BY LIZETTE BORRELI
In a new study, investigators identified alcohol use and psychological distress among other risk factors for rapid eye movement sleep behavior disorder (RBD), in which patients violently act out their dreams. The disorder also has been associated with other neurodegenerative disorders, such as Parkinson disease (PD), dementia with Lewy bodies, or multiple system atrophy.
For their analysis, the team observed 30,097 people ages 45 to 85 (mean age 63) recruited between 2012 to 2015 from the Canadian Longitudinal Study on Aging (CLSA), a large, national, longitudinal study that collects information on the changing biological, medical, psychological, social, lifestyle and economic aspects of participants' lives.
The researchers conducted in-person interviews with participants and screened them for a series of health conditions and asked about lifestyle, behavior, social, economic and psychological factors. Overall, the study's findings show male sex, low education, heavy drinking, smoking, antidepressant use, and measures of mental health are linked to RBD, but they do not prove a cause-and-effect relationship.
Published online in Neurology on December 26, the cross-sectional, nationwide Canadian study found that people with RBD were more likely to be moderate to heavy drinkers (18.9 percent versus 14.3 percent), current smokers (8.9 percent vs 6.4 percent), and past smokers (42.7 percent vs 36.9 percent) than those without the disorder.
Moreover, those with RBD used antidepressants more frequently (13.4 percent vs 6.2 percent), scored higher on the Kessler Psychological Distress Scale (15.2 ± 5.33 vs 13.9 ± 1.86) and were likely to report at least moderate psychological distress (10.9 percent vs 6.6 percent).
Patients also had a diagnosis of mental illness (34.9 percent vs 21.9 percent), with a higher incidence of physician-diagnosed anxiety (13.8 percent vs 7.3 percent) and depressive disorder (20.7 percent vs 13.9 percent).
They also had a higher rate of positive screening for post-traumatic stress disorder (10.5 percent vs 4.0 percent).
The study investigators, led by Chun Yao, MSc, of McGill University in Montreal, noted that there may be several explanations for the relationship between mental illness and risk for RBD. "One is that those with mental illness may tend to endorse multiple symptoms, including multiple sleep symptoms, as part of their illness. Another is that RBD itself can lead to psychosocial distress via disruption in sleep patterns or bed partner relations…," they wrote.
The cohort will continue to be observed to determine how many of these participants will go on to develop PD.
Study limitations included the reliance on self-reported data; differential misclassification, such as nonspecific sleep disturbance with depression, PTSD, apnea cases missed by screening questionnaires; and the lack of a diverse study sample—many participants were white, which may limit the generalizability of the findings to other ethnic groups.
The Canadian Institutes of Health Research and the Health Research Fund of Quebec supported the study.
The researchers reported 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.
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Yao C, Fereshtehnejad SM, Keezer MR, et al. Risk factors for possible REM sleep behavior disorder: A CLSA population-based cohort study. Neurology 2018; Epub 2018 Dec 26.