Monthly research recap
Depression research: May 2026
What May 2026's 25 new studies found, synthesized from the papers below. All Depression research →
The synthesis
Synthesized from 25 studies in the library · AI-generated, grounded in the abstracts below
Found by searching the library for Depression, major depressive disorder, MDD, depressive disorder, treatment-resistant depression, then ranked by relevance.
Research published in May 2026 on depression focused heavily on ketamine and esketamine, with mixed results: while several studies and reviews report rapid antidepressant and anti-suicidal effects, a small RCT found ketamine was not significantly better than midazolam, and blinding failures were common. Psilocybin showed sustained benefits up to 12 months in one trial but not at one year in another. Overall, evidence supports short-term efficacy of ketamine and psilocybin, but durability, blinding, and long-term safety remain key caveats.
Evidence by study
Direction is which way each study's own result points, not our rating of the study.
What the directions mean
- Supports:
- the study found the intervention worked, or its hypothesis held.
- Opposes:
- it found the opposite, no benefit or a harm.
- No effect:
- no significant difference either way.
- Mixed:
- effects in both directions within the same study.
- Unclear:
- the abstract does not report a direction.
| Study | Design | Sample size | Direction | Finding |
|---|---|---|---|---|
| Preliminary Non-Randomized Clinical Trial of Subcutaneous Esketamine in Treatment-Resistant Depression: Exploring Adjunctive Effects of Ketamine-Assisted Psychotherapy 2026 | review | Unclear | Argues that ketamine's neuroplasticity and psychological openness could complement psychotherapy, but the adjunctive potential remains largely unexplored. | |
| Microbiota-Derived SCFAs Mediate the Synergistic Antidepressant Effects of Dajianzhong Decoction and Ketamine via FFAR2-NLRP3-IL-1β Signaling. 2026 | animal study with fecal microbiota transplantation, metabolomic profiling, pharmacological interventions, and behavioral approaches | Supports | Microbiota-derived short-chain fatty acids mediate the synergistic antidepressant effects of DJZT and ketamine by activating FFAR2 and suppressing NLRP3-IL-1β signaling in the medial prefrontal cortex. | |
| Mindfulness Yoga for Body and Mind Program Promotes Self-Compassion and Depression for Care-Workers 2026 | pre-post intervention study | 11 | Supports | A mindfulness yoga program significantly reduced depression scores (K6 from 11.2 to 9.1) and increased self-compassion, but did not significantly change resilience or happiness. |
| Differences in how NMDA antagonists modulate negative affective biases in male rats may serve as a predictor of clinical efficacy in major depressive disorder. 2026 | preclinical study | Supports | Differences in how NMDA antagonists modulate negative affective biases in male rats may serve as a predictor of clinical efficacy in major depressive disorder. | |
| The Use of Ketamine for Depression in Cancer Patients: A Systematic Review of Efficacy, Safety, and Clinical Applications. 2026 | systematic review | 14 | Supports | Ketamine provides rapid relief from depressive symptoms in adult cancer patients, often within hours to days, with additional benefits in anxiety, pain, and quality of life. |
| The Serotonin 2B (5‐ HT2B ) Receptor: A Narrative Review of Preclinical and Clinical Evidence on the Safety Considerations and Therapeutic Potential for the Treatment of Depression 2026 | narrative review | Unclear | Argues that peripheral 5-HT2B receptor agonism is linked to valvular heart disease, while centrally selective antagonism represents a tractable augmentation target for treatment-resistant depression provided peripheral activation is avoided. | |
| Long-Term Efficacy of Psilocybin with Adjunct Psychotherapy in Treatment-Resistant Major Depression (EPIsoDE): 6- and 12-Month Naturalistic Follow-Up of a Phase 2b Trial. 2026 | naturalistic follow-up of a phase 2b, randomized, active placebo-controlled trial | 126 | Supports | One or two 25 mg doses of psilocybin with adjunct psychotherapy produced a stable and clinically meaningful antidepressant effect lasting up to twelve months in treatment-resistant depression. |
| Ketamine: Is It Superior to Midazolam for Depression? 2026 | randomized controlled trial | 63 | No effect | Serial intravenous ketamine was not significantly more effective than midazolam in reducing depressive symptoms or improving quality of life, with blinding failures potentially influencing results. |
| Improving access to novel treatments for treatment-resistant depression: The potential role of specialist clinics in Australia 2026 | review | Unclear | Argues that lack of public access to novel treatments for treatment-resistant depression in Australia could be addressed by establishing specialist clinics in the public sector. | |
| A novel sequential ketamine and D-cycloserine/lurasidone therapy for bipolar depression with acute suicidal ideation. 2026 | review | Unclear | Argues that a two-step therapeutic approach using initial IV ketamine followed by D-cycloserine and lurasidone may provide rapid and sustained anti-suicidal effects, but uncertainties remain about efficacy and optimal use. | |
| Effects of virtual reality mindfulness interventions on depression and anxiety: a meta-analysis 2026 | meta-analysis | 864 | Supports | VR-based mindfulness interventions were associated with significant reductions in depressive and anxiety symptoms, with larger effects among older adults and in Eastern regions. |
| Pharmacotherapeutic Options in Drug-Resistant Bipolar Depression: From Molecular Mechanisms to Rational Polypharmacotherapy. 2026 | review | Supports | Argues that ketamine has the fastest and most pronounced antidepressant effect with low risk of phase change, while celecoxib significantly increased response and remission rates compared to escitalopram alone. | |
| Early suicidal ideation change and suicidality-associated emergency department utilization after ketamine or esketamine treatment in treatment-resistant depression. 2026 | observational cohort | Supports | Early reduction in suicidal ideation after ketamine or esketamine treatment is associated with lower rates of emergency department visits for suicidality. | |
| Shorter to be effective: subanesthetic-dose ketamine infusion reduces the global and regional path length of brain functional connectivity in patients with treatment-resistant depression and suicidal ideation. 2026 | preprint | Supports | Subanesthetic-dose ketamine infusion reduces the global and regional path length of brain functional connectivity in patients with treatment-resistant depression and suicidal ideation. | |
| Innovations in Depression Diagnosis and Treatment: A Review of Biological, Cognitive, and Psychosocial Advances. 2026 | review | Unclear | Argues that depression involves dysregulated neurotransmitter systems, neuroinflammation, and disrupted neural connectivity, with emerging treatments including neurosteroid therapies and psychedelic-assisted psychotherapy for treatment-resistant cases. | |
| Effect of ketamine intervention on hemodynamic responses in patients with treatment-resistant depression. 2026 | randomized controlled trial | 45 | Supports | Ketamine induced region-specific changes in hemodynamic response function parameters in brain regions linked to sensory-cognitive integration, mood regulation, and cognitive control, with changes in the thalamus and superior frontal gyrus associated with improvements in suicidal ideation. |
| Treatment-emergent psychiatric adverse events in patient-reported outcomes during ketamine use for major depressive disorder: a retrospective analysis. 2026 | retrospective analysis | Opposes | Psychiatric adverse events were reported by patients during ketamine treatment for major depressive disorder. | |
| The multilevel exploration test, a novel paradigm to measure exploratory behavior in depression animal models and the involvement of the PL-ZI circuit. 2026 | experimental study | Supports | Activation of the prelimbic cortex to zona incerta circuit restored exploratory deficits and alleviated other depression-like behaviors in depressed mice. | |
| Corrigendum to "Intranasal esketamine in treatment-resistant depression: long-term dosing patterns and clinical outcomes in a 5-year observational study". 2026 | corrigendum | Unclear | Corrigendum to a 5-year observational study on intranasal esketamine dosing patterns and clinical outcomes; no new findings. | |
| Interdisciplinary, Delphi-driven consensus guidelines on the use of intravenous ketamine infusions for depressive disorders from the American Society of Ketamine Physicians, Psychotherapists, and Practitioners (ASKP3). 2026 | consensus guidelines | Unclear | The guidelines establish expert consensus on the use of intravenous ketamine infusions for depressive disorders, covering patient selection, dosing, safety, and treatment protocols. | |
| Short-term effects of oral ketamine for the treatment of depression: A systematic review and meta-analysis of randomized controlled trials. 2026 | systematic review and meta-analysis | Supports | Oral ketamine produces short-term antidepressant effects compared to placebo or control conditions. | |
| Short-Term and Late-Term Effects of Psilocybin on Symptoms in Major Depression 2026 | randomized controlled trial | 35 | Mixed | A single dose of psilocybin (25 mg) produced significantly greater reduction in depressive symptoms compared to placebo by day 8, with effects lasting through day 42 but not at one year. |
| Toward Integrating Intranasal Esketamine with Traumatic-Memory Psychotherapy in Treatment-Resistant Depression: A Narrative Review and Feasibility-Oriented Protocol Proposal. 2026 | narrative review | Unclear | Argues that the strongest evidence for ketamine in PTSD comes from three randomized trials of intravenous ketamine, while data on intranasal esketamine and psychotherapy combinations are mainly from pilot studies, retrospective analyses, or case reports, and the evidence base remains small, heterogeneous, and largely uncontrolled. | |
| Changes in depression symptom network structure following ketamine treatment in treatment-resistant depression. 2026 | observational cohort | 447 | Mixed | Pre-treatment symptom network density was significantly higher in non-responders than in responders, and changes in network density after treatment differed between groups. |
| [Ketamine and esketamine in treatment-resistant depression - Pharmacological effects and augmented psychotherapy]. 2026 | review | Unclear | Argues that functional unblinding due to esketamine's side effects and general limitations of psychotherapy studies make it difficult to scientifically investigate causal relationships between ketamine administration and improved psychotherapeutic efficacy. |
Points of agreement
- Ketamine and esketamine show rapid antidepressant and anti-suicidal effects in treatment-resistant depression.
- Psilocybin with psychotherapy produces significant antidepressant effects lasting up to 12 months in some trials.
- Mindfulness-based interventions, including VR and yoga, reduce depressive symptoms.
- Blinding failures are a common methodological issue in ketamine trials.
- Long-term safety and durability of ketamine and psilocybin effects remain uncertain.
Conflicts
- One RCT found ketamine not significantly better than midazolam, while other studies and reviews report significant antidepressant effects.
- Psilocybin effects lasted up to 12 months in one trial but not at one year in another.
- Some reviews highlight potential psychiatric adverse events with ketamine, while others emphasize its benefits.
Gaps
- Long-term safety and efficacy data for ketamine and esketamine are limited.
- Optimal dosing strategies for ketamine and psilocybin are not established.
- Blinding in ketamine trials is often compromised, affecting result validity.
- Most studies lack diverse populations and long-term follow-up.
- The adjunctive role of psychotherapy with ketamine and esketamine remains largely unexplored.