Night-to-night REM sleep variability: a relevant marker of early amyloid-β deposition

INTRODUCTIONSleep disturbances are prevalent in patients with Alzheimers disease (AD) and may emerge before overt clinical symptoms. We characterized sleep alterations in cognitively unimpaired older adults with cerebral amyloid deposition, and assessed their associations with regional amyloid deposition, cognitive and psychoaffective outcomes. METHODSSeventy-six older adults (69.1 {+/-} 3.4 years, 63.2% female) underwent a multi-night (4.5 {+/-} 0.8 nights) objective sleep assessment using the Somno-Art(R) wearable device, Florbetapir-PET scanning, and an extensive neuropsychological and psychoaffective evaluation. RESULTSAmyloid {beta} (A{beta})-positive individuals had a shorter total sleep time (TST) and greater night-to-night variability in rapid eye movement (REM) sleep duration than A{beta}-negative individuals. Across the whole sample, these sleep characteristics were associated with increased A{beta} deposition in widespread brain regions, but not with cognitive or psychoaffective measures. DISCUSSIONShorter sleep duration and greater REM sleep variability may index early AD-related brain changes, warranting longitudinal studies to establish their prognostic significance. Age-Well randomized clinical trial of the Medit-Ageing European Project. Trial registration number: EudraCT:2016-002,441-36; IDRCB:2016-A01767-44; ClinicalTrials.gov Identifier: NCT02977819