Place of Birth and Cognitive Function Among Older Americans: Findings From the Harmonized Cognitive Assessment Protocol

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 investigated the extent to which state of birth contributes to a wide range of domains of later-life cognitive function. Methods A nationally representative sample of Americans aged 65 and older (N=3,333) from the Health and Retirement Study (HRS) Harmonized Cognitive Assessment Protocol (HCAP) was utilized. Cognitive function was assessed in HCAP and linked to HRS state of birth data to explore the contribution of PoB to later-life cognitive disparities. Regression-based Shapley decompositions were employed to quantify this contribution. Results PoB significantly contributed to all assessed cognitive domains including memory, executive function, language and fluency, visuospatial function, orientation, and general cognitive function. Geographic disparities in cognitive function were evident across PoB, with individuals born in US southern states and foreign-born individuals performing worse than those born in other states. Overall, state of birth accounted for 2.2-9.7% of the total variance in cognition after adjusting for age, sex, and race/ethnicity. This contribution declined to 2.0-7.0% after further adjusting for comprehensive socioeconomic and health factors over the life course, and were robust to the control of current state of residence. Discussion PoB has lasting contributions to later-life cognition, with significant geographic disparities observed. Addressing these disparities requires more equalized place-based policies, resources, and early-life environments to promote health equity over the life course.