Characterization, feasibility, acceptability, target engagement, and efficacy of a novel exposure-based treatment module for bulimia nervosa
Authors:   , Clark Kelsey Elizabeth , Juarascio Adrienne S. 
Published: July 2021

As many as 60% of bulimia nervosa (BN) patients treated with current approaches do not experience long-term remission, necessitating the development of improved interventions. Cognitive-behavioral therapy (CBT) is the most-researched treatment for BN and is widely considered the current first-line treatment. However, CBT may fail to sufficiently treat BN due to three reasons: 1. It does not effectively reduce patients' fears related to overvaluation of body shape and weight, 2. It does not adequately improve patients' distress tolerance skills and negative affect reactivity, and 3. It does not appropriately provide in-session opportunities to practice skills learned in treatment. One type of intervention that is well-poised to address these three limitations is exposure-based treatment (EBT). EBTs are behavioral interventions that immerse patients in feared situations to facilitate the development of new associations with feared or avoided stimuli. While exposure-based treatments (EBTs) hold promise for treating BN, their applications to disordered eating have been underexplored and previous applications of EBTs have not fully addressed the shortcomings of CBT for eating disorders. To address limitations of existing EBTs, a novel three-session EBT module was developed as part of a larger pilot randomized controlled trial of an acceptance-based behavioral treatment for BN. The present study aims to characterize and examine the feasibility, acceptability, target engagement, and efficacy of the novel EBT module for BN. Establishing the feasibility, acceptability, target engagement, and efficacy of the treatment module will inform protocol revisions and determine if larger-scale research and clinical dissemination is appropriate. Moreover, many clinicians have concerns about the feasibility and acceptability of EBTs (e.g., concerns that it is infeasible to deliver, concerns that it will be unacceptable to patients), resulting in the underutilization of EBTs in treating anxiety and fear-based disorders and especially in treating eating disorders. Therefore, there is additional need to explore the feasibility and acceptability of the EBT module. Patients (N = 17) completed personalized in vivo exposures and negative affect inductions. The EBT module allowed patients and clinicians to collaboratively design individualized exposures to target patients' unique fears related to overvaluation of body shape and weight, as well as practice distress tolerance skills learned in treatment. In the present study, video coding of therapy sessions and patient/clinician pre- and post-session self-report data were used to conduct mixed methods analysis of the implementation of the module. Results indicated that the EBT module is indeed feasible to implement and is acceptable, and patterns indicated preliminary efficacy. Preliminary patterns suggested that the EBT module did not target the theorized mechanisms as predicted. Results from the present study will be used to revise the EBT module to ultimately create an innovative, effective EBT for BN. Findings related to feasibility and acceptability contradicted the concerns of clinicians found in prior studies as the module was deliverable and patients' responses were highly positive. Additional exploration in research and clinical settings will improve our understanding of the untapped potential of EBTs for treating eating disorders.