Parkinson's disease in 1984: an update.

This update reviews several important topics in the field of Parkinson's disease, including etiologic studies, the types and mechanisms of drug complications and their treatment, when and how to begin treatment, the association of dementia with Parkinson's disease, and the development of the newer research tools. The recent discovery of a highly selective neurotoxin (MPTP) that causes parkinsonism in humans and other primates and the use of positron emission tomography in living patients should improve our understanding of the cause of cell death in Parkinson's disease and assist in the development of more definitive treatment for this common, disabling neurologic condition.