Psychedelic Science Newsletter
Issue #53August 31, 20267 studies

One psilocybin session held antidepressant effects for 52 weeks in a new follow-up study

Psilocybin research had a busy week, and the results are genuinely interesting—with some important asterisks attached.

From 52-week depression follow-ups to float tanks mimicking psychedelic states, here's what the evidence actually shows.

🍄 A Single Psilocybin Session, One Year Later

  • A 52-week follow-up study found that a single 25 mg psilocybin session produced dose-dependent maintenance of antidepressant benefit through a full year—the longest durability window reported so far.
  • Separately, a pilot in Veterans with severe treatment-resistant depression reported a 60% response rate at three weeks, and a first safety trial in PTSD found that symptom improvement tracked with self-transcendent experience intensity but worsened when session anxiety was high.
  • A living review of 15 randomized trials confirmed a meaningful antidepressant effect overall—then flagged functional unblinding as a substantial threat to those effect estimates.

Why it matters: The durability signal is real and worth watching, but the field's central methodological problem—participants usually know whether they got the drug—hasn't been solved, which means the true effect size remains genuinely uncertain.

Top 20% journal 🔗 Journal of clinical medicine Review 🗓️ Aug 27

Key Findings

🌊 Float Tanks Produce Psychedelic-Adjacent States—Without Any Drug

  • In a randomized trial of 75 adults with anxiety and depression, floatation therapy produced altered states characterized by oceanic boundlessness, disembodiment, and experience of unity—a profile that overlapped with psilocybin and ketamine along boundary-dissolution dimensions.
  • Effects were strongest among participants who chose longer, more flexible sessions, and oceanic boundlessness specifically was linked to increases in positive affect.
💡 Floatation therapy may be a drug-free way to access psychedelic-adjacent states.
🎖️ Top 10% journal 🔗 Neuroscience of consciousness Journal Article 🗓️ Aug 27

💊 Ketamine for OCD: Promising but Short-Lived

  • A systematic review evaluated ketamine for moderate-to-severe obsessive-compulsive disorder, a condition where 40–60% of patients fail standard serotonergic and behavioral therapies.
  • Results suggested efficacy signals, but durability and long-term safety remain unresolved—a recurring theme for glutamate-based treatments.
💡 Ketamine moves the needle on OCD, but nobody knows how long it lasts.
Top 20% journal 🔗 Psychopharmacology Review 🗓️ Aug 26

🏥 Oncology Providers Want to Help—But Feel Unprepared

  • A survey across six institutions found that 49% of oncology providers had received patient inquiries about psychedelic-assisted therapy, yet 80% did not feel comfortable counseling patients on its use.
  • Willingness to recommend it was tied to familiarity with the emerging data and knowledge of legal status—not to provider age, specialty, or other demographic factors.
💡 Patient demand for psychedelic therapy in oncology is outpacing provider readiness.

🧪 High-Dose THC vs. Psilocybin: Not the Same Trip

  • A pilot study compared high-dose THC to high-dose psilocybin and placebo in the structured context of a classic psychedelic therapy session, examining whether THC can occasion genuinely psychedelic-like experiences.
  • The study aimed to characterize both the doses required and the phenomenology of those experiences—suggesting the two compounds produce meaningfully different experiential profiles.
💡 High-dose THC and psilocybin are not interchangeable, even in the same therapeutic setting.
Top 20% journal 🔗 Psychopharmacology Journal Article 🗓️ Aug 26

🔬 Salvia's Active Compound: Fast, Strange, and Understudied

  • A systematic review of 12 clinical trials covering 174 participants found that salvinorin A—the psychoactive compound in Salvia divinorum—produces effects that peak within 1–2 minutes and resolve within 30 minutes when inhaled, with no serious adverse events reported.
  • Its mechanism is kappa-opioid receptor agonism, making it pharmacologically distinct from serotonergic psychedelics and a potential tool for studying opioid receptor-mediated alterations of consciousness.
💡 Salvinorin A is fast, unusual, and barely studied in humans—that gap is worth closing.

⚖️ Oregon, Colorado, New Mexico: Three Bets on Psilocybin Policy

  • A legal analysis compared the three state regulatory frameworks currently governing psilocybin: Oregon prioritizes broad access outside the healthcare system, Colorado blends regulated services with decriminalization, and New Mexico limits use to a clinician-directed medical model for qualifying patients.
  • The analysis argues that New Mexico's model offers the strongest foundation for future regulation, while Colorado's framework provides the best protections for Indigenous community practices.
💡 How states regulate psilocybin now will shape who gets access for years.
🔗 The Journal of legal medicine Journal Article 🗓️ Aug 25

Implications

The week's evidence pulls in two directions at once: durability data and new populations are expanding the case for psilocybin, while functional unblinding and provider unpreparedness are compressing confidence in what the numbers actually mean. The unresolved tension is whether any trial design can credibly blind participants who know they took a psychedelic.

Studies in this issue

Primary sources used for this newsletter.

  1. Psilocybin Therapy in Mental Health: How It Works, Uses, and New Findings (2025-2026)
    main storyJournal of clinical medicine2026-08-27PMID 42652632
  2. Salvinorin A in humans: How it is processed, affects the body, and its safety
    key findingJournal of psychopharmacology (Oxford, England)2026-08-25PMID 42638533
  3. Comparing State Rules to Find the Best Way to Regulate Psilocybin
    key findingThe Journal of legal medicine2026-08-25PMID 42640727
  4. Altered consciousness from floatation therapy in people with anxiety and depression
    key findingNeuroscience of consciousness2026-08-27PMID 42657182
  5. Cancer Care Providers' Views on Therapy Using Psychedelic Drugs
    key findingThe American journal of hospice & palliative care2026-08-28PMID 42661611