Pesticides Plus Gene Variant Increase Parkinson’s Risk

LOS ANGELES – Exposure to pesticides may increase the risk of Parkinson’s disease, and certain gene variants may make some people even more susceptible to the disease, according to a new study.

The research, published recently in the journal Neurology, indicates that specific pesticides inhibiting aldehyde dehydrogenase (ALDH) are linked to an increased risk of Parkinson’s disease. The enzyme helps detoxify substances in cells and has a role in metabolism of alcohol, the authors note.1

In addition, people with a variant of the ALDH2 gene were two to five times more likely to develop Parkinson’s disease with exposure to these pesticides than people who did not have that gene variant, the report pointed out.

“These results show that ALDH inhibition appears to be an important mechanism through which pesticides may contribute to the development of Parkinson’s disease,” said study author Jeff M. Bronstein, MD, PhD, of the Los Angeles VAMC and the David Geffen School of Medicine at UCLA. “Understanding this mechanism may reveal several potential targets for preventing the disease from occurring or reducing its progression.”

For the study, researchers focused on 360 Parkinson’s disease patients in three rural California counties, comparing them to 816 people in the area who did not have the disease. Participants’ exposure to pesticides at work and at home was measured using a geographic computer model based on information from the California Department of Pesticide Regulation.

Using a test to identify which pesticides inhibited ALDH, the researchers determined that the 11 pesticides that inhibited ALDH, all used in farming, fell into four structural classes — dithiocarbamates, imidazoles, dicarboxymides and organochlorides.

Study results found that exposure to an ALDH-inhibiting pesticide at both the workplace and at home was associated with increased risks of developing Parkinson’s disease, ranging from 65% for the pesticide benomyl to six times the risk for the pesticide dieldrin. In fact, those exposed to three or more of the pesticides at both work and home were 3.5 times more likely to develop Parkinson’s disease as those who were not exposed.

The relationship between the gene variant and Parkinson’s only appeared when people had been exposed to the pesticides, however.

“In other words, having this gene variant alone does not make you more likely to develop Parkinson’s,” he said. “Parkinson’s is a disease that in many cases may require both genetics and environmental factors to arise.”

1 Fitzmaurice AG, Rhodes SL, Cockburn M, Ritz B, Bronstein JM. Aldehyde dehydrogenase variation enhances effect of pesticides associated with Parkinson’s disease. Neurology. 2014 Feb 4;82(5):419-26. doi: 10.1212/WNL.0000000000000083. PubMed PMID: 24491970; PubMed Central PMCID: PMC3917685.


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