Conversion from sleep disorder to neurodegeneration studied
Ronald B. Postuma, M.D., from McGill University in Montreal, and colleagues examined the risk for neurodegenerative disease and predictors of neurodegeneration in a large cohort of iRBD patients. Prospective follow-up data from 24 centers were combined. Polysomnographically confirmed iRBD patients without parkinsonism or dementia underwent sleep, motor, cognitive, autonomic, and special sensory testing at baseline. Data were included for 1,280 patients who were followed for an average of 4.6 years.
The researchers found that the overall conversion rate from iRBD to an overt neurodegenerative syndrome was 6.3 percent per year; after 12-year follow-up, 73.5 percent had converted. Significant increases in the rate of phenoconversion were seen in association with abnormal quantitative motor testing (hazard ratio [HR], 3.16), objective motor examination (HR, 3.03), olfactory deficit (HR, 2.62), mild cognitive impairment (HR, 1.91 to 2.37), erectile dysfunction (HR, 2.13), motor symptoms (HR, 2.11), an abnormal DAT scan (HR, 1.98), color vision abnormalities (HR, 1.69), constipation (HR, 1.67), REM atonia loss (HR, 1.54), and age (HR, 1.54). Cognitive variables were the only predictive marker that differed at baseline between those converting to primary dementia versus parkinsonism.
"As new disease-modifying treatments are being developed for neurodegenerative synucleinopathies, RBD patients are ideal candidates for neuroprotective trials," the authors write.
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