Classic psychedelics are linked to lasting increases in openness and reductions in neuroticism, with effects shaped by mystical experiences and ego dissolution

Classic psychedelics are associated with small but lasting increases in openness and decreases in neuroticism after use, according to a systematic review and meta-analysis of longitudinal studies. Personality changes appear strongest when experiences include mystical-type effects, emotional breakthrough, or ego dissolution. The evidence pool covers compounds such as psilocybin, LSD, ayahuasca, DMT, and mescaline across clinical and non-clinical settings. Across studies, neuroticism tended to decline while openness rose, and some changes persisted for weeks or months. Extraversion, agreeableness, and conscientiousness showed less consistent shifts. Set, setting, dose, and the subjective intensity of the experience likely shape whether these traits change in durable ways. The findings support the view that psychedelics can alter relatively stable personality dimensions, but small samples, heterogeneous methods, and limited long-term follow-up keep the overall certainty moderate rather than definitive.