Journal of Psychopharmacology
March 4, 2021
Tim Hirschfeld, Timo T Schmidt
90 citations
Psilocybin, the psychoactive compound in magic mushrooms, intensifies almost all characteristics of altered states of consciousness measured by standard questionnaires. A meta-analysis of data from the Altered States Database found that higher psilocybin doses correlated with stronger ratings of perceptual alterations and positively experienced ego dissolution, while measures of challenging experiences showed only small effects and were barely influenced by dose. These dose-response relationships were established in controlled laboratory experiments with healthy participants and patient groups, and may not apply to recreational use because individual and environmental factors also shape subjective experiences.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
October 1, 2023
Tim Hirschfeld, Johanna Prugger, Tomislav Majić et al.
24 citations
LSD produces a sigmoid-like increase in altered states of consciousness that plateaus around 100 micrograms, with the strongest effects on perception and illusory imagination, followed by positive ego-dissolution. Anxiety and dread of ego dissolution show only small effects. Considerable variability in most measures indicates that non-pharmacological factors also shape subjective experiences. These dose-response relationships can serve as general references for future research to compare observed with expected effects and to explore phenomenological differences between psychedelics.
bioRxiv (Cold Spring Harbor Laboratory)
June 11, 2020
Tim Hirschfeld, Timo Torsten Schmidt
8 citations
preprint
Psilocybin, the active component of magic mushrooms, produces subjective experiences that vary with dose. A meta-analysis of data from the Altered States Database examined dose-response relationships for three standardized questionnaires: the Altered States of Consciousness Rating Scale, the Mystical Experience Questionnaire (MEQ30), and the Hallucinogen Rating Scale (HRS). Ratings on most dimensions and subscales correlated positively with psilocybin dose. Because individual differences and environmental factors also influence subjective experiences, these findings from controlled laboratory experiments may not generalize to recreational use. The analysis provides a reference for expected subjective effects in experimental and clinical psilocybin research.
Progress in neuro-psychopharmacology & biological psychiatry
April 2, 2025
Simon Reiche, Tim Hirschfeld, Anna Lena Gröticke et al.
5 citations
People who have used psychedelics such as psilocybin, LSD, or ayahuasca a mild to moderate number of times over their lives show broadly equivalent neuropsychological performance to non-users, but with a modest advantage in executive functions, particularly cognitive flexibility as measured by the Wisconsin Card Sorting Test (WCST). In matched-pair analyses, users performed better on the WCST, and dose-response analyses within the user group found that greater lifetime use was positively associated with fewer total errors, perseverative responses, perseverative errors, non-perseverative errors, and more conceptual level responses. The study did not find any negative associations between sporadic psychedelic use and cognition.
bioRxiv (Cold Spring Harbor Laboratory)
November 7, 2022
Tim Hirschfeld, Johanna Prugger, Tomislav Majić et al.
4 citations
preprint
Lysergic acid diethylamide (LSD) produces a sigmoid-like increase in altered states of consciousness, with effects plateauing around 100 micrograms. The strongest changes involve perception and illusory imagination, followed by positively experienced ego-dissolution, while anxiety and dread of ego dissolution show only small effects. Considerable variability in responses highlights the importance of non-pharmacological factors. These dose-response relationships can serve as references for future research on LSD.
May 3, 2024
Kasey Devitt, Johanna Prugger, Tim Hirschfeld et al.
preprint
The Altered States Database (ASDB) is an open data initiative that collects psychometric questionnaire data on subjective experiences from pharmacologically and non-pharmacologically induced altered states of consciousness. The current update adds data published in 2023, identified through a systematic literature review following PRISMA guidelines. Of 454 items screened, 13 journal articles were included: ten report on the 11-ASC, eight on the 5D-ASC, six on the MEQ-30, and one on the PCI. The ASDB now contains data on 22 substances and 13 techniques, from 198 journal articles and 847 datasets, accessible online.