Teenagers’ Brain Size May Indicate Risk of Developing an Eating Disorder

They discovered that girls with anorexia nervosa had a larger insula, a brain region that is active when one tastes food, and a larger orbitofrontal cortex, a region of the brain that communicates to an individual when to stop eating.

Guido Frank, MD, assistant professor of psychiatry and neuroscience at University of Colorado’s School of Medicine, and his colleagues reported that the bigger brain may be the reason people with anorexia are able to starve themselves. Similar findings in children with anorexia nervosa and in adults who had recovered from the disease, raise the prospect that insula and orbitofrontal cortex brain size could predispose a person to develop eating disorders. “While eating disorders are often triggered by the environment, there are most likely biological mechanisms that have to come together for an individual to develop an eating disorder such as anorexia nervosa,” Dr. Frank stated.

The researchers recruited 19 adolescent girls with anorexia nervosa and 22 in a control group and used magnetic resonance imaging (MRI) to study brain volumes. Individuals with anorexia nervosa showed greater left orbitofrontal, right insular, and bilateral temporal cortex gray matter compared to the control group. In individuals with anorexia nervosa, orbitofrontal gray matter volume related negatively with sweet tastes. An additional comparison of this study group with adults with anorexia nervosa and a healthy control group supported greater orbitofrontal cortex and insula volumes in the disorder across this age group as well.

The medial orbitofrontal cortex has been associated with signaling when people feel full by a specific type of food (termed “sensory-specific satiety”). This study suggests that larger volume in this brain area could be a trait across eating disorders that promote these individuals to stop eating faster than in healthy individuals, before eating enough.

The right insula is a region that processes taste, as well as incorporates body perception and this could contribute to the perception of being fat in spite of being underweight.

The findings were published July 22, 2013, in the Journal of the American Academy of Child and Adolescent Psychiatry. This study is complementary to another that found adults with anorexia and individuals who had recovered from this illness also had differences in brain size, published earlier in 2013 in the American Journal of Psychiatry.

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University of Colorado’s School of Medicine