Objective: To investigate whether spectral analysis at baseline in rapid eye movement (REM) sleep can differentiate patients with REM sleep behavior disorder (RBD) who will later develop a neurodegenerative disease from those who will not, during longitudinal follow-up.

Background: RBD is strongly associated to the subsequent development of Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). In previous studies, we noted that waking EEG slowing in RBD was associated with mild cognitive impairment and with higher risk of developing disease. Considering that cholinergic denervation occurs in the early stages of those neurodegenerative diseases and that the cholinergic system is crucial for REM sleep activation, spectral analysis of this sleep stage could be used as a potential marker of neurodegeneration in this population.

Methods: A total of 61 RBD patients, 26 of which developed PD, DLB or MSA (mean follow-up: 3.6 years) and 28 control subjects underwent a night of polysomnography and neurological and neuropsychological assessments at baseline. Analysis of the absolute and relative spectral power was performed for four frequency bands (delta, theta, alpha, beta) in five cortical regions namely frontal, central, parietal, temporal and occipital. Analyses of variance (Group x Region) for each band were used to compare the two groups.

Results: A significant Group effect was found for the absolute delta and theta power. Patients who later developed neurodegeneration showed higher absolute delta and theta power in all regions at baseline compared to patients who remained disease free. A significant group effect was also found for the theta relative power. Patients who later developed disease showed higher relative theta power in all regions compared to patients who remained disease free.

Conclusions: This study indicates the presence of REM sleep EEG abnormalities in RBD patients who will later develop a neurodegenerative disease. These results suggest that early neurodegeneration impacting cortical and subcortical cholinergic transmission in RBD patients could alter their brain rhythms in this state of consciousness. Thus, REM sleep EEG alterations represent a potential marker of neurodegeneration in RBD patients.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/spectral-analysis-of-rapid-eye-movement-rem-sleep-as-a-potential-marker-of-neurodegenerative-disease-in-rem-sleep-behavior-disorder/