Childhood obesity could be psychological disorder

24 Aug 2017 --- New evidence regarding the brain’s relationship with obesity has emerged. A study by a team of researchers, including Senior Investigator Bradley Peterson, MD, Director of the Institute for the Developing Mind at Children's Hospital Los Angeles, has found that neural responses to food cues are different in overweight compared with lean adolescents while there is less activity in the brain’s self-regulation and attention circuits. The findings may also be a useful predictor of adult obesity.

The potentially important study comes at a time when half of all adolescents in the US are either overweight or obese, according to the Johns Hopkins Medicine press release. It adds that children of overweight parents, or two-thirds of adults in the US, already are or are likely to become overweight.

In a report of the study's findings, published in NeuroImage, the investigators suggest that reduced activity in the brain's self-regulation system may be a better predictor of obesity than heightened responses of the reward system to food cues.

“Our findings suggest that we may be able to predict which teens will ultimately become obese adults by effectively looking at how their brains respond when they read a food menu. It's remarkable to me that we see these effects just by having participants read words like ‘French fries’ or ‘chocolate spread,’” says Susan Carnell, Ph.D., Assistant Professor of Psychiatry and Behavioral Sciences at the Johns Hopkins University School of Medicine.

“This study establishes that risk for obesity isn't driven exclusively by the absence or presence of urges to eat high-calorie foods, but also, and perhaps most importantly, by the ability to control those urges,” comments Peterson, who is also a professor at the Keck School of Medicine at the University of Southern California, of his team’s findings.

Problems with self-regulation
Peterson’s team’s study observes that food stimuli activated regions of the brain associated with reward and emotion in all groups. However, adolescents at an increasing risk for obesity had progressively less neural activity in circuits of the brain that support self-regulation and attention.

Of the 36 adolescents (ages 14 to 19 years) enrolled in the study, ten were overweight/obese, 16 were lean but considered at high risk for obesity because they had overweight/obese mothers and 10 were lean/low risk since they had lean mothers.

The adolescents underwent brain scanning using functional MRI (fMRI), noninvasive, minimal risk method of assessing neural activation based on the flow of oxygenated blood to different brain regions. They viewed words that described high-fat foods such as chicken wings, low-fat foods such as Brussels sprouts and nonfood office supply items such as Post-it notes. Then they rated their appetite in response to each word stimulus. Following the activity, all participants were offered a buffet that included low- and high-calorie foods to relate participants’ test responses to real-world behavior.

The investigators report that after viewing food-related words, all participants experienced stimulation of the insula and pregenual anterior cingulate cortex – areas of the brain that support reward and emotion. In adolescents who were overweight or were lean but at high familial risk for obesity, however, the research team saw less activation in the brain's dorsolateral prefrontal cortex, dorsal anterior cingulate cortex and basal ganglia nuclei, which support self-regulation.

Brain circuits that support attention and self-regulation showed the greatest activation in lean/low-risk adolescents, less activity in lean/high-risk participants and least activation in the overweight/obese group. Real world relevance also mirrored the fMRI findings – food intake at the buffet was greatest in the overweight/obese participants, followed by the lean/high-risk adolescents and the lean/low-risk group in which it was lowest.

“Clearly, we are not suggesting that we should scan the brains of every teenager, which would not be practical or cost-effective,” says Carnell, who researches as part of the Johns Hopkins Children's Center. “But our findings suggest that obesity treatments and prevention interventions designed to strengthen the self-regulatory system may be more useful for teenagers than typical programs focusing purely on diet and physical activity, which have not been very successful at reducing or preventing obesity.”

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