For Your Child

Children's Height Affected By Medications For ADHD

Study Shows Slower Growth

Stimulant medications used to calm children with attention deficit hyperactivity disorder may have an unexpected side effect - slightly slower growth, according to a study appearing in the medical journal Pediatrics.

Researchers report that after two years of follow-up, stimulant medications used to treat ADHD are still effective, but they may slow growth in height a small amount.

"Stimulant medications are really extremely safe medications with very few side effects," says study co-author Dr. James Swanson, a psychologist and professor of pediatrics at the University of California, Irvine.

"I don't think this is necessarily a cause for great alarm in parents," Dr. Swanson says. "The effect was rather modest, only about a centimeter (about one-third inch) less over a year."

ADHD is the most common of the psychiatric disorders that appear in childhood. Estimates suggest that between 3 percent and 5 percent of all adolescents have ADHD. Boys are two to three times more likely to have ADHD than girls.

Growth Slowed Early; May Come Later

Dr. Swanson also noted that many questions remain unanswered. For example, researchers do not know if children on ADHD medications will have a growth rebound later.

He added that many children with ADHD are larger than average for their age, so the slight growth reduction for those on medication may just put them back into the normal height range.

It is estimated that 2 million children in the US have ADHD, according to the National Institute of Mental Health. That translates to almost one child with ADHD in every classroom. Symptoms include an inability to focus, hyperactivity, and impulsivity.

For the current study, Dr. Swanson and his colleagues followed up with 540 children with ADHD who had participated in an earlier randomized clinical trial. The trial compared the use of the stimulant medication Ritalin to behavioral therapy, a combination of Ritalin and behavioral therapy, or no treatment.

Children in the study were recruited from six sites across the US and one in Canada. All were between seven and nine years old at the start of the study.

The first study lasted 14 months, and researchers found that the children who received medication or medication in conjunction with behavioral therapy had fewer symptoms than those who received no medication.

Children on medication also grew slightly less than their non-medicated peers. Children on medication alone gained 1.9 inches centimeters, while those on combination therapy grew 1.7 inches. 

Youth receiving behavioral therapy grew an average of 2.4 inches, while a "control" group of children grew 2.2 inches.

After 24 months, the researchers followed up with the study participants and found that symptom reduction difference in the medication and non-medication groups had dropped by 50 percent.

Dr. Swanson says the researchers suspected this change was due to children in the medication group no longer taking their medication, or because those in the non-medication group may have started taking medication.

That is because the researchers only supervised treatment for the first 14 months. After that, treatment decisions were made by the parents and the children's physicians.

For the new study, the researchers re-interviewed the children and parents to assess what was truly happening in treatment. With the new information, Dr. Swanson says they found that both the effects of medication and the effects of behavioral therapy were actually fairly consistent throughout the 24 months.

They also confirmed that children on medication showed a slight reduction in height, but Dr. Swanson says the effect was less pronounced at 24 months. He said those assigned to medication grew about a one-third inch less per year than those not on medication.

Monitoring Needed During Treatment

Dr. Ernest Krug, medical director of Beaumont Hospital's Center for Human Development in Royal Oak, Mich., says, "The issue of growth suppression is something we always monitor in kids on medication.

"This study reinforces the importance of careful follow-up of children when they're on medication," Dr. Krug says. "It's a good idea for them to be seen every three to four months."

With any medication, parents should be convinced that the drug is providing beneficial effects for their children without causing unreasonable side effects, Dr. Krug said.

Always consult your child's physician for more information.

Online Resources

(The Medical University of South Carolina is not responsible for the content of Internet sites.)

Centers for Disease Control and Prevention (CDC)

National Institute of Child Health & Human Development

National Institute of Mental Health

National Institutes of Health (NIH)

US Food and Drug Administration

June 2004

Children's Height Affected By Medications For ADHD

Growth Slowed Early; May Come Later

Monitoring Needed During Treatment

ADHD Signs and Symptoms

NIMH Studies Children with ADHD

Online Resources

ADHD Signs and Symptoms

According to the National Institute of Mental Health (NIMH), symptoms of ADHD will appear over the course of many months, often with the symptoms of impulsiveness and hyperactivity preceding those of inattention, which may not emerge for a year or more.

Different symptoms may appear in different settings, depending on the demands the situation may pose for the child's self-control. A child who "can't sit still" or is otherwise disruptive will be noticeable in school, but the inattentive daydreamer may be overlooked.

The NIMH states that the impulsive child who acts before thinking may be considered just a "discipline problem," while the child who is passive or sluggish may be viewed as merely unmotivated.

Yet both may have different types of ADHD. All children are sometimes restless, sometimes act without thinking, and sometimes daydream the time away.

When the child's hyperactivity, distractibility, poor concentration, or impulsivity begin to affect performance in school, social relationships with other children, or behavior at home, ADHD may be suspected.

But because the symptoms vary so much across settings, ADHD is not easy to diagnose. This is especially true when inattentiveness is the primary symptom.

Always consult your child's physician for more information.

NIMH Studies Children with ADHD

Children with attention deficit hyperactivity disorder (ADHD) are often the subject of great concern on the part of parents and teachers, according to the National Institute of Mental Health (NIMH).

Children with ADHD are unable to stay focused on a task, cannot sit still, act without thinking, and rarely finish anything.

If untreated, the disorder can have long-term effects on a child's ability to make friends or do well at school or in other activities, the NIMH states. Over time, children with ADHD may develop depression, lack of self-esteem, and other emotional problems.

Health experts estimate that ADHD affects 3 percent to 5 percent of school-age children and two to three times as many boys as girls.

Children with untreated ADHD have higher than normal rates of injury. ADHD frequently co-occurs with other problems, such as depression and anxiety disorders, conduct disorder, drug abuse, or antisocial behavior.

Although ADHD is relatively common, understanding of the problem is incomplete.

Current ADHD treatment includes a mix of approaches, such as drug therapy, counseling, supportive services in schools and communities, and various combinations of the three.

NIMH sponsors an ongoing, treatment study of children with ADHD. Called "The Multimodal Treatment Study of Children with Attention Deficit Hyperactivity Disorder (MTA)," the study's first findings, published in December 1999, provide important guidance for physicians and parents of children with ADHD.

The MTA study demonstrates the safety and relative effectiveness of medication and behavior therapy treatments (including a behavioral therapy-only group) for a time period up to 14 months, and compares these treatments to routine community care.

The children involved in the study are being tracked into adolescence to document and evaluate long-term outcomes.