Race/Ethnic Disparities in Mild Cognitive Impairment and Dementia: The Northern Manhattan Study

ABSTRACT OBJECTIVE Estimate the prevalence of mild cognitive impairment (MCI) and probable dementia in the racially and ethnically diverse community-based Northern Manhattan Study cohort and examine sociodemographic, vascular risk factor, and brain imaging correlates. METHODS Cases of MCI and probable dementia were adjudicated by a team of neuropsychologists and neurologists and prevalence was estimated across race/ethnic groups. Ordinal proportional odds models were used to estimate race/ethnic differences in prevalence rates for MCI or probable dementia adjusting for sociodemographic variables (model 1), model 1 plus potentially modifiable vascular risk factors (model 2), and model 1 plus structural imaging markers of brain integrity (model 3). RESULTS There were 989 participants with cognitive outcome determinations (mean age 69 ± 9 years; 68% Hispanic, 16% Black, 14% White; 62% women; mean (±SD) follow-up five (±0.6) years). Prevalence rates for MCI (20%) and probable dementia (5%) were significantly different by race/ethnicity even after accounting for age and education difference across race-ethnic groups; Hispanic and Black participants had greater prevalence rates than Whites. Adjusting for sociodemographic and brain imaging factors explained the most variance in the race/ethnicity associations. White matter hyperintensity burden explained much of the disparity between Black and White, but not between Hispanic and White, participants. CONCLUSIONS In this diverse community-based cohort, white matter hyperintensity burden partially explained disparities in MCI and dementia prevalence in Black but not Hispanic participants compared to Whites. Longer follow-up and incidence data are needed to further clarify these relationships.