Racial residential segregation is known to be associated with poor health outcomes, but its link to cognitive function isn't clear. As part of a prospective cohort study, researchers examined the relationship between cumulative exposure to racial residential segregation during 25 years of young adulthood and cognitive performance in middle-age Black adults.

The final analysis included 1,568 Black participants. At baseline, mean age of the participants was 25 years, and most were living in highly segregated neighborhoods. Cognitive performance was measured at year 25 of the study, using three standardized tests representing distinct domains of cognition.

Greater cumulative exposure to racial residential segregation throughout young adulthood was associated with worse processing speed in middle-age participants. The estimate for the association between high racial segregation and test scores was more than fivefold greater than for the association between age and test scores.

The study authors note that they couldn't identify specific mechanisms through which segregation may influence cognitive function. Another limitation of the study is that cognition was measured at only one point in the study, at year 25. Policies that address racial residential segregation may help to reduce inequities in cognitive performance, the authors conclude.