The journey between brain and gut: A systematic review of psychological mechanisms of treatment effect in irritable bowel syndrome.

A mediational model amalgamating the results of studies is proposed to illustrate the findings of the review. The model depicts the process by which psychotherapy changes illness-specific cognitions, behaviours, and anxiety to achieve reduction in symptom severity. Statement of contribution What is already known on this subject? Cognitive behavioural therapy (CBT) is the predominant psychological treatment for irritable bowel syndrome (IBS), although there is some research supporting other treatments such as mindfulness and hypnotherapy. Mediation analysis in the context of psychological treatments for IBS has just begun to explore possible mechanisms of treatment effect especially within CBT studies. Some studies include anxiety in a basic mediation analysis, whilst others include cognitions with inconsistent results for each. What does this study add? Reviews mediators included in mediation analysis and the methods used for mediation analysis Proposes a mediation model informed by the results of the review for future studies to investigate Provides clinical implications for the targeting of cognitions and behaviours rather than general anxiety.