ADHD meds do not induce cell damage

NEW YORK (Reuters Health) - Countering the findings from a 2005 study, new research supported by the United States National Institutes of Health indicates that stimulants used in the treatment of attention deficit/hyperactivity disorder (ADHD) do not cause chromosomal changes in children.

The earlier work identified an increased frequency of DNA damage and structural aberrations in chromosomes, which are associated with an increased risk of cancer. The abnormalities were observed in the white blood cells (lymphocytes) of 12 children after 3 months of methylphenidate, a drug commonly used to treat ADHD, Kristine L. Witt and associates explain in the Journal of the American Academy of Child and Adolescent Psychiatry.

Although research since then failed to replicate the earlier findings, "the enormous public health significance of this issue requires additional investigation," note Witt, at the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina, and co-investigators.

To this end, they recruited 63 previously untreated patients ages 6 to 12 diagnosed with ADHD. The children were randomly assigned to treatment with methylphenidate (Ritalin LA or Concerta) or to mixed amphetamine salts (Adderall or Adderall XR). The 3-month trial was completed by 25 and 22 subjects, respectively.

No significant treatment-related increases in cell damage were detected in the lymphocytes of the group as a whole or in the 47 subjects who were treated for the full 90 days.

According to Witt's team, these results add to the growing body of evidence that therapeutic levels of methylphenidate or mixed amphetamine salts do not induce chromosomal damage in humans.

Still, the investigators recommend that studies "continue to monitor these and related genetic damage endpoints in larger study groups...after longer exposure periods."

SOURCE: Journal of the American Academy of Child and Adolescent Psychiatry, December 2008.