A new meta-analysis published by BMC Psychology finds that psilocybin treatment is associated with substantial reductions in depressive symptoms among cancer patients, while effects on anxiety appear more mixed and less consistent.
The analysis was conducted by researchers from Shiraz University of Medical Sciences, Arak University of Medical Sciences, and The University of Texas MD Anderson Cancer Center. It reviewed both randomized and non-randomized clinical studies examining the mental health effects of psilocybin in people with cancer-related psychological distress.
Researchers evaluated outcomes related to depression, anxiety, quality of life, and spiritual well-being, drawing from trials identified across six major scientific databases through November 2024. Outcomes were assessed at both short-term follow-ups, defined as two to five weeks after treatment, and longer-term follow-ups at six months.
In randomized controlled trials, psilocybin produced large reductions in depressive symptoms. Scores on commonly used depression measures showed strong improvements, with effects that were statistically significant and sustained over time. Short-term results showed clear reductions in depression and anxiety scores, while longer-term data indicated that improvements in depression remained evident six months after treatment.
Anxiety outcomes were less consistent. Some measures showed meaningful short-term improvement, while others did not reach statistical significance, suggesting variability depending on how anxiety was assessed. The researchers noted that anxiety results were more mixed compared to the robust findings seen for depression.
Beyond mood symptoms, psilocybin was also associated with improvements in spiritual well-being. Measures assessing meaning, peace, and spiritual quality of life increased following treatment, aligning with previous research suggesting psychedelic experiences may influence existential distress in patients facing serious illness. Improvements in overall quality of life were also observed, though primarily in single-arm studies without control groups.
The authors cautioned that the findings should be considered preliminary. The number of available studies remains small, and many trials involved psychotherapy alongside psilocybin, making it difficult to isolate the drug’s effects. Challenges with blinding and expectancy effects were also noted.
Researchers concluded that larger, more rigorously designed trials are needed to better determine the safety and clinical effectiveness of psilocybin for psychological distress in cancer patients.
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