Study Summary

Twenty healthy subjects participated in this randomised, placebo-controlled, double-blind, cross-over study aimed at investigating the acute effects of lysergic acid diethylamide (LSD) on the neural substrate of emotional processing in humans. Participants completed two study sessions in which they were orally administered placebo or 100 μg LSD with a washout period of at least 7 days between sessions. Outcomes were brain activity measured by functional MRI during a facial expression paradigm task, subjective drug effects measured on a visual analogue scale, and LSD blood plasma concentration levels measured using liquid chromatography-tandem mass spectrometry. The administration of LSD reduced reactivity of the left amygdala and the right medial prefrontal cortex relative to placebo during the presentation of fearful faces. There was also a significant negative correlation between LSD-induced amygdala response to fearful stimuli and the LSD-induced subjective drug effects.