Disparities in dementia and AD biomarkers in the ARIC study: The important contribution of social determinants of health

Abstract

AbstractBackgroundDementia disproportionately impacts people of color in the U.S.. Whether these disparities are due to differences in vascular risk factors, cognitive reserve, or AD pathophysiology remains unclear.MethodBlack and White participants from four U.S. communities were recruited into the Atherosclerosis Risk in Communities (ARIC) study at ages 45‐64. Vascular risk factors were evaluated in midlife and at multiple visits over 30+ years, as were markers of cognitive reserve, with expert classification of dementia. In participants with brain MRI, brain volumes were evaluated in association with dementia. In nondemented participants in the ARIC‐PET ancillary study, florbetapir PET scans were used to quantify brain cortical amyloid; differences in levels by race, vascular risk factors, and white matter hyperintensities (WMH) were evaluated.ResultIn 15744 ARIC participants, dementia was more common in Black vs White participants. Although midlife vascular risk factors were related to dementia, the impact of these risk factors on dementia risk and cortical volumes didn’t differ by race. Lower education was nonsignificantly more strongly associated with dementia in Blacks vs Whites, and an APOE e4 allele was more strongly associated with dementia in Whites. In ARIC‐PET (N=322), vascular risk factors from midlife were associated with PET amyloid, without similar associations for late‐life risk factors; these associations did not significantly differ by race. WMH volume was more strongly associated (cross‐sectionally) with PET amyloid in Blacks vs Whites, but differences were not statistically significantly different. Finally, Blacks had an over two‐fold increased odds of elevated florbetapir PET vs Whites, independent of vascular risk factors, demographics, WMH volume, cognitive status, and APOE genotype.ConclusionConsideration of racial disparities in dementia should consider vascular risk, cognitive reserve, and social determinants of health, across the life course. Vascular risk factors do not appear to differentially impact dementia risk or brain amyloid in Blacks vs Whites, but the greater prevalence of these risk factors in Blacks must be considered. Although the A/T/N framework may clarify underlying biology contributing to Alzheimer’s disease, inclusion of these additional factors is needed to understand and reduce racial disparities in dementia rates.