New research from the University of Colorado shows that the 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 the brain's dopamine pathways that are involved in addiction. The study was published in Neuropsychopharmacology.
Researcher Guido Frank used MRI to examine the brain activity in 63 women who were either anorexic or obese and then compared them to women considered "normal" weight. The participants 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.
The authors found that during these MRI sessions, an unexpected sweet-tasting solution resulted in increased neural activation of reward systems in the anorexic patients and diminished activation in obese individuals. In rodents, food restriction and weight loss have been associated with greater dopamine-related reward responses in the brain.
"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."
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Source: University of Colorado Denver