IntroductionLysergic acid diethylamide (LSD) is a classic serotonergic psychedelic with a broad history of early psychiatric research and recreational use [1, 2]. LSD induces a range of complex alterations of the mind that have been shown to depend on serotonin 5-hydroxytryptamine-2A (5-HT2A) receptor stimulation [3,4,5]. Renewed interest has been seen in using LSD in psychiatric research and to assist psychotherapy [6,7,8,9]. However, all recent placebo-controlled high-dose studies of LSD used ...