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dc.contributor.authorLipnicki, Darren Men
dc.contributor.authorCrawford, John Den
dc.contributor.authorDutta, Rajiben
dc.contributor.authorThalamuthu, Anbupalamen
dc.contributor.authorKochan, Nicole Aen
dc.contributor.authorAndrews, Gavinen
dc.contributor.authorFernanda Lima-Costa, Men
dc.contributor.authorCastro-Costa, Ericoen
dc.contributor.authorBrayne, Carolen
dc.contributor.authorMatthews, Fionaen
dc.contributor.authorStephan, Blossom CMen
dc.contributor.authorLipton, Richard Ben
dc.contributor.authorKatz, Mindy Jen
dc.contributor.authorRitchie, Karenen
dc.contributor.authorScali, Jacquelineen
dc.contributor.authorAncelin, Marie-Laureen
dc.contributor.authorScarmeas, Nikolaosen
dc.contributor.authorYannakoulia, Maryen
dc.contributor.authorDardiotis, Efthimiosen
dc.contributor.authorLam, Linda CWen
dc.contributor.authorWong, Candy HYen
dc.contributor.authorFung, Ada WTen
dc.contributor.authorGuaita, Antonioen
dc.contributor.authorVaccaro, Robertaen
dc.contributor.authorDavin, Annalisaen
dc.contributor.authorKim, Ki Woongen
dc.contributor.authorHan, Ji Wonen
dc.contributor.authorKim, Tae Huien
dc.contributor.authorAnstey, Kaarin Jen
dc.contributor.authorCherbuin, Nicolasen
dc.contributor.authorButterworth, Peteren
dc.contributor.authorScazufca, Marciaen
dc.contributor.authorKumagai, Shuzoen
dc.contributor.authorChen, Sanmeien
dc.contributor.authorNarazaki, Kenjien
dc.contributor.authorNg, Tze Pinen
dc.contributor.authorGao, Qien
dc.contributor.authorReppermund, Simoneen
dc.contributor.authorBrodaty, Henryen
dc.contributor.authorLobo, Antonioen
dc.contributor.authorLopez-Anton, Raulen
dc.contributor.authorSantabarbara, Javieren
dc.contributor.authorSachdev, Perminder Sen
dc.contributor.authorInt, Cohort Studies Memoryen
dc.description.abstractBackground The prevalence of dementia varies around the world, potentially contributed to by international differences in rates of age-related cognitive decline. Our primary goal was to investigate how rates of age-related decline in cognitive test performance varied among international cohort studies of cognitive aging. We also determined the extent to which sex, educational attainment, and apolipoprotein E ε4 allele (APOE*4) carrier status were associated with decline. Methods and findings We harmonized longitudinal data for 14 cohorts from 12 countries (Australia, Brazil, France, Greece, Hong Kong, Italy, Japan, Singapore, Spain, South Korea, United Kingdom, United States), for a total of 42,170 individuals aged 54–105 y (42% male), including 3.3% with dementia at baseline. The studies began between 1989 and 2011, with all but three ongoing, and each had 2–16 assessment waves (median = 3) and a follow-up duration of 2–15 y. We analyzed standardized Mini-Mental State Examination (MMSE) and memory, processing speed, language, and executive functioning test scores using linear mixed models, adjusted for sex and education, and meta-analytic techniques. Performance on all cognitive measures declined with age, with the most rapid rate of change pooled across cohorts a moderate -0.26 standard deviations per decade (SD/decade) (95% confidence interval [CI] [-0.35, -0.16], p < 0.001) for processing speed. Rates of decline accelerated slightly with age, with executive functioning showing the largest additional rate of decline with every further decade of age (-0.07 SD/decade, 95% CI [-0.10, -0.03], p = 0.002). There was a considerable degree of heterogeneity in the associations across cohorts, including a slightly faster decline (p = 0.021) on the MMSE for Asians (-0.20 SD/decade, 95% CI [-0.28, -0.12], p < 0.001) than for whites (-0.09 SD/decade, 95% CI [-0.16, -0.02], p = 0.009). Males declined on the MMSE at a slightly slower rate than females (difference = 0.023 SD/decade, 95% CI [0.011, 0.035], p < 0.001), and every additional year of education was associated with a rate of decline slightly slower for the MMSE (0.004 SD/decade less, 95% CI [0.002, 0.006], p = 0.001), but slightly faster for language (-0.007 SD/decade more, 95% CI [-0.011, -0.003], p = 0.001). APOE*4 carriers declined slightly more rapidly than non-carriers on most cognitive measures, with processing speed showing the greatest difference (-0.08 SD/decade, 95% CI [-0.15, -0.01], p = 0.019). The same overall pattern of results was found when analyses were repeated with baseline dementia cases excluded. We used only one test to represent cognitive domains, and though a prototypical one, we nevertheless urge caution in generalizing the results to domains rather than viewing them as test-specific associations. This study lacked cohorts from Africa, India, and mainland China. Conclusions Cognitive performance declined with age, and more rapidly with increasing age, across samples from diverse ethnocultural groups and geographical regions. Associations varied across cohorts, suggesting that different rates of cognitive decline might contribute to the global variation in dementia prevalence. However, the many similarities and consistent associations with education and APOE genotype indicate a need to explore how international differences in associations with other risk factors such as genetics, cardiovascular health, and lifestyle are involved. Future studies should attempt to use multiple tests for each cognitive domain and feature populations from ethnocultural groups and geographical regions for which we lacked data.
dc.rightsAttribution 4.0 International
dc.titleAge-related cognitive decline and associations with sex, education and apolipoprotein E genotype across ethnocultural groups and geographic regions: a collaborative cohort studyen
prism.numberARTN e1002261en
prism.publicationNamePLOS ONEen
dc.contributor.orcidBrayne, Carol [0000-0001-5307-663X]
dc.contributor.orcidMatthews, Fiona [0000-0002-1728-2388]
rioxxterms.typeJournal Article/Reviewen
pubs.funder-project-idMRC (1185)

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Attribution 4.0 International
Except where otherwise noted, this item's licence is described as Attribution 4.0 International