In a large multicenter study of 1,280 patients diagnosed with rapid eye movement (REM) sleep behavior disorder (RBD), published in Brain, patients’ scores on motor testing were shown to be predictive for developing Parkinson’s disease (PD). Patients were followed for up to 19 years (mean = 3.6 years) for a total of 4,890 years of follow up, and measures of motor, cognitive, autonomic, and sensory function were collected. The rate of phenoconversion to a neurodegenerative disorder (ie, PD, multiple system atrophy [MSA] or dementia with Lewy bodies [DLB]) was 6.25 annually.
After adjusting for age, sex, and testing location, hazard rations were calculated and showed that patients with lower scores on quantitative measures of motor function were 3 times more likely (HR = 3.16) to develop PD or related dementias, which increased to 3.77 when the Movement Disorder Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) was used. Other significant prognosticators for neurodegenerative diseases were olfactory dysfunction (HR =2.62) and mild cognitive impairment (HR = 2.37). Notably, the motor scores had higher predictive value than dopamine transporter single positron emission CT (DAT-SPECT) (HR = 1.98)
Previous studies have shown a strong correlation between RBD and PD; however, the period between developing RBD and PD is years long and RBD is a heterogenous condition. Determining which patients with RBD are more likely to develop PD will help identify patients for potential early treatments of PD being tested in clinical trials.
First author of the study, Ronald B. Postuma of The Neuro (Montreal Neurological Institute and Hospital) and the Montreal General Hospital of the McGill University Health Centre said, “We confirmed a very high risk of PD in people with REM sleep disorder and found several strong predictors of this progression. As new disease-modifying treatments are being developed for PD and related diseases, these patients are ideal candidates for neuroprotective trials.”