Genetic Mutation Linked To Increased Risk Of ADHD In Children Exposed To Lead

Children with a particular gene mutation who are exposed to small amounts of lead may be at an increased risk of attention-deficit hyperactivity disorder (ADHD), according to a recent study.

Researchers evaluated blood levels in 386 healthy children between the ages of 6 and 17-half of whom had been diagnosed with ADHD. All children were within the safe lead exposure range as defined by the Centers for Disease Control and Prevention, and the blood lead level in the sample was typical of the national U.S. population of children. Findings revealed a heightened association between lead exposure and ADHD symptoms among those with a gene mutation known as HFE C282Y, which is estimated to be present in approximately 10 percent of US children; researchers also found hyperactivity-impulsivity was particularly common among these children. 

"This research is valuable to the scientific community as it bridges genetic and environmental factors and helps to illustrate one possible route to ADHD. Further, it demonstrates the potential to ultimately prevent conditions like ADHD by understanding how genes and environmental exposures combine," said lead researcher Joel Nigg, professor of psychiatry and behavioral neuroscience at the OHSU School of Medicine, in a news release.

As shown in previous studies, researchers also found that the effects of lead were more common in males than females. Children without HFE C282Y mutations also showed amplified symptoms as lead exposure increased, but not as consistently, researchers say. 

Researchers note that the study findings do not show that exposure to lead will guarantee an ADHD diagnosis, but rather, that environmental pollutants may play a role in the explanation of this behavioral disorder.

Unfortunately, the neurotoxin is still found in common objects, including some children's toys, costume jewelry, aging pipes and contaminated dust and soil.

The study is published in the journal Psychological Science.

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