DMT plus harmine changes the pattern of brain activity states on EEG in healthy adults

The question

Does an ayahuasca-inspired combination of DMT and harmine change the way the brain moves between brief, recurring patterns of electrical activity?

What they did

Twenty-five healthy volunteers each took part in three separate testing days in random order: a DMT and harmine formulation (DMT given through the nose, harmine held in the cheek), harmine on its own, and a placebo. Neither participants nor researchers knew which was given on which day. Brain activity was recorded with EEG, which measures electrical signals from the scalp. The researchers used “microstate” analysis, which breaks EEG into very short, repeating patterns of activity across the scalp, and looked at these near the peak of the drug effect.

What they found

Compared with harmine alone and with placebo, the DMT and harmine combination was linked to shorter-lasting microstates, more of them occurring, and greater complexity in the patterns. Statistical analysis of how one state followed another showed that the sequence of transitions became less random under DMT and harmine. The authors describe this as a more diverse but also more predictable repertoire of brain states, consistent with theories that psychedelics increase signal diversity and flexibility in brain dynamics.

The fine print

This was a small study of 25 healthy volunteers, so the results may not apply to people with mental health conditions. The outcomes are brain-activity measures, not symptoms, wellbeing or any clinical benefit. Blinding is difficult to maintain when a psychedelic produces obvious effects. The abstract does not report the doses, effect sizes or safety data, and this summary is based on the abstract alone.

What it means

In healthy volunteers, a DMT and harmine formulation shifted the timing and ordering of brief brain activity states measured by EEG. This adds detail to how psychedelics change brain dynamics, but it says nothing about treatment effects.

Evidence grade: Moderate. A double-blind, placebo-controlled randomized study in which each person received all three conditions, but with only 25 participants and brain-activity measures rather than health outcomes.

This summary is based on the study’s published abstract.