Association between dopaminergic medications and REM sleep behavior disorder in Parkinson's disease: a preliminary cohort study

Background Rapid eye movement sleep behavior disorder (RBD) is highly comorbid with Parkinson's disease (PD). Emerging evidence suggests that dopamine-replacement therapies (DRTs) for PD may modify the course of RBD, yet the nature of the association between DRTs and RBD remains unclear. To begin addressing this issue, we conducted a preliminary retrospective study to document whether DRTs are associated with the occurrence of RBD symptoms in PD patients. Methods The study included 250 PD patients who were screened for probable RBD via the RBD Screening Questionnaire (RBDSQ). For each patient, disease severity data were collected, in addition to their therapy and the associated levodopa equivalent daily dose (LEDD). The association between DRTs and RBDSQ scores was analyzed using logistic regression and correlation models. Results RBD scores were found to be associated with the LEDD of levodopa alone, but not of dopaminergic agonists (mainly D2/D3 receptor agonists) or their combination with levodopa. This association was not accounted for patient age or Hoehn and Yahr (H&Y) severity scores. Conclusions Our study detected a significant association between doses of levodopa and RBD symptoms in PD patients. Future longitudinal studies are needed to establish what causal nexus may link these variables.