Existing pharmacological treatments for psychiatric disorders have demonstrated limited efficacy, delayed onset of action, and significant burden of side effects. Recent findings from human studies with psychedelics have shown promise, demonstrating rapid and sustained clinical benefits of these compounds for a variety of psychiatric disorders. Classical psychedelics have a rich history and some of these compounds have been used in shamanic and spiritual ceremonies for millennia. The psychoactive effects of these drugs, particularly on human consciousness, have generated great scientific curiosity, and early research on psychedelics suggested their clinical benefits for psychiatric conditions, including alcohol use disorders and anxiety and depressive symptoms in terminal illness and life-threatening conditions. Since the 1990s, after a period of dormancy that followed the criminalization of psychedelic drugs since the Controlled Substance Act of 1970, the continued interest in their unique psychoactive effects along with the pursuit for novel and more effective treatments in psychiatry have led to a renewed interest in research on these compounds. While preliminary findings on psychedelics are encouraging, current evidence is still insufficient to support extensive use of these drugs routinely. Long-term safety and efficacy of these compounds remain unclear, and several clinical trials are underway and may add clarity to these questions. Therefore, this article intends to provide an overview of the evidence to date on psychedelic drugs - particularly psilocybin, MDMA, and LSD - for the treatment of psychiatric disorders.
