Brain Changes Underlying Irritable Bowel Syndrome Symptom Improvement in Response to Mindfulness‐Based Stress Reduction

Background: Although the efficacy of mindfulness-based interventions for improvements in IBS symptoms has been demonstrated, the specific neural mechanisms contributing to these changes remain unclear.

Methods: A single arm interventional design was employed to explore functional brain network changes underpinning IBS symptom improvement in response to an 8-week mindfulness-based stress reduction (MBSR) intervention. Differences in brain resting state functional connectivity (RSFC) changes between 32 MBSR Responders and 16 Nonresponders with IBS after MBSR were computed using general linear models. An elastic-net regression model determined which RSFC changes were most impactful in determining MBSR responder status. Integrative association analyses elucidated the relationships between RSFC and symptom changes post MBSR. KEY

Results: Following MBSR, Responders compared to Nonresponders showed large effect size decreases in IBS symptom severity and increased mindfulness. Responder status was associated with widespread changes in RSFC. In particular, decreases in the intrinsic connectivity of the default mode network along with decreased cognitive control-somatomotor network connectivity after MBSR contributed 56% variance explained in IBS symptom severity improvement. Decreases in these two connections were associated with extensive increases in connectivity between salience, default mode, somatomotor, control, and dorsal attention networks that were further linked to reductions in comorbid psychological symptoms.

Conclusions: AND INFERENCES: Overall, Responders compared to Nonresponders showed widespread RSFC changes suggesting a shift from a predominantly inward, ruminative focus to one characterized by more externally focused attention to the body and the environment. The results suggest that MBSR may improve IBS symptom severity via impact on the brain's RSFC.