Lower slow wave sleep and rapid eye-movement sleep are associated with brain atrophy of AD-vulnerable regions.

Study Objectives: Sleep deficiency is associated with Alzheimer's disease (AD) pathogenesis. We examined the association of sleep architecture with anatomical features observed in AD: (1) atrophy of hippocampus, entorhinal, inferior parietal, parahippocampal, precuneus, and cuneus regions ("AD-vulnerable regions") and (2) cerebral microbleeds.

Methods: In 271 participants of the Atherosclerosis Risk in the Communities Study, we examined the association of baseline sleep architecture with anatomical features identified on brain MRI 13~17 years later. Sleep architecture was quantified as the proportion of slow wave sleep (SWS), proportion of rapid eye-movement sleep (REM), and arousals index using polysomnography. Outcomes included (1) volumetric measurements of each AD-vulnerable region and (2) the presence of any cerebral microbleeds (CMBs) and that of lobar CMBs, which are more specifically associated with AD. We analyzed the association of each sleep predictor with each MRI outcome, adjusting for covariates.

Results: Having less SWS was associated with smaller inferior parietal region (β=-44.19 mm [95%CI=76.63, -11.76]) and cuneus (β=-11.99 mm [-20.93, -3.04]) after covariate adjustment. Having less REM was associated with smaller inferior parietal region (β=-75.52 mm [-129.34, -21.70]) and precuneus (β=-31.93 mm [-63.79, -0.07]). After FDR adjustments, lower SWS and REM, respectively, were associated with smaller inferior parietal region. Arousal index was not associated with the volumes of AD-vulnerable regions. None of the sleep architecture variables were associated with CMBs or lobar CMBs.

Conclusions: Sleep deficiency is associated with the atrophy of the inferior parietal region, which is observed in early AD. Sleep architecture may be a modifiable risk factor for AD.