A cross-sectional analysis of two community-based cohorts found that from midlife, black people showed an accelerated pattern of brain ageing – the association of age with cortical thickness and white matter hyperintensity (WMH) volume, while for white and Latinx participants, the findings were greater in late life than midlife, said the researchers.
The Columbia University New York City team of Adam Brickman, PhD, and colleagues reported in JAMA Neurology that black participants had a similar magnitude of brain ageing both in mid-and late life.
“We postulate that race and ethnicity disparities in brain ageing are due to lifetime cumulative exposure to structural and social forces that elevate subsequent exposure to risk factors for brain pathology,” they wrote.
Previous studies have identified worse brain health in racial and ethnic minorities in late life, but have not compared brain health at midlife versus later life relative to white adults, they added.
The analysis assessed MRI markers of cerebrovascular disease and neurodegeneration in 970 participants in the Washington Heights–Inwood Columbia Ageing Project (WHICAP) late-life cohort and 497 of their adult children who participated in the Offspring Study of Racial and Ethnic Disparities in Alzheimer Disease (Offspring) midlife cohort. Participants without a diagnosis of dementia at the time of MRI scanning were enrolled from 2011 in WHICAP and from 2017 in Offspring to January 2021
Mean age of WHICAP participants was about 75; about 35% were black, 40% were Latinx, and 25% were white. Mean age of Offspring participants was about 55 and about 24% were black, 70% were Latinx, and 6.4% were white. About 65% of both cohorts were women. At time of the MRI scan, participants reported any history of diabetes, hypertension, heart disease, and clinical stroke.
Outcomes included WMH volume and cortical thickness. “Overall, comparable with other reports, black-white disparities were larger than Latinx-white disparities for both measures, while black-Latinx disparities were minimal,” Brickman and co-authors wrote.
WMH disparities occurred in both midlife (black-white B=0.357, P=0.046) and late life (black-Latinx B=0.149, P<0.001; black-white B=0.166, P<0.001). Disparities in cortical thickness were evident in late life only (black-Latinx B=-0.037, P<0.001; black-white B=-0.064, P<0.001).
Brain ageing was greater in late life compared with midlife for Latinx (cortical thickness B=0.006, P<.001; WMH volume B=-0.010, P=0.03) and white (cortical thickness B=0.005, P=0.001; WMH volume B=-0.021, P=0.07) participants. However, this was not the case for black participants (cortical thickness B=0.001, P=0.64; WMH volume B=0.003, P=0.61), who showed similarly strong associations between age and MRI measures in midlife and late life.
“White matter hyperintensities and cortical thickness are well known determinants or correlates of cognitive health, including in the current study, and the results have obvious implications for cognitive ageing,” the group wrote.
That the magnitude of race and ethnicity disparities in WMH volume was greater in midlife than late life may be due to differential survival across race and ethnicity, the researchers cautioned.
Limitations included the study’s cross-sectional design and its potentially limited generalisability due to the lower proportion of white participants in the middle-aged cohort compared with the older cohort, reports MedPage Today.
“Future studies should incorporate measurement of these forces across the life course to determine whether they mediate disparities observed in brain health, their functional consequences, and secular trends over time,” the team noted.
Future work also should include pathological biomarkers like amyloid and tau to clarify contributors to disparities in brain aging and Alzheimer’s disease, they added.
Study details
Brain Ageing Among Racially and Ethnically Diverse Middle-Aged and Older Adults
Indira Turney, Patrick Lao, Miguel Arce Rentería, et al.
Published in JAMA Neurology on 14 November 2022
Key Points
Question To what extent are racial and ethnic disparities in cortical thickness and white matter hyperintensity volume present in midlife and late life?
Findings In this cross-sectional study of 2 community-based cohort studies in midlife (n = 497) and late life (n = 970), race and ethnicity disparities in Alzheimer disease–related neuroimaging measures in midlife persisted in late life, which was most prominent in black adults.
Meaning Race and ethnicity disparities in ageing and Alzheimer disease and related dementias may be due partially to social forces that accelerate brain ageing, especially in black middle-aged adults.
Abstract
Importance
Neuroimaging studies have documented racial and ethnic disparities in brain health in old age. It remains unclear whether these disparities are apparent in midlife.
Objective
To assess racial and ethnic disparities in magnetic resonance imaging (MRI) markers of cerebrovascular disease and neurodegeneration in midlife and late life.
Design, Setting, and Participants
Data from 2 community-based cohort studies, Washington Heights–Inwood Columbia Ageing Project (WHICAP) and the Offspring Study of Racial and Ethnic Disparities in Alzheimer Disease (Offspring), were used. Enrolment 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 Measures
Cortical thickness in Alzheimer disease–related regions, white matter hyperintensity (WMH) volume.
Results
The 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 ageing, 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 Relevance
In this study, racial and ethnic disparities in small vessel cerebrovascular disease were apparent in midlife. In Latinx and white adults, brain ageing was more pronounced in late life than midlife, whereas black adults showed accelerated pattern of brain ageing beginning in midlife.
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