Serial Dopamine Transporter Imaging of Nigrostriatal Function in Parkinson’s Disease With Probable REM Sleep Behavior Disorder

The current study aimed to confirm whether probable rapid eye movement sleep behavior disorder (pRBD) is associated with a specific pattern of striatal dopamine depletion in an international, multicenter, prospective cohort of patients with Parkinson’s disease (PD). Two hundred and seventy de novo, drug-naïve patients with PD underwent dopamine transporter (DAT) single photon emission computed tomography with (123)I-FP-CIT at baseline and 1, 2, and 4 years after the initial scan. The diagnosis of pRBD was based on the 10-item RBD Screening Questionnaire. Striatal DAT binding levels and their rates of decline were compared between patients with pRBD and those without. At baseline, patients in the PD-pRBD+ group showed lower striatal DAT binding in the caudate (which was more pronounced in the less-affected hemisphere) and in the putamen. During the 4-year follow-up, patients in the PD-pRBD+ group consistently exhibited greater DAT loss than patients in the PD-pRBD− group with comparable disease duration in all four striatal subregions. These patients also exhibited a more rapid decrease in DAT binding in the caudate and a less prominent interhemispheric asymmetry in the putamen. The distinct pattern of striatal DAT depletion may contribute to a more malignant phenotype of PD associated with RBD, specifically faster progression of motor symptoms.