The aim of the study was to characterize and compare the acute subjective effects of LSD and MDMA in healthy subjects and in patients with psychiatric disorders in different settings. Acute effects of LSD and MDMA were investigated in placebo-controlled, double-blind, cross-over studies in a laboratory setting in a total of 40 and 194 healthy subjects, respectively. Acute effects of 200 mcg LSD were assessed in 11 patients suffering from anxiety associated with a life-threatening disease, treated alone within a placebo-controlled clinical trial. Additionally, acute effects of LSD (100-200 mcg) and MDMA (100-175 mg) were assessed in 11 patients with various psychiatric diagnoses treated in Swiss psychiatric practices in group Settings.
The results have shown that in healthy subjects, LSD and MDMA both acutely and dose-dependently increased ratings of feelings of openness, trust, and closeness to others. MDMA significantly increased ratings of experience of unity after 125 mg compared with 75 mg. On the Mystical Experience Questionnaire MEQ, LSD significantly increased all scores compared with placebo after 100 and 200 mcg, whereas MDMA only increased ineffability, and positive mood in healthy subjects. In patients LSD and MDMA both induced similar mystical-type experiences on the MEQ compared with healthy subjects.
LSD and MDMA both produced acute empathogenic effects that may be beneficial in drug-assisted psychotherapy. Preliminary findings indicate that LSD and MDMA induced largely comparable acute alterations in consciousness and mystical-type experiences in healthy subjects in an experimental setting and in psychiatric patients in different treatment settings