A single dose of psilocybin produced lasting shifts in brain activity and possible structural changes detectable up to one month later, according to a new study from researchers at UC San Francisco and Imperial College London.
The study, published in Nature Communications, gave 28 healthy adults who had never used psychedelics either a 1 mg placebo dose or a 25 mg dose of psilocybin. Researchers tracked brain activity with EEG during the sessions and followed up with fMRI and diffusion tensor imaging one month later.
Brain entropy, or the variety of neural activity, rose sharply within 60 minutes of the higher dose. One month afterward, scans showed denser neural tracts with greater integrity, a pattern opposite to typical age-related changes.
Participants reported greater psychological insight the day after the 25 mg dose, and those with the largest entropy increases showed the strongest gains in well-being four weeks later. Cognitive flexibility also improved at the one-month mark.
Senior author Robin Carhart-Harris said the data indicate that the psychedelic experience itself drives later mental health benefits. First author Taylor Lyons noted that the changes appear to loosen entrenched patterns of thought.
