && && 0.92& 0.64& 1.31& 0.95& 0.66& 1.36& 0.74& 0.48& 1.14&
Uncontrolled/&
undiagnosed&
hypertension
4&
&& && && && && && && && && 0.90& 0.63& 1.29& 0.92& 0.65& 1.31&
Diabetes& && && && && && && && && && 1.43& 0.92& 2.23& 1.40& 0.90& 2.19&
Heart&disease& && && && && && && && && && 1.48% 1.00% 2.21% 1.24& 0.79& 1.94&
Stroke& && && && && && && && && && 0.82& 0.44& 1.53& 0.85& 0.46& 1.59&
Cancer&(excluding&
skin)& && && && && && && && && && 1.50& 0.95& 2.36& 1.49& 0.95& 2.35&
Japan*alone& && && && && && && && && && && && && 2.27% 1.06% 4.86%
Japan*heart&disease& && && && && && && && && && && && && 2.52% 1.01% 6.29%
&& && && && && && && && && && && && && %% %% %%
Chi;square& 27.99& && && 134.92& && && 2398.44& && && 2329.84& && && 2321.14& %% %%
1
68,69!years!old!was!use!as!the!referent.!
2
Normal!weight!(18.5,<25!kg/m
2
)!was!used!as!the!referent.!
3
Never!smoked!was!used!as!the!referent.!
4
No!hypertension!was!used!as!the!referent.!
!
! !
!
!
!
110!
Table!3b.!Men!
Men&(n=1948)&
&& Model&I& Model&II& Model&III& Model&IV& Model&V&
&& OR& 95%&CI& OR& 95%&CI& OR& 95%&CI& OR& 95%&CI& OR& 95%&CI&
70;74&years
1&
1.32& 0.67& 2.58& 1.19& 0.52& 2.71& 1.24& 0.53& 2.89& 1.21& 0.51& 2.86& 1.26& 0.53& 3.01&
75;79&years& 1.68& 0.87& 3.23& 1.79& 0.79& 4.06& 1.25& 0.54& 2.93& 1.09& 0.46& 2.59& 1.15& 0.48& 2.76&
80;84&years& 4.05% 2.14% 7.66% 2.84% 1.25% 6.46% 1.71& 0.73& 4.03& 1.57& 0.65& 3.75& 1.70& 0.70& 4.11&
85;89&years& 4.62% 2.32% 9.22% 3.53% 1.44% 8.61% 2.02& 0.79& 5.16& 1.88& 0.73& 4.89& 2.14& 0.81& 5.62&
90+&years& 10.73% 4.53% 25.40% 5.51% 1.52% 19.88% 2.30& 0.59& 8.93& 2.40& 0.61& 9.47& 2.70& 0.68& 10.79&
Country&(Japan=1)& 0.91& 0.67& 1.24& 0.60& 0.18& 1.97& 0.27% 0.08% 0.94% 0.32& 0.09& 1.14& 0.37& 0.10& 1.36&
Country*70;74&
years& && && && 1.24& 0.30& 5.12& 0.96& 0.22& 4.09& 1.01& 0.23& 4.36& 0.99& 0.23& 4.29&
Country*75;79&
years& && && && 0.86& 0.22& 3.35& 0.97& 0.24& 3.89& 1.16& 0.28& 4.72& 1.06& 0.26& 4.36&
Country*80;84&
years& && && && 2.25& 0.60& 8.39& 2.79& 0.72& 10.85& 3.23& 0.82& 12.79& 2.76& 0.69& 11.10&
Country*85;89&
years& && && && 1.89& 0.46& 7.84& 1.62& 0.37& 7.08& 1.76& 0.40& 7.80& 1.50& 0.33& 6.78&
Country*90+&years& && && && 3.60& 0.60& 21.77& 3.21& 0.48& 21.61& 3.43& 0.50& 23.71& 3.02& 0.43& 21.15&
Underweight
2&
&& && && && && && 2.26% 1.19% 4.32% 2.13% 1.11% 4.11% 2.13% 1.10% 4.12%
Overweight/&obese& && && && && && && 0.39% 0.25% 0.59% 0.36% 0.23% 0.55% 0.36% 0.23% 0.56%
Former&smoker
3&
&& && && && && && 1.79% 1.16% 2.77% 1.83% 1.18% 2.85% 1.85% 1.19% 2.89%
Current&smoker& && && && && && && 4.14% 2.38% 7.20% 4.53% 2.58% 7.95% 6.78% 3.39% 13.56%
CES;D& && && && && && && 1.10& 0.94& 1.29& 1.09& 0.93& 1.28& 1.09& 0.93& 1.28&
Total&cognitive&
score& && && && && && && 0.91% 0.87% 0.95% 0.90% 0.86% 0.95% 0.91% 0.87% 0.95%
Total&functioning&
difficulties& && && && && && && 1.27% 1.13% 1.42% 1.31% 1.16% 1.47% 1.30% 1.16% 1.47%
Grip&strength&(kg)& && && && && && && 0.07% 0.01% 0.38% 0.08% 0.01% 0.49% 0.08% 0.01% 0.48%
Education&(years)& && && && && && && 0.99& 0.93& 1.05& 0.98& 0.93& 1.04& 0.98& 0.92& 1.04&
!
!
!
111!
Rural&childhood&
residence& && && && && && && 0.84& 0.60& 1.17& 0.82& 0.58& 1.15& 0.82& 0.58& 1.15&
Living&alone& && && && && && && 0.92& 0.57& 1.49& 0.87& 0.54& 1.43& 0.87& 0.53& 1.42&
Uncontrolled/&
undiagnosed&
hypertension
4&
&& && && && && && && && && 0.81& 0.57& 1.15& 0.81& 0.57& 1.15&
Diabetes& && && && && && && && && && 2.03% 1.38% 3.00% 2.04% 1.38% 3.01%
Heart&disease& && && && && && && && && && 1.54% 1.06% 2.24% 1.54% 1.06% 2.24%
Stroke& && && && && && && && && && 0.52% 0.29% 0.94% 0.53% 0.29% 0.96%
Cancer&(excluding&
skin)& && && && && && && && && && 1.43& 0.93& 2.21& 1.17& 0.71& 1.92&
Japan*current&
smoker& && && && && && && && && && && && && 1.44& 0.93& 2.23&
Japan*cancer& && && && && && && && && && && && && 0.62& 0.38& 1.01&
&& && && && && && && && && && && && && && && &&
Chi;square& 15.77& && && 106.88& && && 2092.40& && && 2035.84& && && 2028.81& && &&
1
68,69!years!old!was!use!as!the!referent.!
2
Normal!weight!(18.5,<25!kg/m
2
)!was!used!as!the!referent.!
3
Never!smoked!was!used!as!the!referent.!
4
No!hypertension!was!used!as!the!referent.!
!
!
!
112!
Appendix!
Figure!A1.!Reasons!for!loss!of!sample,!Japan!
!
! !
Japan:!68+years!
and!in!2006!data!
3395!
Mortality!followEup!
2879!
BMI!
2630!
Smoking!
2628!
Uncontrolled/!
undiagnosed!
hypertension!
1898!
Diabetes!
1869!
Heart!disease!
1865!
Stroke!
1862!
Cancer!
1862!
CESED!
1860!
Total!cognitive!
1838!
Total!functioning!
difViculties!
1837!
Grip/kg!
1814!
Education!
1752!
Rural!childhood!
1417!
Living!alone!
1417!
!
!
!
113!
Figure!A2.!Reasons!for!loss!of!sample,!United!States!
US:!68+years!
and!in!2006!data!
9262!
Eligible!for!faceEtoE
face!
4734!
Mortality!followEup!
4582!
BMI!
4536!
Smoking!
4499!
Uncontrolled/!
undiagnosed!
hypertension!
3391!
Diabetes!
3386!
Heart!disease!
3384!
Stroke!
3381!
Cancer!
3376!
CESED!
3374!
Total!cognitive!
3374!
Total!functioning!
difViculties!
3374!
Grip/kg!
3130!
Education!
3130!
Rural!childhood!
2947!
Living!alone!
2947!
!
!
114!
Table!A1.!Characteristics!of!participants!who!are!missing/not!missing!on!mortality!follow;up.!
!! Japan! United!States!
!!
Not!missing!!
(n=1417)! Missing!(n=1462)! !! Not!missing!!(n=2947)! Missing!(n=1816)! !!
!! Mean/!%! SD! Mean/!%! SD! !! Mean/!%! SD! Mean/!%! SD! !!
Underweight!BMI!(%)! 9.4! EEE ! 14.6! EEE ! ***! 1.3! EEE ! 4.0! EEE ! ***!
Normal!BMI!(%)! 70.0! EEE ! 67.3! !! !! 28.1! EEE ! 34.8! EEE ! ***!
Overweight/obese!BMI!(%)! 20.6! EEE ! 18.2! EEE ! !! 70.6! EEE ! 61.3! EEE ! ***!
Never!smoked!(%)! 37.3! EEE ! 46.2! EEE ! ***! 45.1! !! 43.4! !! !!
Former!smoker!(%)! 50.4! EEE ! 43.1! EEE ! ***! 47.4! EEE ! 49.4! EEE ! !!
Current!smoker!(%)! 12.3! EEE ! 10.7! EEE ! !! 7.5! EEE ! 7.2! EEE ! !!
Controlled/no!hypertension!(%)! 26.2! EEE ! 21.0! EEE ! !! 60.7! EEE ! 58.7! EEE ! !!
Uncontrolled/diagnosed!
hypertension!(%)! 73.8! EEE ! 79.0! EEE ! !! 39.3! EEE ! 41.3! EEE ! !!
Diabetes!(%)! 10.5! EEE ! 11.5! EEE ! !! 19.5! EEE ! 23.7! EEE ! **!
Heart!disease!(%)! 7.6! EEE ! 8.1! EEE ! !! 31.3! EEE ! 37.2! EEE ! ***!
Stroke!(%)! 5.2! EEE ! 12.4! EEE ! ***! 9.7! EEE ! 18.7! EEE ! ***!
Cancer!(excluding!skin)!(%)! 4.4! EEE ! 4.9! EEE ! !! 20.7! EEE ! 19.7! EEE ! !!
CESED!score! 0.92! 1.24! 1.09! 1.32! ***! 0.58! 1.13! 1.08! 1.49! ***!
Total!cognitive!score! 11.84! 5.43! 10.40! 5.97! ***! 12.54! 4.16! 10.92! 4.73! ***!
Total!functioning!difficulties! 0.27! 1.37! 1.47! 3.54! ***! 0.39! 1.04! 1.29! 1.97! ***!
Grip!strength!(kg)! 0.45! 0.14! 0.44! 0.15! *! 0.37! 0.11! 0.37! 0.11! !!
Age!(years)! 75.74! 7.51! 79.29! 9.22! ***! 76.41! 6.25! 78.24! 6.82! ***!
Education!(years)! 10.08! 3.34! 9.19! 3.49! ***! 12.67! 2.95! 11.31! 3.48! ***!
Female!(%)! 53.5! EEE ! 57.0! EEE ! !! 57.8! EEE ! 61.7! EEE ! ***!
Rural!childhood!residence!(%)! 54.7! EEE ! 57.4! EEE ! !! 46.7! EEE ! 47.2! EEE ! !!
Living!alone!(%)! 14.4! EEE ! 15.7! EEE ! !! 30.3! EEE ! 36.4! EEE ! ***!
*p<.05,!**p<.01,!***p<.001
!
!
115!
Tables!A2a;b.!CATMOD!logistic!regression!of!pooled!data.!!Mortality!regressed!on!age!groups!and!country!(Model!I);!age!and!
country!interactions!(Model!II);!health!behavior,!cognitive!performance,!frailty,!and!sociodemographic!characteristics!(Model!
III);!chronic!conditions!(Model!IV);!country!interactions!(Model!V).!Results!show!comparison!between!living!and!unknown!
vital!status.!
Table!A2a.!Women!
Women!(n=2416)!
!! Model!I! Model!II! Model!III! Model!IV! Model!V!
!! OR! 95%!CI! OR! 95%!CI! OR! 95%!CI! OR! 95%!CI! OR! 95%!CI!
70E74!years
1!
0.86! 0.54! 1.36! 1.78! 0.18! 1.40! 1.66! 0.17! 1.34! 1.45! 0.18! 1.37! 1.50! 0.17! 1.34!
75E79!years! 0.83! 0.54! 1.29! 5.59! 0.34! 2.22! 3.96! 0.25! 1.69! 3.82! 0.25! 1.71! 4.07! 0.25! 1.66!
80E84!years! 0.91! 0.57! 1.46! 12.05! 0.38! 2.87! 7.23! 0.25! 1.94! 6.93! 0.26! 2.05! 7.54! 0.24! 1.96!
85E89!years! 0.76! 0.41! 1.40! 10.18! 0.27! 3.13! 6.55! 0.16! 1.97! 5.74! 0.16! 2.01! 6.62! 0.15! 1.89!
90+!years! 2.06! 0.99! 4.28! 22.34! 0.62! 8.95! 8.91! 0.35! 5.50! 8.98! 0.31! 5.00! 10.51! 0.27! 4.67!
Country!(Japan=1)! 5.39% 3.82% 7.61% 1.49% 2.17% 11.61% 1.15% 3.39% 21.54% 1.39! 3.13! 20.64! 1.03% 3.25% 22.40%
Country*70E74!years! !! !! !! 1.08! 0.65! 6.39! 1.14! 0.42! 4.76! 1.31! 0.40! 4.53! 1.27! 0.40! 4.64!
Country*75E79!years! !! !! !! 0.42! 0.32! 2.69! 0.51! 0.21! 2.08! 0.44! 0.21! 2.08! 0.36! 0.22! 2.16!
Country*80E84!years! !! !! !! 0.12! 0.26! 2.50! 0.12! 0.16! 1.89! 0.12! 0.14! 1.71! 0.10! 0.15! 1.85!
Country*85E89!years! !! !! !! 1.02! 0.19! 3.22! 0.75! 0.11! 2.20! 0.88! 0.11! 2.25! 0.75! 0.12! 2.51!
Country*90+!years! !! !! !! 1.27! 0.18! 4.54! 0.57! 0.07! 2.08! 0.55! 0.06! 1.89! 0.34! 0.06! 2.16!
Underweight
2!
!! !! !! !! !! !! 3.05% 2.05% 5.45% 2.93% 2.03% 5.43% 2.95% 2.02% 5.41%
Overweight/!obese! !! !! !! !! !! !! 0.47! 0.93! 2.01! 0.47! 0.92! 2.02! 0.48! 0.92! 2.01!
Former!smoker
3!
!! !! !! !! !! !! 1.43! 0.40! 1.02! 1.38! 0.39! 1.00! 1.38! 0.39! 1.00!
Current!smoker! !! !! !! !! !! !! 1.11! 0.18! 1.06! 1.10! 0.19! 1.10! 1.12! 0.19! 1.09!
CESED! !! !! !! !! !! !! 1.22! 0.92! 1.20! 1.18! 0.93! 1.21! 1.20! 0.92! 1.21!
!
!
116!
Total!cognitive!score! !! !! !! !! !! !! 0.91% 0.87% 0.95% 0.91% 0.87% 0.94% 0.91% 0.87% 0.94%
Total!functioning!difficulties! !! !! !! !! !! !! 1.15! 0.91! 1.19! 1.13! 0.89! 1.18! 1.13! 0.89! 1.19!
Grip!strength!(kg)! !! !! !! !! !! !! 0.02% 0.02% 0.87% 0.02% 0.01% 0.81% 0.02% 0.01% 0.82%
Education!(years)! !! !! !! !! !! !! 1.00! 0.98! 1.13! 0.99! 0.99! 1.13! 0.99! 0.99! 1.14!
Rural!childhood!residence! !! !! !! !! !! !! 1.62! 0.63! 1.18! 1.53! 0.61! 1.15! 1.60! 0.60! 1.14!
Living!alone! !! !! !! !! !! !! 0.92! 0.66! 1.35! 0.95! 0.64! 1.32! 0.74! 0.58! 2.08!
Uncontrolled/!undiagnosed!hypertension
4!
!! !! !! !! !! !! !! !! !! 0.90! 0.85! 1.66! 0.92! 0.86! 1.67!
Diabetes! !! !! !! !! !! !! !! !! !! 1.43! 0.42! 1.21! 1.40! 0.42! 1.22!
Heart!disease! !! !! !! !! !! !! !! !! !! 1.48! 0.68! 1.85! 1.24! 0.60! 2.34!
Stroke! !! !! !! !! !! !! !! !! !! 0.82% 0.04% 0.72% 0.85% 0.04% 0.72%
Cancer!(excluding!skin)! !! !! !! !! !! !! !! !! !! 1.50! 0.57! 1.97! 1.49! 0.57! 1.97!
Japan*alone! !! !! !! !! !! !! !! !! !! !! !! !! 2.27% 0.37% 1.75%
Japan*heart!disease! !! !! !! !! !! !! !! !! !! !! !! !! 2.52! 0.35! 2.60!
!! !! !! !! !! !! !! !! !! !! !! !! !! %% %% %%
ChiEsquare! 27.99! !! !! 134.92!!! !! 2398.44!!! !! 2329.84!!! !! 2321.14!%% %%
1
68;69!years!old!was!use!as!the!referent.!
2
Normal!weight!(18.5;<25!kg/m
2
)!was!used!as!the!referent.!
3
Never!smoked!was!used!as!the!referent.!
4
No!hypertension!was!used!as!the!referent.!
! !
!
!
117!
Table!A2b.!Men!
Men!(n=1948)!
!! Model!I! Model!II! Model!III! Model!IV! Model!V!
!! OR! 95%!CI! OR! 95%!CI! OR! 95%!CI! OR! 95%!CI! OR! 95%!CI!
70E74!years! 0.59! 0.33! 1.07! 1.19! 0.36! 8.23! 1.24! 0.37! 8.53! 1.21! 0.39! 9.15! 1.26! 0.39! 9.22!
75E79!years! 1.00! 0.60! 1.68! 1.79! 0.90! 18.09! 1.25! 0.70! 14.24! 1.09! 0.65! 13.46! 1.15! 0.65! 13.67!
80E84!years! 1.08! 0.61! 1.91! 2.84! 0.52! 13.33! 1.71! 0.34! 8.78! 1.57! 0.32! 8.47! 1.70! 0.32! 8.61!
85E89!years! 0.93! 0.45! 1.95! 3.53! 0.06! 9.86! 2.02! 0.03! 5.58! 1.88! 0.03! 5.28! 2.14! 0.03! 5.40!
90+!years! 3.99% 1.73% 9.19% 5.51% 1.07% 73.36% 2.30! 0.41! 31.03! 2.40! 0.41! 32.13! 2.70! 0.42! 33.43!
Country!(Japan=1)! 3.81% 2.57% 5.66% 0.60% 2.75% 52.73% 0.27% 1.81% 37.42% 0.32% 1.82% 39.45% 0.37% 1.88% 42.99%
Country*70E74!
years! !! !! !! 1.24! 0.05! 1.51! 0.96! 0.04! 1.35! 1.01! 0.04! 1.28! 0.99! 0.04! 1.29!
Country*75E79!
years! !! !! !! 0.86% 0.04% 0.88% 0.97% 0.04% 0.89% 1.16! 0.04! 1.00! 1.06! 0.04! 0.98!
Country*80E84!
years! !! !! !! 2.25! 0.06! 2.05! 2.79! 0.07! 2.27! 3.23! 0.07! 2.57! 2.76! 0.07! 2.56!
Country*85E89!
years! !! !! !! 1.89! 0.09! 19.31! 1.62! 0.08! 17.87! 1.76! 0.09! 20.23! 1.50! 0.08! 19.95!
Country*90+!years! !! !! !! 3.60! 0.04! 4.38! 3.21! 0.04! 5.32! 3.43! 0.04! 5.29! 3.02! 0.04! 5.15!
Underweight! !! !! !! !! !! !! 2.26! 0.84! 3.14! 2.13! 0.84! 3.20! 2.13! 0.84! 3.21!
Overweight/!obese! !! !! !! !! !! !! 0.39% 0.31% 0.84% 0.36! 0.28! 0.77! 0.36% 0.28% 0.77%
Former!smoker! !! !! !! !! !! !! 1.79! 0.86! 2.22! 1.83! 0.79! 2.08! 1.85! 0.79! 2.07!
Current!smoker! !! !! !! !! !! !! 4.14! 0.79! 2.76! 4.53! 0.79! 2.79! 6.78! 0.51! 6.57!
CESED! !! !! !! !! !! !! 1.10! 0.92! 1.31! 1.09! 0.93! 1.33! 1.09! 0.93! 1.32!
Total!cognitive!
score! !! !! !! !! !! !! 0.91% 0.86% 0.95% 0.90% 0.86% 0.95% 0.91% 0.86% 0.95%
Total!functioning!
difficulties! !! !! !! !! !! !! 1.27! 0.89! 1.21! 1.31! 0.89! 1.21! 1.30! 0.89! 1.21!
Grip!strength!(kg)! !! !! !! !! !! !! 0.07% 0.01% 0.65% 0.08% 0.02% 0.81% 0.08% 0.02% 0.81%
Education!(years)! !! !! !! !! !! !! 0.99! 0.94! 1.07! 0.98! 0.93! 1.07! 0.98! 0.93! 1.07!
!
!
118!
Rural!childhood!
residence! !! !! !! !! !! !! 0.84! 0.79! 1.65! 0.82! 0.79! 1.68! 0.82! 0.79! 1.68!
Living!alone! !! !! !! !! !! !! 0.92! 0.80! 2.38! 0.87! 0.80! 2.40! 0.87! 0.80! 2.41!
Uncontrolled/!
undiagnosed!
hypertension! !! !! !! !! !! !! !! !! !! 0.81! 0.88! 2.04! 0.81! 0.88! 2.05!
Diabetes! !! !! !! !! !! !! !! !! !! 2.03% 1.24% 2.96% 2.04% 1.24% 2.96%
Heart!disease! !! !! !! !! !! !! !! !! !! 1.54! 0.87! 2.27! 1.54! 0.87! 2.27!
Stroke! !! !! !! !! !! !! !! !! !! 0.52! 0.79! 2.47! 0.53! 0.79! 2.47!
Cancer!(excluding!
skin)! !! !! !! !! !! !! !! !! !! 1.43! 0.64! 2.12! 1.17! 0.56! 2.74!
Japan*current!
smoker! !! !! !! !! !! !! !! !! !! !! !! !! 1.44! 0.59! 2.26!
Japan*cancer! !! !! !! !! !! !! !! !! !! !! !! !! 0.62! 0.56! 1.86!
!! !! !! !! !! !! !! !! !! !! !! !! !! !! !! !!
ChiEsquare! 15.77! !! !! 106.88! !! !! 2092.40! !! !! 2035.84! !! !! 2028.81! !! !!
1
68;69!years!old!was!use!as!the!referent.!
2
Normal!weight!(18.5;<25!kg/m
2
)!was!used!as!the!referent.!
3
Never!smoked!was!used!as!the!referent.!
4
No!hypertension!was!used!as!the!referent.!
!
!
!
119!
Table!A3.!Characteristics!of!participants!who!dead!or!alive!on!mortality!follow;up.!
!! Japan! United!States!
!! Dead!(n=97)! Alive!(n=1320)! !! Dead!(n=185)! Alive!(n=2762)! !!
!!
Mean
/!%! SD!
Mean
/!%! SD! !!
Mean
/!%! SD!
Mean
/!%! SD! !!
Underweight!BMI!(%)! 9.1! EEE ! 27.1! EEE ! ***! 1.3! EEE ! 6.7! EEE ! ***!
Normal!BMI!(%)! 70.4! EEE ! 64.2! !! !! 28.5! EEE ! 43.3! EEE ! ***!
Overweight/obese!BMI!(%)! 20.6! EEE ! 8.8! EEE ! ***! 70.2! EEE ! 50.1! EEE ! ***!
Never!smoked!(%)! 40.4! EEE ! 42.7! EEE ! !! 44.1! !! 36.9! !! **!
Former!smoker!(%)! 47.2! EEE ! 46.7! EEE ! !! 48.4! EEE ! 53.0! EEE ! !!
Current!smoker!(%)! 12.4! EEE ! 10.6! EEE ! !! 7.5! EEE ! 10.1! EEE ! !!
Controlled/no!hypertension!(%)! 25.8! EEE ! 32.1! EEE ! !! 60.5! EEE ! 62.6! EEE ! !!
Uncontrolled/diagnosed!hypertension!(%)! 74.2! EEE ! 67.9! EEE ! !! 39.5! EEE ! 37.4! EEE ! !!
Diabetes!(%)! 10.6! EEE ! 13.2! EEE ! !! 19.3! EEE ! 26.7! EEE ! ***!
Heart!disease!(%)! 7.6! EEE ! 13.1! EEE ! **! 30.9! EEE ! 48.8! EEE ! ***!
Stroke!(%)! 7.6! EEE ! 10.9! EEE ! !! 10.6! EEE ! 19.1! EEE ! ***!
Cancer!(excluding!skin)!(%)! 4.2! EEE ! 8.0! EEE ! **! 19.6! EEE ! 29.2! EEE ! ***!
CESED!score! 1.28! 1.33! 0.93! 1.24! ***! 1.03! 1.37! 0.69! 1.25! ***!
Total!cognitive!score! 8.95! 6.24! 11.78! 5.50! ***! 9.40! 4.37! 12.37! 4.31! ***!
Total!functioning!difficulties! 2.92! 4.39! 0.48! 2.04! ***! 1.82! 2.25! 0.56! 1.33! ***!
Grip!strength!(kg)! 0.41! 0.15! 0.46! 0.14! ***! 0.35! 0.12! 0.38! 0.11! **!
Age!(years)! 82.81! 8.65! 76.41! 7.93! ***! 81.52! 6.68! 76.52! 6.31! ***!
Education!(years)! 8.84! 2.97! 9.84! 3.44! ***! 11.88! 3.15! 12.29! 3.22! *!
Female!(%)! 54.6! EEE ! 45.7! EEE ! **! 59.1! EEE ! 56.0! EEE ! !!
Rural!childhood!residence!(%)! 56.1! EEE ! 59.2! EEE ! !! 46.8! EEE ! 45.9! EEE ! !!
Living!alone!(%)! 14.8! EEE ! 14.6! EEE ! !! 31.7! EEE ! 31.6! EEE ! !!
!
!
120!
Chapter!5:!Conclusion!
Summary'
! There!are!major!differences!in!health!outcomes!between!the!US!and!Japan!
that!are!difficult!to!explain!despite!comparable!nationally!representative!measures.!!
The!data!captured!health!circumstances!crossCsectionally!in!participants!68!yearsC
orColder!who!had!already!experienced!a!lifetime!of!various!environmental!factors!
(i.e.!physical!activity,!diet,!stress,!smoking,!etc.)!that!collectively!influence!risk!of!
hypertension,!lower!cognitive!performance,!and!mortality.!!This!dissertation!
attempts!to!look!backwards!in!explaining!some!of!the!differences!in!health!and!life!
expectancy!through!two!primary!questions:'
1) Using!comparable!nationally!representative!data!on!the!elderly,!what!are!the!
differences!in!levels!of!hypertension,!cognitive!performance!scores,!and!
mortality!between!the!US!and!Japan?!
2) What,!if!any,!are!the!country!differences!in!the!size!and!direction!of!the!
effects!of!risk!factors!for!hypertension,!low!cognitive!performance,!and!
mortality?!
Findings'
The!hypertension!chapter!found!evidence!of!significant!differences!between!
the!two!countries!in!the!levels!of!hypertension!using!both!measures!of!
hypertension.!!The!Japanese!older!persons!had!higher!levels!of!hypertension.!!The!
fact!that!the!relative!difference!in!measured!hypertension!was!twice!as!great!as!that!
in!overall!hypertension!indicates!the!effect!of!control!of!hypertension!in!the!US!in!
reducing!the!differential!between!the!US!and!Japan.!!There!was!a!marked!difference!
!
!
121!
in!the!presence!of!risk!factors!and!comorbidities!across!the!two!countries.!!People!in!
the!US!have!substantially!more!diseases!and!adverse!health!conditions;!however,!
these!conditions!played!little!role!in!determining!the!differences!in!the!two!
countries!in!hypertension.!!Overweight/obese!BMI!and!diabetes!had!an!effect!in!
Japan!but!not!in!the!US.!!It!is!possible!that!these!conditions,!which!are!relatively!rare!
in!Japan,!are!not!as!wellChandled!medically!in!Japan.!!American!public!health!and!
health!care!efforts!might!be!differentially!focused!on!monitoring!the!blood!pressure!
levels!of!people!who!are!overweight/obese!or!diabetic!compared!to!Japanese!public!
health!and!health!care!efforts.!!Additionally,!when!hypertension!control!is!added!to!
the!outcome!variable,!as!it!is!in!overall!hypertension,!the!main!effect!of!country!and!
heart!disease!are!reduced!or!no!longer!significant,!respectively,!suggesting!that!
hypertension!control!plays!an!important!role!in!country!differences.!!We!have!
evidence!that!hypertension!does!not!appear!to!be!as!well!managed!in!Japan!and!
other!conditions!may!be!similar.!!The!findings!suggest!that!Japanese!better!overall!
health,!rather!than!health!care,!might!be!contributing!to!the!country!differences!
observed.!!
The!cognitive!chapter!reveals!that!Americans!of!both!genders!perform!better!
on!immediate!and!delayed!word!recall!and!total!cognitive!performance,!whereas!the!
Japanese!perform!better!on!serial!7’s.!!When!performance!was!examined!by!age!and!
gender,!the!differences!persisted!for!women!more!so!than!for!men.!Examining!
differences!in!coefficients!between!Models!I!and!II!in!Tables!3aCb!indicate!that!
education!is!a!key!factor!in!cognitive!performance!scores.!!The!sociodemographic!
characteristics!were!associated!with!cognitive!performance!in!all!groups.!!An!
!
!
122!
increase!in!a!year!of!education!had!an!effect!of!0.35!on!cognitive!performance!in!
Japanese!women!and!0.54!in!American!women;!this!is!similar!to!findings!by!other!
researchers!who!have!observed!only!very!weak!effect!of!more!years!of!education!on!
better!health!outcomes!in!Japan!(Yong!&!Saito,!2012).!!Chronic!conditions!were!
strongly!associated!with!cognitive!outcomes!in!both!genders,!however!the!
conditions!associated!with!each!gender!varied!slightly.!!For!example,!BMI,!diabetes,!
and!measured!hypertension!were!associated!with!cognitive!performance!in!women,!
but!stroke,!heart!disease,!and!only!overweight/obese!BMI!were!associated!with!
performance!in!men.!!The!frailty!indicators!showed!a!different!pattern,!a!higher!
number!of!functioning!difficulties!was!associated!with!lower!cognitive!performance!
among!both!genders,!whereas!grip!strength!was!only!associated!with!cognitive!
performance!in!men.!!It!is!important!to!emphasize!that!overweight/obese!BMI!was!
associated!with!better!performance!and!underweight!BMI!was!associated!with!
worse!performance.!!American!women!have!more!than!three!times!the!prevalence!
of!overweight/obese!BMI,!compared!to!Japanese!women,!and!American!men!have!
nearly!four!times!the!prevalence,!compared!to!Japanese!men,!while!Japanese!women!
have!five!times!the!prevalence!of!underweight!BMI,!compared!to!American!women,!
and!8.3%!of!Japanese!men!are!underweight,!compared!to!only!0.2%!of!American!
men.!!The!findings!suggest!that!American’s!BMI!levels!are!contributing!to!the!
country!differences!in!cognitive!performance!observed!in!Table!1.!!Given!Americans’!
higher!BMI!and!more!than!two!years!educational!advantage!over!the!Japanese,!it!is!
surprising!that!country!differences!in!cognitive!performance,!while!significant,!are!
so!low,!only!0.4!for!women!and!0.9!for!men.!!If!Japanese!effects!of!risk!factors!were!
!
!
123!
the!same!as!those!for!Americans,!the!Japanese!would!be!expected!to!perform!much!
worse;!likewise!if!American!levels!of!education!and!BMI!were!similar!to!the!
Japanese,!Americans!would!perform!much!worse.!!
The!mortality!chapter!did!not!find!evidence!of!significant!differences!
between!the!two!countries!in!the!levels!of!mortality!before!controlling!for!risk!
factors,!though!levels!of!mortality!risk!factors!differed!significantly!between!
countries.!!When!all!but!the!chronic!condition!risk!factors!were!controlled,!the!main!
effect!of!country!indicated!that!Japanese!men!experienced!73%!lower!mortality!risk!
than!American!men.!!It!is!also!interesting!to!note!that!when!chronic!conditions!was!
controlled!in!men,!the!Japanese!advantage!was!lost.!!This!finding!suggests!that!the!
higher!presence!of!chronic!conditions!and!frailty!at!older!ages!has!a!greater!effect!on!
men’s!risk!of!mortality!than!on!women’s,!as!the!effect!of!age!groups!was!lost!for!men!
when!controlling!for!other!risk!factors!but!persisted!for!women.!!Even!though!the!
effect!of!80C84!age!interaction!was!significant!in!women,!the!difference!was!not!
substantial!in!the!final!model.!!Lastly,!education,!while!well!established!as!a!factor!
affecting!mortality!rates,!is!not!a!cause!of!differences!in!mortality.!!Differences!
between!Japan!and!US!appear!to!be!relatively!weak!as!they!pertain!to!mortality.!!
Implications'
The!findings!revealed!that!the!Japanese!advantage!varies!across!health!
outcomes.!!For!example,!Americans!had!higher!cognitive!performance!scores!
compared!to!the!Japanese,!which!can!be!explained!by!Americans’!higher!level!of!
education!(Harrington!et!al.,!2000;!Zelinski!et!al.!1998).!!!
!
!
124!
Japanese!levels!of!risk!factors!for!many!chronic!conditions!are!already!low!
(low!prevalence!of!overweight/obese!BMI,!diabetes,!heart!disease,!and!fewer!
functioning!difficulties),!whereas!American!levels!are!comparatively!high.!!At!the!
same!time,!the!Japanese!diet!and!lifestyle!are!becoming!increasingly!westernized!
and!BMI!levels!for!the!population!are!increasing!(Yoshiike,!Kaneda,!&!Takimoto,!
2002).!!On!the!one!hand,!westernization!can!have!positive!effects!on!health,!via!
education,!which!can!help!improve!cognitive!performance!outcomes!(Skirbekk,!
Loichinger,!&!Weber,!2012).!!On!the!other!hand,!westernization!can!have!
deleterious!health!outcomes!for!the!Japanese!population,!particularly!since!diabetes,!
overweight/obese!BMI,!and!heart!disease!have!stronger!effects!on!hypertension,!
lower!cognitive!performance,!and!mortality!in!the!Japanese!population!compared!to!
the!American.!!Fortunately,!the!Japanese!government!already!has!policies!in!place!to!
curb!increases!in!BMI!and!metabolic!syndrome,!but!their!effectiveness!in!curbing!
weight!gain!and!metabolic!syndrome!at!the!population!level!is!still!not!clear.!!
Japanese!women!in!younger!cohorts,!in!particular,!have!added!health!risks!from!
Westernization,!which!will!manifest!as!the!cohorts!age,!since!women!in!these!
cohorts!have!higher!rates!of!smoking!than!older!ones.!!
The!findings!point!to!characteristics!that!can!be!addressed!through!
preventative!measures!focused!on!factors!related!to!overweight/obese!and!current!
smoking!in!the!US!and!Japan!and!diabetes!in!Japan.!!Japan!already!has!policies!in!
place!to!address!overweight/obese!BMI!and!diabetes!in!the!working!population,!
however!such!program!would!be!difficult!to!implement!in!the!US.!!As!for!smoking,!
younger!cohorts!of!Americans!have!lower!smoking!rates!than!older!cohorts,!
!
!
125!
however!the!opposite!is!true!for!Japan,!particularly!for!women.!!Education!was!
another!variable!significantly!associated!with!an!outcome!of!interest,!particularly!
cognitive!performance,!years!of!education!in!younger!cohorts!in!both!countries!are!
already!higher!than!older!cohorts.!!Future!research!may!address!whether!education!
works!in!the!same!way!across!cohorts!of!different!education!levels..!The!data!show!
that!the!oldest!American!survivors!are!not!necessarily!in!worse!health,!and!thus!
Japan’s!reputation!as!the!longest!lived!country!is!based!on!a!larger!percentage!of!
people!reaching!the!older!ages.!!Since!the!elderly!were!the!focus!of!these!studies,!the!
effects!of!a!survivor!effect!can!not!be!ignored.!
Limitations'and'Future'Research'
Studying!health!and!mortality!in!nationally!representative!samples!comes!
with!the!limitations!of!limited!detail!available!for!key!predictors!of!health!including!
diet,!comparable!measures!of!access!to!quality!care,!and!types!of!drugs!participants!
are!using!to!manage!their!health!between!Japan!and!the!US.!!Additionally,!successive!
measures!of!blood!pressure!might!be!a!valuable!way!to!validate!hypertension!and!
see!the!effects!of!hypertension!control!over!time.!!In!some!cases!participants!may!
have!controlled!their!blood!pressure!through!medication!after!the!data!were!
collected!and!their!trajectory!might!different!from!someone!who!remains!
uncontrolled!or!undiagnosed.!!!
Japan!has!unique!cultural!differences!that!may!limit!our!knowledge!of!
participants’!health.!!For!example,!doctors!often!do!not!tell!older!people!that!they!
have!cancer,!and!instead!inform!family!members.!!Thus,!some!participants!may!not!
be!aware!of!their!cancer.!!Also,!the!Japanese!sample!has!experienced!very!dramatic!
!
!
126!
and!rapid!economic!and!cultural!changes!over!the!course!of!their!lives,!and!thus!a!
greater!proportion!of!their!population!may!be!less!aware!of!their!disease!and!risk!
factors!than!their!American!counterparts!who!have!lived!under!more!economic!
stability.!!Japan’s!healthcare!system!capabilities!and!access!has!rapidly!evolved!and!
now!includes!capabilities!similar!to!the!US,!whereas!access!to!quality!healthcare!
several!decades!ago!was!very!limited.!!Also,!education!about!prevention!and!
smoking!in!particular!varies!dramatically!across!countries.!!Smoking!remains!very!
common!in!Japan!even!among!highly!educated!individuals,!while!it!is!more!
commonly!associated!with!low!education!in!the!US!and!has!declined!over!time.!!
Finally,!while!most!health!effects!associated!with!being!obese!are!linked!to!a!BMI!of!
more!than!30!kg/m
2
,!there!are!few!people!in!Japan!who!meet!this!criterion.!!The!cutC
point!used!in!this!study!was!the!same!in!each!country,!despite!the!fact!that!the!
distribution!of!weight!is!very!different.!!Tests!of!different!cutCpoints!to!identify!
obesity!were!used!for!each!country,!but!the!results!were!not!substantially!different.!
All!of!the!variables!used!in!this!study!are!experiencing!change!at!the!
population!level.!!Future!studies!could!investigate!trends,!and!quantify!how!changes!
in!the!prevalence!of!conditions,!frequency!of!key!health!behaviors,!and!other!
measures!of!health!and!sociodemographic!characteristics!affect!each!outcome.!!
Interventions!to!improve!population!level!health!are!difficult!to!implement!
effectively,!but!more!detailed!research!investigating!known!measures!of!health!
might!shed!light!onto!the!characteristics!of!an!effective!intervention.!!Studies!can!
also!focus!on!longitudinal!associations!between!risk!factors!and!outcomes.!!
Westernization!has!changed!Japan!dramatically,!and!the!natural!experiment!
!
!
127!
underway!is!most!valuable!if!we!have!longitudinal!data!to!measure!key!
characteristics!and!track!how!they!change!over!time.!!
!
! !
!
!
128!
References!
Harrington!F,!Saxby!BK,!McKeith!IG,!Wesnes!K,!Ford!GA.!Cognitive!performance!in!
hypertensive!and!normotensive!older!subjects.!Hypertension!2000;!36:1079C
1082.!
Skirbekk!V,!Loichinger!E,!Weber!D.!Variation!in!cognitive!functioning!as!a!refined!
approach!to!comparing!aging!across!countries.!PNAS!2012;!109(3):770C774.!
Yong!V!&!Saito!Y.!Are!there!education!differentials!in!disability!and!mortality!
transitions!and!active!life!expectancy!among!Japanese!older!adults?!Findings!
from!a!10Cyearprospective!cohort!study.!Journals'of'Gerontology,'Series'B:'
Psychological'Sciences'and'Social'Sciences!2012;!67:343C353.!
Yoshiike!N,!Kaneda!F,!Takimoto!H.!Epidemiology!of!obesity!and!public!health!
strategies!for!its!control!in!Japan.'Asia'Pc'J'Clin'Nutr!2002;!11:S727CS731.!
Zelinski!EM,!Crimmins!E,!Reynolds!S,!Seeman!T.!Do!medical!conditions!affect!
cognition!in!older!adults?.!Health'Psychol!1998;!17:504C512!
!

Abstract (if available)

Abstract Japan and the United States (US) are unique models for studying health and aging. While it is well established that the Japanese experience lower levels of most chronic conditions and longer life-expectancy compared to Americans, there are several characteristics associated with health and longevity that don't seem to explain the differences we observe between countries. In fact, compared to the Japanese, Americans have higher levels of education, which is ordinarily associated with better health outcomes. Additionally, Americans have lower rates of smoking (among men), which should give Americans an advantage given that smoking has been shown to reduce life-expectancy. ❧ This dissertation examines country differences between Japan and the US in the level and the size and direction of associations of risk factors with three health outcomes: hypertension (chapter 2), cognitive performance (chapter 3), and mortality (chapter 4). A comparative study between a relatively healthy and long-lived population, like Japan, and a relatively unhealthy population, like the US, helps us better understand aging through the examination of the similarities and differences in risk factors and outcomes.

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Asset Metadata

Creator Davarian, Shieva (author)

Core Title Health differences between the elderly in Japan and the United States

School Leonard Davis School of Gerontology

Degree Doctor of Philosophy

Degree Program Gerontology

Publication Date 11/28/2015

Defense Date 10/17/2013

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag cognitive performance,elderly,hypertension,Japan,mortality,North America,OAI-PMH Harvest

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Crimmins, Eileen M. (committee chair), Douglas Joines (committee member), Hagedorn, Aaron (committee member)

Creator Email davarian@usc.edu,sdavarian@gmail.com

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c3-352239

Unique identifier UC11288056

Identifier etd-DavarianSh-2196.pdf (filename),usctheses-c3-352239 (legacy record id)

Legacy Identifier etd-DavarianSh-2196.pdf

Dmrecord 352239

Document Type Dissertation

Rights Davarian, Shieva

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

Repository Name University of Southern California Digital Library

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