Speaker Bio
Yasmin Schmid is a physician specializing in general medicine, clinical pharmacology, and toxicology. She is currently working as a senior physician at the Department of Clinical Pharmacology and Toxicology at the University Hospital Basel, where she has also been a member of Matthias Liechti's psychopharmacology research group for several years. She has been involved in the conduct of several placebo-controlled, double-blind, cross-over studies investigating the effects of various psychoactive substances, including MDMA, LSD, and mescaline, in healthy subjects. Currently, her research focuses on the potential therapeutic applications of LSD, and she is conducting clinical studies involving patients with cluster headaches and patients in palliative care in collaboration with the respective specialists.
ICPR 2024 Abstract
Direct comparison of acute effects of mescaline, psilocybin, and lysergic acid diethylamide (LSD) in healthy volunteers
Theoretical Background and Rationale: Mescaline, a classic serotonergic psychedelic that has been used for centuries, lacks modern data on its acute effects, which have never been directly compared to psilocybin and lysergic acid diethylamide (LSD).
Research Questions and Hypothesis: To directly compare mescaline, psilocybin, and LSD and determine psychoactive-equivalent doses.
Methods and Analysis: In a randomized, double-blind, cross-over study, healthy volunteers received 20mg psilocybin, 100mcg LSD, placebo (all n=32), and 300mg or 500mg mescaline (each n=16). We measured vital signs, assessed subjective effects using visual analog scales (VASs) and the 5 Dimensions of Altered States of Consciousness (5D-ASC) scale, and evaluated adverse effects using the List of Complaints (LC). After each study day, participants described their effects using adjectives to assess qualitative differences in subjective drug experience.Main findings: All three substances induced similar, moderate increases in blood pressure, heart rate, and body temperature. Acute subjective effects of 300mg mescaline were smaller, but subjective effects of 500mg mescaline were comparable to those of 100mcg LSD and 20mg psilocybin on the VAS and 5D-ASC. However, effect duration differed significantly (psilocybin < LSD < mescaline), and only mescaline produced significant subacute adverse effects (12-24 h). Nausea was more frequently reported after mescaline, and participants more often described mescaline as “exhausting”.
Conclusion: Higher doses of mescaline, which appear to be less well tolerated, are required to produce similar psychedelic effects compared to doses of psilocybin and LSD commonly used. However, at psychoactive-equivalent doses, mescaline, psilocybin, and LSD produced qualitatively similar subjective effects.