Safety, feasibility, and preliminary clinical outcomes of psilocybin-assisted therapy for veterans with severe, treatment-resistant PTSD: an open-label pilot clinical trial

This open-label pilot trial investigated the safety, feasibility, and clinical outcomes of psilocybin-assisted therapy (PAT) for U.S. military veterans suffering from severe, treatment-resistant post-traumatic stress disorder (PTSD). Given the high rates of treatment resistance and suicide risk in this population, the researchers sought to determine if a structured regimen of psychotherapy combined with two doses of synthetic psilocybin (15 mg and 25 mg) could provide meaningful relief where standard treatments have failed.

Twelve veterans completed the study, which involved approximately 16 hours of psychotherapy—split between preparation and integration sessions—alongside two psilocybin dosing sessions spaced 2–3 weeks apart. The primary endpoints were safety and the monitoring of suicidal ideation, while secondary endpoints measured PTSD symptom severity using the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5). The study also explored the influence of pre-dosing preparation and participant expectations on clinical outcomes.

The trial demonstrated that PAT is safe and well-tolerated in this cohort. No serious adverse events occurred, and common side effects like headaches and anxiety were mild and transient. Clinically, the results were striking: participants showed a large, statistically significant reduction in PTSD symptoms from baseline to the one-month follow-up. Notably, 75% of the participants met the criteria for treatment response and remission. The researchers also observed that symptom improvement began during the preparation phase, suggesting that the therapeutic alliance and preparatory work play a crucial role in the overall treatment effect.

Veterans with PTSD often face chronic, severe symptoms that do not respond to traditional pharmacotherapy or standard psychotherapies. This study provides important proof-of-concept evidence that PAT may be a viable, potent alternative for this high-risk population. While the results are promising, the authors emphasize that the small sample size and lack of a control group necessitate larger, randomized, and blinded trials to confirm these findings and better understand the long-term durability of the treatment.