Fairfax Mental Health Blog

Do Stimulants for ADHD Stunt Growth?

Parents frequently ask me if the stimulant medications their children receive might affect their height as adults. This takes on the proportion of a public health matter, with the prevalence of attention deficit hyperactivity disorder (ADHD) among school-aged children and adolescents is estimated to be 3% to 16%, depending on the classification system used, with boys 2 to 4 times more likely to be diagnosed with ADHD than girls.

While there have been many scientific and popular articles over the past 40 years stating that these medications can stunt growth, none were based on careful, well designed, long term scientific studies until now. Published in the Journal of Pediatrics, this landmark study actually began in 2000 and continued until 2010. The researchers at Massachusetts General Hospital and Harvard Medical School conducted the 10-year study specifically to look at the effect stimulants would have on growth rates from childhood into adolescent and adult years.  They looked at the heights and weights of boys and girls beginning at 7 – 10 years old diagnosed with ADHD; 124 children not on stimulants (the control group) and 137 treated with stimulants.

According to Dr. Joseph Biederman, the lead investigator, “We found no evidence that ADHD was associated with trajectories of height over time or differences at follow-up in any growth outcomes. Similarly, we found no evidence that stimulant treatment was associated with differences in growth.” As an incidental finding, he added, “However, among subjects with ADHD, major depression was associated with significantly larger weight in females and smaller height in males.” The bottom line? “Our results do not support an association between deficits in growth outcomes and either ADHD or psychostimulant treatment for ADHD. These findings extend the literature on this topic into young adulthood and should assist clinicians and parents in formulating treatment plans for children with ADHD.”

So what about the multitudes of studies that indicate a significant lower growth rate in kids who take stimulants compared with their peers who do not take stimulants? First, extensive reviews of all of the literature on the subject resulted in the conclusion that there is no consensus regarding stimulants causing stunted growth and that “further study is needed.   Second, the effects on growth diminish with age with no clear net effect on height. Third, very few studies actually followed patients for any significant length of time, four years at most. Fourth, none of the studies followed subjects from childhood to adulthood in order to answer the only really important question – does any reduction in growth rate during childhood and adolescence effect the final adult weight and height at 18? Fifth, there are some studies that suggest that the delays in growth are related to the underlying genetics of the disorder itself.

Most of the studies also show that there is no significant delay in normal weight gain, any of which is explained by reduction in body fat, despite the fact that the stimulants suppress appetite. This validates the observation that appetite suppression occurs only while the drug is in the bloodstream; as the drug effects wear off, there is a rebound increase in appetite and calorie consumption, so that the total number of calories consumed every day is about equal to those not on stimulants. And many studies conclude that stopping the stimulants for short period, e.g., over summer recess reverses any growth and the children catch up to their peers.

This last point bears some consideration. Should children be taken off of their ADHD medications over the summer? The answer to this question was in the affirmative in the 1970’s with the emerging widespread use of Ritalin by pediatricians. Parents and doctors noticed the temporary delay in growth with these medications, and along with significant decrease in appetite noted during the day, doctors recommended a drug holiday during school vacations. As explained above, this resulted in the children catching up to normal by the end of summer, which led to the theory that a drug holiday was necessary for normal maturation. With the results of the 10-year study, it becomes more important to consider the risks associated with taking their children off of stimulants when not in school. ADHD is not limited to school activities – it affects social interactions; part of the disorder is impulsivity such as constantly interrupting others’ conversation, not paying attention when spoken to, difficulty waiting one’s turn, procrastination and inattention to daily chores. This can adversely affect personal relationships, with peers and parents and explains divorce rates twice the average in those with ADHD. Substance abuse is also increased in untreated ADHD. Impulsivity can lead to more accidents with sports activates, such as skateboarding, or use of power tools, for instance. When your kids reach driving age, I highly recommend no break in their medication, especially on weekends; people with ADHD are at three times the risk of motor vehicle crashes than the rest of the population – “No meds, no keys.” Letting ADHD go untreated can interfere with physical, emotional and social wellbeing, not just academic performance. Ultimately decisions about the duration of treatment, medications used and dosages depend on both parents’ and doctors’ carefully monitoring the patients’ progress and reactions to the treatment to establish the lowest doses of medication that is effective, and utilizing non-medication therapies as much as they are effective.

An important consideration is that stimulant medications, including methylphenidate (Ritalin®, Concerta®, Focalin®) and amphetamine (Adderall®, Vyvanse®), and the non-stimulant atomoxetine (Strattera®) are safe and effective in children and adolescents with attention deficit hyperactivity disorder, as indicated by the Food and Drug Administration (FDA).  My next blog will look at medical and psychiatric disorders that commonly co-occur with ADHD.