The science of psychedelic medicine

Classic psychedelics typically act at the serotonin 5-HT_2A receptor to profoundly alter brain function and consciousness. Research on these compounds has accelerated. Major strides have been made in understanding their unique mechanisms of action and clinical potential. This Review outlines the state of psychedelic science, spanning cellular mechanisms, systems neuroscience and clinical investigation. We show that preclinical and human research findings converge on two complementary processes: acute neural desynchronization, which destabilizes entrenched network patterns, and subacute neuroplasticity, which opens a window for psychological and behavioral change. We review evidence of therapeutic response across neuropsychiatric indications and consider how this integrates with mechanistic findings. We also explore challenges and opportunities, including discrepancies between preclinical evidence that non-hallucinogenic psychedelic analogs engage putative therapeutic mechanisms, and clinical evidence linking the subjective experience to therapeutic response; the risks inherent to enhanced neuroplasticity; and questions surrounding trial design, scalability and regulatory approval. The growth of psychedelic science and medicine may compel a fundamental rethinking of the relationship between subjective experience and biological change in psychiatry.