Drugs for the treatment of Parkinson's disease, 1990s.
© Science Museum / Science & Society Picture Library
Drug treatments for Parkinson's disease aim to boost the activity of the surviving dopamine-releasing neurons in the brain. The most succesful is a substance called L-dopa, which is turned into dopamine by the neurons. It is very effective for several years, but then the effects begin to wear off and unpleasant side-effects become more noticable. Other drugs which stop the brain breaking down dopamine or enhance dopamine action can be useful for treating the early stages of Parkinson's.