Association between race/ethnicity and neuroimaging biomarkers in middle‐ and older‐aged adults

Abstract

Background Alzheimer’s disease and related disorders (ADRD) disproportionately affect African American, Hispanic, and American Indian older adults. Previous studies report racial/ethnic differences in markers of aging and neurodegeneration, but results are inconsistent due to small, non‐representative samples. We hypothesized that accelerated aging would manifest as a stronger negative relationship between age and MRI biomarkers among community‐dwelling racial/ethnic minorities compared with non‐Hispanic Whites. Method ADRD‐related neuroimaging measures of composite cortical thickness (CT) in AD signature regions and white matter hyperintensity (WMH) volume were assessed in White (n=274), Black (n=451), and Hispanic (n=663) participants from community‐based, intergenerational studies of cognitive aging and dementia. WHICAP participants are Medicare‐eligible participants aged 65 and older. The Offspring cohort includes middle‐aged children of the WHICAP study participants (of the 1482 participants, 1209 families were represented). We examined the association of cohort age and race/ethnicity with each imaging marker, after adjusting for sex/gender and family relatedness, and tested interactions between cohort age and race/ethnicity in separate models. Result WHICAP participants were 75±6.5 years old and Offspring participants were 55±10.5 years old at time of MRI. As expected, WHICAP participants had lower CT in AD signature regions than Offspring (β=‐.06,95%CI:‐.05,‐.08). Compared with Whites, Blacks and Hispanics had lower CT in AD signature regions, but an interaction between cohort age and race/ethnicity revealed that older Blacks had disproportionately thinner CT in AD signature regions (β=‐.05,95%CI:‐.01,‐.10). Offspring participants had lower WMH volume than WHICAP participants (β=‐1.4,95%CI:‐2.1,‐.58). Blacks had more WMH burden overall (β=1.04,95%CI:.13,2.0), but there were no interactions between race/ethnicity and cohort age on WMH burden. Conclusion Among diverse, community‐based participants, there are disparities in markers of brain atrophy in both cohorts but this effect is intensified with age, where older Blacks show disproportionately greater brain atrophy compared with other groups. Disparities in small vessel cerebrovascular disease are apparent in middle‐age and late‐life, but this effect is similar across age‐groups. Results suggest that racial/ethnic disparities in markers of brain aging and disease are apparent even in middle‐age and, in the case of neurodegeneration, may amplify with increasing age. These differences may be due to accelerated aging secondary to sociocultural factors and experiences.

Role of white matter hyperintensity in effects of apolipoprotein E on cognitive injury

“…Compared to E3, E4 is associated with increased risk to develop cardiovascular disease and AD (Farrer et al, 1997). These E4 effects are sex-and ethnicity-dependent (Farrer et al, 1997;Turney et al, 2020). In contrast, compared to E3, E2 is associated with reduced risk of developing AD (Farrer et al, 1997).…”

Peak width of skeletonized mean diffusivity (PSMD) as neuroimaging biomarker for vascular cognitive impairment in the context of cerebral amyloid angiopathy

“…41 Black and Hispanic minorities have higher prevalence of vascular risk factors, greater risk of dementia, and more severe neuroimaging findings documented in several studies. [270][271][272][273] Sex-specific differences have also been reported. 274 Neuroimaging population-based cohorts also face recruitment and survival biases.…”