Classic psychedelics and personality: An updated systematic review

Area of Science:

• Psychopharmacology and personality science.
• Neuroscience of consciousness and behavior.

Background:

• Classic psychedelics (5-HT2A receptor agonists) have a long history of study regarding their impact on personality traits.
• Hypotheses link psychedelic-induced personality changes to 5-HT2A receptor agonism, but research findings are inconsistent.
• This study updates a previous systematic review (Bouso et al., 2018) with data from 2016-2024.

Purpose of the Study:

• To systematically evaluate the effects of classic psychedelics on personality traits.
• To update existing systematic reviews on psychedelic effects on personality.
• To identify consistent findings and areas for future research.

Main Methods:

• Systematic review of randomized controlled trials, open-label, and observational studies.
• Searched four databases: PubMed, LILACS, PsycINFO, and SciELO.
• Included studies involving classic psychedelics (LSD, psilocybin, ayahuasca, mescaline) and personality assessment instruments, adhering to PRISMA guidelines.

Main Results:

• 48 studies were included from 6043 screened references.
• Consistent findings include increased Openness and decreased Neuroticism, particularly with psilocybin and ayahuasca.
• Changes in Extraversion, Agreeableness, and Conscientiousness were variable; microdosing showed modest Neuroticism reduction and increased Absorption.

Conclusions:

• Classic psychedelics show potential for inducing lasting personality changes, primarily enhancing Openness and reducing Neuroticism.
• Future research should integrate experimental and naturalistic designs with longer follow-ups and diverse personality models.
• Understanding the psychedelic-personality interplay is crucial for guiding clinical applications.