Development of Japanese Versions of the 4-Item Mystical Experience Questionnaire and 7-Item Challenging Experience Questionnaire.

INTRODUCTION: Interest in therapeutic applications of psychedelics has recently resurged. Mystical-type and challenging experiences that are elicited by psychedelics are commonly assessed using the 30-item Mystical Experience Questionnaire (MEQ-30) and the 26-item Challenging Experience Questionnaire (CEQ), respectively. The brief 4-item MEQ (MEQ-4) and 7-item CEQ (CEQ-7) may reduce respondent burden, but Japanese versions have not yet been developed. This study developed Japanese versions of the MEQ-4 and CEQ-7. METHODS: In translating the MEQ-4 and CEQ-7, our procedures were informed by the recommendations of the "Principles of Good Practice for the Translation and Cultural Adaptation Process for Patient-Reported Outcomes (PRO) Measures: Report of the ISPOR Task Force for Translation and Cultural Adaptation." Separately, experts in psychedelics reviewed semantic nuances and the naturalness and appropriateness of the Japanese wording. Cognitive debriefing was not conducted because recruiting an appropriate Japanese-speaking sample with psychedelic experience was not feasible. RESULTS: The final, approved back-translated versions of the MEQ-4 and CEQ-7 were developed, and the authorized Japanese versions of the MEQ-4 and CEQ-7 were established. CONCLUSIONS: In the present study, Japanese versions of the MEQ-4 and CEQ-7 were developed, enabling more rapid and efficient assessments of mystical and challenging experiences among Japanese speakers. Future studies should evaluate their comprehensibility, interpretability, cultural appropriateness, reliability, and validity in Japanese-speaking samples.