How Does Psilocybin Therapy Work? an Exploration of Experiential Avoidance as a Putative Mechanism of Change
Bibliographic record
Abstract
Although psilocybin therapy is currently receiving attention as a novel intervention for a wide range of mental health concerns, limited research has examined the underlying psychological mechanisms (i.e., how) through which psilocybin therapy may bring about positive therapeutic changes. Qualitative research highlights the role of reductions in experiential avoidance (i.e., avoidance or suppression of aversive states) within psilocybin therapy. However, no quantitative research has examined experiential avoidance as a mechanism of change underlying psilocybin therapy's effects. Accordingly, the purpose of this dissertation is to investigate whether psilocybin therapy: (a) leads to reductions in experiential avoidance and (b) improved mental health (e.g., increased well-being and decreased depression severity, anxiety, and suicidal ideation) via reductions in experiential avoidance. This dissertation examined these questions within two studies that included the administration of psilocybin. Study 1 was a quasiexperimental study that examined the effect of administering 1 mg (very low-dose) psilocybin and 25 mg (high-dose) psilocybin to healthy individuals (N = 28). Relative to participants' experiential avoidance when they enrolled in the study, no significant reductions in experiential avoidance were observed throughout the study. Non-significant increases in experiential avoidance were observed following 1 mg psilocybin. Subsequently, significant reductions in experiential avoidance were observed 2 and 4 weeks after 25 mg psilocybin. These reductions in experiential avoidance following 25 mg psilocybin were significantly greater than those observed following 1 mg psilocybin. Decreases in experiential avoidance were sustained at 3 months (but not at 6 months) after 25 mg psilocybin. Reductions in experiential avoidance that occurred 2 weeks after 25 mg psilocybin (but not 1 mg psilocybin) predicted improvements in mental health (i.e., increases in well-being and decreases in depressed and anxious mood) 4 weeks after 25 mg psilocybin. Relative to 1 mg psilocybin, reductions in experiential avoidance following 25 mg psilocybin was a significantly greater predictor of changes in anxious mood (but failed to reach significance for well-being and depressed mood). Study 2 was a randomized controlled trial that compared psilocybin therapy with escitalopram (a selective serotonin reuptake inhibitor) for major depressive disorder (N = 59). Relative to escitalopram, psilocybin therapy led to significant reductions in experiential avoidance. Within the psilocybin therapy (but not the escitalopram) condition, reductions in experiential avoidance indirectly affected improvements in mental health (i.e., increased well-being and decreased depression severity, suicidal ideation, and trait anxiety). These indirect effects were significantly larger in the psilocybin therapy condition (for well-being, depression severity, and trait anxiety but not for suicidal ideation), providing evidence for the role of experiential avoidance being specific to psilocybin therapy. These results provide preliminary support for the positive effects of psilocybin therapy on experiential avoidance and the potential role of experiential avoidance as a putative mechanism underlying psilocybin therapy’s positive therapeutic outcomes. Limitations of the present studies include difficulties surrounding establishing temporal causality, issues with the experimental designs, relatively small sample sizes, and reliance upon self-report. The present findings may help to tailor and refine psilocybin therapy and its delivery as a transdiagnostic mental health intervention.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.007 | 0.008 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.004 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".