title: Mediators of change in cognitive behaviour therapy and mebeverine for irritable bowel syndrome.
abstract: BACKGROUND
  Cognitive behaviour therapies (CBTs) have through several trials been demonstrated to reduce symptoms and disability in irritable bowel syndrome (IBS) patients, but the mechanisms responsible for the changes are still unknown. The aim of this study was to test a theoretical model of CBT and investigate if cognitions and/or behaviour mediated the changes seen in CBT for IBS.
  
  
  METHODS
  To assess for possible mediating effects, we applied path analysis to the dataset of 149 diagnosed participants randomized to mebeverine hydrochloride plus CBT or mebeverine hydrochloride alone. Primary outcome was symptom severity, while secondary outcomes were work and social adjustment and anxiety.
  
  
  RESULTS
  The path analyses supported mediational paths for all outcomes. Changes in behaviour and cognitions mediated all three outcomes, with models placing behaviour change 'upstream' of cognition change having best fit. The analyses of model fits revealed best fit for the anxiety model and hence provide increased confidence in the causal model of anxiety.
  
  
  CONCLUSIONS
  Changes in behaviour and cognitions mediate the change in CBT given to IBS patients. The results strengthen the validity of a theoretical model of CBT by confirming the interaction of cognitive, emotional and behavioural factors in IBS.
authors.affiliation: Department of Psychological Medicine, and Department of Primary Care, King's College Hospital, London. silje.reme@uib.no
authors.forename: S E
authors.initials: SE
authors.lastname: Reme
authors.forename: D
authors.initials: D
authors.lastname: Stahl
authors.forename: T
authors.initials: T
authors.lastname: Kennedy
authors.forename: R
authors.initials: R
authors.lastname: Jones
authors.forename: S
authors.initials: S
authors.lastname: Darnley
authors.forename: T
authors.initials: T
authors.lastname: Chalder
mesh_terms: D000293:Adolescent; D000328:Adult; D001007:Anxiety / Q000523:psychology / Q000628:therapy; D015928:Cognitive Behavioral Therapy / Q000379:methods; D003131:Combined Modality Therapy; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000188:drug therapy / Q000523:psychology / Q000628:therapy*; D008875:Middle Aged; D008962:Models, Theoretical; D010276:Parasympatholytics / Q000627:therapeutic use*; D010627:Phenethylamines / Q000627:therapeutic use*; D011581:Psychological Tests; D012720:Severity of Illness Index; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D010276:Parasympatholytics; D010627:Phenethylamines; C005096:mebeverine