As a whole, eating disorders have been characterised as having the following key features: a persistent over concern with body size and shape; and weight control behaviours such as fasting, exercise, and self-induced vomiting. However, there tends to be a blurred line between those that do and do not meet diagnostic thresholds as the level of psychological distress is comparably similar. This study examined whether psychological inflexibility (from an Acceptance and Commitment Therapy perspective) was associated with eating disorders and whether it mediated the relationship between childhood abuse and invalidation and eating disorders. This was considered to be important because high rates of abuse have consistently been found in this population, yet not everyone goes on to develop an eating disorder. In addition, the role of emotional abuse has been largely neglected. A clinical sample of 190 participants with a clinical or subclinical eating disorder were recruited from eating disorder charities and support forums; they completed a range of questionnaires measuring experiences of abuse and maternal/paternal emotional invalidation in childhood, current levels of cognitive fusion and experiential avoidance and current levels of eating pathology. The sample was split into three groups based on their Eating Disorder Risk Composite scores: elevated, typical and low clinical range. It was found that those in the elevated clinical range (most severe eating pathology) had the poorest emotional processing and significantly higher levels of psychological inflexibility, thought-shape-fusion, depression and anxiety than those in the low clinical range (least severe eating pathology). In terms of predicting current levels of eating pathology, three variables emerged as significant predictors: emotional processing, thought-shape fusion and depression. In terms of predicting current levels of psychological inflexibility, five variables emerged as significant predictors: childhood emotional abuse, emotional processing, thought-shape-fusion, depression and anxiety. The results add novel findings to the literature regarding the role of early experiences on the development of psychological inflexibility, and the role of psychological inflexibility in the maintenance of eating pathology and psychological distress. Clinical implications of these findings in relation to assessment, formulation, intervention and prevention are discussed.

Despite well-established diagnostic measures and measures of specific dimensions of eating disorder symptomatology, little work has been done to develop a brief, comprehensive, and valid measure for assessing change in eating disorder symptoms. Further, empirically-supported change indices to assess treatment progression and outcome have not yet been developed. The Change in Eating Disorder Symptoms Scale (CHEDS) is a new comprehensive measure designed to assess progress and change during treatment in persons with diagnoses on the eating disorder spectrum. Previous studies have demonstrated the subscale structure, reliability, and validity of the CHEDS. This study determined clinically significant change criteria for the CHEDS to complement the studies that have supported the CHEDS as a reliable and valid measure of eating disorder symptomatology. The CHEDS was also compared to a life functioning scale, the Clinical Impairment Assessment. A reliable change index (RCI) was developed, which generated an inferential statistic that estimates the magnitude of change in a score necessary for a change score to be considered statistically reliable. A cutscore was also developed, which differentiates between functional and dysfunctional populations, between eating disordered clinical subjects and non-clinical subjects. Trajectories were identified using hierarchical linear modeling methods for use in conjunction with clinical significance criteria to aid in the tracking of symptoms during treatment, treatment decision-making, and tailoring treatment according to expected and observed progress. The clinical significance change criteria were then applied to the clinical sample to determine change patterns descriptive of recovered, reliable improvement, deterioration, and no change. Finally, a scoring program with clinical significance change criteria and trajectory analyses for total and subscale scores was developed.