Megan Brooks
March 17, 2014
Treating attention-deficit/hyperactivity disorder (ADHD) with stimulants changes growth trajectories in childhood and is likely to be behind the reported association between ADHD and obesity, a new study suggests.
The study showed that children with untreated ADHD or ADHD treated without stimulants had a faster increase in body mass index (BMI) than those without ADHD. Conversely, children with ADHD treated with stimulants demonstrated slower BMI growth early in childhood, but they rebounded later in adolescence with higher BMIs ― higher than in children without a history of ADHD or stimulant use.
“Given the rapid increases in both ADHD diagnosis and stimulant treatment over the past decades, our findings might suggest to clinicians that long-term impacts on childhood and adolescent BMI growth trajectories, and perhaps continuing into adulthood, may result from stimulant use in childhood,” Brian S. Schwartz, MD, from Johns Hopkins University Bloomberg School of Public Health in Baltimore, Maryland, and the Geisinger Center for Health Research in Danville, Pennsylvania, told Medscape Medical News.
The study was published online March 17 in Pediatrics.
Strong, Consistent Link
There is substantial evidence linking stimulant use to growth deficits, and there is some evidence of growth delays in ADHD. However, “increasingly, and paradoxically,” concerns have been raised about a possible link between ADHD and obesity, the investigators note. They add that this is the first longitudinal study to examine associations between ADHD and stimulant use on BMI growth trajectories.
Dr. Schwartz and colleagues examined electronic health record data from the Geisinger Health System on 163,820 children aged 3 to 18 years. They used random effects linear regression models to determine BMI trajectories in relation to ADHD diagnosis, age at first use of stimulant medication, and duration of stimulant use, while controlling for confounding variables.
They found that children with unmedicated ADHD had faster rates of BMI growth after about age 10 years compared with control individuals with neither a history of ADHD nor stimulant use. Children with ADHD treated with stimulants had reduced rates of BMI growth in early to mid childhood, but they experienced a rebound in BMI in late childhood and an acceleration in BMI growth after that, leading to BMIs in late adolescence that were higher than those in the control individuals.
The data are “quite consistent and strong in implicating stimulant use for ADHD in changing childhood BMI growth trajectories,” Dr. Schwartz told Medscape Medical News. “We found that the earlier in childhood that stimulants were started and the longer they were used, the stronger were the effects in producing both delayed BMI growth in early childhood and rebound BMI growth in late adolescence,” he said.
“These kind of ‘dose-response’ relations are very important in causal inference and quite persuasive to epidemiologists. This BMI growth rebound has not, to my knowledge, been previously reported, so requires replication,” Dr. Schwartz added.
In the study, the investigators note that their findings “should motivate greater attention to the possibility that longer-term stimulant use plays a role in the development of obesity in children.”
Metabolic Stressor
Commenting on the study for Medscape Medical News, L. Eugene Arnold, MD, professor emeritus of psychiatry, Ohio State University in Columbus, said that it is “interesting and fits” the developmental origins of health and disease (DOHaD) hypothesis.
This hypothesis holds that an “unfavorable uterine environment (eg, gestational smoke exposure) both predisposes to ADHD and also tricks an epigenetic transformation to thrifty phenotype in anticipation of an unfavorable postnatal environment. The calorie-saving metabolic changes then lead to large size after encountering a more favorable environment postnatally than the genes ‘expected,’ ” he explained.
“By showing that stimulant treatment makes this worse, the article extends the DOHaD hypothesis to a postnatal metabolic stressor, the appetite suppression of stimulants, with a similar rebound after that appetite suppression is taken away,” Dr. Arnold said. However, it is important to remember that this is a hypothesis and is not proven, he added.
The study was funded by the National Institutes of Health. The authors and Dr. Arnold report no relevant financial relationships.
Pediatrics. Published online March 17, 2014. Abstract