Classification schemes of altered states of consciousness.
Larry Douglas Fort, Cyril Costines, Marc Wittmann, Athena Demertzi, Timo Torsten Schmidt
Neuroscience & Biobehavioral Reviews August 1, 2025 DOI: 10.1016/j.neubiorev.2025.106178 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Review Peer reviewed |
|---|---|
| Topics | Altered states of consciousness Philosophy of mind |
| Keywords | Classification Altered mental states Modified consciousness Neuroscience brain science Neural studies Psychedelics hallucinogens Entheogens |
| Citations | 14 |
| Key findings | Classification schemes for altered states of consciousness fall into three groups—state-based, method-based, and neuro/physio-based—and clustering concepts from state-based schemes can aid future clinical research. |
Abstract
In recent years, there has been a renewed interest in the conceptual and empirical study of altered states of consciousness (ASCs), induced pharmacologically or otherwise, driven by their potential clinical applications. To draw attention to the rich history of research in this domain, we review prominent classification schemes that have been proposed to introduce systematicity into the scientific study of ASCs. The reviewed ASC classification schemes fall into three groups according to the criteria they use for categorization: (1) based on the nature, variety, and intensity of subjective experiences (state-based), including conceptual descriptions and psychometric assessments, (2) based on the technique of induction (method-based), and (3) descriptions of neurophysiological mechanisms of ASCs (neuro/physio-based). By comparing and extending existing classification schemes, we can enhance efforts to identify neural correlates of consciousness, particularly when examining mechanisms of ASC induction and the resulting subjective experiences. Furthermore, an overview of what defining ASC characteristics different authors have proposed can inform future research in the conceptualization and quantification of ASC subjective effects, including the identification of those that might be relevant in clinical research. This review concludes by clustering the concepts from the state-based schemes, which are suggested for classifying ASC experiences. The resulting clusters can inspire future approaches to formulate and quantify the core phenomenology of ASC experiences to assist in basic and clinical research.
Comparable studies
Other narrative reviews on altered states of consciousness, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| The Subjective Effects of Psychedelics Are Necessary for Their Enduring Therapeutic Effects. | 2020 | Review | |
| Psychobiology of Altered States of Consciousness. | 2005 | Review | |
| Intrinsic Brain Activity in Altered States of Consciousness | 2008 | Review | |
| Dynamic functional connectivity and brain metastability during altered states of consciousness | 2017 | Review | |
| A default mode of brain function in altered states of consciousness. | 2013 | Review |
Citations in the library
Cited by 12
- Key competencies for psychedelic treatment in real-world mental health care settings. General Hospital Psychiatry 2025
- Integrating the Mystical Experience Questionnaire Into a Broader Psychometric Framework: English Validation of the Psychedelic Experience Scale and Comparison of Psilocybin and LSD Sessions Across Two Controlled Settings. International Journal of Methods in Psychiatric Research June 1, 2026
- Understanding mystical experiences through the lens of entropy: introduction to the special issue on ‘mystical entropy’ Philosophical Psychology April 27, 2026
- The Neurophenomenology of a Self-Induced Transcendental Visionary State: A Case Study. Neuroimage February 4, 2026
- États modifiés de la conscience : Revue systématique PRISMA et preuve de concept Cortica December 15, 2025
and 7 more in the library
Cites 121
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and 116 more in the library