Differential striatal dopamine binding in Parkinson's Disease with and without REM sleep behavior disorder: A Tc-99 m TRODAT-1 SPECT study.

BACKGROUND

Rapid eye movement (REM) sleep behavior disorder (RBD) is an early and significant prodromal marker for Parkinson's disease (PD). While the association between RBD and PD has been well-documented, the underlying pathophysiology differentiating PD patients with RBD (PD-RBD +) from those without RBD (PD-RBD-) remained unclear. This study aims to investigate the possible relationship between RBD and striatal dopamine depletion in de novo PD patients.

METHODS

A retrospective, cross-sectional study was conducted on 151 PD patients. We used standard questionnaires and measurements to assess motor and nonmotor symptoms. The dopaminergic function was assessed utilizing Tc-99 m TRODAT-1 SPECT imaging, and statistical analyses were performed to compare dopamine transporter (DAT) binding between patients with or without probable RBD (pRBD).

RESULTS

The PD-pRBD + group exhibited significantly lower DAT binding in the caudate nucleus (OR 0.618; 95% CI 0.392-0.618; p = 0.039) and putamen (OR 0.554; 95% CI 0.319-0.962; p = 0.036) compared to the PD-pRBD- group. The PD-pRBD + group also had a higher prevalence of non-motor symptoms, including depression (OR 7.499; 95% CI 2.770-20.299; p < 0.001) and constipation (OR 2.356; 95% CI 1.090-5.092; p = 0.029). Although trends toward increased dementia (12.3% in PD-pRBD + , 6.4% in PD-pRBD-, p = 0.266) and falls (16.4% in PD-pRBD + , 11.5% in PD-pRBD-, p = 0.482) were observed in the PD-pRBD + group, these did not reach statistical significance.

CONCLUSION

The presence of RBD in PD patients is associated with greater striatal dopaminergic dysfunction, suggesting a distinct subtype with potentially faster disease progression. These findings highlight the importance of early RBD identification in PD patients to guide more personalized interventions.