Assessing the Potential Cardiovascular Risk of Microdosing the Psychedelic LSD in Mice

Microdosing, the prolonged ingestion of psychedelics at subhallucinogenic doses, has gained popularity for its perceived cognitive and emotional benefits. Psychedelics have high affinity for 5-HT_2B receptors, a receptor known to cause human heart disease with strong chronic activation. We investigated the effects of microdosed psychedelics on cardiovascular health in mice using echocardiography after chronically administering either serotonin or d-fenfluramine as positive controls or lysergic acid diethylamide (LSD) at two subhallucinogenic doses. Serotonin produced significant ventricular thickening at 4- and 8-weeks, and d-fenfluramine caused aortic valve regurgitation at 4-weeks. No significant changes were observed in any vehicle or LSD group. We determined the affinity and potency of LSD, psilocybin, and norfenfluramine at mouse and human 5-HT_2BRs and observed no significant differences. We calculated that levels of 5-HT_2B activation by low-dose LSD were substantial, but short-lived, compared to the cardiotoxin d-fenfluramine. Together, these data provide no evidence of ventricular or valvular remodeling associated with prolonged administration of low-dose LSD in mice.