Researchers from the University of California have found that the risk to Parkinson is increased by exposure to pesticide. The risk of the disease is dependent on an individual’s genetic make up which can increase the risk for developing Parkinson’s disease. The study was published in the Journal of Neurology and also found that people with a modified genetic variant of the ALDH2 gene, (the gene implicated in increasing the risk of Parkinson), are particularly sensitive to the effects pesticides that inhibit the gene.
A prior study by the same team published last year discovered a link between Parkinson’s and the pesticide benomyl, a fungicide that has been banned by the U.S. Environmental Protection Agency. That study found that benomyl inhibited an enzyme called aldehyde dehydrogenase (ALDH), which converts aldehydes highly toxic to dopamine cells into less toxic agents, and therefore contributed to the development of Parkinson’s.
The exposure to pesticides starts a molecular chain reaction, preventing ALDH from controlling DOPAL, a toxin that naturally occurs in the brain. When ALDH does not detoxify DOPAL sufficiently, it accumulates, damages neurons and increases an individual’s risk of developing Parkinson’s.
The purpose of this study was to test the impact of other pesticides and found 11 other substances that also inhibit ALDH and increased the risk of Parkinson’s. In this case the levels used to trigger a response were substantially lower that the levels applied in every day use according to lead author Jeff Bronstein, a professor of neurology and director of movement disorders at UCLA. The study examined 360 Parkinson patients compared to 816 healthy people who all lived in a pesticide rich region in central California
“We were very surprised that so many pesticides inhibited ALDH and at quite low concentrations, concentrations that were way below what was needed for the pesticides to do their job,” Bronstein said. “These pesticides are pretty ubiquitous, and can be found on our food supply and are used in parks and golf courses and in pest control inside buildings and homes. So this significantly broadens the number of people at risk.”
“ALDH inhibition appears to be an important mechanism by which these environmental toxins contribute to Parkinson’s pathogenesis, especially in genetically vulnerable individuals,” said study author Beate Ritz, a professor of epidemiology at the Fielding School of Public Health at UCLA. “This suggests several potential interventions to reduce Parkinson’s occurrence or to slow its progression.”
The study is especially concerning in light of the trend to produce genetically modified organisms that have been engineered to be pesticide resistant and which have been linked to increased pesticide exposure and application.
A. G. Fitzmaurice, S. L. Rhodes, M. Cockburn, B. Ritz, J. M. Bronstein. Aldehyde dehydrogenase variation enhances effect of pesticides associated with Parkinson disease. Neurology, 2014; 82 (5): 419 DOI: 10.1212/WNL.0000000000000083