May 1, 2006 - Kids who take stimulant drugs for their ADHD are shorter and lighter than their peers, a review of existing studies concludes.
It's one of the most controversial aspects of treatment for ADHD (attention deficit hyperactivity disorder). Stimulant drugs can be a great benefit to these kids. They also have side effects. One of these effects is a reduced appetite. For that reason, it's often been suggested that kids taking ADHD drugs may not grow as fast as they should.
Since the 1960s, researchers have studied the issue. About half the studies show ADHD drugs don't have much, if any, effect on growth. Other studies show a significant effect.
It's hard to compare these studies because they look at different drugs, in different-aged kids, using different ways of defining "normal" height and weight, says Omar Khwaja, MD, PhD, a fellow in neonatal neurology at Children's Hospital, Boston.
New Approach to Data
Khwaja and colleagues took a new tack. After looking at 845 published articles, they found 22 studies with data they could extract. A new analysis of the data showed that kids on ADHD drugs are shorter and weigh less than they should.
"We have been able to clarify previously conflicting studies, showing that ADHD drugs have significant restricting effects on height and weight," Khwaja tells WebMD. "It was slightly more for weight than for height, and slightly more for amphetamines -- but also significant for Ritalin-like drugs. So for a 10-year-old boy on these drugs for a year, there is a 1- to 2-centimeter [two-fifths to four-fifths of an inch] restriction in height."
Khwaja and colleagues reported their findings at the annual meeting of the Pediatric Academic Societies, held April 29-May 2 in San Francisco.
Growth Effect Temporary?
Khwaja and colleagues may have clarified the issue -- but they have not settled it, says psychiatrist Jon A. Shaw, MD, director of child and adolescent psychiatry at the University of Miami.
"In terms of long-term effects on height, I think it is still an open question," Shaw tells WebMD. "There are longitudinal studies of children on ADHD drugs -- going on into adulthood -- where they did not find a significant impairment of height attained. This study does not answer the question finally."
Shaw notes that there's good evidence that when kids with ADHD reach early adulthood -- and stop taking stimulant medications -- they undergo catch-up growth.
Khwaja, too, is aware of this evidence. She says it's important for future studies to see whether, in the last analysis, kids who take ADHD drugs really end up shorter or thinner than other kids.
Benefits of ADHD Drugs
Regardless of what these studies show, Donna Palumbo, PhD, rejects the idea that ADHD drugs stunt kids' growth. Palumbo, whose ADHD studies have been funded by drug companies as well as by the National Institutes of Health, is director of the ADHD program at Strong Hospital, University of Rochester in New York.
"In the 50 years since this idea first appeared, we have learned that kids do not stop eating and growing when treated for ADHD," Palumbo tells WebMD. "With newer treatments, we see that if there is any effect on growth, it is very minimal. And it looks like kids catch up at adulthood."
Palumbo warns parents not to overreact when they hear about the risks of ADHD treatment. While the treatment risks may be scary, she notes that the risks of untreated ADHD are even scarier.
"The risks of not treating ADHD are pretty significant in terms of long-term outcomes," Palumbo says. "We try to put it into perspective. We say your child may have a difference of a couple of centimeters of height over years of treatment. But treatment reduces school drop-out rates, increases school performance, and prevents other psychiatric disorders. A lot people think of no treatment as a benign choice. But it is not a benign choice."