Brain Aging Among Racially and Ethnically Diverse Middle-Aged and Older Adults

Abstract

ImportanceNeuroimaging studies have documented racial and ethnic disparities in brain health in old age. It remains unclear whether these disparities are apparent in midlife.ObjectiveTo assess racial and ethnic disparities in magnetic resonance imaging (MRI) markers of cerebrovascular disease and neurodegeneration in midlife and late life.Design, Setting, and ParticipantsData from 2 community-based cohort studies, Washington Heights–Inwood Columbia Aging Project (WHICAP) and the Offspring Study of Racial and Ethnic Disparities in Alzheimer Disease (Offspring), were used. Enrollment took place from March 2011 and June 2017, in WHICAP and Offspring, respectively, to January 2021. Of the 822 Offspring and 1254 WHICAP participants approached for MRI scanning, 285 and 176 refused participation in MRI scanning, 36 and 76 were excluded for contraindications/ineligibility, and 4 and 32 were excluded for missing key variables, respectively.Main Outcomes and MeasuresCortical thickness in Alzheimer disease–related regions, white matter hyperintensity (WMH) volume.ResultsThe final sample included 1467 participants. Offspring participants (497 [33.9%]) had a mean (SD) age of 55 (10.7) years, had a mean (SD) of 13 (3.5) years of education, and included 117 Black individuals (23.5%), 348 Latinx individuals (70%), 32 White individuals (6.4%), and 324 women (65.2%). WHICAP participants (970 [66.1%]) had a mean (SD) age of 75 (6.5) years, had a mean (SD) of 12 (4.7) years of education, and included 338 Black individuals (34.8%), 389 Latinx individuals (40.1%), 243 White individuals (25.1%), and 589 women (65.2%). Racial and ethnic disparities in cerebrovascular disease were observed in both midlife (Black-White: B = 0.357; 95% CI, 0.708-0.007; P = .046) and late life (Black-Latinx: B = 0.149, 95% CI, 0.068-0.231; P < .001; Black-White: B = 0.166; 95% CI, 0.254-0.077; P < .001), while disparities in cortical thickness were evident in late life only (Black-Latinx: B = −0.037; 95% CI, −0.055 to −0.019; P < .001; Black-White: B = −0.064; 95% CI −0.044 to −0.084; P < .001). Overall, Black-White disparities were larger than Latinx-White disparities for cortical thickness and WMH volume. Brain aging, or the association of age with MRI measures, was greater in late life compared with midlife for Latinx (cortical thickness: B = 0.006; 95% CI, 0.004-0.008; P < .001; WMH volume: B = −0.010; 95% CI, −0.018 to −0.001; P = .03) and White (cortical thickness: B = 0.005; 95% CI, 0.002-0.008; P = .001; WMH volume: B = −0.021; 95% CI −0.043 to 0.002; P = .07) participants but not Black participants (cortical thickness: B = 0.001; 95% CI, −0.002 to 0.004; P =.64; WMH volume: B = 0.003; 95% CI, −0.010 to 0.017; P = .61), who evidenced a similarly strong association between age and MRI measures in midlife and late life.Conclusions and RelevanceIn this study, racial and ethnic disparities in small vessel cerebrovascular disease were apparent in midlife. In Latinx and White adults, brain aging was more pronounced in late life than midlife, whereas Black adults showed accelerated pattern of brain aging beginning in midlife.

Unhealthy white matter connectivity, cognition, and racialization in older adults

“…No racialized group differences in associations between unhealthy white matter connectivity and cognition Relative to nHW participants, BA individuals exhibited more UWMC and lower MoCA scores. These findings are consistent with reports of racialized group differences in global and regional WMH burden [4][5][6] and global neuropsychological test performance. 58,59 UWMC-and-MoCA score associations were more often significant in nHW, versus BA, participants for both Aβ-and tau-affected regions.…”

“…WMH are markers of cerebral small vessel disease that are common in older adults and associated with cognitive decline. 3 Notably, WMH burden is more severe in BA individuals than in those who are nHW [4][5][6] and may confer comparatively greater risk of cognitive impairments. 7,8 In both BA and nHW populations, there is growing interest in the overlap between WMH and clinical and pathological AD as they share many of the same risk factors.…”

Retirement and cognitive aging in a racially diverse sample of older Americans

“…Black retirees may adjust to retirement better than White participants because of better established social support networks and cultural practices that favor community cohesiveness to a greater extent than is typical for White adults 32 . The finding is also consistent with prior research showing that Black participants have lower initial cognitive scores but less decline than White participants as they enter older adulthood, irrespective of retirement considerations, 33 and that Black adults may experience brain aging earlier than White (or Hispanic) adults 34 …”

“…32 The finding is also consistent with prior research showing that Black participants have lower initial cognitive scores but less decline than White participants as they enter older adulthood, irrespective of retirement considerations, 33 and that Black adults may experience brain aging earlier than White (or Hispanic) adults. 34 Historically, Black workers in the United States have faced substantial barriers to more engaging occupations due to longstanding structural disparities in education and hiring practices in the United States. 35 Our findings suggest that one outcome of the resulting race-based occupational segregation is that Black workers may not experience the same level of disruption in engagement and other health-enhancing aspects of employment when they retire, reducing the expected rate of post-retirement cognitive decline.…”

Characterization of Brain Volume Changes in Aging Individuals With Normal Cognition Using Serial Magnetic Resonance Imaging

“…This study has several limitations. First, the cohort was limited to Japanese individuals; therefore, our results may not be generalizable to other races and ethnicities . Second, relatively few participants were in their 80s, which may have increased measurement variability in this age group.…”