EEG alterations during wake and sleep in mild cognitive impairment and Alzheimer's disease

Aurora D'Atri; Serena Scarpelli; Maurizio Gorgoni; Ilaria Truglia; Giulia Lauri; Susanna Cordone; Michele Ferrara; Camillo Marra; Paolo Maria Rossini; Luigi De Gennaro

doi:10.1016/j.isci.2021.102386

EEG alterations during wake and sleep in mild cognitive impairment and Alzheimer's disease

iScience. 2021 Apr 1;24(4):102386. doi: 10.1016/j.isci.2021.102386. eCollection 2021 Apr 23.

Authors

Affiliations

¹ Department of Psychology, University of Rome "Sapienza", Via dei Marsi, 78, Rome 00185, Italy.
² Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, Coppito (L'Aquila) 67100, Italy.
³ IRCCS Fondazione Santa Lucia, Rome, Italy.
⁴ Foundation Policlinico Universitario Agostino Gemelli IRCCS - Department of aging, neuroscience, orthopaedic and head-neck, Rome 00168, Italy.
⁵ Department of Neuroscience & Neurorehabil., IRCCS San Raffaele-Pisana, Rome, 00163, Italy.

Abstract

Patients with Alzheimer's disease (AD) undergo a slowing of waking electroencephalographic (EEG) rhythms since prodromal stages, which could be ascribed to poor sleep quality. We examined the relationship between wake and sleep alterations by assessing EEG activity during sleep and (pre-sleep/post-sleep) wakefulness in AD, mild cognitive impairment (MCI) and healthy controls. AD and MCI show high sleep latency and less slow-wave sleep. Reduced sigma activity characterizes non-rapid eye movement (NREM) sleep, reflecting sleep spindles loss. The EEG slowing characterizes REM sleep and wakefulness of AD and MCI, with strong correlations among the two phenomena suggesting common neuropathological mechanisms. Evening-to-morning variations in waking EEG revealed the gradual disappearance in MCI and AD of overnight changes in delta activity, indicating a progressive decay of sleep restorative functions on diurnal activity that correlates with the impairment of sleep high-frequency activity in AD. Our findings support a linkage between wake and sleep alterations, and the importance of sleep-related processes in Alzheimer's disease progression.

Keywords: Chronobiology; Cognitive Neuroscience; Human Physiology.