Residential segregation of Black and Latinx older adults and brain imaging outcomes.

Ethnoracial segregation has been associated with worse cognitive functioning among Black older adults, while its impact on Latinx individuals is less clear. We investigated whether Black and Latinx older adults living in segregated neighborhoods demonstrate worse magnetic resonance imaging (MRI) outcomes. We used data on participants from the University of California Davis Alzheimer's Disease Research Center. MRI outcomes included hippocampal and white matter hyperintensity (WMH) volumes. Black and Latinx segregation was defined using the Getis-Ord (Gi∗) statistic, which compares the proportion of Black or Latinx residents, respectively, in the participant's Census tract to surrounding neighborhoods and greater study region (higher Gi∗ = greater clustering/segregation). Multivariable linear regression analyses examined associations between Gi∗ segregation measures and MRI outcomes, stratified by the participants' ethnoracial group (Black, Latinx, or White). Participants (n = 269) were on average 74 ± 7 years of age and 24 % were Black, 25 % were Latinx, and 51 % were White. In adjusted analyses, Black participants in more Latinx segregated neighborhoods had lower hippocampal volumes, and Latinx participants in more Black segregated neighborhoods had lower hippocampal volumes. Latinx participants in more Latinx segregated neighborhoods had greater white matter hyperintensity volumes. Overall, Black and Latinx but not White participants living in segregated neighborhoods had worse MRI outcomes. Future studies are needed to replicate our findings in geographically diverse samples and to elucidate the potential psychosocial/social determinant and biological mechanisms that relate segregation to brain health (e.g., Latinx segregated neighborhoods may have fewer recreational and physical activity resources to promote healthy lifestyles).