More Evidence that Dopamine Agonists Are Not Neuroprotective for Parkinson Disease
Michael S. Okun, MD reviewing Schapira AHV et al. Lancet Neurol 2013 May 31.
Results from the PROUD study
Whether dopamine agonists could be neuroprotective or disease-modifying for Parkinson disease (PD) is controversial. Cell culture and animal studies suggested that this class of medications might reduce dopaminergic cell loss, possibly via a mitochondria-mediated antiapoptotic mechanism. Researchers have now tested this neuroprotection hypothesis, examining the clinical and neuroimaging effects of early versus delayed pramipexole. They recruited PD patients within about 2 years after diagnosis at one of 98 centers. Randomized patients received double-blind placebo (274 patients) or pramipexole (1.5 mg per day; 261 patients). The primary outcome variable was the change from baseline in the total Unified Parkinson's Disease Rating Scale (UPDRS) at 15 months. After approximately 6 to 9 months of therapy, placebo recipients were switched to pramipexole and the early-treatment group continued on pramipexole. The authors used single photon emission computed tomography to assess striatal dopamine-transporter binding in a subset of patients.
At 15 months, the pramipexole and placebo groups did not differ on the primary outcome variable. Imaging in 62 immediate-treatment and 61 delayed-treatment patients showed no difference in striatal transporter binding.