Probable RBD is increased in Parkinson's disease but not in essential tremor or restless legs syndrome

Objective: Compare the frequency of REM sleep behavior disorder (RBD) and excessive daytime sleepiness (EDS) in Parkinson's disease (PD), restless legs syndrome (RLS), essential tremor (ET), and control subjects. Methods: Subjects enrolled in a longitudinal clinicopathologic study, and when available an informant, completed the Mayo Sleep Questionnaire, which asks "Have you ever been told that you act out your dreams?", and the Epworth Sleepiness Scale (ESS). Results: Probable RBD (based on informant response to the questionnaire) was much more frequent in PD (34/49, 69%, P < 0.001) than in RLS (6/30, 20%), ET (7/53, 13%), or control subjects (23/175, 13%), with an odds ratio of 11 for PD compared to controls. The mean ESS and the number of subjects with an ESS >= 10 was higher in PD (29/60, 48%, P < 0.001) and RLS (12/39, 31%, P < 0.001) compared with ET (12/93, 13%) and Controls (34/296, 11%). Conclusions: Probable RBD is much more frequent in PD with no evidence to suggest an increase in either RLS or ET. Given the evidence that RBD is a synucleinopathy, the lack of an increased frequency of RBD in subjects with ET or RLS suggests the majority of ET and RLS subjects are unlikely to be at increased risk for developing PD. (C) 2011 Elsevier Ltd. All rights reserved.