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Eating Disorder Behaviors Alter the Brain's Reward Response Process

Jim Windell

            All clinicians have encountered clients with eating disorders. Often, the most common eating disorders – such as anorexia nervosa, bulimia nervosa, and binge-eating – are serious mental disorders that are difficult to treat and can lead to severe complications. The behaviors you typically see with the common eating disorders include binge-eating, purging, and restricting food intake.

           Guido Frank, M.D., at the University of California San Diego, and his colleagues set out in a recent study to see how behaviors across the eating disorder spectrum affect reward response in the brain. Furthermore, Frank and his associates were interested in how changes in reward response alter food intake control circuitry and if these changes reinforce eating disorder behaviors.

           The study, recently published in JAMA Psychiatry, involved 197 women with a variety of the most common eating disorders and 120 women without eating disorders. Each of the participants with eating disorders had different body mass indexes (BMIs) associated with their eating disorder behaviors. Frank and his colleagues used cross-sectional functional brain imaging to study brain responses during a taste reward task. During this task, participants received or were denied an unexpected, salient sweet stimulus (a sugar solution). The researchers analyzed a brain reward response known as “prediction error” – a dopamine-related signaling process that measures the degree of deviation from the expectation, or how surprised a person was receiving the unexpected stimulus. A higher prediction error indicates that the person was more surprised, while a lower prediction error indicates they were less surprised. The researchers also investigated whether this brain response was associated with ventral-striatal-hypothalamic circuitry, a neural system associated with food intake control.

           Among the findings of the study, researchers found that there was no significant correlation between BMI, eating disorder behavior, and brain reward response in the group of women without eating disorders. However, in the group of women with eating disorders, higher BMI and binge-eating behaviors were associated with lower prediction error response. Also, for the women with eating disorders, the direction of ventral-striatal-hypothalamic connectivity was the reverse of those without eating disorders; in those without eating disorders the connectivity directed from the ventral striatum to the hypothalamus. This connectivity was positively related to the prediction error response and negatively related to feeling out of control after eating.

           These results suggest that for the women with eating disorders, eating disorder behaviors and excessive weight loss or weight gain modulated the brain's dopamine-related reward circuit response. This, then, changed the brain circuitry associated with food intake control, and may reinforce eating disorder behaviors. For example, a woman with anorexia nervosa, restrictive food intake, and low BMIs will have a high prediction error response. This response may strengthen their food intake-control circuitry. This, then, may lead this woman to be able to override hunger cues. In the case of a woman with a binge-eating problem and a higher BMI, the opposite may be true.

           According to Dr. Frank, “The study provides a model for how behavioral traits promote eating problems and changes in BMI, and how eating disorder behaviors, anxiety, mood, and brain neurobiology interact to reinforce the vicious cycle of eating disorders, making recovery very difficult.”

          “This work is significant because it links biological and behavioral factors that interact to adversely impact eating behaviors,” said Janani Prabhakar, Ph.D., of the Division of Translational Research at the National Institute of Mental Health, part of NIH. “It deepens our knowledge about the underlying biological causes of behavioral symptom presentation related to eating disorders and will give researchers and clinicians better information about how, when, and with whom to intervene.”

           Although this study suggests that behavioral traits, including food intake behavior, contribute to eating disorder maintenance and progression by modulating one's internal reward response and altering food intake control circuitry and may help explain why eating disorder behaviors become chronic, how clinician can use this for treatment is unclear. It is likely that further research is needed to investigate treatments that could target and change behaviors for people with eating disorders in order to achieve lasting recovery.

           To read the original article, find it with this reference:

Frank, G. K. W., Shott, M. E., Stoddard, J., Swindle, S., & Pryor, T. Reward processing across the eating disorders spectrum implicates body mass index and ventral striatal-hypothalamic circuitry. JAMA Psychiatry, 2021 DOI: 10.1001/jamapsychiatry.2021.1580