Childhood obesity leads to poorer brain health

Childhood obesity is a growing concern in the United States, where approximately one in five children are obese. According to a new study presented at the annual meeting of the Radiological Society of North America (RSNA), higher weight and body mass index (BMI) in pre-adolescence are associated with poorer brain health.

“We know being obese as an adult is associated with poor brain health,” said Simone Kaltenhauser, a post-graduate research fellow in Radiology and Biomedical Imaging at Yale University. “However, previous studies on children have often focused on small, specific study populations or single aspects of brain health.”

Now, the scientists used imaging data from the Adolescent Brain Cognitive Development (ABCD) study, which included 11,878 children aged 9-10 from 21 centers across the U.S. After excluding children with eating disorders, traumatic brain injury, and psychiatric and neurodevelopmental disorders, the study group included 5,169 children, among which 51.9 percent were females. According to the children’s BMI z-scores (measures of relative weight adjusted for a children’s age, sex, and height), the overweight and obesity rates within the cohort were 21 percent and 17.6 percent, respectively.

The researchers evaluated data from structural MRI and resting-state functional MRI (fMRI), which enabled them to measure brain activity by detecting changes in blood flow. Moreover, they also used data from diffusion tensor imaging – a method that helps assess white matter – and restriction spectrum imaging, an advanced diffusion MRI technique. After correcting for age, sex, race, ethnicity, handedness, and socioeconomic status, the experts employed linear models to determine the associations between weight and BMI z-scores and the imaging metrics.

The analysis revealed structural brain changes in children with higher weight and BMI z-scores, including impairments in the integrity of white matter. Regions of most significant degradation included the white matter of the corpus callosum – the main connector between the brain’s two hemispheres – and tracts within the hemispheres which connect the lobes of the brain. Moreover, the researchers also observed a thinning of the cortex (the outermost layer of the brain), which has been linked in previous studies with impaired executive function. Finally, resting-state fMRI images have shown that higher weight and BMI z-scores were associated with decreased connectivity in the functional networks of the brain responsible for cognitive control, motivation, and reward-based decision making.

“We expected the decrease in cortical thickness among the higher weight and BMI z-score children, as this was found previously in smaller subsamples of the ABCD study. However, we were surprised by the extent of white matter impairment,” Kaltenhauser said.

“Increased BMI and weight are not only associated with physical health consequences but also with brain health. Our study showed that higher weight and BMI z-scores in 9- and 10-year-olds were associated with changes in macrostructures, microstructures, and functional connectivity that worsened brain health,” he concluded.

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By Andrei Ionescu, Earth.com Staff Writer

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