A study has found that a single high dose of psilocybin can lead to physical changes in the human brain.
The study, which is in pre-print and has not yet been peer-reviewed, involved 28 healthy participants who had no prior experience with psilocybin or other psychedelics.
Participants were first given a 1mg placebo dose of psilocybin before being given a 25mg dose one month later.
Results from electroencephalography (EEG), functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) recordings were analysed to assess if the human brain underwent any physical changes after consuming psilocybin.
The results showed that anatomical and functional brain changes were detected from one hour to one month after the administration of the 25mg dose of psilocybin in all subjects, changes that were not seen after the 1mg dose.
While numerous studies have shown that psilocybin can produce profound psychological changes in humans, this is the first study to show that the brain is physically altered after consumption.
In a post on X (Twitter), Dr Robin Carhart-Harris explained that the physical changes observed were in two prefrontal cortex to sub cortex tracts, which became more compact after 1 month following the 25mg dose. Add that there was “no change after placebo. We don’t know what it means but it was a solid change.”
The brain contains cells that stretch across it like wires or cables. A fat collection of cables from the front to the middle looked thinner or more tightly packed one month after people took a big dose of magic mushroom powder. We don’t know if it’s a good or bad thing but on…
— Robin Carhart-Harris (@RCarhartHarris) October 16, 2024
The results echo previous studies finding that single doses of psilocybin can alter the brain. In 2021, a groundbreaking study by researchers at Yale University found that psilocybin given to mice increased the density and size of dendritic spines, nerve cells that aid in the transmission of information between neurons in the brain.
Behavioural analysis after 1mg and 25mg psilocybin
In the current study, increases in cognitive flexibility, psychological insight, and well-being were seen one month after the 25mg dose of psilocybin. All but one participant rated their high-dose experience with psilocybin as the single most unusual conscious state of their entire lives. The single exception rated it within their top five most unusual.
“The present work sheds important new light on human brain changes after first-time high-dose psilocybin,” the authors said in the pre-print. Adding that “between-subject confirmatory studies are now required to examine the reliability of these novel findings.”
