Does Occupational Pesticide Use Affect Penetrance of LRRK2 Parkinson’s Disease?

MIAMI—Occupational pesticide use is associated with increased penetrance of LRRK2 Parkinson’s disease, according to research presented at the First Pan American Parkinson’s Disease and Movement Disorders Congress. “This is the first report of an effect of pesticides on penetrance in LRRK2 Parkinson’s disease,” said Caroline Tanner, MD, PhD, Professor of Neurology at the University of California, San Francisco, and colleagues. Studying the effects of pesticide exposure on the LRRK2 protein may “provide clues to pathogenesis or treatment,” the researchers said.

Caroline Tanner, MD, PhD

To determine the role of occupational pesticide exposure on penetrance in LRRK2-associated Parkinson’s disease, Dr. Tanner and colleagues conducted a study of participants in an international consortium that examined genetic and environmental modifiers in LRRK2-associated Parkinson’s disease. All participants are LRRK2 G2019S mutation carriers. Enrolling neurologists determined whether participants had symptomatic Parkinson’s disease or were asymptomatic.

Participants’ history of occupational pesticide exposure was collected by self-report or interview. Participants reported if they ever had a job in which they mixed, applied, or were in some other way exposed to any type of pesticide, including herbicides, fungicides, insecticides, rodenticides, or fumigants. If participants had occupational pesticide exposure, researchers recorded the ages that they were exposed, the number of years they had the job, the number of days per year the pesticide was used, the type of pesticide used, and specific products used.

They then calculated hazard ratios for symptomatic Parkinson’s disease using Cox regression, adjusted for gender and smoking. The study included a total of 274 subjects (123 males) from Africa, Australia, Europe, and North America.

Exposure to any of the three pesticide classes analyzed (ie, herbicides, fungicides, and insecticides) showed a trend to increased risk of symptomatic Parkinson’s disease. Only the risk from fungicide exposure was statistically significant, however (hazard ratio, 3.81 in males and 2.57 overall).

The investigators noted that pesticide exposure was not common in this study population and that few women used pesticides. The findings need to be replicated in additional populations, said the researchers.

—Jake Remaly