Objective: To identify whether the presence and/or timing of rapid eye movement (REM) sleep behavior disorder (RBD) onset were associated with differences in clinical features and sleep parameters of Parkinson disease (PD). Methods: In all, 112 PD patients were enrolled and all underwent extensive clinical evaluations and video-polysomnography (PSG). Clinical features and PSG parameters were compared in PD patients with (PD + RBD) or without (PD - RBD) RBD, RBD preceding (RBD > PD), or not (PD >= RBD) PD onset. Results: Sixty-three of the 112 PD patients were affected by RBD. Adjusted for age, gender, education, body mass index (BMI), levodopa equivalent daily dose (LED) and PD duration, PD + RBD patients had higher Hoehn & Yahr stage, higher scores for UPDRS parts I, II and III, more dyskinesia, higher ratio of axial/limb manifestations, and more hallucinations. Their cognitive and quality-of-life status was significantly lower (all P < 0.05). For PSG, PD + RBD patients exhibited higher percentages of phasic and tonic EMG activities, lower apnea hypopnea (AHI) and oxygen desaturation index (ODI), and less time in arterial oxygen saturation (SaO(2)) <90% during REM sleep (all P < 0.05). PD >= RBD (n = 22) patients did not significantly differ from RBD > PD (n = 41) patients in clinical manifestations, whereas the PD >= RBD subgroup had significantly higher UPDRS part I score, lower PDQ score and lower AHI during REM than the PD - RED group (all P < 0.05), but not RBD > PD subgroup. Correlation analysis showed that worse cognition was associated with shorter interval of RBD preceding PD onset (r = 0.297, P = 0.018), but not RBD duration (P = 0.202). Conclusions: Clinical manifestations of PD may vary depending on the presence and timing of RBD onset. These findings are compatible with the hypothesis that RBD may be a marker of complex subtypes of PD. (C) 2014 Elsevier B.V. All rights reserved.