African Americans who are exposed to neighborhood racial segregation during young adulthood are more likely to have poor cognitive performance as early as midlife, according to recent findings published in JAMA Neurology, and may suggest why disparities in dementia risk at older age exist in black versus white individuals.
“These findings are not surprising, given the harmful impact of racial residential segregation on a variety of factors that are related to cognitive performance,” said Kiarri Kershaw, PhD, MPH, associate professor of Preventive Medicine in the Division of Epidemiology and a co-author of the study.
Previous studies have shown that older African American patients perform worse on cognitive tests than older white patients, and also have a higher risk of dementia. However, few studies have looked at mid-life black adults and the disparities in cognitive performance that exist in this age group, according to Kershaw.
To examine the association between cumulative exposure to racial residential segregation during young adulthood, the authors acquired data from black participants involved in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Using this data, the authors measured for racial residential segregation and cognitive function in the CARDIA cohort, specifically in black participants who participated in cognitive testing for the study’s 25-year follow-up examination in 2010.
To measure racial residential segregation, the authors compared the racial composition of the neighborhood participants lived in and surrounding neighborhoods to the racial composition of the metropolitan area or county they lived in. Cognitive function was measured using the Digit Symbol Substitution Test to evaluate response speed, sustained attention and visual spatial skills; the Stroop color test to assess executive function; and the Rey Auditory Verbal Learning Test to determine participants’ ability to memorize and retrieve words.
The authors found that participants who lived in highly segregated neighborhoods in young adulthood exhibited worse performance in cognitive processing speed, supporting the notion that long-term exposure to racial residential segregation in young adulthood is associated with cognitive aging as early as midlife.
Racial residential segregation may also influence cognitive performance in black individuals owing to a lack of access to high-quality education, according to Kershaw, as schools in racially segregated neighborhoods are often underfunded and lack necessary resources.
Kershaw also noted that these findings emphasize the need for healthcare professionals to account for social and economic disparities when forming patient narratives and administering care.
“These findings, along with studies we’ve seen linking segregation to increased cardiovascular disease risk, and what we’re seeing with COVID-19 in segregated cities in the Midwest, point to the need for people working in healthcare settings to understand how upstream, structural factors like racial residential segregation shape clinical interactions,” Kershaw said.
Currently, Kershaw is exploring ways to use existing observational data and simulation modeling to evaluate the impact of social and economic policies aimed to promote health equity.
“The most important way to address the adverse health impacts of structural factors like segregation is to reshape how resources and opportunities are distributed in our society. This can occur in healthcare settings by doing things like screening for unmet social needs, and it can occur at the policy level through the adoption of social and economic policies to promote equity,” Kershaw said.
This work was supported by grant K01AG047273 from National Institute of Aging (NIA); grant F30NS103462 from the NINDS, NIH; contracts HHSN268201300025C, HHSN268201300026C, HHSN268201300027C, HHSN268201300028C, HHSN268201300029C, and HHSN268200900041C from the National Institutes of Neurological Disorders and Stroke; the Intramural Research Program of the NIA; and intra-agency agreement AG0005 between the NIA and the Heart, Lung and Blood Institute.