TUESDAY, June 10 (HealthDay News) -- St. John's wort isn't effective for treating attention-deficit hyperactivity disorder (ADHD) in children, a new study finds.

Published in the June 11 issue of the Journal of the American Medical Association, the study compared St. John's wort to a placebo in children aged 6 to 17 and found the herb wasn't any more effective than the placebo.

"To my knowledge, this is the first placebo-controlled study of St. John's wort for ADHD. We believed that some parents were using it to treat their children, and there was a potentially plausible biological mechanism, so we went into the study not knowing what we were going to find," said study author Wendy Weber, a research associate professor in the School of Naturopathic Medicine at Bastyr University in Kenmore, Wash.

But, said Weber, "in our study, a pretty standard dose of St. John's wort didn't provide benefit."

She added that most herbal supplements, and especially St. John's wort, have the potential to interact with other medications, which is why it's important to consult your child's doctor before trying anything new. In the case of St. John's wort, said Weber, it increases the metabolism of other drugs.

Previous studies of St. John's wort in children with depression have had mixed results, according to the study. The herb has been found to affect the metabolism of the brain chemicals serotonin, norepinephrine and dopamine. A medication (buproprion hydrochloride) sometimes used to treat ADHD, though not FDA-approved for that purpose, acts in a similar manner on these chemicals.

Because there appeared to be a potential biological explanation for the use of St. John's wort in ADHD, and because the authors suspected that parents were already using the drug for that purpose, they designed a small randomized, double-blind placebo-controlled trial of St. John's wort.

Fifty-four children between the ages of 6 and 17 who met the diagnostic criteria for ADHD were recruited for the study. During the first week, all of the children were given a placebo, and none were allowed to take ADHD medications. Those who had been taking prescription medications underwent a "washout" period before the start of the study to make sure they had no medication left in their bodies.

After the initial placebo period, half of the group was given 300 milligrams of St. John's wort or a placebo three times daily for eight weeks.

The researchers found no statistically significant differences between the groups.

Funding for the study was provided by the National Center for Complementary and Alternative Medicine (NCCAM).

"This was an extraordinarily good study that highlights the need for parents to be as critical of complementary and alternative medicines as they are about conventional medicines," said the author of an accompanying editorial in the same issue of the journal, Dr. Eugenia Chan, director of the ADHD Program at the Developmental Medicine Center at Children's Hospital Boston.

"Parents are typically very leery of stimulant medications, whereas with some of the herbs and dietary supplements, which we don't necessarily know what the side effects are, parents have a harder time being critical. It may be that because they're herbs or supplements, they're not equated with medication or that they seem natural, and natural must mean safer," Chan said.

"The evidence is definitely lagging far behind the interest," said Chan, who added that may be why some physicians are leery of alternative therapies, because without studies, it's difficult for them to weigh the risks and benefits of a treatment.

Chan said that it's important to keep your child's physician well-informed about any therapies they're using because of the potential for adverse interactions.

"If a family is very interested in using alternative and complementary medicine, it's very important to find a physician who will work with them," Chan advised.

More information

To learn more about attention-deficit hyperactivity disorder, visit the National Institute of Mental Health.

SOURCES: Wendy Weber, N.D., Ph.D., M.P.H., research associate professor, School of Naturopathic Medicine, Bastyr University, Kenmore, Wash.; Eugenia Chan, M.D., M.P.H., instructor, pediatrics, Harvard Medical School, assistant in medicine, and director, ADHD Program at the Developmental Medicine Center, Children's Hospital Boston; June 11, 2008, Journal of the American Medical Association

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