519. PSILOCYBIN ASSISTED PSYCHOTHERAPY FOR OBSESSIVE COMPULSIVE DISORDER, BODY DYSMORPHIC DISORDER, AND ANOREXIA NERVOSA: STUDY PROTOCOL

Obsessive compulsive disorder, body dysmorphic disorder, and anorexia nervosa share overlapping cognitive-behavioral and neurobiological features, yet conventional treatments often yield suboptimal outcomes. Psilocybin-assisted psychotherapy shows transdiagnostic potential by improving insight, emotional regulation, and well-being. This paper presents a protocol for an open-label basket trial testing psilocybin-assisted psychotherapy across these three conditions. The protocol was developed from scoping reviews, an international Delphi study on best practices, and qualitative interviews with patients. It uses a transdiagnostic, non-directive approach, includes a psychoeducation booklet and video, a treatment manual for clinicians, clinician- and patient-reported outcomes, opt-in additional support, and long-term follow-up.

Study at a glance

Abstract

Abstract Background Obsessive compulsive disorder (OCD), body dysmorphic disorder (BDD), and anorexia nervosa (AN) are some of the most debilitating and chronic mental health conditions, with impairments across multiple domains of functioning, leading to poor quality of life and well-being. These conditions share overlapping psychopathological determinants in terms of cognitive-behavioural dysfunction and neurobiological underpinnings involving aberrant neurocircuitry. Conventional treatments lead to sub-optimal outcomes; often lacking an integrated approach to psychological and neurobiological determinants of the condition. There is often a lack of engagement and/or specialised interventions, leading to high treatment resistant rates. Although limited, there is theoretical and empirical support for the use of psilocybin assisted psychotherapy (PAP) in treating these conditions. Evidence from major depression trials demonstrate dramatic improvements in insights, perspectives, emotional regulation and well-being. Thus, highlighting transdiagnostic potential in patients with rigid and inflexible cognitive- affective processes. Aims & Objectives To present a protocol of PAP for OCD, BDD and AN in an open label basket design trial. The protocol is informed by existing empirical evidence (scoping reviews), expert consensus (Delphi study), and lived experiences (qualitative interviews). Method The following studies were conducted to collectively inform the study protocol; 1) a scoping review on the efficacy of serotonergic psychedelics for OCD, BDD, AN, 2) a scoping review on integration approaches of serotonergic psychedelics for mental disorders, 3) an international Delphi study on best practices of PAP, and 4) qualitative interviews from a PAP trial in AN. Results The trial involves an open label basket design with a transdiagnostic and non-directive approach for obsessive compulsive and body image disorders. The protocol incorporates a psychoeducation booklet and video to foster patient and carer education and informed consent. A treatment manual is developed to guide clinicians on a non-directive approach with psychotherapeutic techniques relevant to obsessive compulsive and disordered body image psychopathology. The protocol incorporates additional notable elements such as clinician and patient reported outcomes, opt-in additional support, and long term follow-up. Discussion & Conclusions Considering the scarcity of PAP applications in OCD, BDD and AN it is necessary to draw on all available evidence to ensure optimal approaches are adopted. An integrative and comprehensive trial design is developed through combining clinician, researcher, and patient perspectives on the best approaches for patient safety, tolerability and long-term efficacy.