White adults in their midlife showed slower brain aging than Black and Latinx individuals, but between mid- and late life, they showed increased signs of aging.
Black adults in midlife may experience faster brain aging that other racial or ethnic groups, according to new research published in JAMA Network Open.
Brain aging is the association between age, cortical thickness, and white matter hyperintensity (WMH) volume. Increased WMH—a biomarker of neurodegenerative disease and aging—can be further associated with the risk of Alzheimer Disease (AD), cognitive decline, stroke.
“We postulate that race and ethnicity disparities in brain aging are due to lifetime cumulative exposure to structural and social forces that elevate subsequent exposure to risk factors for brain pathology,” the study authors wrote.
Cases of cerebrovascular disease and cortical thickness were also higher in Black adults in mid- and late life compared to White adults. This disparity was less between White and Latinx adults of the same age, but similar between Latinx and Black participants.
One explanation for differences in brain aging may be found in the weathering hypothesis, which states that repeated exposure to stress, suboptimal environments, and social disadvantage can lead to faster wear and tear on the body. Black and Latinx communities may experience more weathering due to factors including institutional racism and material hardship, according to the study authors.
The study serves 2 purposes—to understand differences in cortical thickness and WMH volume between racial and ethnic adults in mid- and late life and to assess patterns of brain aging across various race and ethnic groups.
Researchers looked at 1467 middle-aged and older adults in 2 large community-based studies— 970 older adults participated in the Washington Heights–Inwood Columbia Aging Project (WHICAP) cohort, and 497 middle-aged adults participated in the Offspring Study of Racial and Ethnic Disparities in Alzheimer Disease (Offspring cohort.)
Using in vivo with magnetic resonance imaging (MRI), researchers found disparities in the magnitude of WMH disparities, which was observable across race and ethnicity. Cognitive aging, determined in part by WMH volume and cortical thickness, happened at an earlier age in Black participants—this aging was observed in Latinx and White participants mostly in late life.
Decreased cortical thickness and premature weathering among Black participants could be the result of “cumulative effects of oppression, environmental adversity, and psychological stress… may lead to greater cerebrovascular disease and neurodegeneration,” the study authors wrote. Further, risk of AD may be higher among Black participants, according to the study.
The study includes some limitations. First, the proportion of White participants was lower in the Offspring cohort than the WHICAP, despite both cohorts’ racial and ethnic diversity. Additionally, the study’s cross-sectional design is a limit. Further, the differences in scanners could influence the findings.
“Future efforts will further disentangle the mechanisms underlying potential racial and ethnic disparities in brain aging, which in turn, may improve early detection, diagnosis, and treatment of AD,” the study authors wrote.
Turney, Indira, Lao, Patrick, Renteria, Miguel, et al. Brain Aging Among Racially and Ethnically Diverse Middle-Aged and Older Adults. JAMA Neurol. Published online November 14, 2022. doi:10.1001/jamaneurol.2022.3919