Psychometric validation of the French version of the five-dimensional altered states of consciousness questionnaire (5D-ASC) and associated 11 OAV subscales.
Ewen Kervadec, Pauline Mathieu, Baptiste Fauvel, Lana Strika-bruneau, Ammar Amirouche, Pascale Piolino, Amine Benyamina, Bruno Romeo, Romain Hacquet
Progress in neuro-psychopharmacology & biological psychiatry June 20, 2026 Peer reviewed DOI: 10.1016/j.pnpbp.2026.111770 via PubMed
Summary
The French version of the 5D-ASC questionnaire, used to measure altered states of consciousness from psychedelics, has been psychometrically validated with data from 777 participants. The study found that the 11-subscale solution provided a better fit than higher-order structures, although fit indices were slightly below ideal levels. Internal consistency was high overall, and construct validity was supported. This validation enhances the potential for future research on subjective experiences related to psychedelic therapy in French-speaking populations.
Study at a glance
| Design | psychometric validation |
|---|---|
| Sample size | 777 |
| Population | participants with past naturalistic psychedelic experiences |
| Key finding | The psychometric validation indicates that the French 5D-ASC questionnaire is a reliable and valid tool for measuring altered states of consciousness. |
Abstract
The renewal of psychedelic medicine has garnered significant scientific interest, with large efforts dedicated to the understanding of the complex subjective experiences induced by these substances. The Altered States of Consciousness (ASC) questionnaire represents the most comprehensive instrument for measuring such experiences yet lacks a validated French translation despite its centrality to research. A psychometric validation of the French 5D-ASC and 11 OAV subscales was conducted using data from 777 participants recruited through online platforms. Participants completed the 94-item questionnaire based on a past naturalistic psychedelic experience induced by a classical or non-classical psychedelic substance. Confirmatory factor analysis (CFA) of established factorial structures, multiple-indicator multiple-cause (MIMIC) modeling assessing measurement invariance across substance categories, and comprehensive reliability analyses were used. The 11-subscale solution demonstrated better fit compared to higher-order structures (CFI = 0.882, RMSEA = 0.051, SRMR = 0.061), though comparative fit indices remained marginally below conventional thresholds. Internal consistency was excellent for global scores (α = 0.95) and satisfactory across individual subscales (α = 0.63-0.84). Construct validity was supported by theoretically consistent inter-scale correlations and convergent validity with single-item validators. MIMIC modeling revealed modest differential item functioning but confirmed measurement invariance, with latent factor differences aligning with known pharmacological profiles. This study provides preliminary evidence for the psychometric validity of the French 5D-ASC. These findings enable future research examining the relationship between subjective experience and therapeutic outcomes in francophone contexts, contributing to the international standardization of psychedelic research instruments.