Journal of Psychiatric Research
May 1, 2022
Yazen Alnefeesi, D. Chen-Li, Ella Krane et al.
177 citations
Ketamine shows substantial real-world antidepressant effects in treatment-resistant depression, with about 45% of patients responding and 30% achieving remission, based on a systematic review and meta-analysis of 79 studies involving 2665 patients. The effect varies considerably among individuals; more treatment-resistant cases remit less often, but response rates do not differ. The therapeutic benefit does not significantly decline with repeated treatments, indicating that even the most treatment-resistant patients may benefit and that mid-to-long term treatment is effective for many.
Molecular Psychiatry
May 25, 2021
Ju Lu, Michelle Tjia, Brian Mullen et al.
87 citations
A single dose of the psychedelic analog tabernanthalog (TBG) reduces anxiety and reverses stress-induced deficits in sensory processing and cognitive flexibility in mice exposed to unpredictable mild stress. TBG promotes regrowth of dendritic spines lost during stress, lowers baseline neuronal activity, and enhances whisking-related modulation in the somatosensory cortex. In a texture discrimination task, novel textures activate a greater proportion of cortical neurons than familiar ones; this differential response is diminished by stress and restored by TBG. The findings indicate TBG combats stress effects by modulating basal and stimulus-dependent neural activity in cortical networks.
Journal of Psychiatric Research
March 1, 2021
Joshua D. Di Vincenzo, Ashley N. Siegel, Orly Lipsitz et al.
59 citations
Most antidepressant medication trials have focused on adults aged 18-65, leaving gaps in knowledge about older and younger populations. Ketamine shows promise for treatment-resistant depression, but its effects in adolescents and older adults are not well understood. This systematic review of 13 studies found that ketamine produced rapid antidepressant effects (within two weeks) in ten studies, with better results from larger, repeated doses and in open-label rather than blinded settings. Two case reports in adolescents noted rapid anti-suicidal effects. Ketamine appeared safe and well-tolerated in these age groups. However, the small number of studies, high heterogeneity, and generally low quality prevent firm conclusions, and rigorous randomized controlled trials are still needed.
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.
Journal of affective disorders
July 1, 2024
Cameron N Calder, Angela T H Kwan, Kayla M Teopiz et al.
31 citations
Ketamine is effective for adults with treatment-resistant depression. A systematic review of 21 placebo-controlled randomized trials with 2042 participants calculated the number needed to treat (NNT) for racemic ketamine: 7 at 4 hours, 3 from one day to one week, and 9 at four weeks. Esketamine had an NNT of 2 at one day and 11 at four weeks. Numbers needed to harm indicated low risk. The NNTs under 10 across observation intervals are considered highly clinically meaningful for this difficult-to-treat disorder. Limitations include potential functional unblinding and selective reporting bias.
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).
Psychiatry Research
October 1, 2021
Tuyen T. Le, Joshua D. Di Vincenzo, K. Teopiz et al.
26 citations
Psychotic depression, a severe form of major depression with hallucinations or delusions, affects 0.35-1% of people over a lifetime. Current treatments, such as antidepressants combined with antipsychotics or electroconvulsive therapy, often lead to relapse and side effects like tardive dyskinesia. Some case studies suggest ketamine may improve both mood and psychotic symptoms in treatment-resistant patients, but its safety is debated because ketamine can induce psychotomimetic effects. Most clinical trials have excluded these patients, so it remains unknown whether ketamine would worsen psychosis. Future research should include people with psychotic features to determine ketamine's safety and effectiveness.
Journal of affective disorders
April 1, 2024
Sabrina Wong, Angela T H Kwan, Kayla M Teopiz et al.
19 citations
A systematic review of randomized controlled trials compared the clinical efficacy of psilocybin and esketamine in adults with treatment-resistant depression. 25 mg of psilocybin significantly reduced depressive symptoms at 21 days post-dose, with a number needed to treat (NNT) of 5. Psilocybin-induced nausea had a number needed to harm (NNH) of 5. Fixed doses of esketamine (56 mg and 84 mg) showed significant effects at 28 days post-dose, with NNTs of 7. Esketamine-induced headache, nausea, dizziness, and dissociation had NNHs below 10. The preliminary results may reflect only a small portion of the patient population and require replication and longer-term studies. Both agents showed clinically meaningful NNT estimates and acceptable NNH profiles, underscoring their clinical relevance for treatment-resistant depression.
CNS drugs
October 1, 2022
Niloufar Pouyan, Zahra Halvaei Khankahdani, Farnaz Younesi Sisi et al.
16 citations
A systematic review of psilocybin research organized by the Research Domain Criteria (RDoC) framework found that psilocybin has beneficial effects across multiple domains, particularly on positive valence systems, negative valence systems, and social processes. Short-term (23 assessments) and long-term (15 assessments) benefits were reported for positive valence systems. For the negative valence system, 12 outcome measures indicated increased fear, 19 showed no significant effect, and 7 parameters indicated lowered sustained threat over the long term. Thirty-four outcome measures revealed short-term alterations in social systems, including enhanced perception and understanding of others and affiliation. Cognitive systems findings mostly reported dyscognitive effects. Seven studies suggested transdiagnostic effects.
Journal of affective disorders
October 15, 2024
Angela T H Kwan, Joshua D Rosenblat, Rodrigo B Mansur et al.
13 citations
Ketamine and esketamine are increasingly prescribed for treatment-resistant mood disorders and suicide risk, but ketamine is also misused. Analyzing reports in the World Health Organization pharmacovigilance database up to January 2024, ketamine showed elevated reporting odds ratios for alcohol abuse (3.24), substance dependence (12.48), substance use disorder (170.44), substance abuse (2.94), drug dependence (2.88), drug use disorder (11.54), and drug abuse (2.85). Esketamine had reduced odds for substance abuse (0.41), drug dependence (0.083), and drug abuse (0.052), and no increased odds for any alcohol or substance misuse parameter. These associations do not establish causation.
Journal of affective disorders
April 1, 2025
Angela T H Kwan, Moiz Lakhani, Kayla M Teopiz et al.
11 citations
An analysis of the FDA Adverse Event Reporting System found that reports of hepatobiliary disorders differ between ketamine and esketamine. Compared to acetaminophen, ketamine was associated with disproportionately lower reporting of hepatitis, liver injury, drug-induced liver injury, hepatic failure, and acute hepatic failure, but disproportionately higher reporting of hepatic function abnormalities and hepatic cytolysis. For esketamine, there was no disproportionate reporting of most hepatobiliary toxicities relative to acetaminophen, except for disproportionately higher reporting of hepatic failure. The authors recommend periodic monitoring of liver function tests and clinical surveillance for signs of hepatobiliary disease in individuals receiving chronic ketamine or esketamine, though causality has not been established.
European Psychiatry
January 1, 2026
Andy Lu, Heidi Xu, Gia Han Le et al.
4 citations
Ketamine's antidepressant effects in treatment-resistant depression may be partially mediated by the opioid system, but the evidence is mixed. Because opioid receptor antagonists inconsistently reduce these effects, the opioid system likely acts as a context-dependent modulator rather than a primary mediator, especially at standard antidepressant doses.
Acta Psychiatrica Scandinavica
December 1, 2025
Liyang Yin, A. Imamog ̄lu, Gia Han Le et al.
3 citations
Intravenous ketamine may be efficacious in treating posttraumatic stress disorder (PTSD). A systematic review of seven randomized controlled trials involving 323 participants found that ketamine meaningfully improved PTSD symptoms in two trials, as measured by the Clinician-Administered PTSD Scale for DSM-5 and the Impact of Event Scale-Revised. Multi-infusion schedules achieved greater clinical outcomes than single-dose schedules. Preliminary evidence suggests repeated lower doses (0.2 mg/kg) were more efficacious in sustaining treatment effects than standard doses (0.5 mg/kg). Symptom improvement was associated with top-down inhibition of the amygdala originating in the ventromedial prefrontal cortex.
The Journal of clinical psychiatry
July 7, 2025
Angela T H Kwan, Moiz Lakhani, Joshua D Rosenblat et al.
2 citations
In a global pharmacovigilance analysis of adverse event reports from the World Health Organization's VigiBase database, esketamine was associated with higher reporting odds for suicidal ideation compared to lithium (5.13 times) and fluoxetine (3.34 times), while ketamine showed lower reporting odds for suicidal ideation, suicide attempt, and completed suicide relative to both reference drugs. Both drugs had lower reporting odds for suicide attempts and completed suicides. The authors caution that causality cannot be determined from these observational data.
CNS Spectrums
March 10, 2026
Halima Faisal, Gia Han Le, Angela T.h. Kwan et al.
Ketamine rapidly alters brain reward circuitry in people with major depressive disorder, particularly in fronto-striatal and limbic networks. In a synthesis of 13 neuroimaging studies involving 623 participants (482 with depression, 141 controls), intravenous ketamine (typically 0.5 mg/kg over 40 minutes) changed resting-state connectivity in ventral striatal-prefrontal and default mode, salience, and executive networks within 2 to 48 hours, with some effects lasting up to 10 days. Task-based imaging showed altered ventral striatal responses during reward anticipation and feedback, and changes in medial prefrontal activity during emotion processing. PET scans indicated increased prefrontal-cingulate metabolism and region-specific serotonin receptor binding changes. Few studies directly measured anhedonia, suggesting the findings reflect broader antidepressant mechanisms.
Advances in Therapy
April 30, 2021
Eric P. Mcmullen, Yena Lee, Orly Lipsitz et al.
Ketamine can rapidly improve symptoms in adults with treatment-resistant depression, but its effects often last only a median of 2–4 weeks. This systematic review examined strategies to prolong ketamine's acute antidepressant effects. After searching PubMed/MEDLINE, 22 studies were included: 10 randomized controlled trials, 8 open-label trials, 1 retrospective chart review, and 3 case reports. No treatment modality—including pharmacological interventions, psychotherapies, electroconvulsive therapy, or transcranial magnetic stimulation—significantly prolonged the effects of intravenous ketamine, except for repeat-dose IV ketamine itself. Maintenance esketamine is effective in responders. More multimodality strategies are needed.
Journal of affective disorders
February 1, 2026
Kayla M Teopiz, Sabrina Wong, Gia Han Le et al.
Reward processing disruptions in major depressive disorder (MDD) may relate to altered frontostriatal brain activity. Glutamatergic modulators might improve reward function. This systematic review examined 11 fMRI studies testing glutamatergic agents—ketamine (9 studies), nitrous oxide (1), and memantine (1)—on frontostriatal activity in people with MDD or healthy controls. Preliminary evidence suggests intravenous ketamine may alter functional connectivity in striatal regions, potentially relevant to improved reward function in treatment-resistant depression. More research is needed on how these modulators affect reward-related brain structures, the timing of effects, and baseline characteristics predicting antidepressant response.
CNS drugs
October 1, 2023
Dania Akbar, Taeho Greg Rhee, Felicia Ceban et al.
A systematic review of five studies found that AXS-05, a combination of dextromethorphan and bupropion, rapidly reduces depression severity in adults with major depressive disorder who do not respond to standard antidepressants. Depressive symptoms measured on the MADRS scale decreased significantly compared to placebo as early as one week and compared to an active control at two weeks. The treatment effect was maintained for up to 12 months, with an average 23-point reduction from baseline. The therapy was well-tolerated with only transient side effects. These results support the role of glutamatergic and sigma-1 signaling pathways in depression.