Rest-activity rhythm characteristics associated with lower cognitive performance and Alzheimer's disease biomarkers in midlife women.

INTRODUCTION: Disrupted rest-activity rhythms (RARs) have been linked to poorer cognitive function and Alzheimer's disease (AD) biomarkers. Here we extend this work to midlife women, who commonly experience menopause-related sleep and cognitive problems. METHODS: One hundred ninety-four postmenopausal participants underwent a neuropsychological evaluation, 72 h of wrist actigraphy generating RAR variables, and a blood draw to measure AD biomarkers: phosphorylated tau (p-tau181, p-tau231) and amyloid beta (Aβ40, Aβ42). RESULTS: Lower interdaily stability (IS) and relative amplitude (RA) and higher interdaily variability (IV) and least active 5 h (L5) were associated with worse processing speed, independent of sleep. Adjustment for sleep significantly attenuated the associations of RA with memory. Lower RA was associated with higher p-tau231 level, independent of sleep. Further adjustment for menopause-related factors modestly accounted for the associations between RAR, cognitive measures, and AD biomarkers. DISCUSSION: Weaker RAR, particularly RA, was associated with worse cognitive functions, and higher AD biomarkers levels, possibly linking RAR with AD pathology in women. HIGHLIGHTS: Lower rhythm stability and robustness and higher fragmentation were associated with worse processing speed.Lower robustness was associated with higher levels of phosphorylated tau-231.Menopause factors did not attenuate the association between rest-activity rhythms and cognitive function.