Long-term follow-up of psilocybin-assisted psychotherapy for psychiatric and existential distress in patients with life-threatening cancer.
Level 4 - case-series / case-control
Uncontrolled long-term within-subjects follow-up (case series) of surviving participants from a prior crossover trial
PubMed 31916890 · doi:10.1177/0269881119897615
What was done
Researchers conducted a long-term within-subjects follow-up of participants from a previously published randomized crossover trial investigating single-dose psilocybin versus single-dose niacin combined with psychotherapy for cancer-related psychiatric distress. All 16 surviving participants from the parent trial were contacted, and 15 agreed to complete self-reported assessments of psychological and existential symptoms at an average of 3.2 years and 4.5 years post-psilocybin administration.
What was found
Reductions in depression, anxiety, hopelessness, demoralization, and death anxiety were sustained at both the 3.2-year and 4.5-year follow-ups, with large within-group effect sizes. At the 4.5-year time point, approximately 60% to 80% of participants met criteria for clinically significant antidepressant or anxiolytic responses. Furthermore, 71% to 100% of participants attributed positive life changes to the psilocybin-assisted therapy and rated it among the most spiritually significant and personally meaningful experiences of their lives.
Why it matters
The study suggests that the psychological benefits of a single psilocybin-assisted psychotherapy session may persist for several years in patients with life-threatening cancer, providing extended relief from existential and psychiatric distress.
Limits
The sample size is very small (n=15) and restricted only to trial participants who were still alive at follow-up, introducing substantial survival bias. Because the parent study used a crossover design where all participants eventually received psilocybin, there is no untreated or active control group at long-term follow-up, preventing definitive conclusions regarding treatment efficacy. Outcome measures relied on self-reported symptomatology.
Cited by
- supports In a long-term follow-up of depressed and anxious cancer patients treated with psilocybin, most surviving participants remained in remission from depression two years later without needing antidepressants.