Rapid eye movement sleep behavior disorder (RBD) is commonly accompanied in Parkinson disease (PD). However, the underlying mechanism linking RBD to PD remains unclear. We interviewed and examined 447 consecutive patients with PD to investigate factors associated with the presence of RBD in PD patients. Using the minimal diagnostic criteria for parasomnias provided in the International Classification of Sleep Disorders-Revised (ICSD-R), 164 patients (36.5%) were diagnosed with clinically probable RBD (cpRBD). PD patients with cpRBD were older, had a longer duration of PD, a more severe level of disability, a longer duration of antiparkinsonian medication, and a lower proportion of their Unified Parkinson Disease Rating Scale (UPDRS) scores accounted for by tremor than those without RBD. Multivariate and univariate logistic regression analyses revealed that patient age, PD symptom duration (and, accordingly, more severe motor disability), tremor score, and proportion of the UPDRS score accounted for by tremor were significant factors associated with the presence of RBD in PD patients. The results of the present study support previous observations that PD with RBD may result from a different underlying pattern of neurodegeneration than PD without RBD.
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