How does psilocybin therapy work? An exploration of experiential avoidance as a putative mechanism of change.
Richard J. Zeifman, Anne C Wagner, Candice M Monson, Robin Carhart-Harris
Journal of Affective Disorders August 1, 2023 DOI: 10.1016/j.jad.2023.04.105 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized controlled trial Double-blind Qualitative Peer reviewed |
|---|---|
| Sample size | 59 |
| Population | Individuals with major depressive disorder |
| Interventions | Psilocybin Escitalopram |
| Dose | 25 mg psilocybin, 1 mg psilocybin, 10-20 mg escitalopram |
| Duration | 6-week intervention |
| Topics | Depression Psychedelic-assisted therapy Psilocybin |
| Keywords | Experiential avoidance Mechanism of change Psilocybin therapy Magic mushroom therapy Psychiatric treatment |
| Citations | 56 |
| Key findings | Reductions in experiential avoidance mediated improvements in mental health outcomes following psilocybin therapy but not escitalopram. |
Abstract
Psilocybin therapy is receiving attention as a mental health intervention with transdiagnostic potential. In line with psychotherapeutic research, qualitative research has highlighted the role of reductions in experiential avoidance (and increases in connectedness) within psilocybin therapy. However, no quantitative research has examined experiential avoidance as a mechanism underlying psilocybin therapy's therapeutic effects. Data was used from a double-blind randomized controlled trial that compared psilocybin therapy (two 25 mg psilocybin session plus daily placebo for six weeks) with escitalopram (two 1 mg psilocybin sessions plus 10-20 mg daily escitalopram for six weeks) among individuals with major depressive disorder (N = 59). All participants received psychological support. Experiential avoidance, connectedness, and treatment outcomes were measured at pre-treatment and at a 6 week primary endpoint. Acute psilocybin experiences and psychological insight were also measured. With psilocybin therapy, but not escitalopram, improvements in mental health outcomes (i.e., well-being, depression severity, suicidal ideation, and trait anxiety) occurred via reductions in experiential avoidance. Exploratory analyses suggested that improvements in mental health (except for suicidal ideation) via reduction in experiential avoidance were serially mediated through increases in connectedness. Additionally, experiences of ego dissolution and psychological insight predicted reductions in experiential avoidance following psilocybin therapy. Difficulties inferring temporal causality, maintaining blindness to condition, and reliance upon self-report. These results provide support for the role of reduced experiential avoidance as a putative mechanism underlying psilocybin therapy's positive therapeutic outcomes. The present findings may help to tailor, refine, and optimize psilocybin therapy and its delivery.
Comparable studies
Other randomized controlled trials on psilocybin and psychedelic-assisted therapy, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Psilocybin occasioned mystical-type experiences: immediate and persisting dose-related effects. Healthy adults, mostly hallucinogen-naïve | 2011 | Randomized controlled trial | n = 18 |
| Percentage of Heavy Drinking Days Following Psilocybin-Assisted Psychotherapy vs Placebo in the Treatment of Adult Patients With Alcohol Use Disorder Adults aged 25–65 with DSM-IV alcohol dependence and at least 4 heavy drinking days in... | 2022 | Randomized controlled trial | n = 95 |
| Increased global integration in the brain after psilocybin therapy for depression. Patients with treatment-resistant depression and patients with major depressive disorder | 2022 | Open-label trial and double-blind phase II randomized controlled trial | |
| Single-dose psilocybin-assisted therapy in major depressive disorder: A placebo-controlled, double-blind, randomised clinical trial. Adults diagnosed with major depressive disorder and no unstable somatic conditions | 2023 | Double-blind, randomised clinical trial | n = 52 |
| Implications for psychedelic-assisted psychotherapy: functional magnetic resonance imaging study with psilocybin Healthy participants | 2012 | Randomized controlled trial | n = 10 |