Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial
Summary & key facts
Researchers gave a single high dose of psilocybin (a psychedelic drug) to 51 people with life-threatening cancer who also had depression or anxiety. Each person had two drug sessions weeks apart: one very low dose that acted like a placebo and one high dose, and neither the people nor the staff knew which was which during sessions. The high dose produced big short-term drops in depression and anxiety, bigger life meaning and optimism, and less fear of death. About six months later, roughly 80% of the participants still had clinically meaningful improvements. The study also found that having a strong mystical or spiritual-type experience during the session helped explain why the high dose led to better mental health.
- The study included 51 people with life-threatening cancer who also had symptoms of depression or anxiety.
- Each person took part in two drug sessions a few weeks apart: one very low dose and one high dose of psilocybin, and neither participants nor staff knew which dose was given during a session.
- The very low dose was like a placebo and the high dose was about twenty to thirty milligrams per seventy kilograms of body weight.
- After the high-dose sessions, clinician ratings and patients’ own reports showed large decreases in depressed mood and anxiety.
- People also reported increases in quality of life, feeling that life had more meaning, and greater optimism after the high dose.
- About six months after the sessions, around 80% of participants still showed clinically meaningful decreases in depression and anxiety.
- Outside observers who knew the participants also saw matching improvements in mood and behavior.
- The researchers found that having a strong mystical or deeply meaningful experience during the high-dose session helped explain (or mediated) the link between the dose and the lasting mental health benefits.
Abstract
Cancer patients often develop chronic, clinically significant symptoms of depression and anxiety. Previous studies suggest that psilocybin may decrease depression and anxiety in cancer patients. The effects of psilocybin were studied in 51 cancer patients with life-threatening diagnoses and symptoms of depression and/or anxiety. This randomized, double-blind, cross-over trial investigated the effects of a very low (placebo-like) dose (1 or 3 mg/70 kg) vs. a high dose (22 or 30 mg/70 kg) of psilocybin administered in counterbalanced sequence with 5 weeks between sessions and a 6-month follow-up. Instructions to participants and staff minimized expectancy effects. Participants, staff, and community observers rated participant moods, attitudes, and behaviors throughout the study. High-dose psilocybin produced large decreases in clinician- and self-rated measures of depressed mood and anxiety, along with increases in quality of life, life meaning, and optimism, and decreases in death anxiety. At 6-month follow-up, these changes were sustained, with about 80% of participants continuing to show clinically significant decreases in depressed mood and anxiety. Participants attributed improvements in attitudes about life/self, mood, relationships, and spirituality to the high-dose experience, with >80% endorsing moderately or greater increased well-being/life satisfaction. Community observer ratings showed corresponding changes. Mystical-type psilocybin experience on session day mediated the effect of psilocybin dose on therapeutic outcomes. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00465595.
