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Pesticide levels in blood linked to Parkinson's disease

Thursday July 30, 2009

Virtualmedicalcentre.com - People with Parkinson's disease have significantly higher blood levels of a particular pesticide than healthy people or those with Alzheimer's disease, researchers at University of Texas Southwestern Medical Center have found.

In a study appearing in the July issue of Archives of Neurology, researchers found the pesticide beta-HCH (hexachlorocyclohexane) in 76 percent of people with Parkinson's, compared with 40 percent of healthy controls and 30 percent of those with Alzheimer's.

The finding might provide the basis for a beta-HCH blood test to identify individuals at risk for developing Parkinson's disease. The results also point the way to more research on environmental causes of Parkinson's.

"There's been a link between pesticide use and Parkinson's disease for a long time, but never a specific pesticide," said Dr Dwight German, professor of psychiatry at UT Southwestern and a senior author of the paper. "This is particularly important because the disease is not diagnosed until after significant nerve damage has occurred. A test for this risk factor might allow for early detection and protective treatment."

About 1 million people in the US have Parkinson's, a number expected to rise as the population ages. The disease occurs when brain cells in particular regions die, causing tremors, cognitive problems and a host of other symptoms.

The study involved 113 participants, ages 50 to 89. Fifty had Parkinson's, 43 were healthy and 20 had Alzheimer's. The researchers tested the subjects' blood for 15 pesticides known as organochlorines.

These pesticides, which include the well-known DDT (dichlorodiphenyltrichloroethane), were widely used in the US from the 1950s to the 1970s but are more tightly regulated now. They persist in the environment for years without breaking down. In the body, they dissolve in fats and are known to attack the type of brain nerves that die in Parkinson's disease, the researchers said.

"Much higher levels of the beta-HCH were in the air, water and food chain when the Parkinson's patients were in their 20s and 30s," Dr German said. "Also, the half-life of the pesticide is seven to eight years, so it stays in the body for a long time."