my 2 cents worth in reference to early onset PD patients and the drug/tropic factor trials: one would think the most healthy who have not been on anti PD meds for a long length of time should be the group for whom a quick and robust response would obtain. And that it would be easier to determine what is the trial drug effect vs after effects of drugs that were taken formerly by older patients who have been on therapy. WIth $$$ constraints, getting a drug to trial, obtaining quick, robust results SHOULD help fast track the drug (if it proves effficacious). I'm with Jean--I think testing for 3 different groups is a place to start to determine who benefits most, though that means a much larger number of participants, more time, and thus, more $$$$. With my trust in the insurance industry, my concern with this approach is that if the drug is found to be efficacious for early stage PD,and the drug and or delivery system is very expensive, the insurance cos could refuse to pay for its use in those who are not in early stage because it has not been tested.