Neuroimaging & Brain MeasuresPersonality & Trait FactorsAyahuasca

Long-term use of psychedelic drugs is associated with differences in brain structure and personality in humans

This study (n=44) investigated the long-term effects of regular ayahuasca use on the human brain. Structural MRI showed that regular ayahuasca users had significantly different cortical thickness (with thinning in the posterior cingulate cortex) when compared to non-users. Although direct causation cannot be established, these data suggest that regular use of psychedelic drugs could potentially lead to structural changes in brain areas supporting attentional processes, self-referential thought, and internal mentation.

Authors

  • Jordi Riba
  • Jamie Hallak
  • Sidarta Ribeiro

Published

European Neuropsychopharmacology
individual Study

Abstract

Psychedelic agents have a long history of use by humans for their capacity to induce profound modifications in perception, emotion and cognitive processes. Despite increasing knowledge of the neural mechanisms involved in the acute effects of these drugs, the impact of sustained psychedelic use on the human brain remains largely unknown. Molecular pharmacology studies have shown that psychedelic 5-hydroxytryptamine (5HT)2A agonists stimulate neurotrophic and transcription factors associated with synaptic plasticity. These data suggest that psychedelics could potentially induce structural changes in brain tissue. Here we looked for differences in cortical thickness (CT) in regular users of psychedelics. We obtained magnetic resonance imaging (MRI) images of the brains of 22 regular users of ayahuasca (a preparation whose active principle is the psychedelic 5HT2A agonist N,N-dimethyltryptamine (DMT)) and 22 controls matched for age, sex, years of education, verbal IQ and fluid IQ. Ayahuasca users showed significant CT differences in midline structures of the brain, with thinning in the posterior cingulate cortex (PCC), a key node of the default mode network. CT values in the PCC were inversely correlated with the intensity and duration of prior use of ayahuasca and with scores on self-transcendence, a personality trait measuring religiousness, transpersonal feelings and spirituality. Although direct causation cannot be established, these data suggest that regular use of psychedelic drugs could potentially lead to structural changes in brain areas supporting attentional processes, self-referential thought, and internal mentation. These changes could underlie the previously reported personality changes in long-term users and highlight the involvement of the PCC in the effects of psychedelics.

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Research Summary of 'Long-term use of psychedelic drugs is associated with differences in brain structure and personality in humans'

Introduction

Psychedelic substances have been used across cultures to produce profound alterations in perception, emotion and cognition, and contemporary interest has focused both on their acute neural effects and their potential therapeutic uses. Molecular studies indicate that classic psychedelics acting as 5-HT2A agonists can trigger expression of immediate early genes and increase brain-derived neurotrophic factor, processes linked to synaptic plasticity; however, the long-term impact of repeated psychedelic exposure on human brain structure remains poorly characterised. Bouso and colleagues set out to test whether sustained use of a psychedelic preparation—ayahuasca—relates to differences in cortical structure and to psychometric and neuropsychological measures. They hypothesised that repeated psychedelic exposure would correlate with changes in cortical thickness and therefore compared chronic ayahuasca users with matched controls on MRI-derived cortical thickness (CT), personality, psychopathology and cognitive performance.

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Study Details

References (12)

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Long-term use of psychedelic drugs is associated... — Research Summary & Context | Blossom