Brain Responses during Anticipation and Consumption of Palatable Food in Women with and without Bulimia Nervosa or Binge Eating Disorder: disorder-related changes and modulation by intranasal oxytocin

Background: Bulimia nervosa (BN) and binge eating disorder (BED) are marked by recurrent episodes of binge-eating despite negative consequences. Although dysregulated reward processing has been proposed as a key mechanism, experimental evidence has been inconsistent. Intranasal oxytocin (OT), a neuropeptide involved in reward modulation and appetite regulation has been suggested as a potential treatment; however, its neurobiological effects remain unclear. This study examined brain responses during palatable food anticipation and consumption in BN/BED patients versus healthy controls and evaluated OT’s modulatory impact. Methods: In a randomized, double-blind, placebo-controlled, crossover fMRI study, 24 women with BN/BED and 23 healthy controls received 40 IU of intranasal OT or placebo prior to scanning. During fMRI, participants experienced both anticipation and receipt of palatable (chocolate milk) and neutral (water) stimuli while providing subjective ratings of pleasantness, intensity, and anxiety. Effects of diagnosis, treatment, and their interaction were analyzed using both frequentist and Bayesian methods. Results: Compared with controls, BN/BED participants rated both stimuli as less pleasant and more anxiety-provoking. fMRI revealed significantly greater insula activation during palatable food receipt in BN/BED. In contrast, nucleus accumbens activity did not differ between groups. OT suppressed hypothalamic responses to palatable taste across groups, without significantly affecting behavioral ratings or other regions. Conclusion: These findings challenge the view that binge eating is solely driven by reward dysfunction and highlight a potential role for altered sensory/interoceptive processing in BN/BED. Although OT modulated hypothalamic activity, its broader clinical utility remains uncertain, warranting further dose-response studies to determine clinical efficacy.