Assessment of the acute subjective psychedelic experience: A review of patient-reported outcome measures in clinical research on classical psychedelics

Abstract

Background: The classical psychedelics psilocybin, peyote, ayahuasca/ N, N-dimethyltryptamine, and lysergic acid diethylamide can temporarily produce altered states of consciousness, characterized by changes in sensory perception, thought, mood, and the sense of self-reality and meaning. It is important to have reliable instruments for quantifying these altered states in trials, due to a plausible link between the acute subjective experience and treatment outcome. Methods: We conducted a review of outcome measures applied in research on classical psychedelics to assess one or more dimensions of the acute subjective psychedelic experience. Three relevant databases were searched electronically. Two reviewers independently conducted article selection and data extraction regarding the instruments, dimensions, geography, population, and psychedelic substance investigated in the included studies. We identified the five most utilized instruments for the most recent 6 years, as well as the five most utilized instruments for each psychedelic. Results: We included 93 papers, which reported on 93 unique trials and utilized 17 different rating scales. Of these, the most utilized were the Five-Dimensional Altered States of Consciousness Questionnaire, visual analog or Likert scales specially developed for the trials, the Hallucinogen Rating Scale, the States of Consciousness Questionnaire, and the Abnormer Psychischer Zustand. Discussion: Considerable variability was found in the instruments utilized in clinical trials on classical psychedelics. We advise and encourage the development of a core outcome set for psychedelic research to enable altered state comparisons across compounds, participants, and settings. We further advise that instruments be designed to assess the “setting” of a psychedelic experience.

Large language models auto-profile conscious awareness changes under psychedelic drug effects

“…Consequently, commonly measured outcomes in classical psychedelics research are con ned to the psychological construct intended to be measured by the selected rating scale. However, some of the most widely used scales in psychedelics research were reported to be highly heterogeneous and have suboptimal construct validity (Hovmand et al, 2024) -in other words, many incumbent questionnaires are not capturing faithfully what humans designed them to measure. Furthermore, biases toward the instrumentalization and measurement of positive feelings may obscure other relevant, not a priori considered experience dimensions such as pathological outcomes like the exacerbation of depressive symptoms.…”

“…Furthermore, biases toward the instrumentalization and measurement of positive feelings may obscure other relevant, not a priori considered experience dimensions such as pathological outcomes like the exacerbation of depressive symptoms. In fact, many popular psychedelic questionnaires simply do not attempt to measure negative experiences (Hovmand et al, 2024), such as the MEQ30 (30 question MEQ), the HRS, the Hood Mysticism Scale (M-scale), and the After the Spiritual Experience Questionnaire (ASEQ). Unlike the broader perspectives typically found in unconstrained testimonies, self-reported questionnaires, wherein responses rely on the speci c questions posed, often lack the capacity to effectively track druginduced shifts in cognitive patterns and sensory experiences, with sensitivity to the speci c contexts.…”

“…Still today, there is only a limited set of established questionnaires that are accepted and commonly used in psychedelic research, aside from the MEQ, which mostly includes the Hallucinogen Rating Scale (HRS), developed according to a similar mystical framework like the MEQ, the States of Consciousness Questionnaire, the 5-Dimensional Altered States of Consciousness questionnaire, the Challenging Experience Questionnaire, the States of Consciousness questionnaire, the Emotional Breakthrough Inventory, and the Psychological Insight Scale (Barrett et al, 2016;Barrett et al, 2015;Dougherty et al, 2023;Hovmand et al, 2024;Maclean et al, 2012;Peill et al, 2022;Roseman et al, 2019;Spriggs et al, 2021). But, what if the incumbent psychological questionnaires for psychedelic experiences are missing some key experiential features that we have not planned to probe, and are therefore routinely evading us?…”