Parkinson's disease.

Parkinson's disease is one of the most common neurodegenerative diseases caused by degeneration of dopaminergic neurons in substantia nigra. The neuropathologic hallmark of Parkinson's disease is the presence of Lewy bodies composed mostly of alpha-synuclein and ubiquitin. It is believed that the occurrence of Parkinson's disease is due to a combination of genetic and environmental factors, but the exact mechanism of Parkinson's disease development is not fully elucidated. The most characteristic motor symptoms for Parkinson's disease include bradykinesia, rigidity, resting tremor and postural instability, while many patients also have non-motor signs and symptoms. The key therapeutic agent in the treatment of Parkinson's disease is L-dopa, and the others are dopaminergic agents, monoamine oxidase-B (MAO-B) inhibitors, catechol-O-methyltransferase (COMT) inhibitors, amantadine and anticholinergic agents.