Multimorbidity, Polypharmacy, and Neighborhood Disadvantage as Determinants of Cognitive Performance in the ARCHES Cohort.

BackgroundAfrican American adults experience a disproportionate burden of dementia, shaped by structural and clinical factors that remain unclear.ObjectiveTo quantify associations between multimorbidity, polypharmacy, and cognition in the context of neighborhood disadvantage.MethodsThis study is a cross-sectional analysis of 348 African American adults aged 45-92 years (mean 64.3 years; 73.6% female) from the Aging Research Characterizing Health Exposome via Social drivers (ARCHES) cohort. Comorbidity burden was assessed using a modified Charlson Comorbidity Index (CCI), polypharmacy as ≥5 medications, and neighborhood disadvantage using the Area Deprivation Index (ADI). Linear regression estimated associations with a Preclinical Alzheimer's Cognitive Composite (PACC). The polypharmacy model included modified CCI as a covariate, and effect modification by ADI was assessed using an interaction term between polypharmacy and ADI.ResultsHigher modified CCI was associated with lower cognitive performance (B = -0.071; 95% CI: -0.130, -0.012). Polypharmacy was not independently associated with cognition after modified CCI adjustment (B = -0.081; β = -0.057; p = 0.257). No significant ADI interaction was found (p = 0.064).