In brief
- An international consortium led by McGill University (Canada) has published the largest joint neuroimaging analysis of psychedelics to date in Nature Medicine.
- By cross-referencing 11 databases from five countries (different healthy-adult samples and over 500 MRI sessions), the team identified a brain pattern shared by LSD, psilocybin, mescaline, DMT, and ayahuasca.
- Of the five substances, LSD and psilocybin were found to produce the most similar brain alterations.
For years, it has been assumed that LSD, psilocybin, and DMT act on the mind in similar ways, but each substance has almost always been studied separately, with small sample sizes (between 10 and 30 volunteers) and different scanning protocols that made it difficult to compare studies. An international team led by neuroscientist Danilo Bzdok of McGill University has now gathered 11 neuroimaging studies from five countries to analyze the effects of five classic psychedelics on the brain using the same statistical criteria. The result, published in April in Nature Medicine, is the identification of a common pattern of brain reorganization shared by all five compounds, with LSD and psilocybin being the most similar to each other.
A brain that crosses its own wires
The analysis, which combined more than 500 functional MRI sessions from different healthy samples, found higher between-network coupling, with more selective and uncertain within-network changes in Bayesian modeling. First, brain networks that normally function as well-defined circuits (for example, the default mode network, associated with self-referential thought) showed variable, selective within-network reductions rather than a uniform loss of cohesion in every network. Second, communication increases between networks that usually remain separate: specifically, between higher-order networks (involved in abstract thought) and sensory networks, such as the visual and somatomotor networks. The authors suggest that this cross-talk between circuits that rarely “speak” to each other could explain why psychedelics so characteristically alter perception and the sense of identity.
Five substances, one neural language
“For the first time, we show that there is a common denominator among drugs that we previously considered completely distinct,” said Bzdok, who co-authored the paper with lead author Manesh Girn. The team emphasizes that despite specific differences between substances (DMT, for example, showed more intense network alterations than the others), LSD and psilocybin behaved with similar patterns and overlapping posterior distributions, without demonstrating identity in the analyzed patterns—a striking finding given that both share the same primary mechanism of action on the 5-HT2A serotonin receptor. The researchers themselves acknowledge limitations: the combined data come from scans with different technical specifications, doses, and scanning times that are not always comparable, and more head movement was recorded in participants under the influence of the drug, a factor that can introduce noise into the measurements.
What this implies
This is a basic mechanism study, not a clinical trial: all participants were healthy volunteers, and finding a shared brain pattern does not in itself equate to demonstrating a therapeutic benefit or comparing the safety of the different substances. Its value lies in offering, for the first time, a common reference point with which to measure future studies—which have until now been isolated and difficult to compare—and in providing a more solid neurobiological foundation for the growing clinical research on psychedelics. Bzdok has noted that findings of this type could fuel the debate, already underway in several countries, about relaxing the regulatory framework that restricts research into these substances, whose legal classification and safety are not established by this healthy-volunteer neuroimaging analysis.
Source
- Girn, M., Bzdok, D. et al. An international mega-analysis of psychedelic drug effects on brain circuit function. Nature Medicine, April 2026.
- McGill University. Largest-ever study of psychedelics could help advance their use in treating mental health disorders. McGill Newsroom, April 7, 2026.
Educational content written from a harm reduction perspective and with respect for individual freedom. It is not a substitute for advice from a healthcare professional and is not intended to encourage or condemn any drug use.
