Examination of a new, shorter cognitive behavioural therapy for non-underweight eating disorders: Effectiveness and predictive role of body image

Author: Mia Pellizzer

Pellizzer, Mia, 2018 Examination of a new, shorter cognitive behavioural therapy for non-underweight eating disorders: Effectiveness and predictive role of body image, Flinders University, College of Education, Psychology and Social Work

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Cognitive behavioural therapy for eating disorders (CBT-ED) has the strongest evidence base for non-underweight eating disorders. However, given the length of treatment (≤ 20 sessions) and requirement for experienced therapists, access to CBT-ED is often limited by reduced therapist availability, long waitlists, and high costs. To overcome these systemic barriers, ten-session cognitive behavioural therapy (CBT-T) was developed as a shorter therapy, suitable for delivery by novice therapists under supervision. Findings from an initial pilot study were promising however have not yet been replicated. Thus the first aim of this research was to replicate the initial findings. The second main aim of the research was to better understand the role of body image in eating disorder research, given that the over-evaluation of shape and weight is central to eating disorder psychopathology and a key target of treatment. The role of body image as a predictor and moderator of treatment outcome was examined in the context of a range of other predictors and moderators.

Prior to conducting pilot studies of CBT-T, the first study (N=328) sought to explore the psychometric properties of three measures of body image disturbance pertinent to eating disorder treatment (body image flexibility, avoidance, and checking). Confirmatory factor analysis suggested the original factor structures for the body image flexibility and checking measures were appropriate, while an alternative structure was found for avoidance. Each solution had acceptable reliability and validity and were used in subsequent studies.

CBT-T was examined in two case series (N = 26, N = 52) using trainee psychologists under supervision. Significant improvements for eating disorder cognitions, behaviours, quality of life, and negative affect were found from baseline to post-treatment for both case series and results were maintained at both a one and three month follow-up. Rates of abstinence, remission, and good outcome were comparable to studies of longer versions of CBT-ED.

Data from the two case series were combined (N = 78) to assess predictors of attrition, and predictors and moderators of outcome. Body image flexibility and avoidance emerged as both significant baseline predictors and moderators of outcome while body checking, negative affect, personality beliefs, and self-efficacy were predictors of outcome. No significant predictors of attrition were found. A sub-sample of participants who reported bingeing and/or purging at baseline (N=62) were used to explore the ability of early change variables to predict outcome. Early change in body image flexibility was the most consistent predictor of outcome, followed by body image avoidance. Body checking and the fear of expressing and receiving compassion were significant in several, but not all, analyses.

Results provide support for the effectiveness of CBT-T. Results also demonstrate the importance of considering body image as both a significant predictor and moderator of outcome. Further research is required to assess longer follow-ups and randomised controlled trial designs that compare CBT-T and longer CBT-ED directly. Further research is also required to confirm novel findings and explore the benefit of modifying existing protocols to incorporate a stronger focus on body image and fear of compassion.

Keywords: Eating Disorders, Cognitive-Behavioural Therapy, Body Image

Subject: Psychology thesis

Thesis type: Doctor of Philosophy
Completed: 2018
School: College of Education, Psychology and Social Work
Supervisor: Professor Tracey Wade