Common pesticide may increase risk of ADHD

A commonly used pesticide may alter the development of the brain's dopamine system - responsible for emotional expression and cognitive function - and increase the risk of attention deficit hyperactivity disorder in children, according to a new Rutgers study.

The research published Wednesday in the Journal of the Federation of American Societies for Experimental Biology (FASEB), by Rutgers scientists and colleagues from Emory University, the University of Rochester Medical Center, and Wake Forest University discovered that mice exposed to the pyrethroid pesticide deltamethrin in utero and through lactation exhibited several features of ADHD, including dysfunctional dopamine signaling in the brain, hyperactivity, working memory, attention deficits and impulsive-like behavior.

These findings provide strong evidence, using data from animal models and humans, that exposure to pyrethroid pesticides, including deltamethrin, may be a risk factor for ADHD, says lead author Jason Richardson, associate professor in the Department and Environmental and Occupational Medicine at Rutgers Robert Wood Johnson Medical School and a member of the Environmental and Occupational Health Sciences Institute (EOHSI).

"Although we can't change genetic susceptibility to ADHD, there may be modifiable environmental factors, including exposures to pesticides that we should be examining in more detail," says Richardson.

Attention deficit hyperactivity disorder most often affects children, with an estimated 11 percent of children between the ages of 4-17- about 6.4 million - diagnosed as of 2011. Boys are three to four times more likely to be diagnosed than girls. While early symptoms, including an inability to sit still, pay attention and follow directions, begin between the ages of 3 to 6, diagnosis is usually made after the child starts attending school full time.

Importantly, in this study, the male mice were affected more than the female mice, similar to what is observed in children with ADHD. The ADHD-like behaviors persisted in the mice through adulthood, even though the pesticide, considered to be less toxic and used on golf courses, in the home, and on gardens, lawns and vegetable crops, was no longer detected in their system.

A team of scientists from the University of Montreal and Harvard University has discovered that exposure to organophosphate pesticides may be associated with increased risk of Attention-Deficit Hyperactivity Disorder (ADHD) in children.

Published in the journal Pediatrics, the investigation found a connection between exposure pesticides and the presence of symptoms of ADHD. The study focused on 1,139 children from the general U.S. population and measured pesticide levels in their urine.

The authors conclude that exposure to organophosphate pesticides, at levels common among U.S. children, may contribute to a diagnosis of ADHD.