title: Sleep spindle alterations in patients with Parkinson's disease.
abstract: The aim of this study was to identify changes of sleep spindles (SS) in the EEG of patients with Parkinson's disease (PD). Five sleep experts manually identified SS at a central scalp location (C3-A2) in 15 PD and 15 age- and sex-matched control subjects. Each SS was given a confidence score, and by using a group consensus rule, 901 SS were identified and characterized by their (1) duration, (2) oscillation frequency, (3) maximum peak-to-peak amplitude, (4) percent-to-peak amplitude, and (5) density. Between-group comparisons were made for all SS characteristics computed, and significant changes for PD patients vs. control subjects were found for duration, oscillation frequency, maximum peak-to-peak amplitude and density. Specifically, SS density was lower, duration was longer, oscillation frequency slower and maximum peak-to-peak amplitude higher in patients vs.
  
  
  METHODS
  We also computed inter-expert reliability in SS scoring and found a significantly lower reliability in scoring definite SS in patients when compared to controls. How neurodegeneration in PD could influence SS characteristics is discussed. We also note that the SS morphological changes observed here may affect automatic detection of SS in patients with PD or other neurodegenerative disorders (NDDs).
authors.affiliation: Biomedical Engineering, Department of Electrical Engineering, Technical University of Denmark Kongens Lyngby, Denmark ; Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup University Hospital Glostrup, Denmark ; Stanford Center for Sleep Sciences and Medicine, Psychiatry and Behavioral Sciences, Stanford University Palo Alto, CA, USA.
authors.forename: Julie A E
authors.initials: JA
authors.lastname: Christensen
authors.affiliation: Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup University Hospital Glostrup, Denmark.
authors.forename: Miki
authors.initials: M
authors.lastname: Nikolic
authors.affiliation: Center for Advanced Research in Sleep Medicine, Sacré-Coeur Hospital of Montréal, University of Montréal Montréal, QC, Canada.
authors.forename: Simon C
authors.initials: SC
authors.lastname: Warby
authors.affiliation: Biomedical Engineering, Department of Electrical Engineering, Technical University of Denmark Kongens Lyngby, Denmark ; Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup University Hospital Glostrup, Denmark ; Stanford Center for Sleep Sciences and Medicine, Psychiatry and Behavioral Sciences, Stanford University Palo Alto, CA, USA.
authors.forename: Henriette
authors.initials: H
authors.lastname: Koch
authors.affiliation: Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup University Hospital Glostrup, Denmark ; Department of Neurology, Bispebjerg Hospital Copenhagen, Denmark.
authors.forename: Marielle
authors.initials: M
authors.lastname: Zoetmulder
authors.affiliation: Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup University Hospital Glostrup, Denmark.
authors.forename: Rune
authors.initials: R
authors.lastname: Frandsen
authors.affiliation: Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna Bologna, Italy.
authors.forename: Keivan K
authors.initials: KK
authors.lastname: Moghadam
authors.affiliation: Biomedical Engineering, Department of Electrical Engineering, Technical University of Denmark Kongens Lyngby, Denmark.
authors.forename: Helge B D
authors.initials: HB
authors.lastname: Sorensen
authors.affiliation: Stanford Center for Sleep Sciences and Medicine, Psychiatry and Behavioral Sciences, Stanford University Palo Alto, CA, USA.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Mignot
authors.affiliation: Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup University Hospital Glostrup, Denmark ; Center for Healthy Ageing, University of Copenhagen Copenhagen, Denmark.
authors.forename: Poul J
authors.initials: PJ
authors.lastname: Jennum
keywords: EEG; Parkinson's disease; biomarker; neurodegeneration; sleep spindle morphology