A systematic review of 48 studies (14 experimental, 34 observational) covering 2016–2024 found that classic psychedelics—such as psilocybin and ayahuasca—most consistently increase the personality trait Openness and reduce Neuroticism. Changes in Extraversion, Agreeableness, and Conscientiousness were more variable. Microdosing was linked to modest reductions in Neuroticism and higher Absorption. Most studies used the Five-Factor Model. The findings suggest psychedelics can promote lasting personality changes, but contradictory results remain, and future research should combine experimental and naturalistic designs with longer follow-ups.
A systematic review of 16 studies found that ayahuasca has distinct short- and long-term cognitive effects. In the short term, improvements in working memory and cognitive flexibility were observed, linked to neurochemical modulation of cortical networks. Observational studies reported increased empathy and emotion recognition, while experimental studies only found reduced reaction times in social cognition tasks. Long-term studies generally found no neuropsychological deficits, with some reporting improved memory and executive function. The review notes methodological limitations including small sample sizes, varied protocols, and potential learning effects, calling for more controlled, randomized studies.