Personality & Trait Factors

Post-acute psychological effects of classical serotonergic psychedelics: A systematic review and meta-analysis

This review and meta-analysis (2020) of long-term effects of psychedelics finds a large effect (Hedges' g ≈ 1) on various outcomes, but also notes various biases as issues in current research.

Authors

  • Samuel Goldberg
  • Charles Raison
  • Christopher Nicholas

Published

Psychological Medicine
meta Study

Abstract

“Background: Scientific interest in the therapeutic effects of classical psychedelics has increased in the past two decades. The psychological effects of these substances outside the period of acute intoxication have not been fully characterized. This study aimed to: (1) quantify the effects of psilocybin, ayahuasca, and LSD on psychological outcomes in the post-acute period; (2) test moderators of these effects; and (3) evaluate adverse effects and risk of bias.

Methods

We conducted a systematic review and meta-analysis of experimental studies (single-group pre-post or randomized controlled trials) that involved administration of psilocybin, ayahuasca, or LSD to clinical or non-clinical samples and assessed psychological outcomes ≥24 hours postadministration. Effects were summarized by study design, timepoint, and outcome domain.

Results

A total of 34 studies (24 unique samples, n = 549, mean longest follow-up = 55.34 weeks) were included. Classical psychedelics showed significant within-group pre-post and between-group placebo-controlled effects on a range of outcomes including targeted symptoms within psychiatric samples, negative and positive affect-related measures, social outcomes, and existential/spiritual outcomes, with large between-group effect in these domains (Hedges’ gs = 0.84 to 1.08). Moderator tests suggest some effects may be larger in clinical samples. Evidence of effects on big five personality traits and mindfulness was weak. There was no evidence of post-acute adverse effects.

Conclusions

High risk of bias in several domains, heterogeneity across studies, and indications of publication bias for some models highlight the need for careful, large-scale, placebo-controlled randomized trials.”

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Research Summary of 'Post-acute psychological effects of classical serotonergic psychedelics: A systematic review and meta-analysis'

Introduction

Psychedelic substances have a long history of ritual and medicinal use and re-emerged as a focus of scientific research over the past two decades after a hiatus following mid-20th century legislative restrictions. Classical serotonergic psychedelics share a common pharmacology (5-HT2A receptor agonism) and characteristic subjective effects; recent clinical and non-clinical studies have evaluated psilocybin, ayahuasca (DMT with MAO-A inhibitors), and LSD for outcomes ranging from psychiatric symptoms to well-being, spirituality and personality. Narrative reviews and a small number of meta-analyses have suggested potential therapeutic benefit and acceptable short-term safety, but a comprehensive quantitative characterisation of post-acute psychological effects across outcome domains remained lacking. Goldberg and colleagues designed this study to fill that gap. The paper reports a systematic review and meta-analysis of experimental studies (randomised controlled trials and single-group pre–post designs) that administered psilocybin, ayahuasca or LSD in controlled settings and measured psychological outcomes at least 24 hours after administration. The stated aims were to quantify post-acute effects across multiple outcome domains, test study-level moderators (psychedelic type, clinical versus non-clinical samples, presence of behavioural support, percentage female), and evaluate adverse effects and risk of bias across the literature.

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Study Details

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