Researchers find early signs of obesity risk in children's brain development

A new study by Florida International University reveals that differences in brain regions associated with reward and hunger may be linked to obesity risk in children as young as four, shifting the timeline for early identification.

Florida International University researchers say they have found signs that obesity risk may be reflected in the brains of children as young as four, adding to a growing body of evidence that the links between body weight and brain development may emerge earlier than previously thought. The study, published in Scientific Reports, examined preschool and early school-age children and found that higher body mass index, or BMI, was associated with differences in several brain regions involved in reward, taste and hunger. FIU said the findings were based on MRI scans and several measures of body size, although only BMI showed a clear connection with the brain measures studied. According to the announcement, the work does not show cause and effect.

The researchers scanned 159 children aged four to seven and used a technique called restriction spectrum imaging, which looks at water movement in brain tissue to reveal microstructural differences. They reported changes in regions linked to reward and craving, and said they saw a small signal in the hypothalamus, the part of the brain involved in hunger control. That result, however, was described as preliminary and in need of further study.

Lead author Mohammadreza Bayat said the findings push the timeline for obesity-related brain differences back by several years, compared with earlier studies in adolescents. He said the researchers were not claiming that weight gain caused the brain differences, or that the brain differences caused weight gain. The team also said it had expected stronger links in children with attention deficit hyperactivity disorder, but found a similar overall pattern in children with and without the condition.

The new paper fits with earlier research suggesting that brain structure and obesity risk may be connected in children and adolescents. The National Institutes of Health has reported on work linking cellular differences in reward-related brain regions with increased waist size in youth, while other studies have found structural and connectivity differences in children carrying the FTO obesity-risk allele and in adolescents with obesity.

Researchers at FIU said the study is only a snapshot in time, so it cannot show whether the brain differences came first, followed changes in weight, or developed alongside them. They said they plan to follow children over time and combine brain imaging with measures of metabolism and inflammation to better understand what is driving the pattern. The authors also stressed that the findings are not a basis for parents to change their child’s diet or activity habits in response to the study alone.