Pesticide exposure has long been linked to an increased risk for Parkinson’s disease, the second most common degenerative brain disease after Alzheimer’s. Brain cells, at any age, are extremely sensitive to the chemicals in the environment and can die off as a result of overexposure.

Now scientists have found that exposing rats to a pesticide can bring about Parkinson’s symptoms with surprising speed.

Lab rats were exposed to the pesticide rotenone and within two weeks the previously healthy rats developed muscle rigidity, extremely slow and labored movement, and balance problems. Their brains also showed telltale signs of Parkinson's: accumulation of the protein α-synuclein and eventual cell death.

MPP+, the cause of the couple's symptoms, is also known as cyperquat, a close relative to the pesticide paraquat.

Scientists stumbled on the pesticide-Parkinson’s connection in a strange way. Thirty years ago, a couple of young people sought medical treatment for classic and sudden symptoms of the disease — in particular, extreme muscle rigidity, or appearing “frozen.”

The Parkinson’s drug, levodopa, reversed their symptoms, but the pair didn’t have Parkinson’s. What had happenened was that they had used a designer drug, created in underground labs, and the culprit was a compound that had formed accidentally in the chemical process of making the drug, and which is converted in the brain into a nerve cell killer, MPP+.

MPP+, the cause of the couple's symptoms, is also known as cyperquat, a close relative to the pesticide paraquat.

This odd chain of events first alerted scientists to the idea that pesticides might be linked to Parkinson’s, and animal research since then has supported the connection. The authors point out that just like any other disease, there’s no one trigger for Parkinson’s.

That is why not everyone exposed to pesticides will develop the disease, and many people not exposed to pesticides can still develop it. The reality is that there’s also a strong genetic component to Parkinson’s disease.

This study does, however, bring us closer to understanding at least one factor than can bring on the disease, which may yield a preventive strategy.

The study was carried out by a team at the University of Pittsburgh, and published in Chemical & Engineering News.