Tolerability, assessment, and prediction of psilocybin-induced altered states of consciousness
Zurich Open Repository and Archive (University of Zurich) 2012 DOI: 10.5167/uzh-164092 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Pooled analysis of double-blind placebo-controlled experimental studies Peer reviewed |
|---|---|
| Sample size | 110 |
| Population | Healthy subjects |
| Intervention | Psilocybin |
| Dose | 45-315 μg/kg body weight |
| Duration | 8-16 month follow-up |
| Topics | LSD Psilocybin Altered states of consciousness |
| Keywords | Hallucinogen Tolerability Mood Consciousness Clinical psychology Psychotherapist |
| Citations | 6 |
| Key findings | Psilocybin is well tolerated in controlled settings, with no lasting negative effects such as flashbacks, psychosis, or drug abuse observed at 8-16 month follow-up. |
Abstract
Since the early 1990s, hallucinogenic drugs, such as psilocybin, have been increasingly used to investigate the neuronal basis of altered states of consciousness and psychosis. Furthermore, renewed interest has emerged in using these drugs as an adjunct to psychotherapy. Nevertheless, the therapeutic and experimental use of these substances is still controversial due to fears of potential harm. Although the experience of many investigators suggests that potential risks are minimal when these drugs are administered in a carefully monitored clinical or research environment, the subjective tolerability of these drugs under these conditions has not yet been evaluated in large samples. The revival of hallucinogen research during the past 20 years has also greatly increased the need for well-validated instruments assessing the the acute subjective effects of these drugs. Although Adolf Dittrich’s questionnaires for the assessment of altered states of consciousness (ASCs) were frequently used for this purpose, especially in Europe, the factorial structure of these questionnaires is not clearly established because previous psychometric investigations have serious methodological limitations. Finally, the effects of hallucinogens are believed to be critically dependent on non-pharmacological variables (e.g., the user’s personality, current mood state and environment), but few empirical studies have investigated several of these predictor variables at a time. Thus, little is known about the order of importance of these variables. To solve these problems, three empirical studies were conducted, all of which were based on pooled data from Prof. Vollenweider’s research group at the University Hospital of Psychiatry in Zurich. Vollenweider’s group was one on the first to restart human hallucinogen research in the early 1990s and since then has collected an amount of data that is unrivaled in the world. In the first study, acute, subacute, and long-term subjective effects of psilocybin were investigated by analyzing the pooled data of eight double-blind placebo-controlled experimental studies. The sample included 110 healthy subjects who had received 1-4 oral doses of psilocybin in a dose range of 45-315 μg/kg body weight. It was found that the effects of psilocybin were generally well tolerated. Most subjects described the experience as pleasurable, enriching, and non-threatening. Strong anxiety and/or dysphoria occurred only in the two highest dose conditions in a relatively small proportion of subjects and in all cases resolved by providing emotional support and without pharmacological intervention. Complaints 24 h after drug intake were mild and mostly included headache and fatigue. Furthermore, follow-up interviews conducted 8-16 months after the psilocybin sessions indicated that all of the subjects were healthy and that none of them had experienced any of the most feared negative consequences of hallucinogen exposure, that is, flashbacks, prolonged psychosis, or subsequent drug abuse.
Comparable studies
Other randomized controlled trials on altered states of consciousness, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Changes in global and thalamic brain connectivity in LSD-induced altered states of consciousness are attributable to the 5-HT2A receptor Healthy human participants | 2018 | Double-blind, randomized, counterbalanced, cross-over study | n = 24 |
| Effective connectivity changes in LSD-induced altered states of consciousness in humans. Healthy participants | 2019 | Double-blind, randomized, placebo-controlled, cross-over study | n = 25 |
| Dose-related effects of salvinorin A in humans: dissociative, hallucinogenic, and memory effects. Healthy hallucinogen-using adults | 2013 | Double-blind, placebo-controlled study | n = 8 |
| High doses of dextromethorphan, an NMDA antagonist, produce effects similar to classic hallucinogens. Healthy volunteers with histories of hallucinogen use | 2012 | Randomized controlled trial | n = 12 |
| A placebo-controlled investigation of synaesthesia-like experiences under LSD. | 2016 | Within-groups placebo-controlled pilot study |
Citations in the library
Cited by 5
- The induction of synaesthesia with chemical agents: a systematic review Frontiers in Psychology 2013
- Replication and extension of a model predicting response to psilocybin. Psychopharmacology November 1, 2019
- Examination of the Phenomenology of the Ibogaine Treatment Experience: Role of Altered States of Consciousness and Psychedelic Experiences. Journal of Psychoactive Drugs 2017
- Assessment of the acute subjective psychedelic experience: A review of patient-reported outcome measures in clinical research on classical psychedelics Journal of Psychopharmacology November 16, 2023
- Differences in Existential Perspectives as a Function of Having a Mystical-Type Experience Journal of Humanistic Psychology March 9, 2023
Cites 64
- Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance Psychopharmacology July 7, 2006
- Pilot Study of Psilocybin Treatment for Anxiety in Patients With Advanced-Stage Cancer Archives of General Psychiatry September 7, 2010
- Human hallucinogen research: guidelines for safety. Journal of Psychopharmacology July 1, 2008
- Psilocybin induces schizophrenia-like psychosis in humans via a serotonin-2 agonist action Neuroreport December 1, 1998
- Psilocybin occasioned mystical-type experiences: immediate and persisting dose-related effects. Psychopharmacology December 1, 2011
and 59 more in the library