Brain differences in youth linked to increased waist size

High-fat foods may cause changes in a reward-related area of the brain. Maartje van Caspel / E+ via Getty Images

Obesity in the United States affects about 35% of children and adolescents. It is associated with negative mental and physical health consequences and higher death rates. Children who are obese have more than a fivefold likelihood of becoming obese as adults.

Previous studies have shown a relationship between a reward-related brain area called the nucleus accumbens and unhealthy eating behavior in adults. Animal models of diet-induced obesity suggest a role for inflammation in this brain region, as cells other than neurons appear at higher levels.

To investigate more about the cellular structure of this brain area and weight gain in youth, researchers used data from the Adolescent Brain Cognitive Development (ABCD) Study. ABCD, which is funded by multiple NIH components, is following nearly 12,000 children through early adulthood to assess factors that influence individual brain development and other health outcomes.

The research was supported by NIH’s National Institute on Drug Abuse (NIDA). Results were published on October 12, 2020 in the Proceedings of the National Academy of Sciences.

The researchers examined data from more than 5,300 ABCD Study participants, ages 9- to 10-years-old. More than 2,000 of these participants returned for a one-year follow-up visit. The average waist circumference of the participants was used as a measure of body fat. This increased by an average of 2.76 centimeters per participant over the year.

To investigate the density of cells in the nucleus accumbens, the researchers used a noninvasive technique called diffusion MRI. They found that cellular density in the brain region reflected differences in waist circumference at baseline. It also predicted increased waist circumference at the one-year follow-up. 

“We know that childhood obesity is a key predictor of adult obesity and other poor health outcomes later in life,” says NIDA Director Dr. Nora D. Volkow. “These results extend previous animal studies to reveal what may prove to be a vicious cycle in which diet-related inflammation in brain striatal regions promotes further unhealthy eating behaviors and weight gain.”

The differences in cell density found in this study may be a result of inflammatory processes that are triggered by a diet rich in high fat foods. However, more research is needed to determine precisely what leads to these cellular changes in the brain.

Because the ABCD Study is ongoing, researchers can later assess whether this association holds or changes over the course of adolescent development. They may also be able to tell what factors influence the trajectory.