A-55: Not All Measures of Socioeconomic Status are Equivalent: Associations With Brain Structure and Cognitive Function in Cognitively Unimpaired Older Adults

Abstract

Objective: This secondary analysis examined whether distinct socioeconomic status (SES) measures are differentially associated with medial temporal lobe (MTL) subregional volumes and whether these volumes mediate SES-cognition relationships in older adults. Method/Data Selection: Data were analyzed from 601 cognitively unimpaired participants aged 65-80 years (mean = 69.7 ± 3.7; 72.2% female) across three U.S. metropolitan areas. Cognitive domains included episodic memory, executive function, processing speed, working memory, and visuospatial ability. SES was assessed using objective and subjective measures and the Area Deprivation Index (ADI). MTL morphometry was quantified using Automated Segmentation of Hippocampal Subfields (ASHS). Multivariable regression models adjusted for demographics examined SES-MTL associations; mediation analyses evaluated indirect effects. Results/Data Synthesis: Objective SES was associated with left entorhinal cortex (ERC; β = 0.085, p = 0.036) and bilateral Brodmann area (BA) 36 volumes (left: β = 0.088, p = 0.031; right: β = 0.086, p = 0.031). Subjective SES was associated with right subiculum (β = 0.078, p = 0.040). ADI was negatively associated with left subiculum (β = -0.096, p = 0.031) and positively with left BA36 (β = 0.084, p = 0.050). Left ERC volume mediated associations between objective SES and episodic memory (β = 0.017, 95% CI [0.004, 0.031]), working memory (β = 0.017, 95% CI [0.005, 0.031]), visuospatial ability (β = 0.015, 95% CI [0.004, 0.030]), and executive function (β = 0.011, 95% CI [0.002, 0.023]). Conclusions: Our findings indicate that discrete SES measures are differentially associated with MTL subregions, suggest a morphological mechanism underlying objective SES-cognition relationships, and underscore the need for longitudinal research.