Structural and social determinants of health shape the impact of neurodegeneration and cerebrovascular pathology on cognitive functioning in black adults.

INTRODUCTION

Black adults in the United States experience a disproportionately higher risk of dementia due to cumulative exposure to structural and social determinants of health (S/SDOH). Although structural neuroimaging provides markers of atrophy and cerebrovascular injury, less is known about how these biomarkers interact with S/SDOH to influence cognitive performance within minoritized populations. This study examined independent and interactive associations between a multidimensional S/SDOH Composite Index (S/SDOH-CI) and structural imaging-derived biomarkers among Black adults in an urban setting.

METHODS

We analyzed data from a community-based sample of Black adults aged ≥45 who completed brain MRI, the Preclinical Alzheimer Cognitive Composite (PACC), the Montreal Cognitive Assessment (MoCA), and a comprehensive assessment of structural and social determinants of health (S/SDOH). Structural biomarkers included total brain volume, hippocampal volume, global and regional white matter hyperintensities (WMH), and brain-age gap (BAG). Linear regression models examined independent and interactive associations between the S/SDOH-CI and MRI biomarkers with cognitive performance, adjusting for demographic characteristics and Charleston comorbidity index.

RESULTS

Total brain volume and BAG were associated with MoCA. Significant interactions were observed between S/SDOH-CI and BAG for cognitive outcomes. Across S/SDOH factors, discrimination, and coping moderated associations between WMH and PACC, while education moderated associations between brain volume and MoCA.

DISCUSSION: These findings underscore that biological vulnerability cannot be fully understood without accounting for structural and social disparities. Differential sensitivity of MRI biomarkers highlights the need for neuroimaging research tailored to diverse populations and supports integrating S/SDOH to inform precision-equity approaches to dementia prevention.