Actigraphic Measures of Sleep and White Matter Volume in a Bi‐Racial Cohort

Abstract

ObjectivesAbout 50% of adults report some form of sleep disturbance with deleterious impact on cerebral white matter (WM). Here, we investigated interactive relations of sleep duration or quality and race on cerebral WM volumes in a largely middle‐aged, bi‐racial cohort.MethodsThe cross‐sectional Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) Scan study yielded 119 stroke and dementia‐free participants (mean age ~51y; 37% African American; ~48% women) with complete actigraphy, magnetic resonance imaging (MRI), and covariate data. A triaxial accelerometer (ActiGraph GT3X+, ActiGraph Corp) worn on the wrists for up to seven consecutive days, provided measures of total sleep time (TST), sleep efficiency (SE), and wake after sleep onset (WASO). Self‐rated sleep quality was assessed via the Pittsburgh Sleep Quality Index (PSQI). Brain MRI, acquired by 3.0 Tesla scanner, yielded quantitative measures of average WM volumes for total brain, total lesion, frontal, occipital, temporal, and parietal lobes. Multivariable linear regression analyzed interactive relations of each sleep variable and race to WM outcomes: model 1‐adjusted for age, sex, and race; model 2‐model 1+ body mass index, smoking, alcohol use, and depressive symptoms. Results are expressed as regression coefficients (β), p‐value.ResultsFollowing adjustments, TST*race interactions were noted for total (17.15, <0.05), frontal (13.17, <0.05), and parietal (7.77, <0.05) WM volumes. Shorter sleep duration was related to lower volumes in African Americans but greater volumes in Whites. PSQI*race interactions for total (59.62, <0.01), frontal (40.07, <0.01) and parietal (17.84, <0.05) WM showed relations of poorer sleep quality to lesser WM volumes in African Americans only.ConclusionShorter sleep duration and lesser self‐reported sleep quality were related to lower total and regional WM volumes among African Americans. The mechanisms underlying these racial differences warrant further investigation and may help explain neuropsychological health disparities.Support or Funding InformationSupported by National Institutes of Health grants ZIA‐AG000195 (MKE), R01‐AG034161 (SRW), and the University of Maryland Claude D. Pepper Older Americans Independence Center (P30 AG028747).