fMRI changes in cortical activation during task performance with the unaffected hand partially reverse after ropinirole treatment in de novo Parkinson's disease.

Previous fMRI studies indicated a relationship between changes of the cortical activation pattern and disease severity in Parkinson's disease (PD). Early diagnosis of Parkinson's disease offers the opportunity to evaluate the putative neuroprotective and disease-modifying effects of drugs at a clinical stage when they might be more effective. The aim of this study was to assess motor cortex reorganization at the earliest clinically detectable stage of PD and the effects on it of chronic dopaminergic treatment. We evaluated with fMRI 11 de novo patients with right unilateral parkinsonism during execution of a controlled hand-tapping task by the unaffected left hand. In 7 of them fMRI examination with the same task was repeated after 6 months of ropinirole administration. At baseline, as compared to control subjects, PD patients showed significant hypoactivation of right sensory-motor cortex (SM1) and hyperactivation of the left parietal superior and inferior gyri and frontal superior gyrus and of the right parietal superior gyrus and precuneus. Ropinirole treatment yielded a significant clinical improvement (mean UPDRS score subitem III 13.4 at baseline, 9.4 at follow-up; p < 0.001 at a paired t-test) which was combined with lower activation in the left parietal superior and inferior gyri and in right parietal and occipital superior gyri with respect to their baseline fMRI examination. Our results indicate that in PD patients changes in cortical activation precede the onset of motor symptoms in the clinically unaffected side and are partially reversed by chronic administration of long acting dopamine agonist ropinirole.