The first safety trial built for PTSD itself

THE DISPATCH

In January 2026, the Journal of Psychopharmacology published the first Phase 2 trial designed specifically to test the safety and tolerability of a single psilocybin dose in adults with PTSD as their primary diagnosis, not depression with PTSD symptoms alongside it, but PTSD itself.¹ Separately, a 12-month follow-up of U.S. military veterans with severe treatment-resistant depression, a closely related population this newsletter also tracks, is now the longest-running dataset available on how long a single psilocybin session's effects actually last.³ ⁴ ⁵ Together, they answer two different questions our clinician and patient readers ask most: is it safe, and does it hold.

In this issue:

→ What the first dedicated PTSD safety trial actually found, and what it didn't measure

→ What a year of veteran follow-up data shows about durability, and where it fades

→ What trial participants said about the experience in their own words, and a new FDA rule shaping how future PTSD trials get built

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THE SCIENCE

In January 2026, McGowan and colleagues published results from a Phase 2, multicenter, nonrandomized, open-label trial designed specifically to test the safety and tolerability of a single 25 mg dose of synthetic psilocybin (COMP360) in adults with PTSD as their primary diagnosis, conducted across three sites in the US and UK (Mount Sinai Hospital, Sunstone Therapies, and King's College London) between June 2022 and February 2024.¹ Of the 22 participants enrolled, 117 treatment-emergent adverse events were recorded. Seventy of those, 59.8 percent, occurred on the day of dosing itself, and 64 of those 70, 91.4 percent, had resolved by the end of the following day.¹ The trial's secondary outcomes told an encouraging story. Mean CAPS-5 scores, the clinician-rated measure of PTSD severity, dropped 29.9 points by Week 4 and 29.5 points by Week 12 from a baseline of 47.5, translating to response rates of 81.8 percent and 77.3 percent and remission rates of 63.6 percent and 54.5 percent at those same timepoints.¹ The reduction held across all four PTSD symptom clusters. Self-reported PCL-5 scores followed the same pattern, improving within a day of dosing and holding through Week 12. Functional impairment (Sheehan Disability Scale) and quality of life (EQ-5D-5L) both improved in step, with quality-of-life gains continuing to build between Week 4 and Week 12 rather than fading.¹

What makes this trial notable isn't a dramatic efficacy number, it's that it exists at all. Most psilocybin data available for PTSD comes from trials where PTSD is a secondary or comorbid measure inside a depression study. This is the first trial built around PTSD as the primary condition, with a safety profile clean enough, most adverse events resolving by the next morning, to support larger efficacy trials going forward.

For a read on durability, the closest available data comes from a related population: fifteen U.S. military veterans with severe treatment-resistant depression, first studied by researchers at the VA Palo Alto Health Care System and Stanford University School of Medicine.³ In that original pilot, a single 25 mg psilocybin dose produced a 60 percent response rate and 53 percent remission rate at the three-week primary endpoint, with a mean 23-point reduction in MADRS depression scores.³ Twelve-month follow-up data, published separately, found that response and remission rates declined but didn't disappear: 40 percent of participants still met response criteria, and 30 percent remained in remission a full year after a single dose.⁴ A further analysis of the same cohort found that anxiety scores improved by 59 percent from baseline at week three and stayed improved through 12 months, quality-of-life gains held through at least week 12, and PTSD symptoms in the veterans who had them showed sizable but variable reductions over the same period.⁵ However, it is important to note that both trials were very small (22 participants in the "pure" PTSD study and 15 in the TRD study), and both were open-label, meaning there was no control group. These factors limit what we can learn from these studies, but these early results seem encouraging.

Neither trial answers the other's question fully. The PTSD-specific trial establishes safety in the population that matters most to our core readers, and now also shows a meaningful signal on efficacy, though without its own durability data yet. The veterans study has 12 months of durability data, but its primary diagnosis is depression, not PTSD. Full efficacy and long-term data for psilocybin as a dedicated PTSD treatment doesn't exist yet. These two trials are the foundation it gets built on, and a newly finalized FDA rule on trial design, covered in On Our Radar, will shape exactly how that happens.

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THE STORY

A companion qualitative study, nested inside the same PTSD safety trial, interviewed participants directly about what the experience was actually like.² The pattern that emerged: participants didn't describe confronting their trauma memories head-on, the way standard exposure-based PTSD treatments typically ask them to. Instead, the researchers report that participants described a broader, indirect engagement with traumatic material through affective and somatic experiences, including moments of perceived unity, a temporary dissolution of self, or a felt connection to something larger.² Researchers found that structured preparation and support before and during the session mattered directly to how safely and productively participants engaged with that material.² It's worth noting this is a small, interview-based study nested inside an already small open-label trial, so it reflects what participants chose to share and what researchers chose to report, not necessarily the full range of what people experienced. This suggests that preparation and integration are as important to successful psychedelic therapy as previously thought.

Rose Hill Life Sciences is a psychedelic research organization – specializing in the production and research of Psilocybe cubensis operating at the intersection of science and therapeutic integration.

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ON OUR RADAR

① FDA Finalizes Trial Rules for the Psychedelic Field's Biggest Design Problem In July 2026, the FDA finalized guidance addressing "functional unblinding,” the problem of trial participants correctly guessing whether they received an active psychedelic dose or a placebo, because the perceptual effects are unmistakable.⁶ The guidance now requires sponsors to consider active placebos, blinding questionnaires, expectancy controls, and dose-response designs that don't rely on a placebo arm at all.⁶ The FDA cited this exact issue as a central factor in its 2024 rejection of Lykos Therapeutics' MDMA-assisted therapy for PTSD, which is precisely why this guidance matters for every PTSD trial that follows it, psilocybin included.⁶

② The VA's New MDMA Trial for Combat PTSD The VA began enrolling veterans in May 2026 for its first randomized, placebo-controlled trial of MDMA-assisted therapy, targeting veterans with treatment-resistant PTSD and co-occurring alcohol use disorder, led by researchers at the Providence VA Medical Center and VA Connecticut Healthcare System.⁷ Roughly 80 veterans will be enrolled, with results expected in 2030. It's a different compound than the trials above, but it reflects the same institutional shift: the VA is now running 19 active clinical trials on psychedelic therapies, backed by more than $23 million in external funding.⁷

③ Where the FDA's Fast Track Actually Points Right Now On April 24, 2026, the FDA issued National Priority Vouchers to three companies developing psychedelic-based therapies: Compass Pathways for synthetic psilocybin (COMP360) in treatment-resistant depression, the Usona Institute for psilocybin in major depressive disorder, and Transcend Therapeutics for methylone, an MDMA-like compound, in PTSD.⁸ Worth noting for readers focused on PTSD specifically: the fast-tracked PTSD compound is methylone, not psilocybin. Psilocybin's own regulatory momentum right now is concentrated in depression, not PTSD.⁸

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YOU ASKED

Q: “I have PTSD and haven’t responded to standard treatments. Is there actually a psilocybin study I could realistically get into, or is this all years away?”

Right now, not easily. Most active psilocybin trials for PTSD enroll through specific academic or VA research sites rather than general public sign-up, and the dedicated PTSD safety trial covered in this issue has already finished enrolling. The VA has expanded its psychedelic research substantially, including a new MDMA-assisted therapy trial for veterans with PTSD and alcohol use disorder, though that’s MDMA, not psilocybin, and it’s also limited to specific VA sites. If you’re a veteran, ask your VA care team directly whether you qualify for any active psychedelic-therapy research protocol, since eligibility criteria are specific and change as trials open and close. If you don’t qualify for a trial right now, that’s a real limitation of where the field stands today, not a reflection of whether the treatment could eventually help you. The safety and durability data in this issue is exactly what has to exist before broader access follows.

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This week’s takeaway: the first trial built specifically around PTSD as the primary diagnosis has established a favorable safety profile, and a related veteran population’s 12-month data shows a single dose’s effects can persist, in a meaningful minority, for at least a year. Full efficacy data for psilocybin as a dedicated PTSD treatment doesn’t exist yet. These two trials are the foundation it gets built on. These trials were small and did not include a control group, so we should interpret their results cautiously.

A question worth sitting with: if a treatment’s safety data and its durability data currently come from two small studies on different patient populations, how much should clinicians reasonably infer about a patient who fits neither trial exactly?

Read the trial directly: Journal of Psychopharmacology — Investigating the Safety and Tolerability of Single-Dose Psilocybin for PTSD

Know a veteran still cycling through treatments that aren't working? Forward them this, not as a recommendation, as information they deserve to have.

— Rotem Petranker

PhD, Clinician and Psychedelic Researcher

Advancing the development of novel psychedelic-based therapeutics

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FOOTNOTES

¹ McGowan, N.M., Rucker, J.J., Yehuda, R., Agrawal, M., Modlin, N.L., Simmons, H., Tofil-Kaluza, A., Das, S., Goodwin, G.M. "Investigating the safety and tolerability of single-dose psilocybin for post-traumatic stress disorder: A nonrandomized open-label clinical trial." Journal of Psychopharmacology, 2026. https://journals.sagepub.com/doi/10.1177/02698811251362390

² eClinicalMedicine (The Lancet). "Investigational psilocybin treatment for post-traumatic stress disorder: a qualitative study of participant experience, trauma engagement, and differences from standard treatment." https://www.thelancet.com/journals/eclinm/article/PIIS2589-5370(25)00626-1/fulltext

³ Ellis, S., et al. "Single-dose psilocybin for U.S. military Veterans with severe treatment-resistant depression: A first-in-kind open-label pilot study." Journal of Affective Disorders. VA Palo Alto Health Care System / Stanford University School of Medicine. https://pubmed.ncbi.nlm.nih.gov/39343309/

⁴ ScienceDirect. "Long-term outcomes of single-dose psilocybin for U.S. military Veterans with severe treatment-resistant depression: 12-month data from an open-label pilot study." https://www.sciencedirect.com/science/article/abs/pii/S0165032725010973

⁵ ScienceDirect. "Changes in anxiety, quality of life, and functioning following psilocybin-assisted therapy in veterans with treatment-resistant depression." 2026. https://www.sciencedirect.com/science/article/abs/pii/S0165032726009158

⁶ Applied Clinical Trials Online. "FDA Finalizes Guidance on Clinical Trial Design for Psychedelic Drug Development." July 2026. https://www.appliedclinicaltrialsonline.com/view/fda-finalizes-guidance-clinical-trial-design-psychedelic-drug-development

⁷ VA Press Room. "VA Launches MDMA-Assisted Mental Health Therapy Trial." May 2026. https://news.va.gov/press-room/va-launches-mdma-assisted-mental-health-therapy-trial/

⁸ CNN. "FDA moves to fast-track review of psilocybin and methylone for mental health." April 24, 2026. https://www.cnn.com/2026/04/24/health/fda-psychedelic-drugs-priority-vouchers

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