Rapid Eye Movement Sleep Behavior Disorder in Parkinson’s Disease: A Preliminary Study

OBJECTIVE Rapid eye movement sleep behavior disorder (RBD) is associated with α-synucleinopathies, such as Parkinson's disease (PD). We aimed to assess the differences in the clinical characteristics of PD with and without RBD. METHODS Forty-two patients previously diagnosed with PD were evaluated for clinical history, motor and cognitive functioning using the Unified Parkinson's Disease Rating Scale (UPDRS) and Mini-Mental State Examination (MMSE), autonomic symptoms, sleep characteristics using the Pittsburg Sleep Quality Index (PSQI), and the presence of RBD using the Korean version of the RBD screening questionnaire (RBDSQ). The prevalence of RBD and the patients' demographic features were evaluated. The patients were classified into two groups, PD with RBD and PD without RBD, based on the RBDSQ scores. The motor and cognitive functions, as well as other clinical features of the two groups were compared. RESULTS A total of 42 PD patients were enrolled. Eighteen patients were classified as PD with RBD. Compared to PD without RBD, PD with RBD showed higher scores of rigidity in the UPDRS subscale. Regarding sleep problems, PD with RBD revealed higher sleep disturbance, lower sleep efficiency, and lower overall sleep quality in the PSQI. There was no difference in cognitive dysfunction between the two groups according to the Korean version of the MMSE. CONCLUSIONS PD with RBD was associated with poorer sleep and motor symptoms. Therefore, RBD symptoms in PD are possibly poor prognostic markers.