Children with a specific genetic mutation could be more susceptible to attention deficit hyperactivity disorder (ADHD) when exposed to small amount of lead, according to researchers from the Oregon Health and Science University (OHSU).
"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," Joel Nigg, who headed the research, said in a press release.
Nigg and his team examined the levels of lead in 386 healthy children between the ages of six and 17, half of whom had been diagnosed with ADHD. Blood levels of lead in the subject population were representative of the national U.S. child population and all levels were within the safe exposure range.
The findings showed that children with the HFE C282Y gene mutation, which occurs in approximately 10 percent of U.S. children, exhibited a stronger association between lead exposure and symptoms of ADHD, in particular symptoms related to hyperactivity-impulsivity.
"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," Nigg said.
Furthermore, the study found that these effects of lead in children with the mutation were stronger in males. Although children that lacked the mutation still showed amplified ADHD symptoms with increased lead exposure, they were not as severe or consistent as those with the mutation.
The findings shed light on the role of environmental pollutants in the onset of ADHD and similar disorders, although it does not prove that lead is the sole cause of ADHD.
"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," Nigg said.
The findings were published in the Dec. 28 issue of Psychological Science.
