I was told "we think you have a 60% chance of PD, come back in 6 months" !! In 6 months it was still inconclusive however the Pet scan proved conclusive. Remember by the time you show symptoms 80% of your neurons should be affected so a scan should be a pretty accurate guide. In the UK a scan is accepted as a dx by insurance companies where clinical dx might not be.

I never did the ldopa challenge so cannot provide anything there.

Good luck, this is the worst time,
Neil.