Scientific Reports
September 25, 2023
Rebecka Bremler, Nancy Katati, Parvinder Shergill et al.
102 citations
Negative psychological responses to psychedelics lasting more than 72 hours are real and can include new psychiatric diagnoses or worsened symptoms. In a sample of 32 individuals who completed an online questionnaire, 37.5% received a new psychiatric diagnosis after their psychedelic experience, and 87% experienced anxiety symptoms. Deeper interviews with 15 of the most severe cases revealed potential causes: unsafe environments, unpleasant acute experiences, prior psychological vulnerabilities, high or unknown drug doses, and young age. The findings cannot estimate how common such harms are due to the small, selective sample and study design focused only on negative outcomes.
April 12, 2023
Rebecka Bremler, Nancy Katati, Parvinder Shergill et al.
12 citations
preprint
Negative psychological responses to psychedelics, lasting at least 72 hours, are real and can include new psychiatric diagnoses or worsened symptoms, particularly anxiety. In a sample of 32 individuals who reported such experiences, 37.5% received a new psychiatric diagnosis after psychedelic use, and 87% experienced new or worsened anxiety. In-depth interviews with 15 of the most severe cases suggested that contributing factors include unsafe environments, unpleasant acute experiences, prior psychological vulnerabilities, high or unknown drug doses, and young age. The study's small, self-selected sample means these findings cannot estimate how common such harms are.
Psychedelic Medicine
December 15, 2025
M. Mehmood, Rebecka Bremler, M. Spriggs et al.
People who experienced more adverse childhood experiences (ACEs) showed greater improvements in mental well-being, reductions in experiential avoidance, and lower trait anxiety after participating in psychedelic ceremonies compared to those with fewer ACEs. Higher ACE scores were also linked to stronger emotional breakthrough and mystical experiences during the psychedelic session. Among individuals with four or more ACEs, those who reported stronger mystical or emotional breakthrough experiences had better well-being at two and four weeks afterward, and mystical experiences were linked to less experiential avoidance while emotional breakthrough was linked to less anxiety at four weeks. However, the acute experiences did not significantly change how ACEs affected mental health outcomes overall.