Smoking, Lead Exposure Increase ADHD Risk

By Stephanie Booth from AOL Health ~

Children exposed to lead or whose mothers smokedduring pregnancy are more than twice as likely to be diagnosed with attention deficit hyperactivity disorder (ADHD),new research shows.

The study, published in the December issue of Pediatrics, the journal of the American Academy of Pediatrics, found that children exposed prenatally to tobacco smoke had a 2.4-fold increased likelihood of ADHD diagnosis. Those whose blood showed what researchers categorized as high lead levels were 2.3 times more likely to have ADHD.

Exposure to both lead and prenatal tobacco triggered what head researcher Tanya Froehlich, M.D., a developmental and behavioral pediatric specialist and assistant professor of pediatrics at Cincinnati Children's Hospital Medical Center, called an alarming "synergistic effect." Children in this category had eight times the risk of being diagnosed with ADHD.

Froehlich and other researchers analyzed data on 2,588 children between the ages of eight and 15 who participated in the 2001 to 2004 National Health and Nutrition Examination Survey. Nearly nine percent of the children met the criteria for a diagnosis of ADHD, including inattentiveness, difficulty focusing, impulsivity and hyperactivity. Of those children, 16.8 percent had mothers who said they had smoked during pregnancy. More than five percent of children categorized as having "low" lead blood levels had ADHD and nearly 14 percent had what researchers considered "high" levels.

"These findings are not surprising, but do provide confirmation of what we already know: Lead levels in utero are a potential threat to normal brain development and tobacco can be toxic to embryos and fetuses," says Anthony L. Rostain, M.D., director of the Adult ADHD Treatment and Research Program in the department of psychiatry at the University of Pennsylvania Health System in Philadelphia. "The takeaway message here is that mothers certainly should not smoke and risks for lead exposure in the U.S. are still important to investigate."

The study estimates that up to 35 percent of ADHD cases in children between the ages of eight and 15 could be reduced by eliminating exposure to these environmental toxins. That could translate into 800,000 children.