(RBD), according to a population-based cohort study published in Neurology. In addition, the results also replicate previous findings of an association between possible RBD and smoking, low education, and male sex.
Dr. Ronald B. Postuma
The risk factors for RBD have been studied comparatively little. “While much is still unknown about RBD, it can be caused by medications or it may be an early sign of another neurologic condition like Parkinson’s disease, dementia with Lewy bodies, or multiple system atrophy,” according to Ronald B. Postuma, MD, an associate professor at McGill University, Montreal. “Identifying lifestyle and personal risk factors linked to this sleep disorder may lead to finding ways to reduce the chances of developing it.”
To assess sociodemographic, socioeconomic, and clinical correlates of possible RBD, Dr. Postuma and his colleagues examined baseline data collected between 2012 and 2015 in the Canadian Longitudinal Study on Aging (CLSA), which included 30,097 participants. To screen for possible RBD, the CLSA researchers asked patients, “Have you ever been told, or suspected yourself, that you seem to ‘act out your dreams’ while asleep [e.g., punching, flailing your arms in the air, making running movements, etc.]?” Participants answered additional questions to rule out RBD mimics. Patients with symptom onset before age 20 years, positive apnea screen, or a diagnosis of dementia, Alzheimer’s disease, parkinsonism, or Parkinson’s disease were excluded from analysis.
In all, 3,271 participants screened positive for possible RBD. After the investigators excluded participants with potential mimics, 958 patients (about 3.2% of the total population) remained in the analysis. Approximately 59% of patients with possible RBD were male, compared with 42% of controls. Patients with possible RBD were more likely to be married, in a common-law relationship, or widowed.
Participants with possible RBD had slightly less education (estimated mean, 13.2 years vs. 13.6 years) and lower income, compared with controls. Participants with possible RBD retired at a slightly younger age (57.5 years vs. 58.6 years) and were more likely to have retired because of health concerns (28.9% vs. 22.0%), compared with controls.
In addition, patients with possible RBD were more likely to drink more and to be moderate to heavy drinkers than controls; they were also more likely to be current or past smokers. Antidepressant use was more frequent and psychological distress was greater among participants with possible RBD.
When the investigators performed a multivariable logistic regression analysis, the associations between possible RBD and male sex and relationship status remained. Lower educational level, but not income level, also remained associated with possible RBD. Furthermore, retirement age and having reported retirement because of health concerns remained significantly associated with possible RBD, as did the amount of alcohol consumed weekly and moderate to heavy drinking. Sensitivity analyses did not change the results significantly.
One of the study’s limitations is its reliance on self-report to identify participants with possible RBD, the authors wrote. The prevalence of possible RBD in the study was 3.2%, but research using polysomnography has found a prevalence of about 1%. Thus, the majority of cases in this study may have other disorders such as restless legs syndrome or periodic limb movements. Furthermore, many participants who enact their dreams (such as unmarried people) are likely unaware of it. Finally, the researchers did not measure several variables of interest, such as consumption of caffeinated products.
“The main advantages of our current study are the large sample size; the systematic population-based sampling; the capacity to adjust for diverse potential confounding variables, including mental illness; and the ability to screen out RBD mimics,” the authors concluded.
SOURCE: Postuma RB et al. Neurology. 2018 Dec 26. doi: 10.1212/WNL.0000000000006849.