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About this resource
This is an English version of a 2016 randomized double-blind crossover trial that compared psilocybin conditions under psychological support in 51 patients with depressive or anxiety symptoms associated with a life-threatening cancer diagnosis. The order of high- and very-low-dose conditions was randomized, and mood, anxiety, quality of life, attitudes toward death, and subjective experiences were followed after sessions.
The study did not address an action that treats cancer. It measured changes in psychological-distress scales associated with diagnosis and prognosis and did not show tumor shrinkage, longer survival, or an alternative to anticancer treatment. It also studied standardized psilocybin together with preparation, monitoring, and follow-up discussion; it did not evaluate whole mushrooms or unsupervised use.
Study design
Participants were adults with a cancer diagnosis who met psychiatric interview and symptom criteria. They were screened for serious psychotic disorders, mania risk, certain physical hazards, and other factors. In 2 sessions they received high- or very-low-dose psilocybin in randomized order. The sessions were separated by an adequate interval, and trained monitors remained present throughout.
Assessments used clinician and self-report scales from several weeks to approximately 6 months after the intervention. Multiple outcomes included depression, anxiety, quality of life, meaning in life, attitudes toward death, and mystical-type subjective ratings. Ratings of change were also collected from participants’ family members, friends, and other observers.
Because everyone eventually experienced the high-dose condition in a crossover design, no purely unexposed control remained at long-term time points. The between-condition difference after the first session and the overall course afterward carry different evidentiary strength.
Content
Psychological distress accompanying a life-threatening illness overlaps with general major depressive disorder but also has the distinctive context of fear of death, loss, physical symptoms, and treatment burden. The research team assessed not only experiences during the period of brief pharmacological action but also how participants gave those experiences meaning and integrated them into daily life.
Psychological support included building trust beforehand, nondirective support during sessions, and reflection afterward. Results therefore concern an intervention combining the psilocybin molecule, expectations, supportive relationships, environment, and participants’ own meaning-making. This trial alone cannot separate the contribution of each component.
Analyses also linked mystical-experience ratings with improvement, but correlation does not prove a causal mechanism. A participant who did not report a profound experience did not thereby fail, and the study did not scientifically determine the truth of spiritual content.
Results
After the first session, the high-dose condition produced larger decreases on several depression and anxiety scales and improvements in quality of life and meaning in life compared with the very-low-dose condition. In the group that received the high-dose condition first, a higher proportion met response or remission criteria at the comparison time point. After the second session, both groups had experienced the high-dose condition, and average improvements were reported to persist through the 6-month assessment.
Many participants rated the session as personally and spiritually important. Community observers also reported positive changes in behavior and attitudes. Self-report and observer ratings, however, may be influenced by expectations, research participation, the course of cancer, and other support.
Temporary increases in blood pressure were observed physiologically, and some participants experienced psychological anxiety or fear. Staff continuously observed participants and responded to acute reactions in the research setting. The observation that serious medical complications were not common does not guarantee safety without screening and monitoring.
Limitations
The study was small, with 51 participants from a selected population at one research site. Spiritual or religious interests and expectations about participating in research may differ from those in the general population. Distinctive effects can allow participants and staff to infer the high-dose condition, limiting effective blinding.
The very-low-dose condition was not a fully inactive placebo and could not fully control differences in expectations and subjective effects. After crossover, long-term follow-up had no unexposed control, so natural course, cancer treatment, supportive care, and time cannot be excluded. Multiple scales were assessed, requiring distinction between primary and exploratory outcomes.
Cancer type, stage, physical status, and treatment varied, so the findings do not concern one specific cancer. People with serious psychiatric or physical risks were excluded, limiting generalization.
Safety
In people with cancer, cardiovascular status, liver and kidney function, pain, fatigue, and interactions with anticancer drugs, analgesics, and psychiatric medications are complex. Few serious events in a small trial cannot exclude individual contraindications or rare harms. Assessment of psychotic disorders, mania, and suicide risk is also necessary.
This page does not guide psilocybin ingestion, changes to cancer treatment, or discontinuation of psychiatric medication. Findings cannot be transferred to settings without the research support system, mushrooms of unknown composition, or combinations with other substances. Ordinary medical and emergency support takes priority when severe anxiety, confusion, or physical symptoms occur.
Spiritual meaning is respected as the participant’s subjective experience, but it is not proof of cancer cure, an afterlife, or supernatural facts. It is important not to conflate improvement on psychological scales with the course of the illness itself.
Ratings from family members and supporters supplement observations of participants’ change, but they are not necessarily blinded independent assessments.
Source and rights
Original source: Griffiths RR, et al. Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial. Journal of Psychopharmacology. 2016;30(12):1181–1197. DOI: 10.1177/0269881116675513.
The original article is available under Creative Commons Attribution 4.0 (CC BY 4.0). This page is a source-aligned English translation under that license, reconstructed while preserving the article’s structure and argument. It is not literal, and explanation has been added to avoid conflating cancer treatment with psychological outcomes. Figures and tables are not reproduced. The original source takes precedence for exact scale-specific values, confidence intervals, session conditions, and exclusion criteria.