Psilocybin and Mental Health: What the Research Actually Says

Twenty years ago, psilocybin research was a footnote. Today it is a field. Dedicated centres at Johns Hopkins University and Imperial College London — both opened in 2019 — study psilocybin full-time, and trials have been run at NYU, UCSF, Yale, and dozens of other institutions. This piece is a plain-language tour of what has actually been published.

One thing before we start: we are a directory, not doctors. Nothing here is medical advice, and nothing here means psilocybin is a treatment you should pursue. If you are struggling, talk to a licensed clinician. What follows is reporting on published research, no more.

The headline studies

Depression. In a 2020 study published in JAMA Psychiatry, Johns Hopkins researchers reported that participants with major depressive disorder showed large reductions in depressive symptoms after psilocybin sessions paired with supportive therapy. In 2021, Imperial College researchers published a head-to-head trial in the New England Journal of Medicine comparing psilocybin therapy with a common antidepressant — the two performed similarly on the primary measure. And in 2022, a phase 2b trial of a synthetic psilocybin formulation in 233 participants with treatment-resistant depression reported meaningful symptom reductions at the highest dose, alongside some adverse events — a reminder that this is medicine under study, not a settled treatment.

End-of-life distress. Two landmark 2016 trials — one at Johns Hopkins, one at NYU — reported that a single psilocybin session reduced anxiety and depression in patients facing life-threatening cancer diagnoses, with effects that persisted at six-month follow-ups in a majority of participants.

Habit change. A small Johns Hopkins pilot on smoking cessation reported unusually high abstinence rates months after psilocybin sessions combined with cognitive behavioural therapy. The sample was small and there was no placebo group — promising signal, early evidence.

Wellbeing in healthy adults. The study that restarted the field: a 2006 Johns Hopkins experiment found that a majority of healthy volunteers rated their psilocybin session among the most personally meaningful experiences of their lives, with sustained positive changes in mood and behaviour reported months later.

Why regulators are paying attention

The U.S. Food and Drug Administration has granted psilocybin therapy "breakthrough therapy" designation twice — for treatment-resistant depression in 2018 and major depressive disorder in 2019. The designation does not mean approval; it means the early evidence was strong enough to fast-track further study.

What the research does not say

Honest reporting cuts both ways:

• Sample sizes are small. Most trials enrolled dozens of people, not thousands.
• Blinding is hard. Participants usually know whether they received psilocybin, which can inflate effects.
• Therapy is part of the package. In nearly every trial, psilocybin came wrapped in hours of professional preparation and integration support. The mushroom alone is not what was studied.
• Not for everyone. Trials screen out people with a personal or family history of psychotic disorders, among other conditions. Adverse experiences — including difficult, distressing sessions — are real and documented.

Where to go from here

If the clinical route interests you, clinics and therapy providers in the directory operate in licensed and regulated settings, and education programs teach the underlying science. For the species behind the studies, start at the Species Library.