Patients with irritable bowel syndrome have altered emotional modulation of neural responses to visceral stimuli

Background & aims: In patients with irritable bowel syndrome (IBS), pain amplification and hypervigilance might result from altered affective-motivational modulation of the pain response. We investigated the effects of emotional context on the behavioral and neural response to visceral stimuli in IBS patients.

Methods: We used functional magnetic resonance imaging (fMRI) to assess the blood oxygen level-dependent response to nonpainful and painful rectal distensions in 15 female IBS patients and 12 healthy women. Distensions were delivered during psychologic stress or relaxation; data were compared with those in a neutral condition (control). Group and context-dependent differences in the processing of visceral stimulation were assessed at behavioral and the neuronal levels. Secondary analyses of group differences were performed using anxiety scores as a covariate because of higher anxiety symptoms among patients with IBS.

Results: During rectal stimulation, IBS patients demonstrated more pronounced stress-induced modulation of neural activation in multiple brain regions, including the insula, midcingulate cortex, and ventrolateral prefrontal cortex. In response to relaxation, IBS patients demonstrated reduced modulation of distension-induced activation in the insula. During relaxation, the difference observed between groups could be accounted for by higher anxiety symptoms in patients with IBS; differential effects of stress in the insula and prefrontal regions were not attributable to anxiety.

Conclusions: IBS patients appear to have disrupted emotional modulation of neural responses to visceral stimuli, possibly reflecting the neural basis for altered visceral interoception by stress and negative emotions.