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Adult obesity linked to ADHD

Children who display symptoms of attention deficit hyperactivity disorder are more likely to be obese as adults, a new study suggests.

Funded by grants from the National Institutes of Health and the National Cancer Institute, a team of Duke researchers began investigating the correlation between ADHD symptoms and young-adult obesity starting last year.

The study builds on other scientific literature published in the past 10 or 15 years, which has pointed a direct relationship between clinical populations of individuals diagnosed with ADHD and higher rates of obesity, said Scott Kollins, director of the Duke ADHD Program and co-author of the study.

“We wanted to see what this relationship looked like in people who might have symptoms of ADHD but not meet the full threshold for the diagnosis,” Kollins said, emphasizing that even those not diagnosed with ADHD are at a higher risk.

The researchers began by examining data for 15,197 adolescents who were tracked from 1995 to 2009 as part of the National Longitudinal Study of Adolescent Health. During the study, the adolescents were asked if they had displayed any ADHD symptoms as children. The study’s participants—whose average age was 15 when the study began—represent a random sample of the U.S. population, said Bernard Fuemmeler, lead author of the study and director of the Pediatric Psychology and Family Health Promotion Lab.

Analyzing the data, the researchers sought to determine if ADHD symptoms led to greater weight gain in the transition from adolescence to adulthood. They focused primarily on symptoms related to the ability to focus and stay focused on tasks and those related to being impulsive.

“We looked at the symptoms separately because ADHD is a multidimensional syndrome, and there are two types of symptoms that make up ADHD: attention-deficit symptoms and hyperactive impulsive symptoms,” Fuemmeler said.

The results, published in the International Journal of Obesity, indicate that individuals with more ADHD symptoms tended to gain more weight over time as they moved into adulthood and, on average, had higher body mass indexes. The risk of obesity in individuals with three or more symptoms was more than 40 percent.

“It is part of a dose effect,” Fuemmeler said. “For every increase in symptom that you have, there is an increase in prevalence of obesity.”

Individuals with more symptoms may have a tendency to engage in more unhealthy behaviors because they lose control of the ability to stop themselves, he said.

“[This] impulsiveness might lead to more caloric intake, even when [the individuals] are not hungry,” Fuemmeler noted.

Kollins said these results confirmed the hypotheses researchers had going into the study. In the future, the Duke team hopes to better understand how ADHD symptoms may develop in young children and to better define these behavioral traits.

“If we can refine our study of the traits that might be driving these symptoms, we will get closer to understanding what are some of the causes,” Fuemmeler said.

Given the elevated risks for obesity and other negative health outcomes, there is a need to identify and follow kids with elevated ADHD symptoms, Joe McClernon, a researcher for this study and director of the Health Behavior Neuroscience Research Program, wrote in an e-mail. Conversely, clinicians also need to watch for ADHD symptoms in obese patients, he added.

“[The study is] not a quantum leap, it’s not a breakthrough, but it is important [in helping] us understand some of the risk factors that might be responsible for people developing obesity,” Kollins noted.


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