Planning a binge is reinforcing for women with bulimia nervosa: A functional magnetic resonance imaging study

Binge eating in women with bulimia nervosa (BN) is thought to be maintained through negative reinforcement: individuals experience a reduction in negative mood during and/or after binge eating. Recent findings, however, suggest that women may experience an increase in negative mood following binge eating episodes, thus casting doubt on this reinforcement model. The current study aims to address this problem by examining the reinforcement of binge eating in women with BN in an indirect way, through functional magnetic resonance imaging (fMRI). We induced negative mood in six non-treatment seeking women with BN and three healthy control women and then utilized fMRI to compare blood oxygen level dependent (BOLD) activation changes in brain regions associated with reward (caudate nucleus) and distress (amygdala) when they planned a binge versus when they engaged in a neutral task. Findings were consistent with hypotheses. Women with BN in a negative mood showed greater caudate activation and greater amygdala deactivation when they planned a binge than when they engaged in the neutral task and these activations were different from healthy controls. Both effects were of large magnitude. One way in which binge eating may be maintained for women with BN is during the planning stages of the binge. Women may be distracted from their distress while they plan a binge, thus experiencing a reduction in distress and an increase in reward, making the behavior more likely in the future.