Objective: Rapid eye movement (REM) sleep behavior disorder (RBD) is a risk factor for dementia in Parkinson disease (PD) patients. The objectives of our study were to prospectively evaluate the frequency of RBD in a sample of treatment-naïve, newly diagnosed PD patients and compare sleep characteristics and cognition in RBD and non-RBD groups.

Methods: Fifty-seven newly diagnosed PD patients were consecutively recruited in a university medical center. All patients underwent two overnight polysomnography (PSG) sessions and were diagnosed with RBD according to the International Classification of Sleep Disorders, Second Revision criteria. Daytime sleepiness was measured in a multiple sleep latency test (MSLT). Cognition was assessed in a standard neuropsychologic examination.

Results: Seventeen PD patients (30%) met the criteria for RBD. The RBD patients and non-RBD patients did not significantly differ in mean age, gender ratio, disease duration, motor symptom subtype and severity, total sleep time, percentage of REM sleep, apnea-hypopnea index, mean oxygen saturation, and importantly cognitive performance. However, non-RBD patients had a significantly shorter mean daytime sleep latency than RBD patients (15 vs. 18 min, respectively; P=.014).

Conclusion: A high frequency of RBD was found in our sample of 57 newly diagnosed PD patients. At this stage in the disease, RBD was not found to be associated with other sleep disorders or cognitive decline. Follow-up is needed to assess the risk for developing dementia in early-stage PD patients with RBD.