Parkinson's disease, also called paralysis agitans and shaking palsy is a disorder that affects nerve cells, or neurons, in a part of the brain that controls muscle movement.
In Parkinson's, neurons that make a chemical called dopamine die or do not work properly. Dopamine normally sends signals that help coordinate your movements. No one knows what damages these cells.
Symptoms of Parkinson's disease may include:
As symptoms get worse, people with the disease may have trouble walking, talking or doing simple tasks. They may also have problems such as depression, sleep problems or trouble chewing, swallowing or speaking. Parkinson's usually begins around age 60, but it can start earlier. It is more common in men than in women.
National Institute of Neurological Disorders and Stroke: http://www.nlm.nih.gov/medlineplus/parkinsonsdisease.html