title: Brain Connectivity Alterations Are Associated with the Development of Dementia in Parkinson's Disease.
abstract: Dementia affects a high proportion of Parkinson's disease (PD) patients and poses a burden on caregivers and healthcare services. Electroencephalography (EEG) is a common nonevasive and nonexpensive technique that can easily be used in clinical settings to identify brain functional abnormalities. Only few studies had identified EEG abnormalities that can predict PD patients at higher risk for dementia. Brain connectivity EEG measures, such as multiscale entropy (MSE) and phase-locking value (PLV) analyses, may be more informative and sensitive to brain alterations leading to dementia than previously used methods. This study followed 62 dementia-free PD patients for a mean of 3.4 years to identify cerebral alterations that are associated with dementia. Baseline resting state EEG of patients who developed dementia (N = 18) was compared to those of patients who remained dementia-free (N = 44) and of 37 healthy subjects. MSE and PLV analyses were performed. Partial least squares statistical analysis revealed group differences associated with the development of dementia. Patients who developed dementia showed higher signal complexity and lower PLVs in low frequencies (mainly in delta frequency) than patients who remained dementia-free and controls. Conversely, both patient groups showed lower signal variability and higher PLVs in high frequencies (mainly in gamma frequency) compared to controls, with the strongest effect in patients who developed dementia. These findings suggest that specific disruptions of brain communication can be measured before PD patients develop dementia, providing a new potential marker to identify patients at highest risk of developing dementia and who are the best candidates for neuroprotective trials.
authors.affiliation: 1 Rotman Research Institute, Baycrest Center , Toronto, Canada .
authors.forename: Josie-Anne
authors.initials: JA
authors.lastname: Bertrand
authors.affiliation: 1 Rotman Research Institute, Baycrest Center , Toronto, Canada .
authors.forename: Anthony R
authors.initials: AR
authors.lastname: McIntosh
authors.affiliation: 2 Centre for Advanced Research in Sleep Medicine , Hôpital du Sacré-Cœur de Montréal, Montreal, Canada .|3 Department of Neurology, Montreal General Hospital , Montreal, Canada .
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Postuma
authors.affiliation: 1 Rotman Research Institute, Baycrest Center , Toronto, Canada .
authors.forename: Natasha
authors.initials: N
authors.lastname: Kovacevic
authors.affiliation: 2 Centre for Advanced Research in Sleep Medicine , Hôpital du Sacré-Cœur de Montréal, Montreal, Canada .|4 Department of Psychology, Université de Montréal , Montreal, Canada .
authors.forename: Véronique
authors.initials: V
authors.lastname: Latreille
authors.affiliation: 5 Unité des troubles du mouvement André Barbeau, Centre Hospitalier de l'Université de Montréal , Montreal, Canada .
authors.forename: Michel
authors.initials: M
authors.lastname: Panisset
authors.affiliation: 5 Unité des troubles du mouvement André Barbeau, Centre Hospitalier de l'Université de Montréal , Montreal, Canada .
authors.forename: Sylvain
authors.initials: S
authors.lastname: Chouinard
authors.affiliation: 2 Centre for Advanced Research in Sleep Medicine , Hôpital du Sacré-Cœur de Montréal, Montreal, Canada .|6 Department of Psychology, Université du Québec à Montréal , Montreal, Canada .
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Gagnon
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000473:pathology* / Q000503:physiopathology; D058256:Brain Waves; D016022:Case-Control Studies; D063132:Connectome; D003704:Dementia / Q000473:pathology* / Q000503:physiopathology; D004569:Electroencephalography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000473:pathology* / Q000503:physiopathology
keywords: Parkinson's disease; cognitive decline; delta frequency; gamma frequency; posterior brain regions; resting state EEG