Dose-response relationships of LSD-induced subjective experiences in humans
Hirschfeld, T., Majic, T., Prugger, J., Schmidt, T. T.
This study (n=322) analyses data from previous studies to assess the dose-response relationship and outcomes on the Altered States of Consciousness Rating Scale (ASC) and the Mystical Experience Questionnaire (MEQ) following LSD (25μg to 200μg) administration. Increasing doses were positively correlated with ratings on most factors and scales of the questionnaires, with the strongest responses for visionary phenomena such as audio-visual synesthesia and altered imagery, followed by positively perceived ego dissolution comprising depersonalization and derealization phenomena.
Abstract
Lysergic acid diethylamide (LSD) is a potent classic serotonergic psychedelic, which facilitates a variety of altered states of consciousness. Here we present the first meta-analysis establishing dose-response relationship estimates of the altered states of consciousness induced by LSD. Data extracted from articles identified by a systematic literature review following PRISMA guidelines were obtained from the Altered States Database. The psychometric data comprised ratings of subjective effects from standardized and validated questionnaires: the Altered States of Consciousness Rating Scale (5D-ASC, 11-ASC) and the Mystical Experience Questionnaire (MEQ30). We performed meta-regression analyses using restricted cubic splines for data from studies with LSD doses of up to 200 μg base. Most scales revealed a sigmoid-like increase of effects, with a plateauing at around 100 μg. The most strongly modulated factors referred to changes in perception and illusory imagination, followed by positively experienced ego-dissolution, while only small effects were found for Anxiety and Dread of Ego Dissolution. The considerable variability observed in most factors and scales points to the role of non-pharmacological factors in shaping subjective experiences. The established dose-response relationships may be used as general references for future experimental and clinical research on LSD to compare observed with expected subjective effects and to elucidate phenomenological differences between psychedelics.