Thanks for the posts soccertese. You have addressed John's first question, whereas my post only addressed his second question.

soccertese said: "yopd'ers are still producing their own l-dopa..."

I may be splitting hairs here again, but I think we're more accurately described as "early-stage PDers" rather than "young-onset PDers". After all, you can be both a young-onset PDer and an advanced-stage PDer at the same time.