No definitive tests exist for Parkinson's disease, so it can be difficult to diagnose, especially in the early stages. This is complicated by the fact that parkinsonism (the symptoms of Parkinson's disease) can be caused by many other types of problems, e. g other neurological disorders, toxins, head trauma and even some medications, e. g chlorpromazine (Thorazine), prochlorperazine (Compazine) or metoclopramide (Reglan).
Attribution: Avallain