A Strong Link Between Parkinson’s and Pesticides

New research shows that the risk of Parkinson's disease can more than double due to long-term exposure to pesticides. Parkinson's disease is thought to be due to an interaction between environmental and genetic factors. It affects about one million people in the United States today. This disorder normally develops later in life and can cause symptoms such as muscle rigidity and tremors.

Several gene variations have been tagged as contributing to the disease, but these are considered to be rare defects that account for only a small portion of those affected by Parkinson's disease.

"Previous studies have shown that individuals with Parkinson's disease are over twice as likely to report being exposed to pesticides as unaffected individuals, but few studies have looked at this association in people from the same family or have assessed associations between specific pesticides and Parkinson's disease," says the study written by author Dana Hancock from the Duke University Medical Centre in Durham.

The open-access journal BMC Neurology published a study, which involved scientists from Duke University, Miami University, and the Udall Parkinson's Disease Research Center of Excellence, that found individuals exposed to pesticides had a 1.6 times higher risk of developing the disease after studying 600 people.

In this study 319 people suffering from Parkinson's disease were questioned about their pesticide use. Their answers were compared to those answers belonging to over 200 family members and other subjects who did not have Parkinson's disease.

The researchers found that heavy use of pesticides, over 200 days exposed to them over a lifetime, carried over double the risk. It was also found that herbicides and insecticides were the pesticides most likely to increase the risk of developing the disease.

Men who reported using pesticides often were found to be 2.15 times more likely to develop Parkinson's disease compared to those who did not use them. Women who were frequently exposed were shown to be 2.43 times more likely to develop Parkinson's disease.

Although there has been an established connection between Parkinson's and pesticides, the researchers now need to find "the biological process," Hancock added. "What we noticed in our research was that recreational pesticide use in the home and garden was more of a source of exposure than occupational use."

The director of research at the Parkinson's Disease Society, Kieran Breen, welcomed the findings of this study. He said the study " strengthened the fact that pesticides play a key role." Unfortunately, he added, "we still don't know exactly what causes Parkinson's. It is most likely to be a combination of genetic susceptibility and environmental factors." He also noted that out of a survey of 10,000 patients by the charity, only one in 10 had long-term exposure to pesticides.

Although we still don't know the exact causes of Parkinson's disease, this study shows that experts do feel confident that there is strong evidence of exposure to pesticides significantly increasing the risk for developing Parkinson's disease.