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Opposite neural responses patterns in obesity and anorexia
DOI: 10.1038/npp.2012.51
 
Reward circuits in the brain are sensitized in anorexic women and desensitized in obese women, according to a study published online this week in Neuropsychopharmacology. The findings also suggest that eating behavior is related to brain dopamine pathways involved in addiction.
In rodents, food restriction and weight loss have been associated with greater dopamine-related reward responses in the brain.  However, though it is clear that in humans the brain's reward system helps to regulate food intake, the specific role of these networks in eating disorders such as anorexia nervosa and, conversely, obesity, remains unclear.
Using functional magnetic resonance imaging (fMRI), Guido Frank and colleagues examined brain activity in 63 women with a wide range of body mass indices, who were either anorexic or obese, and healthy controls. 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. This task has been associated with brain dopamine function in the past. The authors found that during these fMRI sessions, an unexpected sweet-tasting solution resulted in increased neural activation of reward systems in the anorexic patients and diminished activation in obese individuals.
 
Author contact:
Guido Frank (The Children's Hospital, Aurora, CO, USA)
Tel: +1 720 777 1909; E-mail: guido.frank@ucdenver.edu
 
Editorial contact for Neuropsychopharmacology:
Natalie Marler (Neuropsychopharmacology, Brentwood, TN, USA)
Tel: +1 615 324 2371; E-mail: nmarler@acnp.org