Lead Exposure May Cause ADHD For Certain Children With Genetic Mutation: Study

Children with certain genetic mutations may be at a higher risk of developing attention deficit hyperactivity disorder (ADHD) if they are exposed to even small amounts of lead, according to the findings of new research that add to the mounting evidence associated with the risk of lead poisoning for children. 

In a study published late last month in the medical journal Psychological Science, researchers from Oregon Health & Science University (OHSU) and Michigan State University indicate that children with the HFE C282Y gene mutation, which is found in about 10% of children in the United States, had a higher association between lead exposure and ADHD symptoms.

The research comes as diagnoses of ADHD are at an all-time high, with about 15% of all high school students in the U.S. diagnosed with the affliction.

The study looked at the lead blood levels for 386 children between the ages six and 17, half of whom had a strong ADHD diagnosis. While all of the children had lead levels below those which would usually cause concerns, the researchers found an association between blood lead levels, children with the HFE C282Y gene mutation, and ADHD symptoms.

Those with higher lead levels and the mutation displayed more hyperactivity-impulsivity than other children in the study, the researchers found. The effects were more pronounced in males

“Because the C282Y gene helps to control the effects of lead in the body and the mutation was spread randomly in the children, the findings of our study are difficult to explain unless lead is, in fact, part of the cause of ADHD, not just an association,” lead researcher Joel Nigg, professor of psychiatry and behavioral neuroscience at the OHSU School of Medicine, said in a press release by the Association for Psychological Science, which publishes the medical journal. “Our findings put scientists one step closer to understanding this complex disorder so that we may provide better clinical diagnoses and treatment options and, eventually, learn to prevent it.”

The researchers caution that lead exposure and genetics are likely not the only factors that contribute to the risk of ADHD.

Nationwide, the CDC estimates that 535,000 children ages 1-5, or about 2.6% of such children in the U.S., have levels of lead in their blood that place them at risk for adverse health effects. To come up with that number, the CDC analyzed data from the National Health and Nutrition Examination Survey from the years 1999 to 2002, and 2007 through 2010.

Lead poisoning for children can result in nervous system injury, brain damage, seizures or convulsions, growth or mental retardation, coma and even death for young children.

One of the more common causes of of lead poisoning is lead-based paint, which was banned in the United States in 1978 due to the risk of severe and permanent brain damage and developmental problems, particularly in children. However, a number of older homes still contain the toxic paint on the walls, and if it flakes or peals off, young children could ingest the paint chips or breathe dust that comes from the paint, resulting in lead poisoning.