Organochlorine exposure, genetic polymorphism and Parkinson's disease

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DESCRIPTION (Taken from application) Parkinson?s disease (PD) is a progressive, disabling disorder of the central nervous system characterized by tremors at rest, muscle rigidity, slowness, imbalance and, in later stages, often dementia. It is caused by loss of neurons in the substantial nigra that produce dopamine. Approximately half a million Americans are estimated to be affected by PD. Recent data suggest that environmental exposure, possibly in concert with genetically determined vulnerabilities, contribute to causation of PD; particularly in patients with onset of disease above age 50. The study will examine 300 cases of PD whose diagnoses have been confirmed by strict, standardized criteria and 300 controls with "minor" neurologic disorders not involving the basal ganglia. A blood sample will be obtained and a detailed questionnaire will be administered to each case and control. The groups will be half male, half female. All eligible minority patients will be enrolled. Cases and controls will be matched on age, gender, and race. This proposal has two inter-related biomedically based, epidemiologic objectives. We propose to determine: 1) whether serum organochlorine levels and/or a past history of exposure to pesticides are elevated in patients with Parkinson s disease; 2) whether polymorphisms in specific enzymes related to pesticide metabolism are more common in patients with PD; and 3) whether there is evidence for a gene-environment interaction. A more exploratory objective is to evaluate whether diet, particularly intake of antioxidants, may protect against development of PD. To test the hypothesis that organochlorine levels, the most common type of chemical pesticide used between 1940 and 1970, are increased in PD patients, DDT, DDE, Dieldrin, and oxychlordane will be determined and compared between cases and controls. PCB, its congeners and trans-nonachlor will also be measured since these are organochlorine compounds as well. The gene polymorphism hypotheses will focus specifically on CYP2D6, GSTP1, and PON1. To evaluate the possible protective role of antioxidants, a detailed dietary history will be taken to obtain extensive information on usual antioxidant intake before diagnosis, including Vitamins A, C and E, carotenoids, lycopene, tocopherol and polyphenols (phytoestrogens).