Obese adolescents have decreased white matter in a brain region that connects the right and left hemispheres of the brain (compared to healthy teens). These changes correlated with markers of inflammation and insulin resistance.

Approximately 20 percent of teens living in the United States are obese. Obesity negatively affects multiple organ systems, including the nervous system. Findings from a new study indicate that the white matter in the brains of obese teens is lower than that of healthy teens.

Obesity is associated with chronic low-grade inflammation, which can drive many disease processes. A specialized magnetic resonance imaging technique, called diffusion tensor imaging (DTI), can measure this inflammation in the brain.

A study involving 59 obese adolescents and 61 normal weight adolescents between the ages of 12 and 16 years used DTI to measure damage to the white matter in the teens' brains. The imaging results revealed that areas of the corpus callosum, a bundle of nerve fibers that connects the left and right hemispheres of the brain, as well as areas of the middle orbitofrontal gyrus, an area responsible for emotional control and reward circuits, were diminished in the obese teens' brains. Damage in these areas was correlated with altered levels of insulin, inflammatory markers, and leptin, a key regulator of appetite, and insulin.

Future research with DTI imaging techniques may reveal whether these changes in the structure of obese teens' brains are reversible.

• Link to press release.