The efficacy of psilocybin assisted psychotherapy (PAP) for treatment resistant obsessive-compulsive disorder (OCD), body dysmorphic disorder (BDD), and anorexia nervosa (AN); a pilot, single-arm basket trial

This single-arm, Phase I/II pilot trial (n=30) will test psilocybin-assisted psychotherapy (25mg x 2 doses, 4 weeks apart) for treatment-resistant obsessive-compulsive disorder (OCD), body dysmorphic disorder (BDD), and anorexia nervosa (AN).

The study is being conducted by Swinburne University in Victoria, Australia from October 2024 to December 2026. This “basket trial” (meaning it studies multiple conditions simultaneously) will examine participants aged 18-65 who have not responded adequately to conventional treatments. The therapy involves preparation sessions, two 8-hour dosing sessions with psilocybin, and integration sessions afterwards. Participants must be under medical care and willing to temporarily stop certain medications that might interfere with psilocybin.

The study will measure changes in condition-specific symptoms using standardised scales, along with secondary measures of depression, anxiety, quality of life, and overall functioning. This is an open-label study, meaning both participants and researchers know what treatment is being given. The trial specifically excludes people with histories of psychosis, serious suicide attempts, or recent use of psychedelics.

Trial Details

Obsessive compulsive disorder (OCD), Body dysmorphic disorder (BDD), and anorexia nervosa (AN) are some of the most debilitating and chronic mental health conditions, sharing overlapping psychopathological determinants in terms of behavioural and cognitive impairments, neurobiological and neurocircuitry mechanisms, and poor response to conventional treatments. This trial aims to investigate the efficacy, safety and tolerability of psilocybin assisted psychotherapy (PAP) for treatment resistant OCD, BDD, and AN. 12 patients from each condition will be recruited in a basket design (multiple conditions) open label trial of 2 dosing sessions with non-directive support, including preparatory and integration therapy, and a 3-month follow up period. It is hypothesised that PAP will lead to statistically significant and clinically significant (35%) improvements in primary symptoms for each condition. Explorative outcomes will be investigated as potential mediators of changes in symptom severity, and lived experience insights will be gained. The outcomes of the trial will enhance scientific understanding and provide rationale for subsequent randomised controlled trials investigating PAP for obsessive-compulsive and body image disorders.

Trial Number ACTRN12624001160527

Data attribution

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