title: Electroencephalographic prodromal markers of dementia across conscious states in Parkinson's disease.
abstract: In Parkinson's disease, electroencephalographic abnormalities during wakefulness and non-rapid eye movement sleep (spindles) were found to be predictive biomarkers of dementia. Because rapid eye movement sleep is regulated by the cholinergic system, which shows early degeneration in Parkinson's disease with cognitive impairment, anomalies during this sleep stage might mirror dementia development. In this prospective study, we examined baseline electroencephalographic absolute spectral power across three states of consciousness (non-rapid eye movement sleep, rapid eye movement sleep, and wakefulness) in 68 non-demented patients with Parkinson's disease and 44 healthy controls. All participants underwent baseline polysomnographic recordings and a comprehensive neuropsychological assessment. Power spectral analyses were performed on standard frequency bands. Dominant occipital frequency during wakefulness and ratios of slow-to-fast frequencies during rapid eye movement sleep and wakefulness were also computed. At follow-up (an average 4.5 years after baseline), 18 patients with Parkinson's disease had developed dementia and 50 patients remained dementia-free. In rapid eye movement sleep, patients with Parkinson's disease who later developed dementia showed, at baseline, higher absolute power in delta and theta bands and a higher slowing ratio, especially in temporal, parietal, and occipital regions, compared to patients who remained dementia-free and controls. In non-rapid eye movement sleep, lower baseline sigma power in parietal cortical regions also predicted development of dementia. During wakefulness, patients with Parkinson's disease who later developed dementia showed lower dominant occipital frequency as well as higher delta and slowing ratio compared to patients who remained dementia-free and controls. At baseline, higher slowing ratios in temporo-occipital regions during rapid eye movement sleep were associated with poor performance on visuospatial tests in patients with Parkinson's disease. Using receiver operating characteristic curves, we found that best predictors of dementia in Parkinson's disease were rapid eye movement sleep slowing ratios in posterior regions, wakefulness slowing ratios in temporal areas, and lower dominant occipital frequency. These results suggest that electroencephalographic slowing during sleep is a new promising predictive biomarker for Parkinson's disease dementia, perhaps as a marker of cholinergic denervation.
authors.affiliation: Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada Department of Psychology, Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Véronique
authors.initials: V
authors.lastname: Latreille
authors.affiliation: Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada Department of Psychology, Université de Montréal, Montreal, Quebec, Canada gagnon.jean-francois.2@uqam.ca julie.carrier.1@umontreal.ca.
authors.forename: Julie
authors.initials: J
authors.lastname: Carrier
authors.affiliation: Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada Department of Psychology, Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Gaudet-Fex
authors.affiliation: Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur 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: Unité des troubles du mouvement André Barbeau, Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Panisset
authors.affiliation: Unité des troubles du mouvement André Barbeau, Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Chouinard
authors.affiliation: Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur 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: Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada gagnon.jean-francois.2@uqam.ca julie.carrier.1@umontreal.ca.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Gagnon
mesh_terms: D000368:Aged; D003243:Consciousness / Q000502:physiology*; D003704:Dementia / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D004569:Electroencephalography / Q000639:trends; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D017286:Polysomnography / Q000639:trends; D062706:Prodromal Symptoms; D011446:Prospective Studies; D014851:Wakefulness / Q000502:physiology
keywords: Parkinson’s disease; dementia; electroencephalography; sleep; wakefulness