Study objectives: REM sleep behavior disorder (RBD) is reported in up to 50% of patients with Parkinson's disease (PD). Only a few systematic, large-scale studies have addressed the characteristics of RBD in PD. The aim of the present study is to assess the frequency of RBD in patients with PD and the association with PD characteristics.
Methods: We sent a questionnaire including items on sleep quality, sleep disorders, and PD characteristics and severity to the members of the national PD patients' organization in Switzerland. To assess and characterize RBD, we used a validated 10-item questionnaire (the RBD screening questionnaire, RBDSQ).
Results: Four hundred seventeen PD patients returned the questionnaire, with RBD scores ≥ 6 in 172 patients. These patients had longer disease duration and lower activity of daily living scores, as well as more frequent nighttime awakenings and hallucinations than PD patients with RBDSQ scores < 6. Age, gender, sleep-wake disorders such as excessive daytime sleepiness, sleep apnea, and insomnia, as well as levodopa equivalent dose did not differ between the 2 groups. Patients with RBDSQ score ≥ 6 were more often treated with antidepressants.
Conclusions: We confirm a frequent (42.6%) history of RBD in PD. Probable RBD in PD is associated with more advanced disease as suggested by the longer disease duration and higher impairment of daily living. It is also linked to sleep fragmentation with significantly more nighttime awakenings and with hallucinations. Hallucinations might be linked to emotional disinhibition and probably to activation of limbic structures. Both sleep fragmentation and limbic activation might facilitate the occurrence of RBD in PD.