I am unfamiliar with Parkinson's Disease so please indulge me in a bit of brainstorming. Please forgive me if I am rehashing old familiar stuff. Here goes.

If Parkinson's has to do with amyloid plaques and amyloid plaques have to do with prions and prions have to do with mad cow disease, then the following article might be of interest - "A Case for the Role of Copper Deficiency in "Mad-Cow" Disease and Human Creutzfeldt-Jakob Disease"

http://www.copper.org/innovations/2001/12/mad-cow.html

On the basis of the above article, could one ask the question, does Parkinsons have anything to do with not enough copper and too much manganese?