Reduced activity in the brain’s “self-regulation” system may be an important early predictor of adult obesity, according to a small study.
Researchers used functional MRI scans on 36 teenagers to measure neural responses to food cues. Participants who were lean but considered at increased risk for adult obesity because of family history had less neural activity in the brain’s self-regulation and attention areas than lean adolescents with lean mothers.
“It’s remarkable…that we see these effects just by having participants read words like ‘French fries’ or ‘chocolate spread.’”
“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,” says lead author Susan Carnell, assistant professor of psychiatry and behavioral sciences at Johns Hopkins University.
“It’s remarkable to me that we see these effects just by having participants read words like ‘French fries’ or ‘chocolate spread.’”
As reported in the journal NeuroImage, researchers suggest that low activity in the self-regulation system in response to food cues may be a better predictor of obesity than heightened responses in the brain’s reward system.
More than half of all adolescents in the United States are either overweight or obese. Children of overweight parents already are or are more likely to become overweight. Since excess weight has been linked to health issues such as high blood pressure, stroke, and diabetes, researchers hope to better understand the causes of obesity in hopes of preventing it.
For the study, researchers recruited 36 New York City teens, 14 to 19, of whom 10 were overweight or obese and 16 were lean but considered at high risk for obesity because they had overweight or obese mothers. Another 10 were lean and at low risk because they had lean mothers.
The teens underwent brain scanning using fMRI while they viewed words that described high-fat foods such as chicken wings, low-fat foods such as Brussels sprouts, and nonfood items such as Post-it notes. Participants rated their appetite in response to each word stimulus. After the activity, all participants were offered a buffet that included low- and high-calorie foods—to see if their brain responses were associated with real-world behavior.
After viewing food-related words, all participants experienced stimulation in the parts of the brain that support reward and emotion. Adolescents who were overweight or were lean but at high familial risk for obesity, however, had 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 self-regulation showed the greatest activation in lean and low-risk adolescents, less activity in lean/high-risk participants, and the least activation in the overweight group.
The buffet portion of the experiment complemented the fMRI findings; overweight participants ate the most, followed by the lean/high-risk adolescents, and then the lean/low-risk group.
“Clearly, we are not suggesting that we should scan the brains of every teenager, which would not be practical or cost-effective,” Carnell says.
“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.”