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Prediction error response may indicate anorexia severity

Recent findings suggested that brain response to prediction error during a reward task may indicate illness severity among adolescents with anorexia nervosa.

“Brain imaging studies in anorexia nervosa have implicated central reward circuits that take part in the control of food intake,” Marisa DeGuzman, BA, BS, of the University of Colorado Anschutz Medical Campus, Aurora, and colleagues wrote. “These studies provide evidence for altered reward system function in anorexia nervosa. However, neurotransmitter-based hypotheses, which are key to developing pharmacological interventions, are largely lacking.”

To assess how brain reward learning in adolescent anorexia nervosa changes with weight restoration, researchers administered a monetary reward task during functional MRI among 21 females with anorexia nervosa and 21 control adolescents. Study participants had a mean age of 16.4 and 15.2 years, respectively.

Participants with anorexia nervosa exhibited greater brain response for prediction error regression within the caudate, ventral caudate/nucleus accumbens and posterior insula; to unexpected reward receipt in the anterior and posterior insula; and to unexpected reward omission in the caudate body, compared with controls.

Response to prediction error and unexpected reward omission had a tendency to normalize with treatment, while response to unexpected reward receipt remained significantly increased.

Increased response to prediction error in the caudate when underweight was associated with lower weight gain during treatment.

Punishment sensitivity was associated with ventral caudate prediction error response.

“This study suggests that reward learning in general, and independently of primary taste reward, is important for our overall understanding of the neurobiology of adolescent anorexia nervosa,” the researchers wrote. “Generalized sensitization of brain reward responsiveness could be a result of food restriction and may last long into recovery, consistent with basic research. Whether individuals with anorexia nervosa have a genetic predisposition for such a sensitization requires further study.” – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.