Hi Wasabi,
First of all, please be warned: don't believe everything you read about what causes or prevents PD. The truth is: nobody knows!
As I understand it so far, PD is basically a combination of disorders caused by the malfunctioning of the basal ganglia. Said part of the brain can be damaged in many ways, i.e. viral infections, head or neck trauma, exposure to pesticides, contaminated water, heavy metals, genetic mutations or all of it together. Whatever the cause of the lesion, the set of neurological symptons (some of them common to other neurodegenerative diseases like MS) are known as Parkinson's Disease. The copper connection comes after the low-iron levels theory we've been hearing about and the mercury, lead and other metal poisoning theories, etc. It all has to be looked into, of course, but it's yet another theory that will swallow research funds and no conclusions will be drawn, because PD has no one single cause.
Take care