TBI and Pesticide Increase Risk of Parkinson's

Head injury and paraquat exposure combined make Parkinson’s disease three times more likely

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) While the exact causes of Parkinson’s disease (PD) are unknown, it is likely to be from a mixture of environmental and genetic factors. Having exposure to more than one risk factor could increase the chances of developing the disease.

A recent study investigated the risk of PD due to traumatic brain injury (TBI) and paraquat, a herbicide commonly used to control weeds.

The study found that people who were exposed to these two factors were more likely to develop PD than those who were not.

Those who experienced both TBI and paraquat exposure were at a significantly greater risk.

"Seek care for head injuries and avoid pesticides when possible."

Pei-Chen Lee, PhD, of the University of California at Los Angeles and colleagues conducted a study of 357 PD patients and 754 control patients. The control patients were from three mostly rural agricultural communities in California.

Study participants reported their residences through their lifetime, workplace addresses and medical histories. Details of any head injury resulting in a loss of consciousness for more than five minutes were also disclosed.

Exposure to paraquat within a 500 meter area of home or work place was estimated using a graphic information system of local pesticide use.

Study participants with PD were almost twice as likely to have had a head injury that resulted in more than five minutes of unconsciousness than the controls. PD patients in the study were 36 percent more likely to have exposure to paraquat than the controls.

While exposure to paraquat and TBI were individually associated with PD, the combination of the two created more than simply the sum of the two totals. People who have had a head injury and were exposed to paraquat were three times more likely to develop PD than those who did not experience TBI or pesticide exposure.

The causes of this increased risk of PD are not known. It is speculated that a head injury triggers physiological process that increases a person’s vulnerability to pesticides.

The study was published in Neurology, the medical journal of the American Academy of Neurology.

Funding was provided by the National Institute of Environmental Health Science and the National Institute of Neurological Disorders and Stroke. Initial pilot funding was provided form National Institutes of Health and the American Parkinson Disease Association.

Reviewed by: 
Review Date: 
November 14, 2012
Last Updated:
May 20, 2013