On the subject of relief from symptoms and possible use of cannibinoids in treatment of Parkinson's here's a
Google search on marijuana and parkinson's

As far as marijuana causing psychosis, that has been limited to young users who are already predisposed to psychosis.
Marijuana-Induced Psychosis May Foretell Future Episodes
Studies link psychosis, teenage marijuana use- Some adolescents carry genetic risk

And "somebody I know" with already existing neurotransmitter issues finds that is has the paradoxical effect of increasing motivation...

Jeffrey- You seem to be old enough to be past the age of onset for schizophrenia. If you're staying home and not out driving around, I don't think it's going to hurt you.
Although using your email address as your logon does show some impairment of judgment...