Background: REM sleep behavior disorder (RBD) is commonly associated with Parkinson disease (PD), and recent studies have suggested that RBD in PD is associated with increased cognitive impairment, waking EEG slowing, autonomic impairment, and lower quality of life on mental health components. However, it is unclear whether the association of RBD in PD has implications for motor manifestations of disease.
Methods: We evaluated 36 PD patients for the presence of RBD by polysomnography. Patients underwent an extensive evaluation on and off medication by a movement disorders specialist blinded to polysomnography results. Measures of disease severity, quantitative motor indices, motor subtypes, complications of therapy, and response to therapy were assessed and compared using regression analysis that adjusted for disease duration and age.
Results: PD patients with RBD were less likely to be tremor-predominant (14% vs. 53%, p<0.02) and had a lower proportion of their Unified Parkinson Disease Rating Scale (UPDRS) score accounted for by tremor (8.2% vs. 19.0%, p<0.01). An increased frequency of falls was noted among patients with RBD (38% vs. 7%, p=0.04). Patients with RBD demonstrated a lower amplitude response to their medication (UPDRS improvement=16.2% vs. 34.8%, p=0.049). Markers of overall disease severity, quantitative motor testing, and motor complications did not differ between groups.
Conclusions: The presence of altered motor subtypes among PD patients with RBD suggests that PD patients with RBD may have a different underlying pattern of neurodegeneration than those without RBD.