Night‐to‐night rapid eye movement sleep variability: A relevant marker of early amyloid‐β deposition

INTRODUCTION: Sleep disturbances are prevalent in patients with Alzheimer's 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 and cognitive and psychoaffective outcomes. METHODS: Seventy-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 wearable device, Florbetapir-positron emission tomography (PET) scanning, and an extensive neuropsychological and psychoaffective evaluation. RESULTS: Amyloid β (Aβ)-positive individuals had a shorter total sleep time (TST) and greater night-to-night variability in rapid eye movement (REM) sleep duration than Aβ-negative individuals. Across the whole sample, these sleep characteristics were associated with increased Aβ deposition in widespread brain regions, but not with cognitive or psychoaffective measures. DISCUSSION: Shorter sleep duration and greater REM sleep variability may index early AD-related brain changes, warranting longitudinal studies to establish their prognostic significance. TRIAL REGISTRATION: 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.