Personality changes following first-time psychedelic use in college students in Germany

Psychedelics may influence personality traits, but longitudinal evidence on first-time use outside clinical settings remains limited. We followed 102 first-time psychedelic users and 1066 never-users over one year among Berlin university students. Personality was assessed with the Big Five Inventory at baseline and follow-up. Linear mixed-effects models showed small relative increases in Openness and decreases in Conscientiousness among first-time users. After adjustment for age, sex, income, psychiatric diagnosis, and baseline substance-use burden, estimates were attenuated but directionally similar (Openness: beta = 0.19, SE = 0.10, p = 0.06; Conscientiousness: beta = -0.20, SE = 0.10, p = 0.05; FDR-adjusted p = 0.16 for both). Change was not clearly different from first-time users of other illicit substances. In exploratory moderation analyses, first-time users with psychiatric diagnoses showed larger Neuroticism reductions. Findings suggest small personality changes after first-time psychedelic use, with limited causal interpretability.