ADHD has been linked to struggles with drugs and alcohol, less schooling and more arrests, but the latest study shows it may also contribute to problems with weight as well.
In the study published in Pediatrics, researchers connected the impulsive behavior that can characterize attention-deficit/hyperactivity disorder (ADHD) with the overeating that contributes to calorie overload.
In the 33-year study that tracked boys with ADHD into adulthood, men who were hyperactive as children were twice as likely to have higher body-mass-index readings and rates of obesity than men who didn’t have the condition as children. Of men diagnosed with ADHD as kids, 41% were obese compared with 22% of men who didn’t have ADHD as children. The average rate of obesity for men in this age group was 24%.
The researchers say they did not set out to explore the relationship between ADHD and weight; the study was designed to investigate new insights into brain-structure differences among people with ADHD. But in 2003, when researchers received a grant to perform brain MRI scans on the men to evaluate their psychiatric health, many of the study participants were too large to fit in the scanner. “One of these gentlemen really wanted to help out, but we had to squeeze him in, inch by inch,” says Dr. Francisco Xavier Castellanos, the study’s senior author and a professor of child and adolescent psychiatry at New York University’s Langone Medical Center.
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For practical reasons, the scientists began asking the men for height and weight measurements to see if they would fit inside the MRI machine, which has a diameter of about 2 ft. They found that nearly three times as many men from the childhood hyperactivity group couldn’t fit in the scanner — 17 men compared with six who did not have the disorder. Intrigued, they decided to systematically collect data on the men’s weight.
“There had been suggestions in the past that ADHD might be related to obesity,” says Castellanos. “There were a lot of checks to make sure this was not due to other conditions. We were able to confirm that this risk seemed really related to childhood diagnosis of ADHD.”
The study controlled for factors including depression, anxiety, drug and alcohol abuse, and education and socioeconomic status, all of which have also been associated in other studies with obesity. But even though the childhood ADHD group had a median income that was $50,000 lower than that of the men in the control group, this economic factor did not appear to be driving the association between ADHD and obesity.
It’s not entirely clear why the disorder, which can make focusing and concentrating on tasks more difficult, would lead men with the disorder to weigh so much more than their peers. But the researchers suspect that impulsivity and poor decisionmaking skills played a role. “We live in a society with supersized amounts of food,” says Castellanos. “If someone has less than the average amount of self-control because of the ADHD, they are less able to withstand the temptations of food.”
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The results suggest that among the other behavioral issues that children with ADHD may face, including problems with drugs and alcohol, maintaining a healthy weight might be an additional concern, since obesity is associated with a host of other chronic conditions such as diabetes and heart disease. Keeping calories in check can be a challenge for even the most determined person, but these findings hint that weight might be a particularly frustrating struggle for those with ADHD.