Screening tools for clinical characteristics of probable REM sleep behavior disorder in patients with Parkinson's disease

INTRODUCTION: The REM sleep behavior disorder (RBD) screening questionnaire (RBDSQ) has been used as a screening tool for RBD. We investigated the clinical characteristics of probable RBD (pRBD) using the RBDSQ in patients with Parkinson's disease (PD). METHODS: Seventy patients with PD (age: 69.2 ± 8.9 years old, 31 males and 49 females, length of PD morbidity: 7.4 ± 6.4 years, Hoehn and Yahr: 2.7 ± 0.8) underwent examination including the RBDSQ and Mini-Mental State Examination (MMSE) in both 2011 and 2013. We assessed the changes and characteristics of pRBD associated with PD during the two year interval. RESULTS: Nineteen patients (27.1%) in 2011 and 27 patients (38.6%) in 2013 were diagnosed as having pRBD because they scored 6 or higher on the RBDSQ. During the 2 year interval, twelve patients showed persistent pRBD, 15 developed pRBD, and 7 showed improved pRBD. In 2013, PD patients with pRBD took higher amounts of levodopa equivalents and scored lower on the MMSE than those without pRBD. Also, more PD patients with pRBD had dementia than those without pRBD. Similarly, more patients with persistent and developed pRBD had dementia than those without. CONCLUSION: We found that RBD symptoms might fluctuate during the clinical course of PD, and RBD symptoms might temporarily affect cognitive impairment.