Relationship between Cortical Thickness and EEG Alterations during Sleep in the Alzheimer’s Disease

Abstract

Recent evidence showed that EEG activity alterations that occur during sleep are associated with structural, age-related, changes in healthy aging brains, and predict age-related decline in memory performance. Alzheimer’s disease (AD) patients show specific EEG alterations during sleep associated with cognitive decline, including reduced sleep spindles during NREM sleep and EEG slowing during REM sleep. We investigated the relationship between these EEG sleep alterations and brain structure changes in a study of 23 AD patients who underwent polysomnographic recording of their undisturbed sleep and 1.5T MRI scans. Cortical thickness measures were correlated with EEG power in the sigma band during NREM sleep and with delta- and beta-power during REM sleep. Thinning in the right precuneus correlated with all the EEG indexes considered in this study. Frontal–central NREM sigma power showed an inverse correlation with thinning of the left entorhinal cortex. Increased delta activity at the frontopolar and temporal regions was significantly associated with atrophy in some temporal, parietal, and frontal cortices, and with mean thickness of the right hemisphere. Our findings revealed an association between sleep EEG alterations and the changes to AD patients’ brain structures. Findings also highlight possible compensatory processes involving the sources of frontal–central sleep spindles.

The role of the sleep K‐complex on the conversion from mild cognitive impairment to Alzheimer's disease

“…Moreover, reduced SWA in healthy aging is associated with pathological markers of AD (Mander et al, 2015; Varga et al, 2016), and its amount in the < 1‐Hz frequency range can predict the speed of Aβ deposition over time (Winer et al, 2020). On the other hand, different findings described the absence of changes in the delta frequency range and SWA ≤ 1 Hz power during NREM sleep in AD/MCI (D'Atri, Scarpelli et al, 2021; De Gennaro et al, 2017) and the absence of a relationship between NREM sleep SWA and cortical thickness in AD (D'Atri, Gorgoni et al, 2021). Crucially, opposite AD‐related SWA changes according to the considered frequency range have been highlighted (Bonanni et al, 2012; Mander et al, 2015).…”

Sex differences in the association of sleep spindle density and cognitive performance among community‐dwelling middle‐aged and older adults with obstructive sleep apnea

“…Cortical thinning has also been associated with poor self‐reported sleep quality among older adults irrespective of cognition, depressive symptoms or BMI (Fjell et al, 2021). On the other hand, studies on patients with dementia during sleep reported that reduced spindle activity was associated with cortical atrophy in parietal regions with a compensatory activity recorded instead in the frontal and central regions (D'Atri et al, 2021; Gorgoni et al, 2016). The present study confirms existing findings on the associations between spindle density and cognitive outcomes, and extends the investigation to an older population with some individuals presenting with OSA.…”

“…Sleep spindles are a hallmark of Stage 2 non‐rapid eye movement (NREM) and can also be identified in NREM Stage 3 (Fernandez & Lüthi, 2020). They are bursts of oscillatory activity generated in the thalamic reticular nucleus detectable in electroencephalographic (EEG) recordings in the 11–16‐Hz frequency range and lasting between 0.5 and 2.0 s (D'Atri et al, 2021; Fernandez & Lüthi, 2020; Guadagni et al, 2021; Purcell et al, 2017). Recent studies have highlighted the association between sleep spindle characteristics and executive functioning among adolescents (Reynolds et al, 2018; Vermeulen et al, 2019) and older adults (Guadagni et al, 2021) as well as memory consolidation and learning in different types of memory tasks (Boutin & Doyon, 2020; Champetier et al, 2022; McDevitt et al, 2017).…”