A relatively common degenerative disorder of the central nervous system.
Parkinson's disease is a degenerative disorder of the central nervous system named for James Parkinson (1755-1824), the physician who first described it in 1817. This disorder is also called paralysis agitans, shaking palsy, or parkinsonism.
Typically, the symptoms of Parkinson's disease begin to appear in late middle life, and the course of the disease is slowly progressive over 20 years or more. In its advanced stages, Parkinson's disease is characterized by poorly articulated speech, difficulty in chewing and swallowing, loss of motor coordination, a general tendency toward exhaustion, and especially by stooped posture, positioning the arms in front of the body when walking, caution and slowness of movement, rigidity of facial expression, and tremor of the hands. Mental ability and the senses are not directly affected by this disease. Parkinson's disease is believed to be caused by a deficiency of dopamine in the basal ganglia of the brain.
McGoon, Dwight. The Parkinson's Handbook. New York: Norton, 1990.