title: Electroencephalographic findings related with mild cognitive impairment in idiopathic rapid eye movement sleep behavior disorder.
abstract: OBJECTIVE
  Mild cognitive impairment (MCI) and electroencephalographic (EEG) slowing have been reported as common findings of idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) and α-synucleinopathies. The objective of this study is to clarify the relation between MCI and physiological markers in iRBD.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Yoyogi Sleep Disorder Center.
  
  
  METHODS
  Thirty-one patients with iRBD including 17 younger patients with iRBD (younger than 70 y) and 17 control patients for the younger patients with iRBD.
  
  
  METHODS
  N/A.
  
  
  RESULTS
  Montreal Cognitive Assessment (MoCA) and n-polysomnogram (PSG) were conducted of all participants. In patients with iRBD, the factors associated with MCI were explored among parameters of REM sleep without atonia (RWA), score of Sniffin' Sticks Test (threshold-discrimination-identification [TDI] score), RBD morbidity, and RBD severity evaluated with the Japanese version of the RBD questionnaire (RBDQ-JP). The younger iRBD group showed significantly lower alpha power during wake and lower MoCA score than the age-matched control group. MCI was detected in 13 of 17 patients (76.5%) on MoCA in this group. Among patients wtih iRBD, the MoCA score negatively correlated with age, proportion of slow wave sleep, TDI score, and EEG spectral power. Multiple regression analysis provided the following equation: MoCA score = 50.871-0.116*age -5.307*log (δ power during REM sleep) + 0.086*TDI score (R² = 0.598, P < 0.01). The standardized partial regression coefficients were -0.558 for age, -0.491 for log (δ power during REM sleep), and 0.357 for TDI score (F = 9.900, P < 0.001).
  
  
  CONCLUSIONS
  Electroencephalographic slowing, especially during rapid eye movement sleep and olfactory dysfunction, was revealed to be associated with cognitive decline in idiopathic rapid eye movement sleep behavior disorder.
authors.affiliation: Japan Somnology Center, Neuropsychiatric Research Institute, Tokyo, Japan ; Yoyogi Sleep Disorder Clinic, Tokyo, Japan ; Department of Somnology, Tokyo Medical University, Tokyo, Japan ; Department of Life Sciences and Bioinformatics, Division of Biomedical Laboratory Sciences, Graduate School of Health Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Taeko
authors.initials: T
authors.lastname: Sasai
authors.forename: Masato
authors.initials: M
authors.lastname: Matsuura
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Inoue
mesh_terms: D000367:Age Factors; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D016022:Case-Control Studies; D060825:Cognitive Dysfunction / Q000150:complications / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D017286:Polysomnography; D020187:REM Sleep Behavior Disorder / Q000150:complications / Q000503:physiopathology*; D012895:Sleep, REM / Q000502:physiology
keywords: Electroencephalogram; Lewy body disease; Parkinson disease; REM sleep behavior disorder; mild cognitive impairment