title: "Idiopathic" rapid-eye-movement (REM) sleep behavior disorder is associated with future development of neurodegenerative diseases.
abstract: OBJECTIVE
  To determine whether a diagnosis of idiopathic rapid-eye-movement sleep behavior disorder (RBD) is associated with a future risk of development of neurodegenerative diseases.
  
  
  METHODS
  We addressed the objective through development of a structured critically appraised topic that included a clinical scenario, structured question, search strategy, critical appraisal, results, summary of best evidence, commentary, and bottom-line conclusions. Participants included consultant and resident neurologists, clinical epidemiologists, medical librarians, and clinical content experts.
  
  
  RESULTS
  A retrospective study of 44 consecutive patients diagnosed with idiopathic RBD demonstrated that 20 patients (45%) developed a neurologic disorder, most commonly Parkinson disease or Lewy body dementia, after a mean of 11.5 years from reported symptom onset and 5.1 years after RBD diagnosis.
  
  
  CONCLUSIONS
  Currently available evidence is limited to cross-sectional and retrospective analyses of patients with RBD. Although ascertainment biases and the retrospective nature of the available evidence limits quantitative analyses, the diagnosis of idiopathic RBD portends a risk of greater than 45% for future development of a clinically defined neurodegenerative disease. This finding has significant implications for clinical neurologic and sleep disorder practice and neurodegenerative disease research.
authors.affiliation: Department of Neurology, Mayo Clinic College of Medicine, Scottsdale, Arizona 85259, USA.
authors.forename: Mark G
authors.initials: MG
authors.lastname: Hickey
authors.forename: Bart M
authors.initials: BM
authors.lastname: Demaerschalk
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Caselli
authors.forename: James M
authors.initials: JM
authors.lastname: Parish
authors.forename: Dean M
authors.initials: DM
authors.lastname: Wingerchuk
mesh_terms: D000368:Aged; D001921:Brain / Q000503:physiopathology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D020961:Lewy Body Disease / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D019636:Neurodegenerative Diseases / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology*; D010300:Parkinson Disease / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D020187:REM Sleep Behavior Disorder / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D012189:Retrospective Studies; D012307:Risk Factors