The risk factors for probable REM sleep behavior disorder: A case-control study

To investigate the risk factors for REM sleep behavior disorder (RBD) in a case-control study. Participants with probable RBD (pRBD) were defined using the RBD Questionnaire–Hong Kong (RBDQ-HK). Controls were collected by matching age and sex. Demographic information, lifestyle, comorbidity, prodromal symptoms of Parkinson's disease (PD), and blood biomarkers were assessed. The associations between these factors and pRBD were investigated by logistic regression. Partial correlation analysis was used to assess the association between the severity of RBD and depression. A total of 278 pRBD participants (age = 58.31 ± 15.82 years) and 556 controls (age = 58.16 ± 15.84 years) were enrolled in this study. Patients with pRBD were more likely to be current alcohol drinkers (OR 1.50, 95% CI 1.0–2.32). Participants with pRBD had a higher Hamilton Depression Rating Scale (HAMD-17) score (OR 1.17, 95% CI 1.11–1.22) than controls and were more likely to report arthritis (OR 1.53, 95% CI 1.08–2.16), constipation (OR 1.93, 95% CI 1.31–2.86), hyposmia (OR 1.71, 95% CI 1.10–2.67), and depression (OR 3.15, 95% CI 2.17–4.58). Higher levels of total cholesterol (OR 1.15, 95% CI 0.99–1.33) and low-density lipoprotein (OR 1.21, 95% CI 0.99–1.47) had borderline associations with pRBD. Additionally, the severity of pRBD was positively related to depression (r = 0.31, P < 0.01). We determined several risk factors for pRBD in this case-control study. Future studies are needed to understand the mechanism underlying the association between these factors and pRBD.