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Roger S. McIntyre

University of Toronto, Brain and Cognition Discovery Foundation

47 papers in the library · 2,177 citations · publishing 2013-2026

Papers

Treatment‐resistant depression: definition, prevalence, detection, management, and investigational interventions

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.

Prevention and reversal of ketamine-induced schizophrenia related behavior by minocycline in mice: Possible involvement of antioxidant and nitrergic pathways

Journal of Psychopharmacology September 17, 2013 Aline Santos Monte, Greicy Coelho de Souza, Roger S. McIntyre et al. 123 citations

Minocycline, an antibiotic, prevented and reversed schizophrenia-like behaviors in mice given ketamine, including changes in movement, startle response, social interaction, and memory. It also corrected ketamine-induced oxidative stress—lowered glutathione and raised lipid peroxidation markers—and altered nitrite levels in the striatum. The effects were similar to those of the antipsychotic risperidone. The findings suggest minocycline's potential as a novel psychotropic agent, with its mechanism involving antioxidant and nitrergic systems.

Predictors of Response to Ketamine in Treatment Resistant Major Depressive Disorder and Bipolar Disorder

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.

Oral Ketamine for Depression

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.

The Canadian Network for Mood and Anxiety Treatments (CANMAT) Task Force Recommendations for the Use of Racemic Ketamine in Adults with Major Depressive Disorder: Recommandations Du Groupe De Travail Du Réseau Canadien Pour Les Traitements De L’humeur Et De L’anxiété (Canmat) Concernant L’utilisation De La Kétamine Racémique Chez Les Adultes Souffrant De Trouble Dépressif Majeur

The Canadian Journal of Psychiatry November 11, 2020 Jennifer Swainson, Alexander McGirr, Pierre Blier et al. 109 citations

A systematic review by the Canadian Network for Mood and Anxiety Treatments evaluated evidence for racemic ketamine in treatment-resistant depression. Single intravenous infusions have Level 1 evidence for efficacy in adults, while multiple or maintenance infusions have only Level 3 evidence. Adverse events include dissociative symptoms and hypertension. Non-IV formulations have Level 3 or 4 evidence. Single-dose IV racemic ketamine is a third-line recommendation; repeated use requires careful case-by-case risk-benefit assessment. Oral and other formulations should be limited to specialists with ketamine expertise at tertiary centers due to limited evidence and risk of misuse.

A New Perspective on the Anti-Suicide Effects With Ketamine Treatment

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.

Treating bipolar depression with esketamine: Safety and effectiveness data from a naturalistic multicentric study on esketamine in bipolar versus unipolar treatment‐resistant depression

Bipolar Disorders January 13, 2023 Giovanni Martinotti, Bernardo Dell’osso, Giorgio Di Lorenzo et al. 72 citations

Esketamine nasal spray reduced depressive symptoms in people with treatment-resistant bipolar depression as effectively as in those with unipolar treatment-resistant depression, with no significant differences in response or remission rates after one and three months. The treatment also showed greater anxiety-reducing effects in the bipolar group. No treatment-emergent affective switch occurred, supporting the safety and tolerability of esketamine for bipolar treatment-resistant depression.

The effectiveness of ketamine on anxiety, irritability, and agitation: Implications for treating mixed features in adults with major depressive or bipolar disorder

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.

The emerging role of psilocybin and MDMA in the treatment of mental illness

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.

Glutamatergic Modulators for Major Depression from Theory to Clinical Use.

CNS drugs November 1, 2024 Roger S. McIntyre, Rakesh Jain 58 citations

Glutamate signaling has emerged as a promising target for treating major depressive disorder (MDD), a chronic condition where standard monoamine antidepressants often have delayed effects and low remission rates. This narrative review describes how glutamate dysregulation is linked to depression, based on preclinical evidence and the rapid improvement seen with ketamine in a proof-of-concept trial. While many NMDA-targeted therapies have been investigated in phase 2 or 3 trials, most were discontinued. However, two glutamate-targeted antidepressants are now FDA-approved: nasal esketamine (Spravato) for treatment-resistant depression and MDD with suicidal ideation, and oral dextromethorphan-bupropion (Auvelity) for MDD in adults. These approvals highlight glutamate's role and offer new treatment options.

The Canadian Network for Mood and Anxiety Treatments (CANMAT) Task Force Report: Serotonergic Psychedelic Treatments for Major Depressive Disorder

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).

Predicting outcome with Intranasal Esketamine treatment: A machine-learning, three-month study in Treatment-Resistant Depression (ESK-LEARNING)

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.

Antidepressant Effects of Psilocybin in the Absence of Psychedelic Effects

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.

A Phase II, Open-Label Clinical Trial of Intranasal Ketamine for Depression in Patients with Cancer Receiving Palliative Care (INKeD-PC Study)

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.

Efficacy of dextromethorphan for the treatment of depression: a systematic review of preclinical and clinical trials

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.

Strategies to mitigate dissociative and psychotomimetic effects of ketamine in the treatment of major depressive episodes: a narrative review

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.

Investigating the Effectiveness and Tolerability of Intranasal Esketamine Among Older Adults With Treatment-Resistant Depression (TRD): A Post-hoc Analysis from the REAL-ESK Study Group

American Journal of Geriatric Psychiatry July 8, 2023 Giacomo D’andrea, Stefania Chiappini, Roger S. McIntyre et al. 36 citations

Esketamine nasal spray (ESK-NS) shows preliminary effectiveness for treatment-resistant depression in adults aged 65 and older, with 53.3% of participants responding (MADRS score reduced by at least 50%) and 33.33% achieving remission (MADRS below 10) after three months. Common adverse effects included dizziness (50%), dissociation (33.3%), sedation (30%), and hypertension (13.33%). Twenty percent of participants discontinued treatment. These findings, from a post-hoc analysis of 30 older adults, suggest ESK-NS can be effective but is associated with high rates of treatment-emergent adverse events, most of which did not require stopping treatment.

Real‐world effectiveness of repeated ketamine infusions for treatment‐resistant bipolar depression

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.

Recent Advances in the Treatment of Treatment-Resistant Depression: A Narrative Review of Literature Published from 2018 to 2023

Current Psychiatry Reports April 1, 2024 John L. Havlik, Syed Wahid, Kayla M. Teopiz et al. 30 citations

Treatment-resistant depression (TRD) has historically had very limited options, but recent advances have expanded knowledge of effective interventions. Psychotherapy can help as an add-on but not alone. Adjunctive non-antidepressant drugs like buprenorphine and antipsychotics show little recent support; side effects and high discontinuation rates may outweigh benefits. Strong recent evidence supports interventional approaches: electroconvulsive therapy, ketamine/esketamine, and transcranial magnetic stimulation. Research on TRD should use internationally defined inclusion criteria for generalizable results.

The efficacy and safety of adjunctive intranasal esketamine treatment in major depressive disorder: a systematic review and meta-analysis

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.

Do sleep changes mediate the anti‐depressive and anti‐suicidal response of intravenous ketamine in treatment‐resistant depression?

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).

Serotonin 5-HT 2B receptor agonism and valvular heart disease: implications for the development of psilocybin and related agents

Expert Opinion on Drug Safety August 15, 2023 Roger S. McIntyre 26 citations

The text discusses concerns about psilocybin, lysergic acid diethylamide (LSD), and ecstasy in relation to valvular heart disease, focusing on 5HT2B receptor agonism and FDA guidance. It highlights the potential risk of these substances to cause heart valve damage through activation of the 5HT2B receptor, a mechanism linked to certain drugs. The abstract underscores regulatory considerations from the FDA regarding this safety issue, suggesting that agonism at this receptor may be a key factor in assessing the cardiac risks of psychedelic compounds.

Does body mass index predict response to intravenous ketamine treatment in adults with major depressive and bipolar disorder? Results from the Canadian Rapid Treatment Center of Excellence

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.

Hallucinogen persisting perceptual disorder: a scoping review covering frequency, risk factors, prevention, and treatment

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.

Ketamine as Potential Treatment for Postpartum Depression: A Narrative Review

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.