A comparison of the progression of early Parkinson's disease in patients started on ropinirole or L-dopa: an 18F-dopa PET study

Objective: To study the relative rates of progression of early Parkinson's disease (PD) in patients started on a dopamine agonist, ropinirole, or L-dopa. Methods: A double-blind study of 45 early PD patients [mean age 61 ± 9.8 SD and mean symptom duration, 26 ± 16 SD months] randomized 2 : 1 (ropinirole : L-dopa). Supplementary L-dopa was allowed if, during the trial, there was lack of a therapeutic effect. 18F-dopa PET scans were performed at baseline (n = 45) and 2 years (n = 37). Results: At two years, the mean percentage reduction in putamen 18F-dopa uptake (Kio) was not significantly different between the two groups (13% ropinirole, n = 28 versus 18% L-dopa, n = 9). Conclusions: We found no significant overall difference in underlying PD progression, after two years treatment, between patients groups. In summary, 18F-dopa PET can be employed to objectively evaluate the effect of potential neuroprotective agents on dopaminergic function.