The study, “Traumatic brain injury, paraquat exposure, and their relationship to Parkinson disease,” published in the journal Neurology surveyed more than 1,000 adults ages 35 and older who lived in central California. Some 357 of the participants were diagnosed with Parkinson’s disease. Participants with the disease were nearly twice as likely as those without the disease to report having had a head injury in which they lost consciousness for more than five minutes. Forty-two Parkinson’s patients, or 12 percent of that group, reported receiving a head injury that knocked them unconscious for five or more minutes, as compared to 50 people in the non-Parkinson’s group, or seven percent. The Parkinson’s patients are nearly twice as likely to have had such injuries. Using a geographical tracking system, the researchers also found that those with Parkinson’s disease were also more likely to live within 500 meters of a spot where the herbicide paraquat was used.
Parkinson’s patients are 36 percent more likely to be exposed to paraquat, which is toxic to both humans and animals. Nearly half of the study subjects with Parkinson’s had been exposed to paraquat, as opposed to 39 percent of the non-Parkinson’s subjects. “While each of these two factors is associated with an increased risk of Parkinson’s on their own, the combination is associated with greater risk than just adding the two factors together,” Beate Ritz, MD, PhD, lead author of the study, said in a public statement. Dr. Ritz says her work suggests that a head injury may trigger a physiological process that increases brain cells’ vulnerability to attacks from toxic pesticides, or vice versa. Constant low-dose exposure to pesticides could place a person at greater risk for Parkinson’s to strike after a head injury.
Previous work has shown a link between the pesticides, rotenone and paraquat, and Parkinson’s disease. One study found that people who used either pesticide developed Parkinson’s disease approximately 2.5 times more often than non-users. Scientists have also been aware for many years that both paraquat and rotenone are neurotoxicants that, when given to animals, reproduce features of Parkinson’s in the brain. Paraquat is known to increase the production of certain proteins in the brain that damages cells that produce dopamine. People with Parkinson’s have a dopamine shortage that causes the motor problems, muscle tremors, and rigidity that characterize Parkinson’s. Rotenone inhibits the function of mitochondria in the brain, which is responsible for regenerating certain brain cells. Both pesticides are largely restricted, due to concerns about links to Parkinson’s. Paraquat is restricted to certified applicators and rotenone is only permitted to kill invasive fish species.
Sources: ABC News, http://www.beyondpesticides.org, eNews Park Forest, Inc.
http://www.enewspf.com/latest-news/science-a-environmental/38297--14-no…
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