In a small study that scanned the brains of teenagers while exposing them to tempting "food cues," researchers at the Johns Hopkins University School of Medicine report that reduced activity in the brain's self-regulation system may be an important early predictor of adult obesity.
"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 Susan Carnell, assistant professor of psychiatry and behavioral sciences at the School of Medicine, a core faculty member of the Global Obesity Prevention Center at JHU's Bloomberg School of Public Health, and the paper's first author. "It's remarkable to me that we see these effects just by having participants read words like 'French fries' or 'chocolate spread.'"
The researchers used functional MRI scans on 36 New York teenagers between the ages of 14 and 19. The study included:
- 10 teens who were overweight
- 16 who were lean but were considered at high risk for obesity because they had overweight mothers
- 10 teens who were lean and considered low risk for obesity 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 office supply 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.
The investigators reported that after viewing food-related words, all participants experienced stimulation in areas of the brain that support reward and emotion. The researchers then examined the area of the brain associated with self-regulation—the dorsolateral prefrontal cortex, dorsal anterior cingulate cortex, and basal ganglia nuclei—and found the greatest activation of self-regulation in lean/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—that is, overweight participants ate the most, followed by the lean/high-risk adolescents, and then the lean/low-risk group.
Since excess weight has been linked to a variety of health issues such as high blood pressure, stroke, and diabetes, researchers want to better understand the causes of obesity in hopes of preventing it.
"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," Carnell says, "which have not been very successful at reducing or preventing obesity."Read more from Hopkins Medicine