Treatment-Resistant Depression (TRD)
Research into psychedelics as a treatment for Treatment-Resistant Depression (TRD) is advancing rapidly, with compounds like psilocybin showing particular promise. Approximately 30% of depression sufferers experience TRD, which reflects a significant unmet need in mental health treatment.
Key Insights
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Psilocybin has shown promise in recent studies, demonstrating significant antidepressant effects in patients with TRD.
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Psychedelics may facilitate a therapeutic experience that can lead to profound insights and emotional breakthroughs, contributing to clinical improvement in depressive symptoms.
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Current research indicates that psychedelic treatments may help reset neural pathways that have become rigid due to chronic depression.
What is Treatment-Resistant Depression (TRD)?
Treatment-Resistant Depression (TRD) is characterised by a lack of response to at least two different antidepressant treatments. This condition presents a significant challenge in mental health care, as individuals with TRD experience persistent and often debilitating symptoms of depression despite multiple treatment attempts.
The pathophysiology of TRD involves complex neurobiological mechanisms, including dysregulation of neurotransmitter systems—primarily serotonin, norepinephrine, and dopamine—and alterations in neural connectivity and plasticity. Symptoms may include profound sadness, lack of motivation, feelings of worthlessness, and in severe cases, suicidal ideation.
Current Treatments
Standard treatments for TRD include off-label use of medications, such as ketamine and esketamine, psychotherapy, and, in some cases, electroconvulsive therapy (ECT). Traditional antidepressants like SSRIs or SNRIs may be used in combination with other strategies, such as augmentation with atypical antipsychotics.
Psychedelic Effect Matrix
Compound efficacy and evidence levels for Treatment-Resistant Depression (TRD).
| Compound | Magnitude | Evidence | Consistency |
|---|---|---|---|
| Psilocybin Psilocybin has demonstrated efficacy in Phase II trials specifically for TRD. | Large | Moderate | Consistent |
| Esketamine Esketamine is FDA-approved for TRD and has shown robust effects in clinical settings. | Large | High | Highly Consistent |
| Ketamine Ketamine has shown positive results in various studies for rapid relief of depressive symptoms. | Medium | Moderate | Consistent |
Psilocybin and Treatment-Resistant Depression (TRD)
Psilocybin acts as a serotonin receptor agonist, and its effects can lead to significant shifts in mood and perception. Clinical studies suggest that psilocybin can induce a mystical experience, which may play a role in its antidepressant effects. These experiences can promote psychological healing by enabling individuals to confront and recontextualise their emotional struggles, thus alleviating symptoms of TRD.
Esketamine and Treatment-Resistant Depression (TRD)
Esketamine, a derivative of ketamine, has a rapid onset of action and is particularly effective in immediately reducing depressive symptoms. Administered intranasally, its mechanism is thought to involve NMDA receptor antagonism, which leads to increased glutamate transmission and synaptic plasticity. This effect can facilitate a swift therapeutic response, providing significant relief for patients with TRD.
Clinical Outlook
The future of psychedelic treatments for TRD appears promising, as ongoing clinical trials continue to investigate the efficacy and safety of various compounds. Innovations in therapist training and integration of psychedelic experiences into therapeutic frameworks are expected to enhance treatment outcomes, potentially leading to more effective approaches for this challenging condition.
Industrial Landscape
Key players in the field include COMPASS Pathways, which is advancing psilocybin research through successful clinical trials, and Revixia Life Sciences, which is developing Salvinorin A as a potential therapy. OVID is also noteworthy for its initiatives in developing psychedelic therapy infrastructure in Europe.
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Related Topics
Organisations
Search →Janssen Research & Development
Janssen Research & Development is the pharmaceutical research and development arm of Johnson & Johnson (J&J). Operating under J&J's Innovative Medicine division, Janssen has sponsored clinical trials into ketamine-derived compounds, including esketamine (Spravato), the first FDA-approved psychedelic-adjacent treatment for treatment-resistant depression.
Clexio Biosciences
Clexio Biosciences is a private Israeli clinical-stage CNS company founded in 2018 by Teva Pharmaceuticals R&D veterans. Their lead programme CLE-100 is a once-daily oral tablet formulation of esketamine for MDD — distinguished from the FDA-approved Spravato (intranasal, in-clinic) by enabling outpatient, at-home use. Phase 2 CLEO study results showed a promising safety profile and encouraging efficacy specifically in post-COVID MDD subgroups; the Phase 2 SOLEO study (NCT06340958, higher dose, stricter treatment-resistance criteria) enrolled first patients April 2024 and reached 50% enrollment by December 2024. CLE-100 holds multiple US method-of-use patents (2024). In December 2025, Clexio spun out its muscarinic agonist programme (CLE-905) into a new entity, Syremis Therapeutics, which raised $165M Series A co-led by Dexcel Pharma and Third Rock Ventures. Co-founders Kogan, Levy, and Kagan simultaneously lead Syremis; Clexio continues independently with CLE-100 and preclinical CLE-043.
COMPASS Pathways
COMPASS Pathways is a UK-listed biopharmaceutical company developing COMP360 synthetic psilocybin therapy for treatment-resistant depression, with two successful Phase 3 trials making it the leading candidate for the first regulatory approval of a classic psychedelic medicine.
Entheon Biomedical
Canadian psychedelic biotech that sold its DMT Phase 1 clinical trial assets to Cybin in 2022. Following the sale, Entheon has operated as a near-shell company with minimal employees and no active drug development programme.
National Institute of Mental Health (NIMH)
U.S. federal institute defining mental-health research agendas and evidence-generation priorities including psychedelic-relevant studies.
Filament Health
Clinical-stage natural psychedelic drug development company with publicly announced Nagoya Protocol-compliant iboga import activity from Gabon for R&D and potential therapeutic development.
Florida International University
Miami public research university where Dr. Jerry B. Brown has taught interdisciplinary psychedelics courses since 1975, and Professor Joseph Lichter runs an Honors College Psychedelic Renaissance course covering therapeutic applications of psilocybin, MDMA, and ketamine. FIU also serves as one of 21 sites in a major national psychedelic clinical trial and hosts the Cannadelic conference — the first cannabis and psychedelics conference focused on next-generation research.
University of Amsterdam
The University of Amsterdam (UvA) is one of the Netherlands' leading research universities, with its Amsterdam UMC Department of Psychiatry conducting clinical trials on psilocybin and psychedelic-assisted therapies for treatment-resistant mental health conditions.
University of California, San Francisco
University of California, San Francisco (UCSF) hosts major psychedelic research activity through the Translational Psychedelic Research Program (TrPR), Neuroscape Psychedelics Division, and psychiatry-led clinical research on psychedelic-assisted therapies.
Imperial College London
The Centre for Psychedelic Research, led by Professor David Nutt and Dr. David Erritzoe, focuses heavily on the action of psychedelic drugs in the brain and their clinical utility as aides to psychotherapy. Thanks to their extensive neuroimaging studies, this group has proposed vital mechanisms for how psychedelics work, including the Entropic Brain Theory and REBUS (RElaxed Beliefs Under Psychedelics).
University of Sydney
The Brain and Mind Centre is advancing psychedelic science with a multidisciplinary focus on developing innovative treatments using AI and preparing for human clinical trials to treat severe mental illness.
Charité – Universitätsmedizin Berlin
The MIND Foundation partnered with Charité – Universitätsmedizin Berlin, one of Europe's largest university hospitals. Charité is affiliated with Humboldt University and Free University Berlin. This partnership sees researchers at the hospital carrying out clinical studies with psilocybin in patients with treatment-resistant depression. Studies also take place concurrently at the Central Institute for Mental Health Mannheim.
People
Search →Robin Murphy
Researcher at the University of Auckland School of Pharmacy
She is a coauthor on multiple human psychedelic studies spanning LSD microdosing, sleep, and psilocybin/escitalopram comparisons, making her part of the team contributing to the modern evidence base for psychedelic medicine.
Hartej Gill
Researcher in mood disorders psychopharmacology at the University of Toronto / University Health Network
Notable for coauthoring multiple reviews and meta-analyses on ketamine, esketamine, suicidality, cognition, and psychedelic drug trials in psychiatric research.
Jeanine Kamphuis
Psychiatrist and researcher at the Department for Mood Disorders, University Hospital Groningen (UMCG)
She studies ketamine, esketamine, and classic psychedelics for treatment-resistant psychiatric disorders, including depression, and is a coauthor on multiple psychedelic/ketamine reviews and clinical studies.
Henrik Jungaberle
Dr. sc. hum., CEO and founder of the MIND Foundation; Head of Development at OVID Clinic Berlin
He is a prominent European psychedelic research and implementation figure contributing to psilocybin clinical trials, harm reduction, and healthcare integration work.
Joost Breeksema
Postdoctoral researcher and Executive Director of the OPEN Foundation
He is a prominent psychedelic researcher and advocate whose work helps shape evidence-based psychedelic policy, ethics, and patient-centered understanding of psychedelic and ketamine/esketamine treatments.
Juliana Rocha
Doutoranda em Ciências Médicas / Saúde Mental at the Ribeirão Preto Medical School, University of São Paulo
She is a recurring coauthor on clinical psychedelic studies, especially ayahuasca trials on social anxiety, emotion recognition, personality, and social cognition, helping expand the human evidence base for psychedelic-assisted psychiatric research.
Mathieu Seynaeve
Senior Medical Director and Head of Psychotherapy at Beckley Psytech
He is a clinical development leader behind multiple human studies of 5-MeO-DMT and psilocybin, including trials in alcohol use disorder, treatment-resistant depression, and headache disorders.
Kayla Teopiz
Researcher in psychiatry and ketamine/psychedelic medicine research; likely affiliated with the University of Toronto/Trillium Health Partners research network
Teopiz coauthors multiple systematic reviews and clinical studies on ketamine, esketamine, and psilocybin in depression and suicidality, helping synthesize the evidence base for psychedelic and glutamatergic treatments in psychiatry.
Jolien Veraart
Psychiatrist and PhD researcher at the University Medical Center Groningen / University of Groningen
She is a leading clinical researcher on ketamine and oral esketamine for treatment-resistant depression, including safety, efficacy, and real-world implementation.
Joshua Di Vincenzo
MSc researcher / clinical research staff member at the University Health Network and University of Toronto
He coauthors multiple systematic reviews and real-world studies on ketamine for treatment-resistant depression, making him a visible contributor to the evidence base on psychedelic-adjacent psychiatric therapeutics.
Frederick Sundram
Associate Professor and Deputy Head of the Department of Psychological Medicine at the University of Auckland
He is a psychiatrist and clinical researcher contributing to psychedelic and novel-antidepressant studies, including LSD microdosing and ketamine/depression research.
John Kelly
Associate Professor / Consultant General Psychiatrist at Trinity College Dublin
John R. Kelly is a leading academic psychiatrist in Ireland whose work has helped shape modern psychedelic psychiatry, including psilocybin research across depression, service-user attitudes, and transdiagnostic treatment frameworks.
Connected Evidence
The latest clinical data and verified academic findings associated with Treatment-Resistant Depression (TRD).