title: Electroencephalogram slowing predicts neurodegeneration in rapid eye movement sleep behavior disorder.
abstract: A large proportion of patients with idiopathic rapid eye movement sleep behavior disorder (iRBD) develop a synucleinopathy, mostly Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Therefore, identifying markers of neurodegeneration in iRBD could have major implications. We aimed to assess the usefulness of electroencephalography (EEG) spectral analysis performed during wakefulness for predicting the development of a neurodegenerative disease in iRBD. Fifty-four iRBD patients, 28 of whom developed Parkinson's disease, multiple system atrophy, or dementia with Lewy bodies (mean follow-up: 3.5 years), and 30 healthy controls underwent at baseline a resting-state waking EEG recording, neurological exam, and neuropsychological assessment. Absolute and relative spectral powers were analyzed for 5 frequency bands in frontal, central, parietal, temporal, and occipital regions. The slow-to-fast [(δ + θ)/(β1 + β2)] power ratio for each of the 5 cortical regions and the dominant occipital frequency were calculated as an index of cortical slowing. Patients who developed disease showed higher absolute delta and theta power in all 5 cortical regions compared to disease-free patients and controls. The slow-to-fast power ratio was higher in all regions in patients who developed disease than in the 2 other groups. Moreover, patients who developed disease had a slower dominant occipital frequency compared to controls. The only significant difference observed between disease-free iRBD patients and controls was higher absolute delta power in frontal and occipital regions in iRBD patients. Specific EEG abnormalities were identified during wakefulness in iRBD patients who later developed a synucleinopathy. EEG slowing is a promising marker of neurodegeneration in iRBD patients.
authors.affiliation: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec, Canada; Department of Psychology, Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Jessica
authors.initials: J
authors.lastname: Rodrigues Brazète
authors.affiliation: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec, Canada; Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada. Electronic address: gagnon.jean-francois.2@uqam.ca.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Gagnon
authors.affiliation: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec, Canada; Department of Neurology, Montreal General Hospital, Montreal, Quebec, Canada.
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Postuma
authors.affiliation: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec, Canada; Rotman Research Institute, Baycrest Center, Toronto, Ontario, Canada.
authors.forename: Josie-Anne
authors.initials: JA
authors.lastname: Bertrand
authors.affiliation: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec, Canada; Department of Psychiatry, Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Dominique
authors.initials: D
authors.lastname: Petit
authors.affiliation: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec, Canada; Department of Psychiatry, Université de Montréal, Montreal, Quebec, Canada. Electronic address: jy.montplaisir@umontreal.ca.
authors.forename: Jacques
authors.initials: J
authors.lastname: Montplaisir
mesh_terms: D000368:Aged; D002540:Cerebral Cortex / Q000503:physiopathology; D003700:Delta Rhythm; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D020961:Lewy Body Disease / Q000175:diagnosis / Q000209:etiology; D008297:Male; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000175:diagnosis* / Q000209:etiology*; D010300:Parkinson Disease / Q000175:diagnosis / Q000209:etiology; D011237:Predictive Value of Tests; D020187:REM Sleep Behavior Disorder / Q000150:complications*; D013826:Theta Rhythm; D014851:Wakefulness / Q000502:physiology
keywords: Dementia with Lewy bodies; Parkinson's disease; REM sleep behavior disorder; REM sleep without atonia; quantitative EEG