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ADHD, Medication, and Growth - the latest research results

by Glenn S. Hirsch, MD and Anita Gurian, PhD

Does medication for children with Attention-Deficit/Hyperactivity Disorder (ADHD) help? Does medication affect growth? These questions are often asked by parents of children with ADHD and by the professionals who treat these children. The ongoing follow-up findings of a study of over several hundred children with ADHD published in the April issue of Pediatrics provides some scientifically-based information relevant to these questions.

The Multimodal Treatment Study of ADHD (MTA), the largest clinical trial in children funded by the National Institute of Mental Health, conducted at six university medical centers, (including the NYU Child Study Center under the direction of Howard Abikoff, Ph. D.), has closely followed 579 seven-to-nine-year-old children with ADHD for two years after the treatment phase was completed. It continued to demonstrate treatment with medication alone or with a combination of medication and behavior management were shown to be more effective for the control of ADHD symptoms than behavior management alone or medication in the community, although the effectiveness of the treatment diminished over time.

In this follow-up the investigators also evaluated the side effects of medication on growth. The results showed that stimulant medication, such as Ritalin (methylphenidate), had an effect on the growth of some children. Although there have been concerns for many years that stimulant medications can decrease appetite, caloric intake and growth in weight and height in some children over the short term, the study presents specific data. When the children who were not treated with medication were compared with the children treated with medication (an average of about 38 mg of methylphenidate per day), it was found that the children on medication grew almost a half-inch less per year. The slower growth was maintained for the duration of the two-year follow-up for those children who continued taking the medication. The children who stopped taking medication after the end of a 14-month trial grew more but had not yet completely caught up with the children who never received medication. Ongoing evaluation will determine if the children will catch up to their expected height as they get older.

What does this new information mean for parents of children who are on stimulant medication or who are considering medication? It may well be that for many children the decrease in growth velocity is not of clinical importance. The effects may be important, however, for some children who are already much shorter than most of their peers. This information should be taken into consideration and weighed in relation to the many established benefits of medication when parents and physicians plan individualized treatments and follow-up for children with ADHD. The MTA Group is continuing to monitor these children. We can expect additional information in the future.

For the complete Ongoing Follow-up Findings from the Multimodal Study of ADHD (MTA) reported by Howard Abikoff, Ph. D., Pevaroff Cohn Professor of Child and Adolescent Psychiatry and Director of the Institute for Attention Deficit Hyperactivity and Behavior Disorders.