Tim Hirschfeld, BSc

Psychotropic Substances Research Group, Charité Universitätsmedizin, Berlin

How it feels to be on: Psilocybin, Lysergic Acid Diethylamide (LSD), Salvia Divinorum, Dimethyltryptamine (DMT) or Ketamine


Altered states of consciousness induced by psychoactive substances constitute a research opportunity to relate changes in phenomenological states to underlying biophysical mechanisms. We performed linear meta-regression analyses on psychometric data to establish dose-response relationships for the effects induced by the administration of Psilocybin, Lysergic Acid Diethylamide (LSD), Salvia Divinorum, Dimethyltryptamine (DMT) and Ketamine. The present analyses are based on data collected in the Altered States Database (Schmidt & Berkemeyer, 2018), which contains psychometric data extracted from articles published in MEDLINE-listed journals until 2019. The utilized data were assessed with the Hallucinogen Rating Scale (Strassman, 1994) and both versions of the Altered States of Consciousness Rating Scale: 5D-ASC (Dittrich et al., 2006, 2010) and 11D-ASC (Studerus et al., 2010). The Robust Variance Estimation Framework by Hedges et al. (2010) was used to account for small sample sizes and dependent effect sizes, as implemented in the R package robumeta. Regression analyses for dose-response relationships were conducted for each dimension/factor of the given questionnaires allowing simple visualization in spider plots. Subjective experiences are not only determined by dosage, but also by individual differences and environmental factors, therefore the utilized data do not necessarily generalize to recreational usage, as data stem from laboratory experiments. Nevertheless, these results could serve as a general reference when the assessed substances are used in experimental or clinical research to compare expected and observed subjective experiences in study participants.


Tim Hirschfeld is a Public Health student at the Berlin School of Public Health and part of the Psychotropic Substances Research Group at the Charité – Universitätsmedizin Berlin. He received his bachelor’s degree in Health Promotion from the University of Applied Sciences in Fulda, after investigating the efficacy of Ayahuasca in patients with major depressive disorder and comorbid mental disorders. His main research interests are the long-term effects of psychedelic substances on the quality of life and harm reduction strategies in recreational substance use.



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