mes difficult for the person to perform a movement quickly, which makes it difficult to perform some routine daily tasks. Postural instability follows, with the inability to hold a body position, and problems with balance occur. Mental capacity also declines with disease progression (Petersen, 1998).
Although some studies have found a gene mutation associated with some cases of ParkinsonÆs disease, genetic factors are not thought to play a role in most cases (Cummings, 1999). Patients in whom a genetic factor has been found exhibit an atypical form of ParkinsonÆs disease with a younger onset of symptoms including an earlier appearance of levodopa-related dyskinesia and motor fluctuations, more frequent dystonia as an early or presenting sign and less evidence of cognitive impairment (Cummings, 1999). The disease seems to involve free radicals that damage cell membranes. Substantial evidence indicates that a basic mechanism in the disease is the formation of hydrogen peroxide, and oxygen-derived free radicals produce lipid peroxidation of cell membranes, leading to cell death. Exposure to the chemical 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) can induce a Parkinson like syndrome, and it is now thought that environmental toxins may be a cause of ParkinsonÆs disease.
The speed of progression from diagnosis to severe functional impairment from ParkinsonÆs disease ranges from less than a decade to more than 20 years (Petersen, 1998). Patients often do not require medication in the
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