This is new for me. It appears that, in a survey, anti-rejection drugs taken for organ transplants have a very good protective effect against Alzheimers compared to the general population, see bar graph first http below. This should apply to PD as well. The bad news is we have to wait forever for it.

http://content.iospress.com/download...se%2Fjad150065

Could Toning Down Calcineurin Neutralize α-Synuclein? | ALZFORUM

http://www.psychiatryadvisor.com/alz...rticle/419660/

Overall, no matter what the age group examined, the patients who were taking one of the two drugs had far less prevalence of Alzheimer's and dementia than the general public, the researchers reported in the Journal of Alzheimer's Disease. For example, while 15.3% of the general population over the age of 75 had dementia, just over 0.6% of the study group did.