Rapid Eye Movement Sleep Behavior Disorder Symptoms Correlate With Domains Of Cognitive Impairment In Parkinson’s Disease

Objectives: To investigate the domains of cognitive impairment in patients with Parkinson’s disease(PD) and rapid eye movement(REM) sleep behavior disorder(RBD).To explore the risk factors for PD-mild cognitive impairment(PD-MCI) and the relationship between clinical RBD severity and cognitive impairment in different domains in PD.Methods: We recruited 125 subjects, including 74 PD patients(PD without RBD(PD-RBD, n=42) and PD with RBD(PD+RBD; n=32)), 15 i RBD patients, and 36 age-,sex-, and education level-matched HC subjects from the Department of Neurology from February 2014 to May 2015 in the Second Affiliated Hospital of Soochow University. We obtained the information of basic demographics, motor and non-motor manifestations from all the subjects. All participants underwent a battery of neuropsychological assessment,including attention and working memory, executive function, memory, language and visuospatial function. We paid particular attention to access the severity of RBD by the RBD Questionnaire-Hong Kong(RBDQ-HK) and RBD Screening Questionnaire(RBDSQ). Through the correlation analysis, we examined associations between clinical severity of RBD symptoms and cognitive impairment.Results: Compared to PD-RBD patients, PD+RBD subjects were more likely to have olfactory dysfunction and higher Epworth Sleepiness Scale scores(P<0.05). During neuropsychological testing, PD+RBD patients performed worse in some domains,including delayed memory function, especially. The MCI rates wererespectively33%, 63%,33%, and 8% in PD-RBD, PD+RBD, i RBD, and HC groups. RBD was one of the risk factors for explaining the PD-MCI variance(odds ratio=5.204, P=0.018). During correlation analysis, higher RBD Screening Questionnaire and RBD Questionnaire-Hong Kong(RBD-HK) scores were associated with poorer performance on the Trail MakingTest-B(errors) and Auditory Verbal Learning Test(delayed recall) significantly. In addition,higher RBD-HK scores were also associated with Rey-Osterrieth complex figure(copy)results.Conclusions: When we adjust the severity of motor symptoms in PD-RBD and PD+RBD patients, PD+RBD patients still have sever olfactory dysfunction and daytime somnolence. RBD was one of the risk factors for MCI, including delayed memory. The severe RBD symptoms may be associated with deficits in executive function, verbal delayed memory, and visuospatial function.