The Ibogaine Experience Scale (IES): Development and psychometric properties of a multidimensional measure of ibogaine’s subjective effects
PLoS ONE – October 13, 2025
Source: OpenAlex
Summary
The Ibogaine Experience Scale (IES) emerged from a study involving 499 participants, revealing seven distinct factors that encompass ibogaine's unique subjective effects. These factors explain 53.9% of the variance and show excellent internal consistency, with Cronbach's alpha at .948. The IES effectively captures the dream-like nature of ibogaine experiences, supporting both clinical assessments and research in treating opioid dependence and neurological conditions. Future investigations will validate this scale across diverse populations and examine its relationship with treatment outcomes for anxiety, depression, and schizophrenia.
Abstract
Ibogaine, an indole alkaloid derived from the root bark of Tabernanthe iboga, has long been used in traditional Bwiti healing rituals and shows promise for treating opioid dependence and neurological conditions, but existing psychometric tools fail to capture its distinctive subjective/oneiric (dream-like) effects. To address this gap, we developed the 70-item Ibogaine Experience Scale (IES) through an iterative process informed by a prior qualitative study (n = 20) that identified eight experiential domains. A preliminary 144-item version was completed on site with a mobile device within 48 hours of treatment by 499 participants across two clinical settings-cohort neuropsychiatric treatments (n = 381) and substance use disorder treatments (n = 118). We employed exploratory graph analysis, parallel analysis on polychoric correlations, and iterative item-reduction (Gulliksen's Pool, MIREAL, MSA) to refine the scale. Semi-confirmatory factor analysis used Robust Unweighted Least Squares (RULS) with LOSEFER correction, oblimin rotation, and multiple fit indices (CFI, NNFI, GFI, AGFI, RMSR, WRMR). Cronbach's α, McDonald's ω, H indices, EAP reliability, FDI, ORION, SR, and EPTD assessed internal consistency and factorial quality. The final structure comprises seven factors-Narrative and symbolic visions; Visual changes; Discomfort and challenge; Cosmic/Archetypal Visions; Introspection and personal transformation; Somatosensory hypersensitivity and physiological activation; Dissociation-explaining 53.9% of variance, with excellent fit (CFI = .991; GFI = .983; RMSR = .041; WRMR = .038) and high internal consistency (α = .948; ω = .946; subscale ω = .65-.91). Two subscales exhibited small gender effects. The IES provides a reliable, phenomenologically rich instrument for quantifying ibogaine's distinctive subjective effects. It supports research and clinical assessment by capturing the multidimensional, oneiric/dream-like nature of the ibogaine experience. Future work should confirm this structure in independent, culturally diverse cohorts and explore predictive links between IES domains and therapeutic outcomes.