Ayahuasca and Its Main Component N,N-Dimethyltryptamine (DMT) for the Treatment of Mental Disorders: Mechanisms of Action, Clinical Studies, and Tools to Explore the Human Mind.

In recent years, psychopharmacology has experienced a significant challenge, highlighting a renewed and strong scientific interest in psychedelics as breakthrough therapies for mental disorders. Psychedelics can influence cognitive and emotional processes, showing solid therapeutic potential, particularly in treatment-resistant psychiatric disorders. Amongst the most promising compounds, ayahuasca and its main psychoactive component, N,N-dimethyltryptamine (DMT), have received considerable attention. Ayahuasca is a psychoactive brew traditionally prepared from the liana Banisteriopsis caapi and the leaves of Psychotria viridis. Its psychoactive properties derive mainly from DMT, while -carbolines, which act as monoamine oxidase-A (MAO-A) inhibitors, prevent the metabolic degradation of DMT, enhancing its bioavailability and allowing oral administration. In contrast, in monotherapy, DMT or its analog 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is generally administered via alternative routes, like inhalation, intranasal, or intravenous delivery. DMT is primarily a serotonin (5-HT)2A receptor partial agonist, whereas 5-MeO-DMT has a higher affinity for the 5-HT1A receptor compared to 5-HT2A, though other receptor targets are engaged, fostering neuroplasticity and a reorganization of brain networks involved in perception, cognition, and mood regulation. Despite limited clinical trials, current evidence offers an optimistic outlook on DMT and 5-MeO-DMT efficacy for treatment-resistant depression (TRD) and major depressive disorder (MDD), whereas evidence for other mental disorders studies is still preliminary. There are four phase II studies with 5-MeO-DMT and one with DMT for TRD, while there are two phase II studies with DMT fumarate for MDD. Beyond their therapeutic potential, psychedelics also represent powerful tools for exploring the human mind, offering valuable insights into brain function and mental health.