What factors explain racial differences in memory‐related gray matter volume regions of interest among cognitively normal older adults?

Background Previous studies indicate there are racial differences in the prevalence of Alzheimer’s Disease or other dementias, suggesting older Blacks are about twice as likely to have dementia as older Whites. Incorporating neuroimaging measures is necessary to understand the neural pathology underlying the mechanisms of these racial disparities, however limited data exists on neuroimaging outcomes among racially diverse adults of advanced age. Method We examined cross‐sectional associations of race and memory‐related gray matter volume (GMV) regions of interest (ROIs) in 263 community‐sampled adults (mean age 83, 57% female, 39% Black) from the Healthy Brain Project, a substudy of the Health, Aging, and Body Composition Study. Generalized linear models were used to test associations between race and memory‐related GMV ROIs (hippocampus, posterior cingulate cortex, parahippocampal gyrus, and entorhinal cortex), quantified using magnetic resonance imaging. Result Compared to Whites, Blacks consistently showed smaller GMV in four memory related ROIs, cross‐sectionally. Racial differences in GMV remained in the parahippocampal gyrus (β=‐433.42, 95% CI: ‐642.96, ‐233.87) and entorhinal cortex (β=‐159.18, 95%CI: ‐245.89, ‐72.48), after adjusting for demographic, environmental, and psychosocial covariates. Conclusion The association between gray matter volume of memory‐related ROIs and race is only partially explained by the demographic, environmental, and psychosocial factors considered in the present study. Quantitative bias analysis will be used to address whether these findings are the result of selection bias due to racial differences in recruitment.