Previously unreported links between possible REM sleep behavior disorder (pRBD) and alcohol use, and psychological distress emerged in a nationwide Canadian study, researchers reported.
Heavy drinking, smoking, antidepressant use, psychological distress, and post-traumatic stress disorder (PTSD) all were tied to pRBD in a population-based cohort, according to Ronald Postuma, MD, MSc, of McGill University in Montreal, and co-authors.
And several of these risk factors differed from ones linked to neurodegenerative synucleinopathies, they wrote in Neurology.
People with RBD have disruptive REM sleep — sometimes acting out violent or action-filled dreams — and may be in an early stage of Parkinson’s disease or Lewy body dementia.
“You might think the risk factors for Parkinson’s would be the same as the risk factors for a condition that inevitably leads to Parkinson’s, but they’re not,” Postuma told MedPage Today.
“The most striking example is smoking,” he said. “There is a very strong negative association between nicotine and Parkinson’s, but here we see that, in the prodromal state, people have a higher risk of smoking. Some of that may be explained by factors like social class or the effects of depression and anxiety, but it’s surprising the link is so different.”
In this study, Postuma and his group looked at 30,097 people ages 45 to 85 (mean age 63) recruited from 2012 to 2015 as part of the Canadian Longitudinal Study on Aging. Researchers conducted in-person interviews with participants and screened for possible RBD with the REM Sleep Behavior Disorder Single-Question Screen, which asked “Have you ever been told, or suspected yourself, that you seem to act out your dreams while asleep?”
Because the screening question has 94% specificity and 87% sensitivity, the researchers excluded individuals who screened positive for apnea or non-REM parasomnia (young-onset pRBD) and people who self-reported dementia or Parkinson’s disease to improve diagnostic accuracy. After removing those people, they identified 958 people (3.2%) with possible REM sleep behavior disorder. Male sex and lower education were both associated with pRBD.
People with pRBD were more likely to be moderate to heavy drinkers (18.9% vs 14.3%), current smokers (8.9% vs 6.4%), and past smokers (42.7% vs 36.9%) than those without the disorder.
In addition, people with pRBD more often had a diagnosis of mental illness (34.9% vs 21.9%), including a higher prevalence of physician-diagnosed anxiety (13.8% vs 7.3%) and depressive disorder (20.7% vs 13.9%). They used antidepressants more frequently (13.4% vs 6.2%) and scored higher on the Kessler Psychological Distress Scale (15.2 ± 5.33 vs 13.9 ± 1.86). They also were more likely to report at least moderate psychological distress (10.9% vs 6.6%) and had a higher rate of positive screening for PTSD (10.5% vs 4.0%).
“We may be picking up a trigger effect,” Postuma observed. “Antidepressants can trigger REM sleep behavior disorder. We also may be picking up PTSD, which is not the same as REM sleep behavior disorder.”
The cohort will be studied over time to see how many of these people develop Parkinson’s disease, he added.
“Our hope is that our findings will help guide future research, especially because REM sleep behavior disorder is such a strong sign of future neurodegenerative disease,” Postuma said. “The more we understand about REM sleep behavior disorder, the better positioned we will be to eventually prevent neurologic conditions like Parkinson’s disease.”
This study has several limitations, largely stemming from its reliance on self-reported data. About 3% of the sample reported pRBD compared to polysomnography studies, which report RBD prevalences of about 1%. Despite screening, differential misclassification may be driving results, such as nonspecific sleep disturbance with depression, PTSD, and apnea cases that were missed. Also, nearly all participants were white and results may not apply to people of other ethnic backgrounds.
The study was supported by the Canadian Institutes of Health Research, the Webster Foundation, and the Fonds de la Recherche–Sante Quebec.
Researchers report relationships with Sunovion, Novartis, Sage Therapeutics, UCB, Eisai, the Centre de recherche de l’Universite de Montreal, the Multiple Sclerosis Society of Canada, Fonds de la Recherche en Sante, Parkinson Society of Canada, Weston-Garfield Foundation, Michael J. Fox Foundation, Webster Foundation, Biotie, Roche/Prothena, Teva Neurosciences, Biogen, Boehringer Ingelheim, Theranexus, and GE HealthCare.