Associations between Alzheimer's disease blood biomarkers and neighborhood disadvantage: A HABS-HD community cohort study

BackgroundNeighborhood disadvantage has been associated with reduced cognitive reserve, increased risk for cognitive impairment, and greater Alzheimer's disease (AD) neuropathology, with particularly pronounced effects among Black and Hispanic/Latino older adults. Blood-based AD biomarkers offer a scalable approach to population-level study of AD risk; however, whether neighborhood-level social determinants influence these biomarkers across diverse populations remains unknown.ObjectiveTo characterize associations between neighborhood disadvantage and AD blood biomarkers in a racially and ethnically diverse community sample of older adults with and without cognitive impairment, and to examine whether these associations differ by race, ethnicity, and cognitive status.MethodsRegression models predicting AD biomarkers (amyloid-β 42/40 ratio, phosphorylated tau-181, total tau, and neurofilament light chain) from demographics and the Area Deprivation Index (ADI) were fit for 1179 Non-Hispanic White, 1264 Hispanic/Latino, and 724 Black adults. Models were stratified by cognitive impairment status and fit separately by race and ethnicity.ResultsAmyloid markers were associated with ADI, but only in cognitively impaired individuals living in highly disadvantaged areas. Total tau was elevated in those from disadvantaged neighborhoods, regardless of cognitive status; however, pTau-181 was not associated with ADI for any group. Significant associations were primarily evident among Black and Hispanic/Latino older adults.ConclusionsThe social exposome is an important factor in AD research, and findings show associations between neighborhood disadvantage and AD blood biomarkers; however, associations are mainly evident among ethnic/racial minority older adults living in moderately to severely disadvantaged neighborhoods. More work is needed to understand these associations.