World Psychiatry
September 15, 2023
Roger S. McIntyre, Mohammad Alsuwaidan, Bernhard T. Baune et al.
712 citations
At least 30% of people with depression meet the common definition of treatment-resistant depression (TRD): inadequate response to two or more antidepressants despite adequate trials and adherence. Many cases are actually pseudo-resistant due to insufficient treatment or non-adherence. No consensus definition with proven predictive utility for clinical decisions exists, leading to varied prevalence estimates and inconsistent care. Intravenous ketamine and intranasal esketamine are effective for TRD. Some second-generation antipsychotics (e.g., aripiprazole, quetiapine XR) help as adjuncts in partial responders, but only the olanzapine-fluoxetine combination has been studied in FDA-defined TRD. Repetitive transcranial magnetic stimulation and electroconvulsive therapy are established effective interventions. Evidence for extending trials, switching, or combining antidepressants is mixed, and manual-based psychotherapies are not effective alone but help when added to antidepressants.
International Journal of Environmental Research and Public Health
April 17, 2018
Carola Rong, Caroline Park, Joshua D. Rosenblat et al.
116 citations
Ketamine produces rapid antidepressant effects in treatment-resistant depression associated with major depressive disorder and bipolar disorder. Identifying which patients will benefit remains a priority. This review identifies multiple pretreatment predictors of response, including high body mass index, family history of alcohol use disorder, history of suicide, adiponectin and vitamin B12 levels, delta sleep ratio abnormalities, glutamine/glutamate ratio, anterior cingulate cortex activity, the Val66Met BDNF allele, and processing speed. High BMI and family history of alcohol use disorder were the most replicated predictors. A complete pheno-biotype of depression likely to benefit from ketamine is far from complete, though metabolic-inflammatory alterations, especially cognitive impairment, are emerging as possible predictors.
The Journal of Clinical Psychiatry
April 15, 2019
Joshua D. Rosenblat, André F. Carvalho, Madeline Li et al.
111 citations
Oral ketamine shows significant antidepressant effects with good tolerability, but its effects are not as rapid as intravenous ketamine. In two randomized controlled trials, significant reductions in depressive symptoms were observed only after 2-6 weeks of treatment. Rapid antidepressant effects within 24 hours, antisuicide effects, and efficacy in treatment-resistant depression were reported only in retrospective studies. Dosages ranged from 0.5 to 7.0 mg/kg, with most studies using 1-2 mg/kg every 1-3 days. No clinically significant adverse effects were reported. The review concludes that antisuicide effects and efficacy in treatment-resistant depression have yet to be demonstrated in well-designed trials.
Journal of Clinical Psychopharmacology
December 12, 2015
Yena Lee, Kahlood Syeda, Nadia A. Maruschak et al.
75 citations
A single, low-dose administration of ketamine can rapidly reduce depressive symptoms in adults with treatment-resistant mood disorders and may also have antisuicide effects. The antidepressant effects may be partly mediated by targeting neural circuits involved in executive function and cognitive emotional processing. Pretreatment cognitive function predicts treatment outcomes, suggesting that beneficial effects on cognition could be a proximate mechanism for symptom relief, even though ketamine is known to impair cognitive function. Recent reviews and meta-analyses conclude that ketamine has possible clinical benefits in refractory mood disorders, and its salutary effects, particularly on suicidality, may involve procognitive mechanisms.
Bipolar Disorders
May 14, 2020
Roger S. McIntyre, Orly Lipsitz, Nelson B. Rodrigues et al.
64 citations
Intravenous ketamine reduces anxiety, irritability, agitation, and suicidal thoughts in adults with treatment-resistant major depressive disorder or bipolar disorder. In a retrospective analysis of 201 patients at a community clinic, those with elevated anxiety, irritability, and agitation showed significantly greater improvements in overall depressive symptoms, suicidal ideation, anxiety, irritability, and agitation compared to those without these features, regardless of the number of treatments. The findings suggest IV ketamine may be a rapid treatment option for mood disorder patients with mixed features.
Expert Review of Neurotherapeutics
September 21, 2020
Hartej Gill, Barjot Gill, David Chen‐li et al.
62 citations
Psychedelics like psilocybin and MDMA show promise as a new type of therapy for mental health disorders. Evidence suggests they may work with just one dose, produce rapid effects, and be effective for treatment-resistant conditions, possibly serving as a standalone treatment. More clinical trials are needed to test their safety, tolerability, and effectiveness in real-world patient populations.
The Canadian Journal of Psychiatry
August 17, 2022
Joshua D. Rosenblat, Muhammad Ishrat Husain, Yena Lee et al.
58 citations
Serotonergic psychedelics are being reconsidered as potential treatments for major depressive disorder. A Canadian task force systematically reviewed clinical trials from 1990 to 2021 and found that only psilocybin and ayahuasca have been tested in contemporary studies. Two pilot studies of single-dose ayahuasca for treatment-resistant depression showed preliminary positive effects (Level 3 evidence). Small randomized controlled trials of psilocybin combined with psychotherapy for major depressive disorder showed superiority to waitlist controls and comparable efficacy and safety to escitalopram with supportive psychotherapy, with additional trials showing efficacy in cancer-related depression (Level 3 evidence).
Psychiatry Research
July 29, 2023
Mauro Pettorruso, Roberto Guidotti, Giacomo D’andrea et al.
56 citations
Machine learning models predicted which patients with treatment-resistant depression would respond to esketamine nasal spray. In a retrospective study of 149 patients, three random forest classifiers achieved 68.53% accuracy for response at one month and 66.26% at three months, and 68.60% accuracy for remission at three months. Features such as severe anhedonia, anxious distress, mixed symptoms, and bipolarity positively predicted response and remission, while benzodiazepine use and depression severity were linked to delayed responses. The findings suggest machine learning may aid personalized treatment decisions for treatment-resistant depression.
American Journal of Psychiatry
March 22, 2023
Joshua D. Rosenblat, Marisa Leon-Carlyle, Shaun Ali et al.
53 citations
Psilocybin, a hallucinogen derived from certain mushrooms, shows promise in treating mental health disorders. In a sample of 400 participants, 70% reported significant reductions in depression symptoms after psilocybin therapy. The treatment demonstrated an effect size of 1.5, indicating a substantial impact on psychological well-being. This innovative approach could reshape psychiatry and enhance complementary medicine practices, potentially influencing fields like business and computer science through improved employee mental health. The findings highlight the potential for psychedelics in therapeutic settings.
Cancers
January 7, 2023
Joshua D. Rosenblat, Froukje E. deVries, Zoe Doyle et al.
49 citations
In patients with advanced cancer and major depressive disorder, three flexible doses of intranasal ketamine (50–150 mg) over one week produced rapid antidepressant effects. By day 8, 70% of participants showed a response (depression scores reduced by more than half) and 45% achieved remission. Depression scores dropped from an average of 31 to 11, a decrease of 20 points. Some benefit persisted into the second week without further doses. Side effects were mostly mild and temporary, including fatigue, dissociation, nausea, altered taste, and headaches; one participant withdrew due to a negative dissociative episode. Larger controlled trials are warranted.
Expert Opinion on Emerging Drugs
January 2, 2021
Amna Majeed, Jiaqi Xiong, Kayla M. Teopiz et al.
48 citations
A review of preclinical and clinical studies indicates that dextromethorphan (DXM) is well tolerated and shows clinically significant antidepressant effects; DXM combined with bupropion has demonstrated replicated and relatively rapid onset efficacy in adults with major depressive disorder (MDD). Preliminary reports also suggest efficacy in adults with bipolar depression. The combination represents a pharmacokinetic and pharmacodynamic synergy that may account for its rapid action. The authors consider DXM/bupropion a safe, well tolerated, and efficacious treatment option for adults with MDD, and highlight the relevance of glutamate as a treatment target. Priority questions include whether it is uniquely effective across discrete domains of psychopathology and whether it can improve patient-reported outcomes.
BJPsych Open
July 1, 2023
Muhammad Ishrat Husain, Nicole Ledwos, Elise Fellows et al.
41 citations
A proof-of-concept randomized controlled trial will test whether combining the psychedelic psilocybin with risperidone, a drug that blocks the serotonin 2A receptor, can block psilocybin's psychedelic effects while preserving its antidepressant action in adults with treatment-resistant depression. Sixty participants will be randomly assigned to receive psilocybin plus risperidone, psilocybin alone, or placebo plus risperidone, all with 12 hours of manualized psychotherapy. Feasibility and tolerability will be assessed through recruitment, retention, and adverse events. If successful, this approach could make psilocybin therapy more acceptable and accessible by eliminating the need for a psychedelic experience and continuous monitoring.
The World Journal of Biological Psychiatry
January 11, 2016
Matthew Cooper, Joshua D. Rosenblat, Danielle S. Cha et al.
40 citations
Ketamine produces rapid antidepressant effects but can cause psychotomimetic and dissociative side effects, raising safety concerns. This narrative review synthesizes strategies to reduce those effects, including altering dose and infusion rate, changing the route of administration, choosing a specific enantiomer, co-administering mood stabilizers or antipsychotics, and using alternative NMDA-modulating agents like lanicemine and GLYX-13. Intranasal administration appears the most promising approach for mitigating dissociative and psychotomimetic effects, but the available studies are limited in number and quality, so further investigation is needed.
Bipolar Disorders
December 14, 2022
Farhan Fancy, Nelson B. Rodrigues, Joshua D. Di Vincenzo et al.
35 citations
Four intravenous ketamine infusions (0.5–0.75 mg/kg) given over two weeks to 66 patients with treatment-resistant bipolar depression produced significant antidepressant effects, with depressive symptoms decreasing further after each infusion. Suicidal thoughts and anxiety also significantly decreased, and functioning improved. The response rate was 35% and remission rate 20% after four infusions. Treatment-emergent hypomania occurred in only 4.5% of patients, with no cases of mania or psychosis. Repeated doses were well tolerated and associated with greater symptom reduction.
Expert Opinion on Drug Safety
April 6, 2022
Muhammad Youshay Jawad, Joshua D. Di Vincenzo, Felicia Ceban et al.
29 citations
Intranasal esketamine, when added to an oral antidepressant, is safe and more effective than a placebo nasal spray at reducing depressive symptoms in people with treatment-resistant depression and depression with suicidal thoughts or behavior. Pooling data from seven randomized controlled trials showed a small but significant improvement in depressive symptoms, with higher rates of response and remission. Year-long studies found lower relapse rates and no major long-term side effects. The treatment appears well tolerated and rapidly effective for these difficult-to-treat populations.
Journal of Sleep Research
June 16, 2021
Nelson B. Rodrigues, Roger S. McIntyre, Orly Lipsitz et al.
28 citations
Sleep disturbances are common in treatment-resistant depression (TRD). Intravenous (IV) ketamine improved sleep symptoms, which partially mediated its antidepressant and anti-suicidal effects. In 323 adults with TRD receiving four IV ketamine infusions, self-reported improvements in insomnia, night-time restlessness, hypersomnia, early morning waking, and total sleep partially explained reductions in depression severity. Insomnia, night-time restlessness, early morning waking, and total sleep improvements also mediated reductions in suicidal ideation. Each point improvement in total sleep score was associated with 3.29 times higher odds of achieving response or remission (95% confidence interval 2.00–5.41).
CNS Spectrums
December 3, 2020
Orly Lipsitz, Roger S. McIntyre, Nelson B. Rodrigues et al.
25 citations
Higher body mass index (BMI) does not predict how well patients with treatment-resistant depression respond to intravenous (IV) ketamine. In a study of 230 adults who received four ketamine infusions, people with normal weight, overweight, and obesity (classes I and II) showed similar improvements in depression, suicidal thoughts, anxiety, anhedonia, and daily functioning. The antidepressant effects and rates of partial response, response, and remission were comparable across all BMI groups. The findings are limited by the observational, open-label design of this retrospective analysis.
Expert Opinion on Drug Safety
April 15, 2022
Marcus A. Doyle, Susan Ling, Leanna M.W. Lui et al.
24 citations
Hallucinogen persisting perception disorder (HPPD) is an uncommon but serious condition in which individuals repeatedly experience hallucinations and perceptual disturbances after prior hallucinogen use. As some hallucinogens are being developed to treat mental disorders, understanding HPPD becomes more important. A scoping review of the literature up to July 2021 covered treatments, prevalence, risk factors, and pathophysiology of HPPD. The renewed interest in psychedelics as potential treatments highlights the need to better characterize HPPD's frequency, risk and protective factors, key features, and clinical factors.
Annals of Clinical Psychiatry
November 1, 2022
David Chen‐li, Leanna M.W. Lui, Joshua D. Rosenblat et al.
22 citations
Postpartum depression (PPD) is a severe mood disorder affecting mothers and children, and there is a need for rapid-acting treatments. This narrative review examined the available literature on ketamine for PPD, searching databases for preclinical studies, clinical trials, and reviews. Four clinical trials were identified. The review suggests that ketamine may be a favorable option due to its antidepressant and analgesic effects, short infusion time, and rapid clearance from the mother's bloodstream. However, evidence is insufficient to support its routine use, highlighting the need for more clinical research.
Journal of Psychopharmacology
October 11, 2020
Roger S. McIntyre, Nelson B. Rodrigues, Orly Lipsitz et al.
19 citations
Adults with treatment-resistant depression or bipolar disorder who also have high anxiety show greater improvement in depressive and anxiety symptoms after intravenous ketamine treatment than those with low anxiety. Among 209 patients receiving four ketamine infusions, the 94 with anxious-distress had a significantly larger drop in depression scores and a greater reduction in anxiety symptoms after three and four infusions. Both groups experienced a significant decrease in suicidal thoughts. The findings suggest that ketamine may be particularly effective for people with treatment-resistant mood disorders and prominent anxiety.
Expert Opinion on Drug Safety
May 3, 2022
Danica Nogo, Hana Nazal, Yuetong Song et al.
17 citations
Ketamine is an established treatment for treatment-resistant depression, but long-term adverse effects from repeated doses are not well characterized. Animal models and studies of people with substance use disorder who use high daily doses of ketamine show clear neurotoxic effects, including potential brain lesions. No studies have specifically evaluated the effects of the lower, infrequent sub-anesthetic doses typically prescribed for depression. It is difficult to separate ketamine's direct effects from other factors like comorbidities and dose differences. It remains unknown whether repeated sub-anesthetic dosing in adults with depression causes brain lesions or other neuropathologies. Practitioners should remain vigilant, recognizing that depression itself is linked to neurodegenerative processes.
CNS Spectrums
December 10, 2020
Nelson B. Rodrigues, Ashley Siegel, Orly Lipsitz et al.
17 citations
Intravenous (IV) ketamine effectively reduces symptoms of depression, suicidal ideation, anxiety, and anhedonia in adults with treatment-resistant depression, regardless of whether they have previously undergone neurostimulation. In a retrospective analysis of 238 patients, those without prior neurostimulation experienced an average 6.4-point reduction on a depression severity scale, while those with a history of neurostimulation showed a 4.3-point reduction. No significant differences emerged between the groups, indicating that IV ketamine benefits even highly intractable patients.
Eur Neuropsychopharmacol
November 7, 2025
Mikkel Højlund, Helin Y. Kafali, Begüm Kırmızı et al.
12 citations
A living systematic review with meta-analysis examined the efficacy, safety, and all-cause discontinuation of serotonergic psychedelics and MDMA for treating mental disorders. The review found that these substances show promise in reducing symptoms of conditions such as depression, anxiety, and post-traumatic stress disorder, with some evidence supporting their therapeutic potential. However, the authors note that the overall quality of evidence is limited by small sample sizes, short follow-up periods, and methodological concerns. Safety profiles varied, with most adverse events being mild to moderate, though serious adverse events were reported in some studies. The review emphasizes the need for larger, more rigorous trials to confirm these findings.
Journal of Affective Disorders
July 18, 2025
Mary E. Kittur, Mingyao Liu, Brett D. M. Jones et al.
12 citations
Psilocybin therapy shows promise for rapid and lasting clinical benefits when paired with psychological support, but the field lacks standardized therapeutic guidelines. A systematic review of 22 recent trials across conditions like depression, substance use, and obsessive-compulsive disorders found broad consistency in the structure of therapy sessions—before, during, and after psilocybin administration. However, trials varied widely in therapeutic intensity, diagnostic adaptations, and use of evidence-based psychotherapies. Fewer than half reported standardization measures such as manualized procedures, specific training, or adherence monitoring. These gaps undermine replicability and generalizability, and until support protocols are clearly defined, mechanistic understanding and clinical adoption will remain limited.
Journal of Psychopharmacology
October 3, 2024
Charles Q. Choi, Danica E. Johnson, David Chen‐li et al.
11 citations
Posttraumatic stress disorder (PTSD) can develop after a traumatic event, causing intrusive re-experiencing, mood and cognitive changes, and altered arousal. Few treatments help patients who cannot access or do not benefit from conventional psychotherapy or pharmacotherapy. This review examines the neurobiology of PTSD and psilocybin's mechanism of action, suggesting that psilocybin may be an underexplored treatment option based on pharmacodynamic and psychoanalytic principles, though further research is needed.