Developing a Brief Cognitive-Behaviour Therapy for Underweight Eating Disorders

This project will explore the feasibility, acceptability, and preliminary effectiveness of an adapted Cognitive Behavioural Therapy (CBT) intervention for treating underweight eating disorders. It will contribute to knowledge by extending an existing psychological treatment to a novel population, improving patient outcomes and treatment access. This aligns with the Wellbeing, Health, and Communities (WHC) Pathway mental health agenda.

Introduction

Psychological treatment options for underweight eating disorders (particularly anorexia nervosa) have limited effectiveness, with low recovery rates and reduced life quality (Solmi et al., 2021). Anorexia nervosa affects 8% of the UK's 1.25m people with eating disorders (BEAT, n.d.). It involves a range of physiological and psychological characteristics, such as low weight (typically BMI<18.5) and disordered thoughts, feelings, and behaviours around food and body image. These make it particularly difficult to treat, with poor outcomes relative to non-underweight eating disorders (around 25% versus 50% recovery rate) (Waller, 2016). Demand for treatment, long treatments (over a year), and poor recovery rates result in long waiting lists, which have worsened since the COVID-19 pandemic (Robinson et al., 2020).

Waller et al. (2019) recently developed a brief CBT-based intervention (CBT-T) for non-underweight eating disorders (e.g., bulimia nervosa), taking ten sessions rather than NICE's (NICE, 2020) recommended twenty. Research to date reports medium-to-large effect sizes (Rose et al., 2021; Tatham et al., 2020), showing briefer therapies can be both effective and efficient. This therapy stresses evidence-based elements (e.g., early changes in eating; use of exposure therapy; body image work). These features have the potential to be carried over to briefer work with underweight eating disorders. However, it remains to be established whether a briefer approach to anorexia nervosa can be effective.

The principles of CBT-T are compatible with the needs of anorexia nervosa patients. Early weight restoration and exposure to anxiety about weight gain are necessary elements (Steinglass et al., 2011), key to CBT-T. However, they are not part of existing CBT recommendations for anorexia nervosa (Murphy et al., 2010), potentially explaining existing therapies' limited outcomes. Furthermore, these methods tend to be neglected by most practitioners (Waller et al., 2012), typically because typically because exposure can be uncomfortable and anxiety-provoking for both patients and practitioners. Delivering these anxiety-inducting elements of therapy require practitioners to balance empathic delivery with adhering to treatment guidelines (Elliott et al., 2011). CBT-T address this issue directly in individuals with non-underweight eating disorders and is therefore likely to be applicable to treating anorexia nervosa. However, it has not yet been tested with this clinical group.

This project will therefore seek to develop and pilot an adapted version of CBT-T for underweight eating disorders (CBT-T-AN), exploring its feasibility, acceptability, and effectiveness. Being half the length of existing CBT for anorexia nervosa, it has the potential to enhance efficiency and reduce waiting lists substantially, thus enhancing quality of life and patients' therapeutic experience. It will meet PhD requirements by adapting an existing psychological intervention to a novel population. Aligned with the WHC Pathway's mental health agenda, this project's overall aim is to contribute to improved patient outcomes whilst addressing economic and socio-political problems of treatment demand outstripping supply.