Human brain changes after first psilocybin use
Carhart-Harris, R. L., Douglass, H., Erritzoe, D., Espasiano, L., Gazzaley, A., Girn, M., Godfrey, K., Hampshire, A. D. G., Kerkelä, L., Kettner, H., Lyons, T., Mediano, P. A. M., Nutt, D. J., Oestreich, L., Pagni, B. A., Rosas, F. E., Roseman, L., Sharif, F., Spriggs, M. J., Timmermann, C., Trender, W., Wall, M. B., Zeifman, R. J.
This pre-print, placebo-controlled, within-subjects neuroimaging study (n=28) of psychedelic-naive participants finds that a single high dose of psilocybin (25mg) produces anatomical and functional brain changes from one hour to one month post-dosing. These include decreased axial diffusivity in prefrontal-subcortical tracts, reduced brain network modularity (linked to improved well-being), and increased cortical signal entropy that predicts long-term psychological benefits. These effects were not observed with a 1 mg placebo dose.
Abstract
Psychedelics have robust effects on acute brain function and long-term behavior but whether they also cause enduring functional and anatomical brain changes is unknown. In a placebo-controlled, within-subjects, electroencephalography, and magnetic resonance imaging study in 28 healthy, entirely psychedelic-naive participants, anatomical and functional brain changes were detected from one-hour to one-month after a single high-dose (25 mg) of psilocybin. Increases in cognitive flexibility, psychological insight, and well-being were seen at one-month. Diffusion imaging done before and one-month after 25mg psilocybin revealed decreased axial diffusivity bilaterally in prefrontal-subcortical tracts that correlated with decreased brain network modularity over the same time period. Decreased modularity also correlated with improved well-being. Increased cortical signal entropy at 1- and 2-hours post-dosing predicted improved psychological well-being at one-month. Next-day psychological insight mediated the entropy to well-being relationship. All effects were exclusive to 25mg psilocybin; no effects occurred with a 1mg psilocybin ‘placebo’ dose.