The correlation between possible RBD and cognitive function in Parkinson's disease patients in China

OBJECTIVE: Cognitive impairment is an important symptom of Parkinson's disease (PD) and seriously affects patients’ quality of life and prognosis. However, its cause is still uncertain. In about one‐third of patients, PD is associated with rapid eye movement sleep behavior disorder (RBD), which is an independent risk factor for PD‐associated dementia; but whether or not it relates to the cognitive function of patients with nondemented PD is still controversial. METHODS: The data from 89 enrolled PD patients were retrospectively analyzed. The RBD Questionnaire Hong‐Kong (RBD‐HK) was used to diagnose possible RBD (pRBD). There are 46 patients with possible RBD (the PD‐pRBD) and 43 without (the PD‐npRBD). PD disease severity, neuropsychological function, overall cognitive function, and various cognitive functions were assessed. RESULTS: There were significant between‐group differences in scores on the Montreal Cognitive Assessment (MoCA), Mini‐Mental State Examination (MMSE), Digit Symbol Test (DST), Trail Making Test‐A (TMT‐A)‐Time, TMT‐Trail Making Test‐B (TMT‐B)‐Time, Stroop Color‐word Test, Clock Drawing Test (CDT), Boston Naming Test (BNT), Verbal Fluency Test (fruit), etc. (P < 0.05). INTERPRETATION: Patients in the PD‐pRBD group had more cognitive impairment.