Neuropsychology in REM sleep behaviour disorder and Parkinson’s Disease

Patients with rapid eye movement (REM) sleep behavior disorder (RBD) experience a loss of muscle atonia during REM sleep. RBD has been associated with a high risk of converting to Parkinson’s disease (PD) within 10 years of diagnosis. This suggests that RBD may be a preclinical indication of neurodegenerative disorders like PD. PD is characterized as a movement disorder, but research has identified nonmotor symptoms (eg. anxiety, depression, and cognitive impairment) that can be used as early disease markers. By examining these nonmotor symptoms in RBD and PD, disease progression may be better understood. To investigate similarities between RBD and PD patients in anxiety, depression, and cognitive impairment severity. A case-control study was conducted with 21 healthy controls, 13 RBD, and 21 PD patients enrolled. Participant anxiety, depression, and general cognitive ability were evaluated using Beck Anxiety Index, Beck Depression Index II, and Montreal Cognitive Assessment respectively. Analysis of variance was used to compare questionnaire scores between groups controlling for age and sex as covariates. Anxiety levels in PD patients were higher than both RBD and healthy controls. Both patient groups had higher depression scores than controls and depression levels were higher in PD versus RBD patients. Cognitive ability was not different between the three groups. Results from this study will further our understanding of the neuropsychological profile of RBD and PD. The discovery of similar nonmotor symptoms between RBD and PD may provide the earliest markers of PD development for improved diagnosis