Looking Closer at ADHD and Obesity

ADHD link to obesity in children may be related to medications

(RxWiki News) Attention deficit hyperactivity disorder (ADHD) may be well known, but there is still a great deal that scientists don't know about it.

A recent study looked more closely at the link between ADHD and obesity that scientists already know exists. The researchers found that kids with ADHD who were not treated tended to gain more weight in childhood.

Meanwhile, children who took stimulant medications for their ADHD gained weight more slowly in childhood but rapidly gained more weight in their late teens.

"Discuss ADHD treatment with your child's pediatrician or psychiatrist."

The study, led by Brian S. Schwartz, MD, of the Department of Environmental Health Sciences at Johns Hopkins Bloomberg School of Public Health in Baltimore, looked at the link between ADHD and weight, both in childhood and in the later teens.

Past studies have already found that having ADHD in childhood is linked to a higher risk of obesity in adulthood. However, researchers are not sure of the reasons for this link, and there are several hypotheses about it.

This study explored the hypothesis that ADHD stimulant medications might be related to the obesity risk.

The researchers analyzed the medical records of 163,820 children, aged 3 to 18, in Pennsylvania. They looked at the children's ages when diagnosed with ADHD, their ages when they first started taking ADHD stimulant medications and how long they took the medications.

Then the researchers compared this information to the children's body mass index (BMI) over time, after taking into account other differences between the children — such as age, sex, race/ethnicity and other health conditions.

BMI is a ratio of a person's height to weight and is commonly used to determine whether a person is a healthy weight.

The average age when BMI information became available for each child was about 9 years old, and the records provided an average of three BMI measurements each year. Most of the children in the study were white.

Across the whole group, 8.4 percent of the children had been diagnosed with ADHD, 6.8 percent had been prescribed ADHD stimulant medications.

In combining these, 9.5 percent of the children had either a prescription for stimulant medications or an ADHD diagnosis.

The medications included the following:

The average amount of time the children spent on a medication was 426 days, or one year and two months.

The researchers found that children with ADHD who were not taking medications for their condition tended to have higher BMIs in childhood than those without ADHD or with medication-treated ADHD.

Meanwhile, children with ADHD who were taking stimulant medications tended to gain weight more slowly than the other children, especially if they started the ADHD medications when they were younger and/or were on the medications for longer periods of time.

Yet, these same children tended to have a rapid "rebound" of BMI in their late teens. "The earlier stimulants were ordered, the earlier and stronger that BMI growth “rebounded” and eventually "exceeded" the weights in children without ADHD or medications, the researchers wrote.

In other words, the kids taking ADHD medications — especially starting early and taking them for a long time — had slower growing BMIs as kids, and then they increased more rapidly when they were older.

"Our findings suggest that children with ADHD are at increased risk for obesity," the researchers wrote. "Consistent with current guidelines, clinicians should assess and evaluate BMI at least annually and implement the indicated intervention to prevent obesity."

The authors also mentioned other options for ADHD treatment besides medication.

"It should be noted that behavioral therapy, specifically parent training, can be effective for ADHD management and has no known BMI rebound effect," they wrote.

Glen Elliott, MD, PhD, a clinical professor at the Stanford University Department of Psychiatry and Behavioral Sciences, noted that the study offers interesting findings but has its own flaws to consider.

“The authors report a disturbing trend in those on stimulants for long periods of time in which individuals seem to have a 'rebound' that can result in obesity late in life," he said.

"The measure they use, Body Mass Index (BMI), is a ratio of weight over height," he said. "It is unfortunate that the authors did not examine more closely whether the effects they found are due mainly to increased weight, decreased height or both."

Yet the results of the study still offer valuable insights in looking at the issue of obesity and ADHD, he suggested.

"However, given that their finding occurs in late teens, it seems likely to be significantly a matter of increased weight," Dr. Elliott said. "That they do not find a similar pattern in those with ADHD who do not take stimulants certainly suggests that chronic stimulant use is somehow related to the observed increased risk for becoming overweight or obese.”

The study was published March 17 in the journal Pediatrics. The research was funded by the National Institutes of Health. The authors reported no conflicts of interest.

Review Date: 
March 15, 2014