Psilocybin did not shift personality or symptoms, but did shift reported personal values

The question

Does a single dose of psilocybin change personality traits, psychiatric symptoms or personal values in healthy people, and does the intensity of the drug experience explain any changes?

What they did

Researchers re-analyzed data from a phase I, double-blind, randomized, placebo-controlled trial in 89 healthy volunteers. Participants received a single dose of 10 mg psilocybin (30 people), 25 mg psilocybin (30 people), or an inactive placebo (29 people). They completed questionnaires on personality, psychiatric symptoms and personal values 8 days and 85 days later, plus a computer task measuring mental flexibility at day 8. The team also tested whether features of the acute drug experience, such as feelings of boundlessness or merging with the world, statistically explained any changes.

What they found

There were no differences between the psilocybin groups and placebo on the personality questionnaire, the psychiatric symptom checklist, or the mental flexibility task. Both psilocybin groups reported larger absolute changes in personal values than placebo at both day 8 and day 85. The “oceanic boundlessness” part of the acute experience partly explained those value changes, and fully or partly explained differences on several value subscales. Altered hearing during the session explained the difference on one subscale.

The fine print

This was an exploratory secondary analysis, not the trial’s main question, and the authors call the findings tentative. The sample was small (about 30 people per group) and made up of healthy volunteers, so results may not apply to people with mental health conditions. Value and personality outcomes were self-reported, and the “absolute change” measure captures movement in any direction, not improvement. Follow-up ended at 85 days, and this summary is based on the abstract only.

What it means

In healthy volunteers, a single psilocybin dose did not measurably change personality, psychiatric symptoms or cognitive flexibility, but people did report shifts in what they valued, and those shifts tracked with how profound the acute experience felt.

Evidence grade: Low. This is an exploratory secondary analysis of a small placebo-controlled trial, with multiple outcomes tested and no correction described in the abstract.

This summary is based on the study’s published abstract.