Psilocybin for OCD and Eating Disorders: The Early Evidence
Two of psychiatry's most treatment-resistant conditions — obsessive-compulsive disorder (OCD) and eating disorders, particularly anorexia nervosa — are now being studied as potential applications for psilocybin-assisted therapy. The evidence is early-stage but credible, and the mechanistic case for both is among the strongest in the field.
This guide covers the current research, what makes these conditions particularly relevant for psilocybin, and who is enrolling in trials.
What Connects Them: Rigid, Self-Referential Thought
OCD and eating disorders share a feature that is central to why psilocybin researchers find them compelling: both involve profound rigidity in self-referential thought patterns that are highly resistant to conventional treatment.
In OCD, this is the intrusive thought loop: obsession → anxiety → compulsion → temporary relief → return of obsession. The loop is self-sustaining and, over time, increasingly entrenched.
In anorexia nervosa, this is the distorted body image and identity-level relationship with food restriction: an inflexible cognitive model of self that resists correction even in the face of severe physical harm.
Psilocybin's proposed mechanism directly addresses this kind of rigidity: it reduces activity in the default mode network (DMN) — the brain's self-referential processing system — and elevates neuroplasticity for 2-4 weeks post-session. Both mechanisms are relevant to conditions defined by entrenched, self-referential patterns.
OCD: The Evidence
Moreno 2006 Pilot (University of Arizona)
The first modern clinical evidence. Nine patients with treatment-resistant OCD received psilocybin at three dose levels in a crossover design.
Key results:
- All 9 participants showed significant OCD symptom reduction (Yale-Brown Obsessive Compulsive Scale)
- Reductions occurred at all dose levels — including low doses without full psychedelic effects
- Effects persisted beyond the acute session in most participants
- No serious adverse events
Nine patients, no control group — this is proof of concept, not clinical evidence of efficacy. But the result was striking enough and the unmet need great enough to justify controlled trials.
Yale University Randomized Controlled Trial
The first controlled trial. Michael Bloch's group at Yale is comparing psilocybin to niacin (active placebo) in a randomized crossover design.
Status as of 2026: Ongoing. Preliminary conference data suggests significant Y-BOCS reduction in the psilocybin condition. Full peer-reviewed results expected 2026-2027.
Imperial College London
Following the Moreno pilot, Imperial College launched OCD studies as part of their broader program examining conditions with rigid, self-referential thought patterns. Results expected 2027.
The SSRI problem in OCD: Most OCD patients are on high-dose SSRIs (required for OCD response, higher than depression doses). SSRIs significantly blunt psilocybin effects through 5-HT2A receptor downregulation. Clinical trials are working out protocols for this — options include washout (with OCD relapse monitoring) or low-dose psilocybin approaches.
Eating Disorders: The Evidence
Imperial College London — Anorexia Pilot (2023)
The first-ever clinical trial of psilocybin in eating disorders. 10 adults with anorexia nervosa.
Key results at 1-month follow-up:
- Significant reductions in eating disorder psychopathology (EDE-Q)
- Reductions in BMI-related preoccupation
- Several participants described perceiving their body differently — outside the distorted framework of the disorder
- No serious adverse events
Limitations: n=10, open-label, no control. Establishes safety and suggests efficacy signal. A landmark starting point.
UCSD — Anorexia RCT (2024-ongoing)
The first North American randomized controlled trial of psilocybin for anorexia nervosa. Comparing psilocybin (25mg) to low-dose active control (1mg) with specialized eating disorder psychotherapy.
Status as of 2026: Active recruitment. Results expected 2027-2028.
Johns Hopkins
A psilocybin anorexia protocol in development following UCSD precedent. Early recruitment stage.
Why These Are Hard Cases (And Why That Matters)
OCD and anorexia nervosa are hard cases in an important sense: conventional treatment works for many patients, but leaves a substantial minority with persistent, severe symptoms despite extensive treatment.
- OCD: First-line treatment (SSRI + ERP) achieves meaningful response in ~50-60% of patients. Treatment-resistant OCD causes enormous disability.
- Anorexia: Has the highest mortality rate of any psychiatric disorder (~10% within 10 years of diagnosis). Existing treatments produce full recovery in fewer than half of patients.
These are populations where the risk-benefit calculation shifts substantially. For someone with severe, treatment-resistant OCD or anorexia who has engaged extensively with conventional treatment, the early-stage evidence for psilocybin represents a genuinely meaningful option — particularly clinical trial participation, which offers free treatment with expert monitoring.
Medical Considerations
For OCD:
- Most patients on SSRIs — taper requires medical coordination, with close OCD symptom monitoring during washout
- OCD can incorporate the psilocybin experience itself as intrusive content — facilitators need OCD-specific training
- Integration should include continuation of ERP work in the post-session neuroplasticity window
For Anorexia:
- Cardiac risk from restriction history (electrolyte abnormalities, cardiac muscle wasting) requires cardiac screening and ECG before treatment
- Minimum weight threshold for trials (generally BMI 16+, medically stable)
- Body image work during the session requires eating disorder-specialized facilitation — not just general psychedelic therapy training
- Integration requires eating disorder-specific therapeutic support
How to Access Trials
OCD:
- ClinicalTrials.gov: search "psilocybin OCD" or "psilocybin obsessive-compulsive"
- Yale OCD Research Clinic: may be recruiting
- Imperial College London: for UK-based patients
Eating Disorders:
- ClinicalTrials.gov: search "psilocybin anorexia" or "psilocybin eating disorder"
- UCSD Eating Disorders Center: primary US trial site
- Johns Hopkins Psychedelic Research Center: developing protocol
General: Both conditions require careful psychiatric and medical screening. Contact the trial site directly — eligibility requirements are detailed and site coordinators can assess fit before a full screening visit.
Resources
- ClinicalTrials.gov — search by condition and "psilocybin"
- International OCD Foundation — iocdf.org — ERP therapist directory, OCD education
- National Eating Disorders Association — nationaleatingdisorders.org — helpline: 1-800-931-2237
- Project Heal — theprojectheal.org — eating disorder treatment access support
- Fireside Project — 623-473-7433 — psychedelic peer support during or after
- LearnShrooms OCD Guide — /therapy/ocd-treatment/
- LearnShrooms Eating Disorders Guide — /therapy/eating-disorders/