Parkinson disease is a brain disorder. It occurs when certain nerve cells (neurons) in a part of the brain called the substantia nigra die or become impaired. Normally, these cells produce a vital chemical known asdopamine. Dopamine allows smooth, coordinated function of the body's muscles and movement. When approximately 80% of the dopamine-producing cells are damaged, the symptoms of Parkinson disease appear.
Signs and symptoms of Parkinson disease
The loss of dopamine production in the brain causes the primary symptoms of Parkinson disease. The key signs of Parkinson disease are:
