- Treatment-resistant depression (TRD) is depression that has not responded to two or more adequate antidepressant trials. About 30% of MDD patients meet this definition.
- COMPASS Pathways Phase 2b (Goodwin 2022, NEJM, n=233): a single 25 mg psilocybin session produced significant MADRS reduction at week 3, with around 30% sustained response at week 12.
- The 25 mg arm beat the 10 mg and 1 mg arms convincingly. Dose matters.
- Effect is rapid (days, not weeks like SSRIs), but durability varies. Some patients need a second session.
- Tapering off SSRI is required before any trial protocol. Standard washout is 2 to 6 weeks.
Treatment-resistant depression, in plain terms
TRD is the diagnostic label for depression that has not improved after two or more adequate trials of antidepressant medication. About one in three patients with major depressive disorder eventually meet criteria. They are the population most affected by suicide risk, hospitalization rates, and lost years of life.
Standard escalation: SSRI, SNRI, atypical antipsychotic augmentation, ketamine/esketamine, ECT, transcranial magnetic stimulation. Each step has decreasing response rates. Psilocybin therapy is the newest entry, with 2025-2027 reading out the largest Phase 3 trials.
How psilocybin appears to work
Two complementary effects in the trial data:
- Acute 5-HT2A activation on cortical pyramidal neurons drives the experience. fMRI shows a state of hyperconnectivity across normally segregated networks. Patients describe loosening of depressive narrative, perspective shift on life events.
- Sustained neuroplasticity for around 30 days post-session. BDNF rises, dendritic spine density increases (Olson lab). Behavioral therapy and integration during this window appear to “lock in” the new pattern.
The mechanism does not look like an SSRI mechanism. SSRIs raise synaptic serotonin chronically. Psilocybin produces a single rewiring window. Different tools, different time courses.
The Phase 2/3 evidence
| Study | Year | n | Dose / arms | Outcome |
|---|---|---|---|---|
| Goodwin et al., COMPASS Phase 2b, NEJM | 2022 | 233 (TRD) | 1× 25 mg vs 10 mg vs 1 mg | 25 mg arm: MADRS −12 at week 3, sustained ~30% remission at week 12 |
| Davis et al., JHU MDD, JAMA Psychiatry | 2020 | 27 (MDD) | 2× 20-30 mg + therapy | 71% response, 54% remission at 4 weeks |
| Carhart-Harris, escitalopram comparison | 2021 | 59 (MDD) | 2× 25 mg vs 6 weeks escitalopram | Numerical advantage psilocybin, no statistical significance on primary |
| COMPASS Phase 3 (COMP005, COMP006) | Reading out 2025-2026 | Multi-site, ~960 expected | 1× 25 mg + therapy | Pending |
| Usona psilocybin MDD Phase 3 | In progress | Multi-site | 1× 25 mg + therapy | Pending |
Psilocybin vs ketamine vs ECT for TRD
| Dimension | Psilocybin | Ketamine / Esketamine | ECT |
|---|---|---|---|
| Mechanism | 5-HT2A agonist + plasticity window | NMDA antagonist + glutamate surge | Generalized seizure under anesthesia |
| Onset | Hours to days | Hours | Days to weeks |
| Duration of effect | 3-6 months per dose | Days to weeks per infusion | Months, often with maintenance |
| Treatment burden | 1-2 sessions + therapy | Repeated infusions, tapered | 6-12 sessions, anesthesia each |
| Approval status | Phase 3 ongoing, Oregon/Colorado regulated | FDA approved (esketamine for TRD) | FDA approved, decades of use |
| Cognitive side effects | Minimal at 1 month | Dissociation acutely; long-term unclear | Memory loss, often persistent |
Practical read: ketamine has the strongest legal access and the fastest onset. Psilocybin has the most durable single-dose effect when it works. ECT remains the most reliable for severe, suicidal, melancholic depression.
Trial protocols
The Goodwin protocol that produced the NEJM result: 1 dose of 25 mg synthetic psilocybin in a quiet room with two trained therapists, 6 to 8 hours, eyeshades and curated music. Preparation: 2 sessions before. Integration: at least 2 sessions in the following weeks.
The Imperial and JHU protocols use 2 doses spaced 1 to 3 weeks apart for moderate to severe TRD. Outcomes were stronger in the 2-dose arms.
Excluded from trial protocols:
Bipolar I or family history of bipolar I · Personal or family history of schizophrenia spectrum · Currently taking lithium (seizure risk) · Severe cardiovascular disease, recent MI, uncontrolled hypertension · Pregnancy · Active suicidality with imminent risk requiring inpatient stabilization · Current SSRI/SNRI without supervised taper.
Risks specific to depressed populations
- Tapering off SSRI is medically real. Discontinuation syndrome and rebound depression in the washout window are higher near-term risks than the dose itself. Plan with prescriber.
- Increased suicidality during washout. Some patients deteriorate without medication before the dose. Inpatient or close outpatient monitoring may be needed.
- Bad-trip-to-depressive-spiral. Without integration support a difficult session can deepen depressive narrative. Trained sitters are not optional for this population.
- Bipolar masquerading as TRD. Around 10% of “TRD” turns out to be undiagnosed bipolar II. Psilocybin can trigger mania. Screen.
Who should not pursue this now
- Anyone in acute crisis or active suicidal ideation. Stabilize first.
- Anyone without therapist support for preparation and integration.
- Anyone on lithium or first-degree family history of bipolar I.
- Anyone unable to taper SSRI safely with a prescriber.
Integration practices (Micro-Movement Method, TRD-specific)
Treatment-resistant depression often runs alongside long-standing dissociation: the body has been a hostile place for years, and macrodose sessions can briefly puncture that defense. Integration is about gentle re-entry into embodiment without forcing it. The Micro-Movement Method approaches this through sustained micro-movement, breath as a motivation anchor, and slow nervous-system re-regulation across the full plasticity window.
- Gentle re-entry to embodimentFirst 72 hours: warm baths, slow walks, soft fabrics, predictable food. Avoid mirrors, intense exercise, and high-stimulus environments. After dissociation lifts, the body can feel raw. Give it low-stakes positive input first.
- Sustained micro-movement to rebuild interoceptive accuracy15 to 20 minutes twice daily of slow, small-range movement. Toe spread, ankle circles, spinal undulations, jaw release. The Micro-Movement Method is built around exactly this: tiny, repeatable shapes that rebuild the body map after long depression has eroded it. Do this before any cardio is reintroduced.
- Breath as motivation anchor4 in, 6 out, 10 minutes, every morning. On TRD-pattern days where motivation is at floor, the breath is the only practice the system can reliably complete. Completing one thing reliably is the seed of behavioral activation. See our breathwork resources.
- Slow nervous-system re-regulationNo supplements, no new protocols, no big life decisions for 21 days post-session. The plasticity window is for stabilizing the new baseline, not for adding inputs that confound it.
- Therapist continuationWeekly for 8 weeks minimum. Depression-aware, ideally with somatic competence. The therapy alliance is what holds the new pattern when the acute effect fades.
- Substance disciplineAlcohol blunts integration. Cannabis raises depressive rebound. Both worth avoiding for 30 days.
When to seek professional help
Active suicidality, plan, or means: do not wait for psilocybin. Contact 988 (US) or findahelpline.com. Hospital ED for imminent risk. Stabilization first, exploration after.
