This degeneration causes a shortage of a chemical called dopamine, which is needed to control movements. Scientists have identified a gene they believe is responsible for some cases of Parkinson's. They say the gene may not cause all cases of Parkinson's. About 500,000 Americans are believed to have Parkinson's disease, and about 50,000 new cases are reported annually. People who have relatives with Parkinson's are more likely to get the disease.
Tremors often begin on one side of the body, frequently in one hand.
Other common symptoms include slow movement or an inability to move, a shuffling step, stooped posture and rigid limbs. There is no cure for Parkinson's. Many cases are mild and don't need treatment for years. Other dopamine-like drugs may also be prescribed. In very severe cases, brain surgery may be performed.