The Ibogaine Experience Scale (IES): Development and psychometric properties of a multidimensional measure of ibogaine's subjective effects.
Level 4 - case-series / case-control
Cross-sectional psychometric scale development and validation cohort without control group.
PubMed 41082525 · doi:10.1371/journal.pone.0333296
What was done
Researchers developed the Ibogaine Experience Scale (IES) to quantify the subjective and dream-like (oneiric) effects of ibogaine. Based on an initial qualitative study (n = 20) identifying eight domains, a preliminary 144-item version was completed within 48 hours post-treatment by 499 participants across two clinical cohorts: neuropsychiatric treatments (n = 381) and substance use disorder treatments (n = 118). Investigators applied exploratory graph analysis, parallel analysis, iterative item reduction, and semi-confirmatory factor analysis using Robust Unweighted Least Squares to refine the instrument and evaluate its psychometric properties.
What was found
The final 70-item IES resolved into seven factors (Narrative and symbolic visions, Visual changes, Discomfort and challenge, Cosmic/Archetypal Visions, Introspection and personal transformation, Somatosensory hypersensitivity and physiological activation, and Dissociation), accounting for 53.9% of total variance. The model demonstrated strong fit indices (CFI = .991, GFI = .983, RMSR = .041, WRMR = .038) and high overall internal consistency (Cronbach's alpha = .948, McDonald's omega = .946; subscale omegas = .65-.91). Two subscales showed small gender differences.
Why it matters
Existing psychedelic questionnaires do not adequately reflect ibogaine's unique dream-like and somatic phenomenology. The IES provides a validated, domain-specific tool to measure subjective states and evaluate their relationship to therapeutic outcomes in ibogaine research.
Limits
The scale relies on retrospective recall up to 48 hours post-treatment. Generalizability is limited by the absence of replication in independent or cross-cultural cohorts, some subscales showed modest internal consistency (omega as low as .65), and predictive validity for clinical efficacy was not assessed in this report.
Cited by
- context The psychedelic effects of ibogaine typically last for around 22 hours.