My mom is currently going for her teacher's certification and is taking a clinical psychology class. She just told me a story that I think you might find quite interesting. In Los Angeles recently several drug dealers were making a batch of heroin, and they made a mistake at some point, so they stopped the process and went out to sell the bad batch. Around 40 people bought it, and every one of them went into seizures within 2 hours. Apon being admitted to the hospital, no one could figure out why everyone was reacting the way they were. It turns out, the bad heroin burnt out the substantia nigra (not sure on the spelling, it's the part of the brain that deals with dopamine). Every one of the people that toook a dose of the bad heroin developed full blown Parkinson's within a couple hours. The lab was of course seized, and it's trying to be determined exactly how the bad batch of heroin
went directly to the people's substantia nigra, and effectively blew it out.