The science

The Library

The practices at Halcyon are old. The research on them is newer, and growing. These are the studies we read and return to, each with a short note in plain language and a link to the original paper. We share them to inform, not to promise, and none of it is medical advice.

8 studies

Psychedelic Assisted Psychotherapy · Consciousness

Human hallucinogen research: guidelines for safety

Johnson MW, Richards WA, Griffiths RR

Journal of Psychopharmacology · 2008

This paper from Johns Hopkins reviews the history of human research with classic psychedelics, the risks involved, and how researchers can reduce them. It is a review and set of guidelines rather than a trial. The authors note that while these substances carry relatively low physical risk and are not considered drugs of dependence, they carry unique psychological risks. The most likely is overwhelming distress during the session, and rarer risks include prolonged psychotic reactions. Recommended protections include screening out people with a personal or family history of psychotic or other severe psychiatric disorders, building trust before the session, careful preparation, a supportive physical setting, and at least two monitors present. A limitation is that these guidelines were written for research settings rather than everyday clinical practice.

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Psychedelic Assisted Psychotherapy

Attenuation of psilocybin mushroom effects during and after SSRI/SNRI antidepressant use

Gukasyan N, Griffiths RR, Yaden DB, et al.

Journal of Psychopharmacology · 2023

Researchers at Johns Hopkins wanted to know whether common antidepressants change how strongly psilocybin mushrooms are felt. They ran an online retrospective survey of people who had used psilocybin mushrooms while taking an antidepressant, or within two years of stopping one. In this study, across 611 reports of use while on an antidepressant, weaker-than-expected effects were reported about 47% of the time with SSRIs, 55% with SNRIs, and 29% with bupropion. Among 1,542 reports after stopping an SSRI or SNRI, reduced effects were still reported up to three to six months later. An honest limitation: this is self-reported, retrospective survey data, so recall and expectation may have shaped the answers. Psilocybin remains a Schedule I substance under US federal law, and regulated access currently exists only through state programs in Oregon and Colorado; it is not available in New Jersey.

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Psychedelic Assisted Psychotherapy

MDMA-assisted therapy for severe PTSD: a randomized, double-blind, placebo-controlled phase 3 study

Mitchell JM, Bogenschutz M, Lilienstein A, et al.

Nature Medicine · 2021

This phase 3 randomized, double-blind, placebo-controlled trial tested MDMA-assisted therapy for severe PTSD in 90 adults, including people with dissociation, depression, substance use histories and childhood trauma. Everyone received the same manualized therapy, with three preparation and nine integration sessions; the difference was whether the medicine sessions used MDMA or placebo. In this study, PTSD symptom scores fell more in the MDMA group than the placebo group two months after the last session, and functional impairment also improved more. The researchers did not observe signs of abuse potential, increased suicidality, or heart rhythm problems. A limitation is that the placebo group also improved considerably, and blinding is difficult with MDMA. MDMA remains a Schedule I substance and is not an approved treatment in the United States.

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Psychedelic Assisted Psychotherapy

Single-Dose Psilocybin for a Treatment-Resistant Episode of Major Depression

Goodwin GM, Aaronson ST, Alvarez O, et al.

New England Journal of Medicine · 2022

This phase 2 double-blind trial studied a single dose of a synthetic psilocybin formulation in 233 adults with treatment-resistant depression across many sites. Participants were randomized to 25 mg, 10 mg, or 1 mg (the control), each with psychological support. In this study, the 25 mg dose reduced depression scores more than the 1 mg dose at three weeks, while the 10 mg dose did not differ significantly from control. The difference was not clearly maintained as sustained response at 12 weeks. Adverse events were reported by 77% of participants, including headache, nausea and dizziness, and suicidal ideation, behavior or self-injury occurred in all dose groups. The authors call for larger and longer trials. Psilocybin remains a Schedule I substance under US federal law, and regulated access currently exists only through state programs in Oregon and Colorado; it is not available in New Jersey.

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Psychedelic Assisted Psychotherapy

Trial of Psilocybin versus Escitalopram for Depression

Carhart-Harris R, Giribaldi B, Watts R, et al.

New England Journal of Medicine · 2021

This phase 2 double-blind trial at Imperial College London compared psilocybin with escitalopram, a common SSRI antidepressant, in 59 adults with long-standing moderate to severe depression. One group received two 25 mg psilocybin doses three weeks apart plus daily placebo pills; the other received two 1 mg doses plus six weeks of escitalopram. Everyone received psychological support. In this study, the main depression measure at six weeks did not differ significantly between groups. Some secondary measures, such as remission rates, leaned toward psilocybin, but these were not corrected for multiple comparisons. The authors state that larger and longer trials are needed, which is the key limitation. Psilocybin remains a Schedule I substance under US federal law, and regulated access currently exists only through state programs in Oregon and Colorado; it is not available in New Jersey.

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Psychedelic Assisted Psychotherapy

Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder

Davis AK, Barrett FS, May DG, et al.

JAMA Psychiatry · 2021

This Johns Hopkins randomized clinical trial asked whether psilocybin-assisted therapy could help adults with major depressive disorder who were not taking antidepressants. Twenty-seven participants were randomized to start treatment right away or after an eight-week wait, and 24 completed it. Treatment was two psilocybin sessions, a few weeks apart, within about 11 hours of supportive psychotherapy. In this study, depression scores in the immediate group dropped substantially compared with the waiting group at both one and four weeks after treatment, and effect sizes were large. An honest limitation: the comparison group was a waiting list rather than a placebo, the sample was small, and follow-up in the main comparison was short. Psilocybin remains a Schedule I substance under US federal law, and regulated access currently exists only through state programs in Oregon and Colorado; it is not available in New Jersey.

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Psychedelic Assisted Psychotherapy · Consciousness

Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: a randomized controlled trial

Ross S, Bossis A, Guss J, et al.

Journal of Psychopharmacology · 2016

This NYU trial, published alongside a similar Johns Hopkins study, examined a single moderate dose of psilocybin given with psychotherapy for anxiety and depression linked to cancer. Twenty-nine patients were randomly assigned in a double-blind crossover design to psilocybin or niacin, an active placebo, with therapy in both conditions. In this study, psilocybin was followed by rapid and lasting reductions in anxiety and depression, less demoralization and hopelessness, and better spiritual wellbeing and quality of life. At about six and a half months, roughly 60 to 80% of participants still had clinically significant reductions. As in the companion study, the intensity of the mystical experience was linked to the benefit. The small sample is an important limitation. Psilocybin remains a Schedule I substance under US federal law, and regulated access currently exists only through state programs in Oregon and Colorado; it is not available in New Jersey.

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Psychedelic Assisted Psychotherapy · Consciousness

Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial

Griffiths RR, Johnson MW, Carducci MA, et al.

Journal of Psychopharmacology · 2016

This Johns Hopkins trial studied psilocybin in 51 people with life-threatening cancer who also had symptoms of depression and anxiety. Using a randomized, double-blind crossover design, each person received a very low, placebo-like dose and a high dose about five weeks apart, with preparation and support from staff. In this study, the high dose was followed by large decreases in depressed mood and anxiety, along with gains in quality of life, sense of meaning and optimism, and less fear of death. About 80% still showed clinically significant improvement at six months, and the strength of a mystical-type experience during the session was linked to the benefits. A limitation is that blinding is hard with psilocybin, since participants can often tell which dose they received. Psilocybin remains a Schedule I substance under US federal law, and regulated access currently exists only through state programs in Oregon and Colorado; it is not available in New Jersey.

Read the original ↗