Racial Inequities in Cognitive Decline of Middle-Aged and Older Adults: Findings of the ELSA-Brasil Study

Background and ObjectivesRacial and ethnic minority groups experience higher burden of cognitive decline but are usually underrepresented in cognition-related research, particularly in cohort studies. We aimed to examine the trajectory of cognitive function over approximately 9 years according to race and ethnicity groups.MethodsWe analyzed data from the Estudo Longitudinal de Saude do Adulto (ELSA-Brasil) study. Participants (35-74 years) were enrolled between 2008 and 2010 and followed up between 2017 and 2019. We categorized participants based on self-reported information into Black, Brown (mixed race), and White groups. We evaluated global and domain-specific (memory, verbal fluency, and executive function) cognitive function at baseline and follow-up, considering incident cognitive impairment as a global cognitive function score at follow-up lower than -1.5 SD from the baseline mean. We investigated the trajectory of cognitive decline according to race and ethnicity groups through cubic spline linear mixed-effects models with random intercept and slope. Relative risk and the difference in median age at onset of cognitive impairment were examined using Poisson and Laplace regression models, respectively.ResultsParticipants (N = 10,308; 56% female) had a mean baseline age of 50.7 years. We observed lower global and domain-specific scores at baseline in Black (n = 1,510) and Brown (mixed race) (n = 2,902) than in White (n = 5,896) participants, with inequities increasing with aging. Declines in global cognitive function, memory, and executive function were faster from early to mid-adulthood in Brown (mixed race) than in White adults. The incidence of cognitive impairment in Black and Brown (mixed race) was 3 times that in White participants, when adjusting for study center, age, and sex. Their onset of cognitive impairment occurred 9.6 (95% CI 8.1-11.1) and 9.4 (95% CI 8.0-10.7) years earlier, respectively. In participants with ≤8 years of schooling, the incidence of cognitive impairment was 90% (95% CI 85%-97%) and 82% (95% CI 73%-96%) higher in Black and Brown (mixed race) than in White adults, whereas in those with ≥12 years, differences were 36% (95% CI 4%-57%) and 68% (95% CI 58%-74%), respectively.DiscussionOur findings revealed early and marked racial inequities in global and domain-specific cognitive function in middle-aged and older Brazilian adults, particularly among those of lower schooling.