A single high dose of psilocybin (25 mg) in 28 healthy, psychedelic-naive participants produced anatomical and functional brain changes lasting from one hour to one month. At one month, participants showed increased cognitive flexibility, psychological insight, and well-being. Diffusion tensor imaging revealed decreased axial diffusivity in prefrontal-subcortical tracts, correlating with reduced brain network modularity. Decreased modularity negatively correlated with increased well-being, consistent with depression findings. Increased cortical signal entropy one to two hours after dosing predicted improved well-being at one month, mediated by next-day psychological insight. No effects occurred with a 1 mg placebo dose.
Among Spanish-speaking individuals who have used 5-MeO-DMT, spontaneous re-experiences of the substance's effects—often called reactivations—are relatively common, typically non-distressing, and often positively valenced. The study reports the prevalence of these reactivations and identifies predictors such as higher doses and greater emotional impact during the original experience. Most users describe these residual effects as neutral or positive, contributing to lasting well-being rather than distress.