Longitudinal associations between racial discrimination and hippocampal and white matter hyperintensity volumes among older Black adults

Rationale: Non-Hispanic Black older adults are at higher risk of Alzheimer's disease and related dementias (ADRD) than non-Hispanic Whites, which reflects racial disparities in both brain and cognitive health. Discrimination may contribute to these disparities, but much of the research on discrimination and ADRD outcomes is cross-sectional and/or does not disaggregate experiences of discrimination by attribution. Focusing specifically on racial discrimination and considering longitudinal brain outcomes may advance our understanding of the role of discrimination in explaining disproportionate rates of ADRD among non-Hispanic Black older adults.Methods: In total, 221 non-Hispanic Black participants in the Washington Heights-Inwood Columbia Aging Project completed multiple measures of discrimination at one time point and structural magnetic resonance imaging (MRI) scans at two time points. Everyday discrimination and lifetime discrimination were operationalized first as aggregate experiences of discrimination (regardless of identity attributions) and then as racial discrimination per se. MRI outcomes included hippocampal and white matter hyperintensity (WMH) volumes. Latent difference score models estimated associations between the discrimination measures and each MRI outcome over four years.Results: Aggregate discrimination (regardless of attributions) was not associated with either outcome. Lifetime racial discrimination was associated with lower initial hippocampal volume. Everyday racial discrimination was associated with faster accumulation of WMH over time.Conclusions: Racial discrimination may be detrimental for brain aging among non-Hispanic Black older adults, which may contribute to their disproportionate dementia burden. Disaggregating discrimination by attribution may clarify research on racial inequalities in brain and cognitive aging, as racial discrimination appears to be particularly toxic.