The effect of stress on delay discounting in female patients with early-onset bulimia nervosa and alcohol use disorder: functional magnetic resonance imaging study.

Aims: Stress could increase delay discounting in subjects with bulimia nervosa and alcohol use disorder (AUD), meaning that the short-term benefits of coping through eating or drinking outweigh the long-term negative consequences. Therefore, this study explores differences in delay discounting between patients and healthy controls, the impact of stress on food and alcohol delay discounting and associated changes in brain activity.

Method: A total of 102 female participants (AUD, 27; bulimia nervosa, 25; healthy controls, 50) underwent repeated functional magnetic resonance imaging scanning. Initially, all participants performed a monetary delay discounting task (DDT), followed by a food or alcohol DDT before and after stress induction. Specifically, those with bulimia nervosa completed a food DDT, those with AUD completed an alcohol DDT and healthy controls were randomly allocated to one or either DDT.

Results: Participants with AUD, but not healthy controls, displayed a higher discounting of alcohol after stress. Healthy controls, but not those with bulimia nervosa, had nominally higher discounting rates of food following stress, although not significant following multiple testing correction. Participants with AUD displayed a lower activity of the right supplementary motor area while discounting alcohol after stress. Healthy controls showed a lower activity of the frontal cortex and a higher activity of the motor cortex while discounting food after stress, while those with bulimia nervosa displayed a higher activity of the occipital cortex.

Conclusions: The results suggest that, in subjects with AUD, stress induces neurobiological changes that cause them to prefer more immediately available alcohol. However, the results observed in participants with bulimia nervosa suggest a more complex relation between stress and food.