Psychedelics, including psilocybin, lysergic acid diethylamide, and dimethyltryptamine, and entactogens such as 3,4-methylenedioxymethamphetamine are being investigated for treatment-resistant depression, post-traumatic stress disorder, anxiety, and substance use disorders. These compounds act primarily through serotonin 5-HT2A receptor agonism (psychedelics) or monoamine release (MDMA),...