Abstract
Objectives Growing evidence suggests that place of birth (PoB) and related circumstances may have long-lasting and multiplicative contributions to various later-life outcomes. However, the specific contributions to different domains of cognitive function in late life remain less understood. This study aimed to investigate the extent to which PoB contribute to a wide range of later-life cognitive outcomes.
Methods A nationally representative sample of Americans aged 65 and older (N=3,216) from the Health and Retirement Study (HRS) Harmonized Cognitive Assessment Protocol (HCAP) was utilized. Cognitive outcomes were assessed in HCAP and linked to HRS state-level PoB data to explore the contribution of birthplace to later-life cognitive disparities. Regression-based Shapley decompositions were employed to quantify this contribution.
Results PoB significantly contributed to all assessed cognitive outcomes including memory, executive function, language and fluency, visuospatial function, orientation, global cognitive performance, cognitive impairment and dementia. Geographic disparities in cognitive outcomes were evident, with individuals born in US southern states and foreign-born individuals performing worse than those born in other states. PoB overall accounted for 2.4-13.9% of the total variance in cognition after adjusting for age and sex. This contribution reduced by half when adjusting for a rich set of sociodemographic and health factors over the life course, but PoB still independently explained 2.0-7.1% of the total variance in cognition.
Discussion PoB has lasting contributions to later-life cognitive health, with significant geographic disparities observed. Addressing these disparities requires promoting more equalized place-based policies, resources, and early-life environments to improve health equities over the life course.
Competing Interest Statement
The authors have declared no competing interest.
Funding Statement
This work was supported by the Career Development Award [K01AG053408] and a major research grant [R01AG077529] from the National Institute on Aging; Claude D. Pepper Older Americans Independence Center at Yale School of Medicine, funded by the National Institute on Aging [P30AG021342]; and Yale Alzheimer's Disease Research Center [P30AG066508]; James Tobin Research Fund at Yale Economics Department; and Yale Macmillan Center Faculty Research Award.
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Footnotes
Email address: Zhuoer Lin (zhuoer.lin{at}yale.edu)
Data Availability
All publicly available data used in the present study are available upon reasonable request to the authors.