A new review of past studies on the effect that attention-deficit hyperactivity disorder (ADHD) drugs have on children's growth concludes that the drugs do, in fact, suppress growth to some degree.

While the effect found was statistically significant, one of the study's authors, Dr. Omar Khwaja, an instructor in neurology at Children's Hospital Boston, said the average growth suppression for a 10-year-old boy was probably about three-quarters of an inch in height and a little more than two pounds in weight.

"Parents need to know that when children are on stimulant treatment...there's a possibility of growth restriction," Khwaja said. "Their physicians need to pay attention and monitor growth in these children" if parents choose to medicate for ADHD.

Results of the study were presented at the Pediatric Academic Societies annual meeting, in San Francisco.

It's estimated that as many as 5 percent of American children have ADHD, according to the National Institute of Mental Health. The main symptoms are an inability to pay attention, hyperactive behavior and impulsivity. The standard treatment is with stimulant medications, such as Ritalin and Adderall. However, these medications have never been scientifically tested in the long-term for the their effect on children's health.

As with any medication, there's a potential for side effects. One suspected side effect is the suppression of appetite, which is believed to have an effect on a child's weight and possibly height. Dr. David W. Goodman, an assistant professor in the department of psychiatry and behavioral sciences at Johns Hopkins University School of Medicine, said the issue of whether these medications contribute to growth suppression has been debated for 35 years.

To try to settle this debate, Khwaja and his colleagues reviewed the literature, looking for studies on ADHD medications and their side effects. They found 22 studies that they considered to have valid, quality methodology.

They pooled the data from these studies and found there was, indeed, an effect on height and weight while children were taking these drugs.

"There was a significant effect on growth for both height and weight during the duration of treatment," Khwaja said.

What can't be gauged from this study, he said, is if those changes are lasting or if the children catch up when they go off the medications, or if they catch up as they get older.

Goodman said other studies have shown a height suppression of about a half inch, and that, in the long-term, children do catch up, but this is not evident in every study.

He said one limitation of the new analysis was that it didn't break down the data for short-term and long-term growth suppression.

What parents need to consider, Goodman said, "Is the quality of life improvement great enough to assume the possible risk of...growth suppression?" Other experts believe it is in the best interests of parents to pursue alternatives that may offer few side effects and long-term health effects for their children.

Khwaja added that he believes more study needs to be done on this topic, and a prospective trial should be performed to look at the long-term effects these drugs have on children's growth.