Parkinson's disease is a chronic, progressive neurodegenerative movement disorder. Tremors, rigidity, slow movement (bradykinesia), poor balance, and difficulty walking (called parkinsonian gait) are characteristic primary symptoms of Parkinson's disease. The cause of Parkinson's disease is unknown. Many researchers believe that several factors combined are involved: free radicals, accelerated aging, environmental toxins, and genetic predisposition. It may be that free radicals-unstable and potentially damaging molecules that lack on electron-are involved in the degeneration of dopamine-producing cells. Free radicals add an electron by reacting with nearby molecules in a process called oxidation, which can damage nerve cells. Chemicals called antioxidants normally protect cells from oxidative stress and damage. If antioxidative action fails to protect dopamine-producing nerve cells, they could be damaged and, subsequently, Parkinson's disease could develop. Dysfunctional antioxidative mechanisms are associated with older age as well, suggesting that the acceleration of age-related changes in dopamine production may be a factor.
