Why does one person become anorexic and another obese? Blame the brain.
A study recently published by a University of Colorado School of Medicine researcher shows that reward circuits in the brain are sensitized in anorexic women and desensitized in obese women. The findings also suggest that eating behavior is related to brain dopamine pathways involved in addictions.
Dr. Guido Frank, assistant professor director of the Developmental Brain Research Program at the CU School of Medicine, and his colleagues used functional magnetic resonance imaging (fMRI) to examine brain activity in 63 women who were either anorexic or obese. Scientists compared their results to women considered normal weight.
According to the researchers, the women were visually conditioned to associate certain shapes with either a sweet or a non-sweet solution and then received the taste solutions expectedly or unexpectedly. This task has been associated with brain dopamine function in the past, researchers explain.
The scientists found that an unexpected sweet-tasting solution resulted in increased neural activation of reward systems in the anorexic patients and diminished activation in obese women. In rodents, food restriction and weight loss have been associated with greater dopamine-related reward responses in the brain, the researchers noted.
“It is clear that in humans the brain’s reward system helps to regulate food intake,” said Frank. “The specific role of these networks in eating disorders, such as anorexia nervosa and, conversely, obesity, remains unclear.”
The study was published in Neuropsychopharmacology.
Source: University of Colorado Denver