This multi-center, randomized, double-blind trial will involve 42 trial centers in the United States and Canada, and enroll 195 people with PD. The primary objective of this neuroprotection trial is to identify agents capable of slowing the progression of PD. In the trial, investigators will assess the impact of CoQ10, an antioxidant, and GPI 1485, a novel immunophilin compound, on the progression of PD and determine if it is futile or non-futile to proceed with further study of these agents.