It is challenging enough to manage a mental or developmental disorder such as attention deficit hyperactivity disorder (ADHD). But there may be long-term consequences to manage as well.
A recent study found an increased risk of obesity among men who had ADHD as children.
About twice as many men in the group with childhood ADHD were obese compared to men who never had ADHD.
This study could not show that ADHD caused obesity.
The study, led by Samuele Cortese, MD, PhD, of the Phyllis Green and Randolph Cowen Institute for Pediatric Neuroscience at NYU Langone Medical Center, followed a group of boys for approximately 33 years.
The authors suggested that difficulties with self-regulation even after outward symptoms are gone might be one possible contributing factor.
A group of 207 white boys with ADHD, between the ages of 6 and 12, were recruited in New York City and followed until they were an average age of 41.
The researchers also followed a group of 178 men without ADHD, recruited at an average age of 18, who were matched to the ADHD boys by location and social class.
When all the participants were an average age of 41, a total of 111 men remained in both groups. They reported their height and weight for researchers to compare.
The researchers found that 41.4 percent of the men who had ADHD in childhood were obese, compared to 21.6 percent of the men who didn't have ADHD.
The average body mass index of the men with childhood ADHD was 30.1, compared to 27.6 among those who never had ADHD.
Body mass index is a ratio of a person's height to weight that is used to indicate how healthy a person's weight is. In this study, a BMI between 25 and 30 was regarded as overweight, and a BMI of 30 or higher was considered obese.
Interestingly, obesity rates were higher among the 87 men who had childhood ADHD but no longer had symptoms of the disorder than they were among the 24 men who still had ADHD. However, the number of men who still had ADHD was so small that it was too difficult to determine what the reason for this difference might be.
The authors suggested that the impulsiveness and lack of inhibition that occur with ADHD might play some part in eating behaviors that contributes to obesity risk.
Or, they suggested, it might be possible that some underlying genetic cause links the risks of obesity and ADHD. However, they do not have evidence to explain why there is a link between obesity and ADHD.
There are other possibilities as well, said Glen Elliott, MD, PhD, the chief psychiatrist and medical director of Children's Health Council and a dailyRx News expert.
“This interesting finding is, as the authors note, contrary to expectation, given that stimulants regularly suppress appetite and weight in children and adolescents," Dr. Elliott said.
"We do know that, long term, stimulants are not good weight loss medications, and this finding may be a reflection of that phenomenon."
He also suggested that changes in physical activity could play a part.
"Alternatively, since physical high activity associated with ADHD typically declines with age, it could be that people’s eating habits did not change but their activity levels decreased, leading to weight gain," Dr. Elliott said.
"This is certainly an important caution for those with ADHD, given the risk factors associated with obesity."
Because the study involved only white boys, it's not clear if a similar pattern would be seen with girls or minorities.
"Sex is a major factor when you look at weight across the lifespan, and different ethnic groups are totally different," F. Xavier Castellanos, a co-author of the study, told dailyRx News.
"That said, what's happened across time is we've become more obese as a nation, so I would guess that if you started right now, you would see even more worrisome trends or trajectories in the long run, though that's speculation," he said.
Dr. Castellanos said these findings mean parents should not be concerned about the way ADHD medications decrease appetite.
"Rather than thinking about how to fatten up a child and encouraging them to become consumers of very high calorie foods, which is already a common tendency in our society, I think this tells us that we don't have to worry about these individuals being overly thin when they're adults," Castellanos said.
The study was published May 20 in the journal Pediatrics. The research was funded by the National Institute of Mental Health and the National Institute on Drug Abuse.
The lead author also received support from a Marie Curie grant for Career Development from the European Commission. He has received travel funding from Eli Lilly & Company and Shire Pharmaceuticals, for whom he has consulted. He has also received research funding from GlaxoSmithKline, Eli Lilly and Genopharm. No other disclosures were noted for other authors.