This illness has existed for thousands of years. Learn more about Parkinson disease by taking this quiz.
About 7 in 10 people with Parkinson first have a slight tremor in a hand or foot, according to the Parkinson Foundation. The tremor usually occurs when the muscles are at rest and relaxed. It usually appears on 1 side of the body. Later it may spread to the other side of the body, often to a lesser degree. Common symptoms as the disease gets worse include:
Secondary symptoms include: