Dose-response relationships of LSD-induced subjective experiences in humans

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 phenomenological states induced by LSD. Data extracted from articles identified by a systematic literature search 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 used a meta-regression approach to obtain estimates for linear dose-response relationships of questionnaire ratings after LSD administration to healthy, highly selected study participants in controlled settings for a dosage range between 25 μg and 200 μg. LSD doses positively correlated with ratings on most factors and scales of the questionnaires, with strongest responses for visionary phenomena such as audio-visual synesthesia and altered imagery, followed by positively perceived ego dissolution comprising depersonalization and derealization phenomena. Measures referring to mystical experiences exhibited weak modulations by dose. The established dose-response relationships in the given range may be used as general references for future experimental and clinical research on LSD with low to moderate dosages to relate observed with expected subjective effects and to elucidate phenomenological differences between psychedelics.