Timely coupling of sleep spindles and slow waves linked to early amyloid-β burden and predicts memory decline
Daphné Chylinski, Maxime Van Egroo, Justinas Narbutas, Vincenzo Muto, Mohamed Ali Bahri, Christian Berthomier, Éric Salmon, Christine Bastin, Christophe Phillips, Fabienne Collette, Pierre Maquet, Julie Carrier, Jean‐Marc Lina, Gilles Vandewalle
Abstract
Sleep alteration is a hallmark of ageing and emerges as a risk factor for Alzheimer’s disease (AD). While the fine-tuned coalescence of sleep microstructure elements may influence age-related cognitive trajectories, its association with AD processes is not fully established. Here, we investigated whether the coupling of spindles and slow waves (SW) is associated with early amyloid-β (Aβ) brain burden, a hallmark of AD neuropathology, and cognitive change over 2 years in 100 healthy individuals in late-midlife (50–70 years; 68 women). We found that, in contrast to other sleep metrics, earlier occurrence of spindles on slow-depolarisation SW is associated with higher medial prefrontal cortex Aβ burden (p=0.014, r² β* =0.06) and is predictive of greater longitudinal memory decline in a large subsample (p=0.032, r² β* =0.07, N=66). These findings unravel early links between sleep, AD-related processes, and cognition and suggest that altered coupling of sleep microstructure elements, key to its mnesic function, contributes to poorer brain and cognitive trajectories in ageing.