Is REM sleep behaviour disorder (RBD) a risk factor of dementia in idiopathic Parkinsons disease?
OBJECTIVE: To study the sequence of occurrence of REM-sleep behaviour disorder (RBD) and dementia and their frequency among a population of patients with idiopathic Parkinson’s disease (PD). METHODS: We performed a cross-sectional study on 65 PD patients seen in a movement disorder clinic and their bed partner, and asked them to complete the validated Mayo Sleep Questionnaire for RBD and sleep disorders. The diagnosis of PD with dementia (PD-D) was based on a clinical diagnosis of dementia; following DSM-IV criteria and MMSE score less than 25 and a battery of cognitive tests. RESULTS: From the 65 patients that completed the study, twenty-four met the clinical diagnosis of RBD. Ten of the 24 (42%) RBD patients met the clinical criteria of PD-D, whereas the remaining 14 patients were non-demented at the time of the study. The frequency of RBD was significantly higher in the PD-D group (n = 10, 77%) compared to the PD-ND group (n = 14, 27%, chi squared test: p = 0.0008). PD non-RBD had a
