Clinical TrialObsessive-Compulsive Disorder (OCD)PsilocybinNot yet recruiting

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).

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Target Enrollment
30 participants
Study Type
Phase I/II interventional
Design
Non-randomized

Detailed Description

Open-label, non-randomised single-arm pilot enrolling adults with treatment-resistant OCD, BDD or AN to receive two oral psilocybin doses (25 mg) four weeks apart paired with structured psychotherapy.

Therapy delivered by a therapist dyad includes preparation (1–2 sessions, ≈3 hours total), non-directive support during 8-hour dosing sessions, and two integration sessions after each dose (four total); sessions predominantly face-to-face with limited online option for the second integration.

Primary outcomes assess disorder-specific symptom severity (YBOCS, BDD-YBOCS, EDE) at baseline and 8 weeks post-baseline with safety monitoring per protocol.

Study Protocol

Preparation

2 sessions
180 min each

Dosing

2 sessions
480 min each

Integration

4 sessions

Therapeutic Protocol

support

Study Arms & Interventions

Psilocybin PAP

experimental

Two oral psilocybin doses (25 mg) given 4 weeks apart with adjunct psychotherapy (preparation, dosing support, integration).

Interventions

  • Psilocybin25 mg
    via Oral• two sessions• 2 doses total

    Oral capsule; paired with preparation, non-directive dosing support, and integration psychotherapy.

Participants

Ages
18 – 65
Sexes
Male & Female

Inclusion Criteria

  • i) Adults aged 18 to 65 years.
  • ii) Primary diagnosis of OCD, BDD or AN according to DSM-5, determined by SCID-5, the BDD Diagnostic Module (BDD-DM) and Eating Disorder Examination (EDE).
  • iii) Moderate to severe symptom severity: YBOCS ≥18 for OCD; BDD-YBOCS ≥20 for BDD; score ≥3 on the shape and/or weight subscales of the EDE for AN.
  • iv) Treatment resistance: ≥1 year illness with continuing symptoms for ≥6 months despite adequate engagement in conventional interventions defined per disorder (OCD: SSRI course and at least one course CBT including ERP; BDD: two courses psychotherapy and/or pharmacology including at least one CBT; AN: two courses psychotherapy and/or pharmacology including in-patient/day program or >1 year extensive therapy or multidisciplinary care; adequate SSRI/SNRI course where applicable).
  • v) Illness duration ≥1 year.
  • vi) Absence of delusionality for OCD/BDD indicated by insight item score <3 on YBOCS/BDD-YBOCS.
  • vii) Absence of mania symptoms (only minor). viii) Sufficient cognitive ability (WASI) and demonstrated understanding of consent procedures.

Exclusion Criteria

  • Psychiatric exclusions:
  • i) Lifetime history of serious suicide attempts requiring hospitalisation or current suicidal ideation with intent warranting immediate hospitalisation.
  • ii) Current or past history of psychosis; DSM-5 Schizophrenia, Psychotic Disorder (unless substance-induced or due to medical condition), Bipolar I/II or Mania.
  • iii) First-degree relative with diagnosed Schizophrenia, Psychotic Disorder (unless substance-induced or due to medical condition), Bipolar I/II or Mania.
  • iv) Significant neurodevelopmental disorder (e.g., ADHD, autism, unremitting Tourette’s) impacting therapeutic effect.
  • v) Current DSM-5 Dissociative Disorder, Bulimia Nervosa, or significant personality disorder judged incompatible with rapport or safe exposure.
  • vi) Personal or situational factors likely to interfere with participation (e.g., lacking social support, unstable housing, ongoing trauma).
  • vii) Complex cases from childhood trauma or other factors as judged by clinicians.
  • General medical exclusions:
  • i) Any disorder with known CNS involvement or disease, including seizures.
  • ii) Hepatic dysfunction: GGT >3×ULN; AST >3×ULN; ALT >3×ULN; Total bilirubin >3.0 mg/dL.
  • iii) Conditions raising risk for hypercalcaemia, Cushing's, hypoglycaemia, SIADH, carcinoid syndrome.
  • iv) Cardiovascular conditions: uncontrolled hypertension (systolic >140 or diastolic >90), angina, clinically significant ECG abnormality (e.g., atrial fibrillation), TIA in last 6 months, stroke or cerebrovascular disease, peripheral or pulmonary vascular disease; QTc >440 ms men, >470 ms women.
  • v) Renal insufficiency (CrCl <40 mL/min by Cockcroft-Gault).
  • vi) Insulin-dependent diabetes; oral hypoglycaemics allowed only if no history of hypoglycaemia.
  • vii) Females who are pregnant, breastfeeding, trying to become pregnant, or become pregnant during study.
  • viii) Untreated or refractory hypothyroidism.
  • ix) Weight <40 kg or BMI <13 kg/m2 (text contained garbled BMI cutoff; exclusion for very low BMI applies).
  • x) Certain long-acting opioids timing allowances as specified in protocol.
  • xi) Macro-dose psychedelic use within past 12 months or >10 macro-doses lifetime.
  • xii) Micro-dose use within past 6 months.
  • xiii) Contraindicated medications (SSRIs, SNRIs, MAOIs) unless appropriately managed/tapered.
  • xiv) Current/past 5 years of alcohol or drug dependence (excluding caffeine/nicotine).
  • xv) Use of illicit drugs or alcohol within 2 days prior to dosing.
  • xvi) Use of potent metabolic inducers/inhibitors (listed in protocol).
  • xvii) Need for drugs with low therapeutic index within 12 hours post-psilocybin.
  • xviii) Significant uncorrected visual impairment.
  • xix) Non-binary participants or those who do not gender identify with their biological sex (per protocol criteria).
  • xx) Unable to swallow tablets.
  • xxi) Enrolled in another interventional trial.

Study Protocol, Arms & Participants

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Study Details

Locations

Unknown facility — Australia

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