Bilingualism and cognitive aging in ethnically diverse older adults: cross-sectional and longitudinal evidence from Health and Aging Brain Study-Health Disparities

OBJECTIVES: Identifying modifiable factors that shape cognitive aging trajectories is a central goal in aging research. This study examined whether bilingualism is associated with dementia status and longitudinal cognitive decline, and whether associations vary by ethnicity or gender. METHODS: We analyzed Wave 7 data from the Health and Aging Brain Study-Health Disparities (HABS-HD), a longitudinal U.S. cohort of adults aged ≥50 years. Bilingualism was defined by self-reported use of a second language. Cross-sectional analyses included 4,140 participants (1,013 bilinguals); longitudinal analyses included 1,760 participants (522 bilinguals) followed for up to 4 visits at approximately 2-year intervals. Outcomes were baseline dementia status and latent factor scores for executive function and episodic memory derived from 11 neuropsychological tests. Regression and linear mixed-effects models assessed associations, adjusting for age, education, gender, ethnicity, and practice effects. RESULTS: Bilingualism was not associated with baseline dementia status or conversion to probable dementia. Cross-sectionally, associations varied by ethnicity: Hispanic bilinguals showed higher executive function and episodic memory scores. No advantage was observed in White participants; conversely, Black bilinguals had lower episodic memory scores. Longitudinally, bilingualism was associated with slower episodic memory decline independent of sociodemographic factors; no longitudinal association was observed for executive function. DISCUSSION: These findings suggest that bilingualism may confer domain-specific benefits for memory trajectories in later life, while cross-sectional differences appear shaped by sociocultural context. The results underscore the importance of considering ethnic diversity and language history when evaluating experiential influences on cognitive aging.