Psychedelics research is booming, with many research labs seeking cheaper, more effective alternative drug treatments to mental health conditions like depression and schizophrenia. But pharmaceutical innovation requires bigger studies with more consistent results. Our international team used AI to analyze data from over 500 brain scans (10 times more than any previous efforts) for the world’s largest study on the effects of psychedelics on brain function in humans.

In our paper, published in the journal Nature Medicine, we found that psilocybin, LSD, mescaline, DMT and ayahuasca all act in a similar way: they flatten functional hierarchies and allow isolated brain areas to communicate. Our findings lay a new foundation on which to build the next generation of drug discovery efforts to effectively tackle the world’s growing mental health challenges.

Building the world’s largest dataset

Despite huge economic incentives, the existing research data on psychedelics is fragmented across an informal network of research labs across the world that often focus on a single molecule and small cohorts. To build on these findings and speed up potential breakthroughs, we gathered the best psychedelics researchers on the planet and pooled data from 500 brain scanning sessions across dozens of labs in North America, South America, and Europe. 

We started by unifying inconsistent MRI data through local analytical protocols before pooling it at Mila. We then applied Bayesian meta-analysis to neuroscience to find patterns in the data with AI, creating a probabilistic map that quantifies confidence in observed brain changes instead of offering binary conclusions (e.g. increased communication between the emotional system and advanced cortex regions).

Anarchy in the brain order

Our systematic mega-analysis revealed that the five different psychedelic drugs we studied all share a similar effect: they break down the functional coherence of highly organized systems and systematically flatten usual hierarchies among brain networks.

Under the influence of psychedelics, areas of the brain that are usually isolated start communicating with one another, challenging the brain's natural top-down processing structure. This allows deep information-generating areas to take over the visual cortex and produce hallucinations, for instance.

New Perspectives

Our AI-powered, large-scale meta-analysis on the effects of psychedelic drugs on the human brain disrupts classic pharmacological methods that focus narrowly on how individual drugs bind to specific receptors like serotonin or dopamine. There is something about how raw drug pharmacology relates to changes in conscious awareness that we have not understood yet. But AI might be able to help us study this relationship.

By proving that varied molecules all share a common macroscopic effect, this large-scale study deepens our understanding of the physical effects of psychedelics and provides crucial data to inspire the next wave of psychedelic drug innovation.