Baseline power of theta oscillations predicts mystical-type experiences induced by DMT in a natural setting

Introduction

Serotonergic psychedelics such as psilocybin, LSD and N,N-dimethyltryptamine (DMT) produce profound alterations in perception, affect and self-awareness, and some of these acute effects appear linked to longer-term psychological benefits. A particular class of subjective responses labelled "mystical-type" experiences — operationalised by instruments such as the MEQ30 (Mystical Experience Questionnaire) — has been associated with therapeutic outcomes in clinical trials of psychedelics. Considerable variability exists in the likelihood of experiencing a complete mystical-type episode across substances and studies, and prior work has identified psychological predictors (for example trait absorption, intentions, and measures of anxiety or attachment) but has left the neurobiological determinants of this variability largely unexplored. Tagliazucchi and colleagues set out to test whether baseline brain activity, measured with electroencephalography (EEG), predicts the magnitude of mystical-type and related subjective experiences induced by inhaled DMT. The study examined source-localised spectral power during an eyes-closed baseline and related those measures to post-DMT questionnaire scores in a sample of participants who self-administered freebase DMT in naturalistic settings. The investigators further tested the robustness of any associations using a machine learning regression approach applied to source theta power across anatomical regions.