Glucocorticoid enhancement of food exposure therapy in Binge Eating Disorder (GEAR)

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Background: Binge Eating Disorder (BED) is the most prevalent eating disorder and primarily characterised by uncontrollable craving for food and regular episodes of binge eating. Although it can be effectively treated by cognitive-behaviour therapy(CBT), approx. 25% of patients drop out from treatment and 50% experience relapse. The uncontrollable craving for food and subsequent food intake can be considered as conditioned responses to internal and external cues of food/eating. Food exposure therapy with response prevention is a crucial component of CBT for BED and aims to reduce such conditioned responses through repeated extinction events. During this extinction, new extinction memories are consolidated. Importantly, preclinical and clinical research has shown that these memory processes can be facilitated by glucocorticoids. Increased glucocorticoid levels inhibit the retrieval of emotionally arousing memory content and facilitate memory consolidation. These effects have been successfully utilised to improve exposure therapy for anxiety disorders. Based on these findings, it appears promising to examine the potential effects of glucocorticoids on memory processes underlying food exposure therapy for BED. Method: This is a double-blind, randomised, placebo-controlled pilot superiority trial with two parallel treatment arms. The overall research question of the project is whether in BED, glucocorticoids enhance extinction learning during food exposure. To this end, 50 patients with BED will be recruited. After baseline assessment of eating disorder psychopathology, food intake, trait and cue-elicited food craving, and food-related anxiety, participants will be randomly allocated to receive three sessions of food exposure therapy and either cortisol or placebo. During and after the intervention as well as 1 month later, participants will be re- assessed for the same parameters. In addition, analyses of changes in the tyrosine-phosphorylation level and DNA binding activity of STAT proteins shall enable a deeper understanding of the molecular cross-talk between the immune system and extinction learning. Clinical relevance and innovation: The planned study translates findings from basic research into a new combined treatment approach. It will be the first study to examine the potentially beneficial effects of glucocorticoids on the enhancement of extinction learning processes underlying exposure therapy for BED. If successful, thiscould pave the way for a significant improvement in the treatment of this disorder. Moreover, on a broader level, the study will contribute to an enriched understanding of the action mechanisms underlying glucocorticoid-augmented exposure therapy by studying the interactions and cooperativity of two important gene transcription factors involved in these processes.