title: NREM sleep alpha and sigma activity in Parkinson's disease: evidence for conflicting electrophysiological activity?
abstract: OBJECTIVE
  Sleep EEG spectral patterns were investigated in eight newly diagnosed, non-depressed, non-demented, drug-naïve Parkinson's disease patients compared to nine controls.
  
  
  METHODS
  Mean relative spectral power density calculated for 0.25 Hz frequency bins and for classical EEG frequency bands.
  
  
  RESULTS
  Differences between patients and controls were most prominent in non-REM sleep, specially around 8.6 Hz (slow alpha), 12.5 Hz (fast alpha/slow sigma) and 15 Hz (fast sigma). Slow alpha showed lower p-values over frontal and occipital electrodes, whereas fast sigma activity was more important on central and parietal sites. Significantly increased NREM sleep alpha activity was found in left and right frontal (Mann-Whitney U=12,000, p=.021; U=14,000, p=.036), left and right central (U=14,000, p=.036), left parietal and left occipital (U=13,000, p=.027; U=15,000, p=.046) areas. Increased sigma activity was found in right frontal (U=14,000, p=.036), left central (U=12,000, p=.021), left and right parietal (U=12,000, p=.021; U=13,000, p=.027) and left occipital (U=15,000, p=.046) areas.
  
  
  CONCLUSIONS
  Concomitantly increased scalp EEG alpha and sigma activity was found during NREM sleep in initial Parkinson's disease.
  
  
  CONCLUSIONS
  These non-REM sleep microstructure changes may represent evidence for altered electrophysiological mechanisms leading to sleep-wake instability in early disease stages.
authors.affiliation: Sleep and Movement Disorders Clinics, Division of Neurology, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Brazil.
authors.forename: Regina
authors.initials: R
authors.lastname: Margis
authors.affiliation: Sleep and Movement Disorders Clinics, Division of Neurology, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Brazil. Electronic address: sschonwald@hcpa.ufrgs.br.
authors.forename: Suzana Veiga
authors.initials: SV
authors.lastname: Schönwald
authors.affiliation: Department of Internal Medicine, Jacobi Medical Center, Albert Einstein College of Medicine, USA.
authors.forename: Diego Zaquera
authors.initials: DZ
authors.lastname: Carvalho
authors.affiliation: Physics and Chemistry Department, Universidade de Caxias do Sul, Brazil.
authors.forename: Günther J L
authors.initials: GJ
authors.lastname: Gerhardt
authors.affiliation: Sleep and Movement Disorders Clinics, Division of Neurology, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Brazil; Movement Disorders Center, Division of Neurology, Universidade Federal de Ciências da Saúde de Porto Alegre, Brazil; Curso de Pós-Graduação em Medicina, Ciências Médicas da Universidade Federal do Rio Grande do Sul, Brazil.
authors.forename: Carlos R M
authors.initials: CR
authors.lastname: Rieder
mesh_terms: D000368:Aged; D000513:Alpha Rhythm; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology*; D012894:Sleep Stages
keywords: Parkinson’s disease; Polysomnography; Quantitative EEG; Sleep; Spectral analysis