Validation of a French Version of the Mystical Experience Questionnaire with Retrospective Reports of the Most Significant Psychedelic Experience among French Users.

Mystical experiences triggered by psychedelic drugs predict symptom reduction in various psychiatric disorders, and increased well-being in healthy individuals. This work aimed at validating a French version of a tool used to measure mystical experiences: the Revised Mystical Experience Questionnaire-30 items (MEQ30). Construct validity, internal consistencies, concurrent, discriminant, and predictive validities of the French MEQ30 were examined using data about the most significant psychedelic experience of 320 French individuals. Results showed that the original four-factor (i.e., mystical, positive mood, transcendence, and ineffability) structure fit the data best, with good to excellent statistical indices. Total French MEQ30 score was strongly associated with subjective ratings of the mystical (i.e., mystical, spiritual, or religious, and personally significant) and drug intensity-related qualities of the experience, but not with non-mystical (i.e., fun, inebriating, and easy) qualities. Moreover, French MEQ30 score was a significant predictor of subjective positive changes in psychological well-being, relations with self and others, feeling of proximity or connection with nature, and creativity, whereas drug intensity-related and non-mystical qualities of the experience were not, or were only weakly associated with such changes. This French version of the MEQ30 seems to be an appropriate tool for measuring mystical experiences among French speaking individuals.