A new study from UCLA is the latest addition to a growing body of research linking pesticides and Parkinson’s disease.

UCLA neurologists examined hundreds of Parkinson’s patients in the Central Valley, where rural residents may have been exposed to a fungicide called benomyl. It was widely used on crops like almonds, apples, and berries before the EPA banned it a decade ago.

The study finds the pesticide triggered cellular changes, preventing a key enzyme from keeping check on a naturally occurring toxin that damages neurons in the brain.

But more importantly, researchers found that process may be at play even in Parkinson’s patients who have not been exposed to pesticides. “So it’s really the mechanism by which it works that is of particular interest to us,” UCLA neurology professor Dr. Jeff Bronstein told me, ”because we think there are going to be other things in the environment — and other genetic variations — that may lead us to one of the causes of Parkinson’s disease.”

Here’s more from the UCLA press release:

Benomyl exposure, they say, starts a cascade of cellular events that may lead to Parkinson’s. The pesticide prevents an enzyme called ALDH (aldehyde dehydrogenase) from keeping a lid on DOPAL, a toxin that naturally occurs in the brain. When left unchecked by ALDH, DOPAL accumulates, damages neurons and increases an individual’s risk of developing Parkinson’s.

The investigators believe their findings concerning benomyl may be generalized to all Parkinson’s patients. Developing new drugs to protect ALDH activity, they say, may eventually help slow the progression of the disease, whether or not an individual has been exposed to pesticides.

The new study appears in the latest online edition of the Proceedings of the National Academy of Sciences.

Listen to Sasha Khokha’s story: