NEW YORK (Reuters Health) – More than half of patients with an idiopathic REM sleep behavior disorder develop a neurodegenerative disease within 12 years of being diagnosed; according to a report in Neurology.

Dr. Ronald Postuma at McGill University and colleagues explain that REM sleep behavior disorder is characterized by a loss of muscle atonia that normally occurs during REM sleep, leading to excessive motor activity in association with dream content.

Small studies have identified idiopathic REM sleep behavior disorder as a risk factor for parkinsonism and dementia, so the researchers conducted a follow-up study of 93 patients diagnosed with idiopathic REM sleep behavior disorder between 1989 and 2006. The mean age of the subjects was 65 years and 80% were male. The average time between onset of the sleep disorder and diagnosis by polysomnography was 7.2 years, and average time from diagnosis to last evaluation was 5.2 years.

The authors report: