Clinical Correlates of RBD in Early Parkinson Disease

Abstract

Objective: Knowledge of the cognitive performance associated with REM sleep behavior disorder (RBD) in newly diagnosed Parkinson disease (PD) patients is limited. We thus wanted to explore 1) the frequency of RBD in patients with PD at a relatively early stage and 2) cognitive performance associated with RBD in PD. We hypothesized that RBD would be associated with cognitive impairment in PD. Methods: 29 non-demented patients recently diagnosed with PD (disease duration<5 years, Hoehn and Yahr stage <2.5 and no dementia) were recruited. The diagnosis of PD was supported by dopamine transporter SPECT. RBD was diagnosed based on standardized clinical interview and confirmed by polysomnography. Overall cognition was assessed by screening tests including the Mini-Mental State Examination (MMSE), and neuropsychological tests of memory, language, executive, attentional and visuospatial functions tests were performed. Results: 13 patients (45%) had probable RBD. There were no significant differences between PD with and without RBD in any of the neuropsychological tests, but a numerically lower performance was observed in the PD RBD group on memory tests Conclusions: RBD is common even in early PD without dementia, but was not found to be associated significantly with cognition.