MacLean · Journal of psychopharmacology (Oxford, England) 2011 · prospective longitudinal follow-up study · n=?

Mystical experiences occasioned by the hallucinogen psilocybin lead to increases in the personality domain of openness.

Cited 922 times in the scientific literature.

Level 3 - non-randomized controlled study

Prospective longitudinal follow-up study evaluating pre-post personality changes.

PubMed 21956378 · doi:10.1177/0269881111420188 · record verified 2026-08-28

What was done

The authors evaluated changes in the five broad domains of personality (Neuroticism, Extroversion, Openness, Agreeableness, and Conscientiousness) in healthy adults following a high-dose psilocybin session, including longitudinal assessment more than 1 year post-session.

What was found

A high-dose psilocybin session produced significant increases in the personality domain of Openness. In participants who had mystical experiences during the session, Openness remained significantly higher than baseline more than 1 year later. The abstract reports no numerical values, effect sizes, p-values, or baseline scores.

Why it matters

This study provides evidence that a discrete pharmacologically occasioned mystical experience can produce enduring changes in a core personality trait in healthy adults, challenging the view that personality traits are largely fixed after age 30.

Limits

The abstract provides no sample size (n is not reported), no demographic breakdown, and no specific details on control groups or blinding procedures in this specific personality report. No numerical statistics or confidence intervals are provided.

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