Parkinson's disease

Parkinson's disease, or Parkinsonism, degenerative brain disorder, usually appearing after age 40, characterized by trembling lips and hands, shuffling gait, and muscular rigidity. Causes are often unknown, although in some cases the disorder is a result of carbon monoxide poisoning, influenza, encephalitis, or drugs. Because the disorder is often accompanied by depression, it is hard to measure its effects on mental capacity, which may often be impaired. Named after the English surgeon James Parkinson, who first described it in 1817, the disease is treated with the drugs L-Dopa (and carbidopa for side effects) and amantadine.