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Title: Mediators of transdiagnostic psychological treatments for eating disorders
Author: Sivyer, Katy
ISNI:       0000 0004 7231 7939
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2017
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Cognitive behaviour therapy and interpersonal psychotherapy are the leading treatments for eating disorders. Little is understood regarding their mechanisms of action. The research described in this thesis investigated the purported mechanisms of action of two transdiagnostic versions of these treatments; enhanced cognitive behaviour therapy (CBT-E) and interpersonal psychotherapy for eating disorders (IPT-ED). A series of mediation studies were embedded within a randomised controlled trial comparing CBT-E and IPT-ED in a transdiagnostic sample of patients with eating disorders. An analytic strategy using multilevel and structural equation modelling was used to assess for statistical mediation. Three of the key purported mediators of action of CBT-E (regularity of eating, frequency of weighing, and frequency of shape checking) and the key purported mediator of IPT-ED (interpersonal problem severity) were studied. Only regularity of eating demonstrated a strong case for being a mediator of the effect of CBT-E (on frequency of binge eating). The findings were inconclusive regarding other putative mediators of the effect of CBT-E, and for interpersonal problem severity being a mediator of the effect of IPT-ED. Limitations of the research included the non-optimal choice of measures and non-optimal timing of measurements for establishing temporal precedence. Future research should investigate the mediating role of both cognitive (e.g. interpretation of weight) and behavioural processes (e.g. frequency of weighing) in CBT-E, and the role of interpersonal functioning in CBT-E and IPT-ED. Research should use daily, or session by session measurement to better assess the temporal relationship between the purported mediator/s and the outcome/s. Experimental designs comparing dismantled versions of treatment would also help determine the relative effects that different treatment procedures have on treatment outcome/s.
Supervisor: Fairburn, Christopher ; Allen, Elizabeth Sponsor: Wellcome Trust
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Statistics ; Psychiatry ; Psychology ; multilevel modelling ; eating disorder ; structural equation modelling ; cognitive behaviour therapy ; cognitive behavior therapy ; treatment personalisation ; treatment personalization ; statistical mediation ; interpersonal psychotherapy