Evaluation of Psilocybin in Anorexia Nervosa: Safety and Efficacy

The primary aim of this study is to assess the safety and tolerability of one 25 mg dose of psilocybin in participants with anorexia nervosa based on adverse events (AEs), changes in vital signs, electrocardiograms (ECGs) and clinical laboratory tests.

The secondary objectives are to explore the efficacy of a single 25 mg dose of psilocybin on eating disorder symptoms and behaviors, body image, anxiety, food related obsessions and rituals, and body weight.

Some data on this trial has been published in late June 2023. And in July of the same year the first paper (see below) was published.

Status Completed
Results Published Yes
Start date 01 May 2021
End date 10 June 2022
Chance of happening 100%
Phase Phase II
Design Open
Type Interventional
Generation First
Participants 16
Sex All
Age 18- 40
Therapy Yes

Trial Details

Because there are no proven treatments that normalize core symptoms in adult anorexia nervosa, a disorder with high chronicity, many individuals seek out alternative approaches to care. Recent evidence has suggested that anxiety, obsessive-compulsive disorder, and diminished reward or motivation play key roles in the development and maintenance of dysfunctional eating, and poor outcome. In recent years, a growing number of studies have demonstrated the safety and preliminary efficacy of psilocybin in clinical trials for a range of psychiatric illnesses including treatment-resistant depression, obsessive-compulsive disorder, addiction, and anxiety. Psilocybin may represent a promising new treatment for anorexia nervosa. However, no studies have tested psilocybin in this eating disorder population. Accordingly, this study aims to establish the safety, tolerability and dosing of psilocybin in adult patients with anorexia nervosa, as well as gather pilot data on possible efficacy. For this study, the investigators will recruit adults who currently have a DSM-V diagnosis of anorexia nervosa. Participants will undergo medical and psychological screening and those who are deemed eligible will partake in a maximum of 7 study visits, lasting from 4-8 weeks. On dosing day, participants will receive a single 25 mg dose of psilocybin along with psychotherapeutic support, which includes preparation and integration sessions surrounding the experience. There will be a follow-up period of one month following the psilocybin session during which a range of psychological measures (questionnaires and interviews) will be collected.

NCT Number NCT04661514

Sponsors & Collaborators

COMPASS Pathways
COMPASS Pathways is a publicly listed company (NASDAQ) that is developing psilocybin for treatment-resistant depression (TRD) for which it has completed a successful Phase IIb trial. COMPASS is one of the largest psychedelic companies and has received substantial investment from atai.

University of California San Diego
The Psychedelics and Health Research Initiative (PHRI) at UC San Diego conducts novel basic and clinical research on the use of psychedelics.


Psilocybin therapy for females with anorexia nervosa: a phase 1, open-label feasibility study
This open-label feasibility study (n=10) examines the effects of a single dose of psilocybin (25mg; COMP360) on adult female participants diagnosed with Anorexia Nervosa (AN) or pAN (partial remission). Results show that the treatment was safe, tolerable, and acceptable, with no significant changes in ECG, vital signs, or suicidality. However, two participants developed asymptomatic hypoglycemia (low blood sugar), which resolved within 24 hours. No significant changes in BMI were found.

Measures Used

Eating Disorder Inventory
The Eating Disorder Inventory (EDI-3) is a self-report questionnaire used to assess the presence of eating disorders (EDs). It consists of 64 questions divided into 8 subscales including; drive for thinness, body dissatisfaction, perfectionism and bulimia, to name a few.

Eating Disorder Examination Questionnaire
The Eating Disorder Examination Questionnaire (EDE-Q) is a self-report questionnaire that has been adapted from the Eating Disorder Examination (EDE).

Columbia-Suicide Severity Rating Scale
The Columbia-Suicide Severity Rating Scale (CSSRS) is a suicidal ideation and behaviour rating scale created by researchers at Columbia University, University of Pennsylvania, University of Pittsburgh and New York University to evaluate suicide risk

Eating Disorder Examination Interview
The Eating Disorder Examination Interview (EDE) is a semi-structured interview conducted by a clinician that has been modified to reflect the current DSM-5 diagnosis. The EDE is rated using four subscales; restraint, eating concern, shape concern and weight concern.

State-Trait Anxiety Inventory
The State-Trait Anxiety Inventory (STAI) is a commonly used measure of trait and state anxiety. The STAI measures two types of anxiety – state anxiety, anxiety about an event, and trait anxiety, anxiety level as a personal characteristic.

Data attribution

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