Study: Psilocybin Produces Lasting Changes in Brain Structure and Function
Researchers from UC San Francisco and Imperial College London have found that a single dose of psilocybin, the active compound in magic mushrooms, can cause physical brain changes that persist for at least a month. The study, published in Nature Communications, observed lasting increases in neural tract density and brain entropy.
Methods and Design
The study involved 28 healthy adults with no prior psychedelic use and no diagnosed mental health conditions. The researchers employed multiple techniques to assess psilocybin's effects: electroencephalography (EEG) for brain electrical activity, functional magnetic resonance imaging (fMRI), and diffusion tensor imaging (DTI) for neural connectivity.
The experiment was conducted in two phases. Initially, participants received a 1 mg dose of psilocybin, considered a placebo. Later, they received a 25 mg dose, sufficient to produce a powerful psychedelic experience. Measurements were taken before dosing, during the peak effects, and one month after each dose.
Brain Entropy Increase
Within 60 minutes of the 25 mg dose, EEG recordings showed a rise in brain entropy, indicating a broader range of neural activity. Larger entropy increases were associated with greater emotional insight the following day. Participants reporting higher insight also showed better well-being one month later.
Structural Changes Over Time
One month after the full dose, DTI revealed denser neural tracts with greater integrity, reversing patterns typically associated with aging. The researchers emphasize that further studies are needed to interpret these structural findings fully.
Participant Experiences
The day after the 25 mg dose, 27 of 28 participants described the experience as the "single most" unusual state of consciousness they had ever encountered; the remaining participant ranked it among the top five. Psychological insight measures were significantly higher after the full dose compared to placebo. Well-being improved at two and four weeks, and cognitive flexibility test scores were higher one month later.
Researcher Insights
Senior author Robin Carhart-Harris stated: "Psychedelic means 'psyche-revealing' – our data suggests that experiences of psychological insight relate to an entropic quality of brain activity and how both are involved in subsequent improvements in mental health." First author Taylor Lyons added: "Psilocybin seems to loosen up stereotyped patterns of brain activity and give people the ability to revise entrenched patterns of thought."
