Risk and predictors of dementia and parkinsonism in idiopathic REM sleep behaviour disorder: A multicentre study

Ronald B. Postuma, Alex Iranzo, Michele Hu, Birgit Högl, Bradley F. Boeve, Raffaele Manni, Wolfgang H. Oertel, Isabelle Arnulf, Luigi Ferini-Strambi, Monica Puligheddu, Elena Antelmi, Valerie Cochen De Cock, Dario Arnaldi, Brit Mollenhauer, Aleksandar Videnovic, Karel Sonka, Ki Young Jung, Dieter Kunz, Yves Dauvilliers, Federica ProviniSimon J. Lewis, Jitka Buskova, Milena Pavlova, Anna Heidbreder, Jacques Y. Montplaisir, Joan Santamaria, Thomas R. Barber, Ambra Stefani, S. Erik K. Louis, Michele Terzaghi, Annette Janzen, Smandra Leu-Semenescu, Guiseppe Plazzi, Flavio Nobili, Friederike Sixel-Doering, Petr Dusek, Frederik Bes, Pietro Cortelli, Kaylena Ehgoetz Martens, Jean Francois Gagnon, Carles Gaig, Marco Zucconi, Claudia Trenkwalder, Ziv Gan-Or, Christine Lo, Michal Rolinski, Philip Mahlknecht, Evi Holzknecht, Angel R. Boeve, Luke N. Teigen, Gianpaolo Toscano, Geert Mayer, Silvia Morbelli, Benjamin Dawson, Amelie Pelletier

Research output: Contribution to journalArticlepeer-review

183 Scopus citations


Idiopathic REM sleep behaviour disorder (iRBD) is a powerful early sign of Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. This provides an unprecedented opportunity to directly observe prodromal neurodegenerative states, and potentially intervene with neuroprotective therapy. For future neuroprotective trials, it is essential to accurately estimate phenoconversion rate and identify potential predictors of phenoconversion. This study assessed the neurodegenerative disease risk and predictors of neurodegeneration in a large multicentre cohort of iRBD. We combined prospective follow-up data from 24 centres of the International RBD Study Group. At baseline, patients with polysomnographically-confirmed iRBD without parkinsonism or dementia underwent sleep, motor, cognitive, autonomic and special sensory testing. Patients were then prospectively followed, during which risk of dementia and parkinsonsim were assessed. The risk of dementia and parkinsonism was estimated with Kaplan-Meier analysis. Predictors of phenoconversion were assessed with Cox proportional hazards analysis, adjusting for age, sex, and centre. Sample size estimates for disease-modifying trials were calculated using a time-to-event analysis. Overall, 1280 patients were recruited. The average age was 66.3 ± 8.4 and 82.5% were male. Average follow-up was 4.6 years (range = 1-19 years). The overall conversion rate from iRBD to an overt neurodegenerative syndrome was 6.3% per year, with 73.5% converting after 12-year follow-up. The rate of phenoconversion was significantly increased with abnormal quantitative motor testing [hazard ratio (HR) = 3.16], objective motor examination (HR = 3.03), olfactory deficit (HR = 2.62), mild cognitive impairment (HR = 1.91-2.37), erectile dysfunction (HR = 2.13), motor symptoms (HR = 2.11), an abnormal DAT scan (HR = 1.98), colour vision abnormalities (HR = 1.69), constipation (HR = 1.67), REM atonia loss (HR = 1.54), and age (HR = 1.54). There was no significant predictive value of sex, daytime somnolence, insomnia, restless legs syndrome, sleep apnoea, urinary dysfunction, orthostatic symptoms, depression, anxiety, or hyperechogenicity on substantia nigra ultrasound. Among predictive markers, only cognitive variables were different at baseline between those converting to primary dementia versus parkinsonism. Sample size estimates for definitive neuroprotective trials ranged from 142 to 366 patients per arm. This large multicentre study documents the high phenoconversion rate from iRBD to an overt neurodegenerative syndrome. Our findings provide estimates of the relative predictive value of prodromal markers, which can be used to stratify patients for neuroprotective trials.

Original languageEnglish (US)
Pages (from-to)744-759
Number of pages16
Issue number3
StatePublished - Mar 1 2019


  • Parkinson's disease
  • REM sleep behaviour disorder
  • dementia with Lewy bodies
  • multiple system atrophy

ASJC Scopus subject areas

  • Medicine(all)


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