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

Abstract

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.

Key mechanisms of cognitive behavioural therapy in irritable bowel syndrome: The importance of gastrointestinal related cognitions, behaviours and general anxiety

“…The finding that GI related cognitions and GI safety behaviours significantly mediated the treatment effect on both outcomes lends support to endogenous models of IBS. This fits with findings from previous mediation studies conducted in CBT trials for IBS, which have demonstrated the mechanistic roles of cognitions, behaviours and GI specific anxiety [16]. However, the finding that general anxiety was also a significant mediator provides some support for exogenous models of IBS.…”

“…stress or general anxiety), are central maintaining factors of IBS [17]. While there is evidence to show that anxiety exogenous to IBS may have a causal role in the onset [19] and that those with IBS have increased stress reactivity [20,21], there is less evidence suggesting that changing such exogenous factors precede change in IBS symptoms [16]. A systematic review of treatment mechanisms in CBT for IBS suggested that across different CBT treatment protocols change in IBS-specific processes, particularly GI related cognitions, were key in reducing symptom severity and improving quality of life (QoL) [16].…”

“…The present study used robust methodology to study the mediation effects of CBT in IBS. Unlike other studies reviewed [16], the inclusion of mediator variables were theoretically informed and assessed at adequate intervals to allow temporal precedence, increasing the plausibility of interpreting effects as causal. Effects of mediator and outcome variables measured at baseline on the mediated effect and outcome were controlled for, to reduce the potential for residual confounding of the non -randomised mediator -outcome relationships in the models.…”

Herbs and Spices in the Treatment of Functional Gastrointestinal Disorders: A Review of Clinical Trials

“…Curcumin also has significant anti-depressant and anti-anxiety behavior [ 34 ]. Due to the high prevalence of psychological comorbidities in patients with FAPDs [ 35 ], it was thought that curcuma species could be useful for the treatment of IBS. Although we did not find any data on the effect of turmeric in FAPDs in children, three studies in adults evaluated the effects of curcumin in patients with IBS [ 36 , 37 , 38 ].…”

The TPH1 rs211105 gene polymorphism affects abdominal symptoms and quality of life of diarrhea-predominant irritable bowel syndrome

“…Indeed, cognitive behavioral therapy was elucidated to be effective for patients with IBS. ( 40 ) 5-HT signaling is the reasonable target associated with GI symptoms and mental manifestation. Inhibition of TPH1 improved the symptoms in patients with IBS to a certain extent.…”