Parkinson's disease is a disorder of the central nervous system, named after Dr. James Parkinson, a London physician who was the first to describe the syndrome in 1817.

Parkinson's may appear at any age, but the risk of developing it increases with age. The cause of Parkinson's is still uncertain although some family associations have been found, suggesting that genetics does play a role together with some yet unfound environmental triggers.

In this disease, degenerative changes occur in the substantia nigra in the brain, resulting in reduced dopamine synthesis.

Symptoms of Parkinson's disease include tremor, bradykinesia, rigidity, poor balance and gait problems. Unlike Alzheimer's disease, dementia is not a characteristic sign, although this may occur late in Parkinson's. Mental function is relatively spared in PD.

Secondary problems associated with PD include constipation, sleep disturbances, dizziness, depression, and stooped posture.

Treatment is with supplemental dopamine, usually given in a tablet form as a compound that is metabolised to dopamine in the body.

Michael J. Fox has been diagnosed with Parkinson's and will eventually be quitting his acting career because of it. His story is a good one for people new to Parkinson's to read.