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ADHD Researchers Turn Attention to Lead and Smoke
By Molly Lee
It is estimated that between 3 and 5 percent of children have attention deficit hyperactivity disorder (ADHD) or approximately 2 million children in the United States. This means that in a classroom of twenty-five to thirty children, it is likely that at least one will have ADHD. Many have been treated with psychotropic medication. There has been a backlash from various activists and parents alike who feel that children should not be put on such medication. Although research shows that combination therapy, stimulant medication along with psychosocial intervention, is the most effective therapy, some parents are tempted to put their children on unproven alternative therapies.
A new study published in Environmental Health Perspectives seems to point to two previously unpublished potential risk factors for ADHD, prenatal tobacco exposure and environmental lead exposure. According to the authors, prenatal exposure to tobacco accounts for an excess of 270,000 cases of ADHD, and exposure to lead accounts for an excess of 290,000 cases. Almost one third of all cases of ADHD could then be attributed to these two risk factors. If these findings are confirmed, it would be an astounding breakthrough in helping prevent a condition that is a growing problem. However, the results raise a number of questions.
First, smoking rates have been in decline for years. Many more women smoked while pregnant in the 1960s before this was proven to be detrimental to a fetus. If prenatal exposure to tobacco was as large a risk factor as this research claims, we would have expected to see an "epidemic" of ADHD in earlier generations, more so than in today's children.
Similarly, exposure to lead has also been in decline for years. If lead exposure is such a large risk factor, ADHD would have been much more prevalent in earlier generations. Dr. Helen Binns, a researcher at Children's Memorial Hospital in Chicago, says the study "doesn't prove lead exposure is among the causes." She explains that it is possible that young children with ADHD are more likely than others to eat leaded paint chips because of their hyperactivity. In other words, this research does not prove a causal link between lead exposure and ADHD. (See also: Lead and Human Health: An Update.)
Finding the cause or causes of ADHD, as this research attempts to do, would be a big victory in the struggle against this condition, and a relief to those parents opposed to medication. However, jumping to conclusions will not help children struggling with ADHD. This is reminiscent of when mercury in childhood vaccinations was blamed for an epidemic of autism (see What's the Story? Childhood Immunizations). Preventing ADHD, if it is possible, would be a better alternative to years of treatment and social therapy for a child. However, pinning one third of all cases of ADHD on two unproven risk factors would be irresponsible. Before ADHD can be considered a preventable disorder, a proven cause, not a hypothetical one, must be found.
Molly Lee is the Earhart Foundation Research Intern at the American Council on Science and Health (ACSH.org, HealthFactsAndFears.com).
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