Race and sex differences in midlife changes in cerebral volume and perfusion

Abstract

AbstractBackgroundCross‐sectional demographic differences in MRI markers of brain health are well established, but less is known about differences in rates of change, particularly in mid‐life. We assessed demographic differences in midlife change of MRI measures of gray matter (GM) volume and perfusion, which are important early markers of late‐life cognitive decline. We also assess the extent to which cardiovascular risk factors explain demographic differences.MethodData are from a subsample attending the 25 and 30 year follow‐up MRI exams [n=478] of Coronary Artery Risk Development in Young Adults (CARDIA), a community‐based cohort study at 3 USA‐based centers. Structural 3T MRI was used to quantify total GM as percent of intracranial volume. GM cerebral blood flow (CBF, ml/100gr/min) was measured using pseudo‐continuous arterial spin labeling. To test for interaction between race and sex, multiple linear regression analysis was used entering MRI feature at follow‐up as dependent variable and as independent variables: MRI feature at baseline, center, age, sex, race and the interaction term(race*sex). Next, MRI features at follow‐up were compared amongst groups of race/sex with ANCOVA, adjusting for baseline MRI feature, center, age and additionally for cardiovascular health(CVH) according to the American Heart Association Life’s Simple 7(LS7) metric.ResultThe sample had mean baseline age 50.4(SD 3.5) years, 48.1% male, and 38.3% black. Over the 5‐year follow‐up period, GM volume and CBF significantly declined. Significant interaction between race and sex was observed for GM (P‐interaction=0.0041), such that black men demonstrated a significantly larger volumetric decline than black women, whereas no significant sex differences were observed in whites. Race*sex interaction was also observed for CBF (P‐interaction=0.023), such that men demonstrated a significantly larger decline in perfusion than women in both races, which associations were more pronounced in blacks. Adjustment for LS7‐CVH metric attenuated results slightly but reported associations remained significant.ConclusionOur results indicate sex/race specific patterns of midlife decline in cerebral GM volume and in perfusion, which were not fully explained by prevalent cardiovascular risk. Race/sex may be crucial variables in heterogeneity of early cerebral disease, an important marker of late‐life cognitive decline. Additional research is needed to identify the factors driving these associations.