Objective: To explore the different patterns of dopaminergic dysfunction between iRBD patients who convert to Parkinson’s disease (PD)/dementia with Lewy bodies (DLB) and those who do not convert within a certain period of time by using a longitudinal dopamine transporter (DAT) PET imaging.

Background: Studies have shown most patients with idiopathic rapid-eye-movement sleep behaviour disorder (iRBD) will eventually develop synucleinopathies such as PD, DLB or multiple system atrophy. Patients with synucleinopathies develop dopaminergic dysfunction and some iRBD patients develop this abnormality before conversion. However, it is still unclear whether the patterns of dopaminergic dysfunction are the same between iRBD patients.

Method: Thirty iRBD patients were followed up for up to 8 years, including 17 patients who did not converte to PD/DLB (iRBDnc) and 13 patients converted to PD/DLB (iRBDc). Age-matched 20 healthy subjects and 20 PD patients with RBD symptoms appearing anterior to PD symptoms (PDRBDa) served as controls. All participants underwent at least two scans of ¹¹C-CFT PET imaging to quantify DAT distribution. Standardized uptake value ratio (SUVR) of local brain tissue was calculated using the occipital cortex as a reference area. Longitudinal studies of dopaminergic dysfunction in different iRBD groups were performed by voxel-based as well as ROI analysis.

Results: At baseline, the striatal ¹¹C-CFT uptake in both iRBD groups was significantly lower than that in healthy controls (HC) but higher than that in PDRBDa group, with a more significant reduction in the iRBDc group (all p<0.05). IRBD patients have generalized deterioration of dopamine function in the whole striatum although PD patients’ deterioration originates in the putamen. In addition, DAT deficit outside of the nigrostriatal pathway was identified, with a significantly reduced ¹¹C-CFT binding in nucleus accumbens in iRBDc and PDRBDa groups (both p<0.001) compared with HC. Furthermore, ¹¹C-CFT uptake in the striatum was gradually decreased with longitudinal follow-up in both iRBD groups but with different decline rates. The iRBDc patients had a significantly higher rate of decline than iRBDnc patients (p<0.0001).

Conclusion: Different progress manifestations of dopaminergic dysfunction presents in iRBD patients, by which we can predict whether iRBD patients will convert to synucleinopathies within a short-term using DAT imaging.

« Back to 2022 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/different-longitudinal-manifestations-in-dopaminergic-dysfunction-in-rem-sleep-behavior-disorder/