Subjective cognitive decline and objective cognitive performance across diverse intersectional identities by gender, race/ethnicity, and educational attainment.

Subjective cognitive decline and subtle objective cognitive impairment are important early clinical stages of dementia, but the extent to which they vary across intersectional identities remains poorly understood. We examined differences in subjective and objective cognition across intersectional identities defined by gender, race/ethnicity, and education. We analyzed 20,814 participants aged 45+ from the Brain Health Registry. Subjective cognition was measured using the 39-item Everyday Cognition Scale. Objective cognition was measured using the Cambridge Cognition Paired Associates Learning test. We defined 24 intersectional strata based on gender (men, women), race/ethnicity (Latino, Asian, Black, White), and education (≤associate's, bachelor's, graduate degree). Using Multilevel Analysis of Individual Heterogeneity and Discriminatory Accuracy (MAIHDA), we estimated age-adjusted linear mixed models then additionally adjusted for the additive effects of gender, race/ethnicity, and education to evaluate whether random effects of the intersectional identity strata explained variance beyond individual fixed effects. Between-stratum variance accounted for ≤6% of the total variance in subjective and objective cognition. Most (79-98%) of this between-stratum variance was explained by additive effects of gender, race/ethnicity, and education. Additive sociodemographic effects explained most disparities in mid- to late-life subjective and objective cognition across intersectional strata, with limited residual intersectional heterogeneity beyond these additive effects.