Multidimensional Ego-Dissolution Assessment (MEDA): Scale Development and Substance-Specific Comparisons

Rationale: Ego-dissolution represents a key therapeutic mechanism in psychedelic-assisted therapy, yet current measurement approaches may inadequately capture its multidimensional nature. Objective: To develop and validate the Multidimensional Ego-Dissolution Assessment (MEDA) and examine substance-specific patterns across classical psychedelics. Methods: Items from three validated scales (Ego-Dissolution Inventory, Mystical Experience Questionnaire, 5D-Altered States of Consciousness) were compiled into a 34-item measure. Exploratory factor analysis was conducted on responses from 207 participants reporting profound experiences with ayahuasca (n=51), DMT (n=28), LSD (n=52), or psilocybin (n=76). Results: Factor analysis revealed a robust 6-factor structure: Dissolving of Identity (α=.94), Experiences of Eternity (α=.89), Dissolving of Physical Body (α=.80), Dissolving into Environment (α=.85), Clarity about Life and Purpose (α=.78), and Pleasure (α=.78). Two distinct substance clusters emerged: ayahuasca/DMT produced significantly higher dissolution scores than LSD/psilocybin across four factors, while all substances showed equivalent high scores on insight and pleasure dimensions. Dosage showed no significant effects. Conclusion: The MEDA provides preliminary evidence for multidimensional ego-dissolution assessment. Substance-specific clustering patterns might inform therapeutic selection, while universal insight and pleasure effects suggest core psychedelic benefits achievable across substances.