British journal of pharmacologyJun 15, 2025

Psychedelic and related drugs for treating depression and similar conditions

Psychedelic Science Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Mar 17, 2026

Abstract

Late-stage clinical trials suggest psychedelics like psilocybin and MDMA may rapidly treat major depressive disorder and PTSD.

Psychedelics and MDMA-assisted psychotherapy have shown effectiveness in treating major depressive disorder, treatment-resistant depression, PTSD, and generalized anxiety disorders.
Psilocybin, MDMA, and LSD have received FDA breakthrough status for treatment-resistant depression, PTSD, and generalized anxiety disorder, respectively.
These substances primarily interact with the 5-HT and monoamine systems, with classical psychedelics acting as 5-HT receptor agonists.
Evidence indicates that psychedelics can have significant anti-inflammatory effects through 5-HT receptor activation.
Imaging studies reveal reduced brain 5-HT levels and impaired neural networks in individuals with depression, which may be restored with psychedelic treatment.
The findings support a biological basis for major depressive disorder, generalized anxiety disorder, and PTSD as mixed biochemical, neurological, and neuroimmune disorders.

Simplified

Currently, the most actively investigated rapidly acting antidepressants, anxiolytics and/or anti PTSD agents, include psychedelics e.g. psilocybin, LSD, N,N-dimethyltryptamine, ayahuasca; non-hallucinogenic entactogens, e.g. MDMA; psychoplastogens which rapidly promote neuroplasticity, e.g. ibogaine, ketamine and esketamine; and other atypicals e.g. dextromorphan/bupropion, esmethadone. Late-stage clinical trials support psychedelics and/or MDMA-assisted psychotherapy as rapidly acting treatments for major depressive disorder (MDD), treatment-resistant depression (TRD), PTSD or generalised anxiety disorders (GAD). Psilocybin, MDMA and LSD were granted FDA breakthrough status for TRD/MDD, PTSD and GAD, respectively, although FDA recently rejected the new drug application of MDMA in PTSD. Most of these drugs target the 5-HT and monoamine systems. Classical psychedelics act as 5-HTreceptor agonists, although LSD, DMT and psilocybin target other 5-HT and/or dopamine receptors. Psychedelic-dependent 5-HTreceptor agonism also has profound anti-(neuro)inflammatory effects. Advanced imaging studies suggest that brain 5-HT levels are reduced in depression. Functional magnetic resonance studies show that neural networks (cortico thalamic, salience, default mode) are profoundly impaired in depression. Such network defects are corrected upon psychedelic/entactogen treatment, offering a unique opportunity to serve as biomarkers for depression, anxiety and PTSD precision medicine trials. Psychedelics and entactogens target common end pathways, namely neuroplasticity/synaptogenesis, either directly via monoamine or glutamate receptors and/or indirectly, via BDNF and mTORC1 pathways. Together, these findings strongly support a biological basis for MDD, GAD, PTSD and related conditions, which can be considered as mixed biochemical, neurological and neuroimmune disorders, and are profoundly modified by psychedelics, entactogens and the newly developed psychoplastogens. 2A2A

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Psychedelic and related drugs for treating depression and similar conditions

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