How psychological interventions reduce symptom severity in irritable bowel syndrome: a systematic review of mechanisms

Abstract

Irritable Bowel Syndrome (IBS) is a functional gastrointestinal disorder characterised by abdominal pain and altered bowel habits. It is estimated to affect 10-22% of the UK population. The use of psychological interventions in IBS is becoming more commonplace. There is substantial empirical evidence supporting the efficacy of the Cognitive Behavioural approach to IBS in the reduction of symptom severity and enhancement of quality of life (QoL). Nevertheless, psychological approaches are often the last resort, once medical and dietary approaches have been tried. Furthermore, it is often assumed that psychological approaches to IBS predominantly target and alleviate the psychiatric comorbidity, rather than the physical complaints. The present review included studies conducting mediation analysis in the context of psychosocial interventions for IBS, focusing on the outcomes of symptom severity and/or QoL. The aim of the review was to assess whether changes in outcome relied predominantly on changes in cognitions and behaviours, or changes in anxiety/psychological distress. Results of the review would indicate that change in cognitions are most likely to be the key mechanism by which psychosocial interventions produce change in both outcomes, rather than anxiety or distress. A theoretical model is proposed to illustrate the process by which cognitions may be able to exert such an effect in IBS. It is proposed that this model may be applicable to other persistent physical symptom conditions.