title: REM sleep behavior disorder preceding other aspects of synucleinopathies by up to half a century.
abstract: BACKGROUND
  Idiopathic REM sleep behavior disorder (RBD) may be the initial manifestation of synucleinopathies (Parkinson disease [PD], multiple system atrophy [MSA], or dementia with Lewy bodies [DLB]).
  
  
  METHODS
  We used the Mayo medical records linkage system to identify cases presenting from 2002 to 2006 meeting the criteria of idiopathic RBD at onset, plus at least 15 years between RBD and development of other neurodegenerative symptoms. All patients underwent evaluations by specialists in sleep medicine to confirm RBD, and behavioral neurology or movement disorders to confirm the subsequent neurodegenerative syndrome.
  
  
  RESULTS
  Clinical criteria were met by 27 patients who experienced isolated RBD for at least 15 years before evolving into PD, PD dementia (PDD), DLB, or MSA. The interval between RBD and subsequent neurologic syndrome ranged up to 50 years, with the median interval 25 years. At initial presentation, primary motor symptoms occurred in 13 patients: 9 with PD, 3 with PD and mild cognitive impairment (MCI), and 1 with PDD. Primary cognitive symptoms occurred in 13 patients: 10 with probable DLB and 3 with MCI. One patient presented with primary autonomic symptoms, diagnosed as MSA. At most recent follow-up, 63% of patients progressed to develop dementia (PDD or DLB). Concomitant autonomic dysfunction was confirmed in 74% of all patients.
  
  
  CONCLUSIONS
  These cases illustrate that the alpha-synuclein pathogenic process may start decades before the first symptoms of PD, DLB, or MSA. A long-duration preclinical phase has important implications for epidemiologic studies and future interventions designed to slow or halt the neurodegenerative process.
authors.affiliation: Department of Neurology, Mayo Clinic College of Medicine, Rochester, MN, USA.
authors.forename: D O
authors.initials: DO
authors.lastname: Claassen
authors.forename: K A
authors.initials: KA
authors.lastname: Josephs
authors.forename: J E
authors.initials: JE
authors.lastname: Ahlskog
authors.forename: M H
authors.initials: MH
authors.lastname: Silber
authors.forename: M
authors.initials: M
authors.lastname: Tippmann-Peikert
authors.forename: B F
authors.initials: BF
authors.lastname: Boeve
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020961:Lewy Body Disease / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D008137:Longitudinal Studies; D008297:Male; D016347:Medical Records Systems, Computerized / Q000639:trends; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D010300:Parkinson Disease / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D020187:REM Sleep Behavior Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D012189:Retrospective Studies; D013997:Time Factors; D055815:Young Adult; D051844:alpha-Synuclein / Q000009:adverse effects / Q000502:physiology*
chemical_list: D051844:alpha-Synuclein