The Mystical Experience Questionnaire 4-Item and Challenging Experience Questionnaire 7-Item

The Mystical Experience Questionnaire (MEQ-30) and Challenging Effects Questionnaire (CEQ) are two of the most widely used, validated instruments to probe subjective effects of psychedelic drugs. However, these assessments are lengthy and can be a burden to study participants or patients if administered during acute psychedelic effects, after resolution of psychedelic effects when participants are often fatigued, or in studies with multiple other assessments. The development of briefer measures can advance research and patient assessment.

This study developed and assessed the validity of brief versions of the MEQ-30 and CEQ (MEQ-4 and CEQ-7) using data collected online from individuals reporting psychedelic use with therapeutic intent in nonstudy settings (N = 1160). Respondents completed full and brief versions as well as mood questionnaires indexing mental health symptoms before their psychedelic experience and now.

Full and brief version total scores showed strong correspondence for the MEQ (r = 0.89) and CEQ (r = 0.90). Brief versions also showed strong correspondence to full-scale subscale scores. MEQ and CEQ scores were higher for classic psychedelics (e.g., lysergic acid diethylamide, psilocybin) than for 3,4-Methylene-dioxymethamphetamine in this sample with both full and brief versions, consistent with previous full-version findings showing drug and dose-related differences using the MEQ. Also consistent with prior findings, higher mystical experience scores on both full and brief MEQ versions were associated with greater reductions in depression and anxiety, whereas challenging experiences on both full and brief CEQ versions showed limited association with changes in mental health variables.

The notably strong association of brief scales with full versions combined with associations with therapeutic outcomes provide initial support for the MEQ-4 and CEQ-7. These findings, combined with substantial reductions in participant/patient burden, support the use of the MEQ-4 and CEQ-7 for a wide variety of research and patient treatment settings.