What We Know About the Long-Term Effects of ADHD Medications
And what we don't know
If you’re faced with the decision whether to put your child on ADHD medication, you want to know what possible long-term effects it could have on his developing body and brain.
Many parents are especially concerned about the effects of medications for treating ADHD because they are usually stimulants, and because kids often continue to take them for years. Stimulant medications are controlled substances, which means they have a potential for abuse, though they are not considered addictive at the doses prescribed for ADHD.
There is a lot of conflicting information in the media about stimulant medications and ADHD. This article is intended to clarify the facts and help you make an informed decision about the risks and benefits of ADHD medication.
An accurate diagnosis
Before you consider medication, it’s important to be sure your child has gotten an accurate diagnosis from a professional who is trained and experienced in child and adolescent mental health. And if medication is being prescribed, make sure your doctor has the time to carefully determine the best dose, and monitor your child over time. Careful diagnosis and thoughtful treatment are key to a good outcome.
Basics of stimulants
It’s important to know that the stimulant medications prescribed for ADHD are short-acting, meaning that they do not stay in the body for an extended period. Whether your child takes them once a day or three times a day, they are basically out of his system when he wakes up in the morning.
That means that they stop working when he stops taking them. Any possible side-effects, like loss of appetite or trouble sleeping, also stop when he stops taking the medication.
Research on effectiveness
Stimulant medications have been prescribed for ADHD for more than 40 years, so there is a lot of research showing that they are safe and effective for reducing the symptoms of ADHD while they are being taken. There are a number of controlled studies of ADHD—studies that compare results of treated and non-treated kids, or those treated with medication and those who get behavioral therapy.
The largest of the controlled studies, called the MTA (or Multi-Modal Treatment Study of ADHD) study, treated nearly 600 children in the late 1990s for 14 months. The longest treated over 100 kids for 2 years. Both found that kids treated with stimulant medications had their symptoms significantly reduced, and the effect was more powerful than in kids treated with behavioral therapy.
Research on long-term effectiveness
There are a number of studies that follow children with ADHD for longer periods, even into adulthood, but the kids in these studies are not being treated in a systematic, scientifically controlled way, so the results are not conclusive.
There’s no way to know what kind of care they are getting, and how many of them really stick with the medication. In addition, some kids outgrow their symptoms as they go through adolescence. Those who stay on medication longest may be those who had the most severe ADHD symptoms to begin with, so the results are skewed.
Some researchers believe that follow-up studies of kids in the MTA study show that the effectiveness of medication declines and disappears when it’s taken longer than two years. But others consider these results meaningless since the use of medication wasn’t controlled or monitored after the first 14 months, and by the time kids are adolescents, few of them take their medication consistently.
Related: Understanding ADHD Medications
Research on long-term safety
A number of studies have followed children with ADHD for longer periods, and none has turned up any negative effects in kids whose parents reported that they were taking medication.
Dr. Rachel Klein, PhD, professor of psychiatry at the New York University School of Medicine, and a group of colleagues did a 2-year controlled study of more than 100 school-aged kids back in the late 1970s, and then followed up with them repeatedly over 33 years. Most are now 41 years old, and those who took ADHD medication showed no negative effects, in terms of medical health or other functioning, compared to those who didn’t.
Dr. Klein notes that we don’t know for sure what the long term effects of this medication on the brain might be, because of the great difficulty of treating patients a scientifically systematic way for a long time, and of measuring the results. But she adds that parents have to weigh the unknowns of long-term use against the known risks of not treating ADHD in children: a higher rate of school failure, conflict with parents and authorities, and dangerous behaviors.
It’s also the case, adds Ron Steingard, MD, a child and adolescent psychiatrist at the Child Mind Institute, that doctors report unusual side-effects or problems their patients encounter to drug companies in what are called “post-marketing surveys.” Over four decades, he notes, nothing significant in terms of long-term effects has surfaced.
This is the same process by which all medications are monitored after their initial FDA approval. It leads to changes in labeling or medications being recalled when a negative effect is discovered.
Related: Side Effects of ADHD Medication
Does ADHD medication slow growth?
There is evidence that taking ADHD medications, which can suppress a child’s appetite, can affect a child’s physical development. Several studies in the last 10 years show that children on medication for as little as 3 years are behind other kids by as much as an inch in height and 6 pounds in weight.
But a new study last year looked at kids over a period of 10 years and found no differences in height or weight between those who had taken stimulant medications and those who hadn’t. Differences were most noticeable in the first 2 years, but most kids on ADHD medications caught up with other kids over time. And kids who took what parents call a “drug holiday” over the summer or on weekends did not show the lag in growth.
Does ADHD medication cause addiction problems?
Stimulant medications are not considered habit-forming in the doses used to treat ADHD, and there is no evidence that their use leads to substance abuse.
Still, substance abuse is, and should be, a big concern for parents of kids with ADHD. A recent study showed that teens and young adults with ADHD are at higher risk for substance abuse than other kids, but treating them with stimulant medications doesn’t increase the risk. What the new study shows is that the risk is linked to the disorder, not to the treatment.
Will stimulant medication have a long-term effect on my child’s brain?
When a child is taking stimulant medication for ADHD, the medication changes levels of dopamine, a chemical in the brain called a neurotransmitter. Studies using brain scans to look at kids who had been treated with stimulant medications have found the number of “targets” for the dopamine, which remove it from the neural pathway, was increased in kids who had been on stimulant medications, compared to other kids.
Some scientists think the increase in density of those targets could be an effect of the brain adapting to the effects of increased dopamine prompted by the medication. This could make sense, since in some kids the medication doesn’t work as well over time, and they need an increase in dosage to get the same results. We don’t know what, if any, effect that increase might have, or how long it might last if medication is no longer used.
“In any case, lots of good medications become ineffective eventually,” adds Michael Milham, a child and adolescent psychiatrist who is the director of the Healthy Brain Network, the research arms of at the Child Mind Institute. “That doesn’t mean we don’t use them for as long as they work.”