The Association Between REM Sleep Behavior Disorder and Autonomic Dysfunction in Parkinson's Disease

Background: REM behavior disorder (RBD) can occur in the context of neurodegenerative alpha-synucleinopathies, such as Parkinson's disease (PD). PD patients with RBD (PD-pRBD) represent more severe symptoms and signs compared with those without RBD (PD-nRBD). On another note, autonomic dysfunction in PD patients is categorized as one of the most prominent non-motor symptoms and has been lately the field of interest in research. Objective: In the current study, we longitudinally studied autonomic dysfunction in PD-pRBD and PD-nRBD groups. Method: This study was conducted on 420 drug-naive PD patients selected from the Parkinson's Progression Markers Initiative database. The RBD Screening Questionnaire was used to define the presence of probable RBD. SCOPA-AUT was used to assess autonomic dysfunction. Additionally, dopamine transporter deficits on [I-123] FP-CIT SPECT imaging was performed for all of the patients. Results: Out of 420 PD patients, 158 individuals (37.6%) were considered to have probable RBD (PD-pRBD) and others without RBD (PD-nRBD). Except for pupillomotor function, all the autonomic symptoms were significantly more severe in PD-pRBD group. In PD-nRBD group, caudate striatal binding ratio was negatively correlated with SCOPA-AUT scores, while no significant correlation was observed in PD-pRBD group. Finally, there was a significant difference considering the longitudinal changes of SCOPA-AUT total between PD-pRBD and PD-nRBD groups, suggesting a more severe autonomic decline in PD-pRBD patients. Conclusion: Our results indicate that PD-pRBD patients have more severe autonomic dysfunction. These results support the theory that PD patients can be categorized based on the clinical presentation, possibly representing differences in the disease pathophysiology.

Automated summary

In this study, PD patients with RBD were found to have more severe autonomic dysfunction compared to those without RBD. The SCOPA-AUT scores showed significant differences between the two groups, indicating a more pronounced decline in autonomic function in PD patients with RBD. These findings support the theory that PD patients can be categorized based on clinical presentation, possibly reflecting differences in disease pathophysiology.