Recent research published in the Journal of the Federation of American Societies for Experimental Biology (FASEB) by Rutgers scientists, as well as researchers from Emory University, the University of Rochester Medical Center, and Wake Forest University, suggests that mice exposed to the pesticide in utero, as well as through breast milk, exhibited multiple symptoms of ADHD. This includes problems with working memory, hyperactivity, impulse-control problems and attention deficits. Findings related to both animal models and humans suggest that exposure to pyrethroid pesticides (in this case, deltamethrin) may constitute an important risk factor for ADHD, according to lead researcher Jason Richardson, associate professor in the Department and Environmental and Occupational Medicine at Rutgers Robert Wood Johnson Medical School as well as 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,” he said. “We need to make sure these pesticides are being used correctly and not unduly expose those who may be at a higher risk.” The oftentimes debilitating disorder affects approximately 11 percent of children between the ages of 4-17, totaling about 6.4 million. Males are 3-4 times more likely to be diagnosed than girls. Diagnosis typically happens after school begins full time, although symptoms oftentimes emerge a great deal earlier. These behaviors include difficulty paying attention and following directions and difficulty sitting still. Likewise, male mice tended to be more notably affected than female mice. Disturbingly, “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.”
The study suggests an environmental role for ADHD, supplementing the already-strong evidence of genetic susceptibility to the disorder. Indeed, researchers have found a great deal of evidence of heritability even though no distinct genes have been marked out as predisposing individuals.
“Using data from the Centers for Disease Control, National Health and Nutrition Examination Survey (NHANES) the study analyzed health care questionnaires and urine samples of 2,123 children and adolescents. Researchers asked parents whether a physician had ever diagnosed their child with ADHD and cross-referenced each child’s prescription drug history to determine if any of the most common ADHD medications had been prescribed. Children with higher pyrethroid pesticide metabolite levels in their urine were more than twice as likely to be diagnosed with ADHD.”