Synthesizing the Evidence for Ketamine and Esketamine in Treatment-Resistant Depression: An International Expert Opinion on the Available Evidence and Implementation

Efficacy of ketamine versus esketamine in the treatment of perioperative depression: A review

Depression is a significant factor contributing to postoperative occurrences, and patients diagnosed with depression have a higher risk for postoperative complications. Studies on cardiovascular surgery extensively addresses this concern. Several studies report that people who undergo coronary artery bypass graft surgery have a 20% chance of developing postoperative depression. A retrospective analysis of medical records spanning 21 years, involving 817 patients, revealed that approximately 40% of individuals undergoing coronary artery bypass grafting (CABG) were at risk of perioperative depression. Patients endure prolonged suffering from illness because each attempt with standard antidepressants requires several weeks to be effective. In addition, multi-drug combination adjuvants or combination medication therapy may alleviate symptoms for some individuals, but they also increase the risk of side effects. Conventional antidepressants primarily modulate the monoamine system, whereas different therapies target the serotonin, norepinephrine, and dopamine systems. Esketamine is a fast-acting antidepressant with high efficacy. Esketamine is the S-enantiomer of ketamine, a derivative of phencyclidine developed in 1956. Esketamine exerts its effect by targeting the glutaminergic system the glutaminergic system. In this paper, we discuss the current depression treatment strategies with a focus on the pharmacology and mechanism of action of esketamine. In addition, studies reporting use of esketamine to treat perioperative depressive symptoms are reviwed, and the potential future applications of the drug are presented.

Psychotropic Drugs Reemerging as Headache Medicines

Scientific and public attention on the therapeutic effects of psychedelics and other psychoactive compounds in headache disorders has recently grown. The use and reported therapeutic effects of such treatments have long been reported, though formal clinical trials are only recently taking place. When considering how these substances might be further studied and eventually applied, it is important to consider the specific headache disorder, the particular drug, and the mode of use. No singular protocol will be applicable across all headache disorders and drugs. In this leading article, the nuance required to consider the value of classic psychedelics, ketamine, and cannabinoids as headache medicines is presented.

The association between ketamine and esketamine with alcohol and substance misuse: Reports to the Food and Drug Administration adverse event reporting system (FAERS)

INTRODUCTION

Ketamine and esketamine have been proven to be effective in treating adults with treatment resistant depression (TRD). Preliminary evidence indicates that, when combined with behavioral and psychological interventions, both agents may offer benefits for individuals with substance use disorder (SUD) and alcohol use disorder (AUD). Notwithstanding, concerns have been raised as to whether either or both agents are associated with abuse and/or gateway activity.

METHODS

Herein, we evaluate disproportionate reporting expressed as reporting odds ratios (ROR) for esketamine and ketamine. The outcomes of interest include alcohol problem, alcoholism, alcohol abuse, substance dependence, SUD, substance abuse, drug dependence, drug use disorder and drug abuse as codified by the Medical Dictionary for Regulatory Activities (MedDRA) within the FAERS. The IC025 values were significant for ketamine in cases of alcohol abuse (0.28), substance dependence (1.88), substance use disorder (0.996), substance abuse (0.61), drug dependence (0.56), drug use disorder (1.17) and drug abuse (1.22). Additionally, oxycontin showed significant IC025 values for substance dependence (0.067), substance use disorder (0.094), substance abuse (0.035), and drug dependence (0.27).

RESULTS

We observed significant increases in the reporting odds ratios (RORs) for ketamine with respect to various outcomes: alcohol abuse (ROR 2.84, 95 % CI 1.53-5.28; p = 0.0010), substance dependence (ROR 18.72, 95 % CI 8.49-41.30; p ≤ 0.0001), SUD (ROR 11.40, 95 % CI 4.24-30.65; p ≤ 0.0001), substance abuse (ROR 2.29, 95 % CI 1.73-3.04; p ≤ 0.0001), drug dependence (ROR 1.99, 95 % CI 1.64-2.42; p ≤ 0.0001), drug use disorder (ROR 4.50, 2.94-6.88; p ≤ 0.0001) and drug abuse (ROR 3.72, 3.36-4.12; p ≤ 0.0001). For esketamine, we observed that the ROR was significantly reduced for substance abuse (ROR 0.37, 95 % CI 0.22-0.63; p = 0.0003), drug dependence (ROR 0.13, 95 % CI 0.076-0.23; p ≤ 0.0001) and drug abuse (ROR 0.048, 95 % CI 0.030-0.078; p ≤ 0.0001). To our knowledge, this is the first report of spontaneous adverse events related to these outcomes of interest in the FAERS.

CONCLUSION

Mixed RORs were observed across aspects of SUD and AUD for both ketamine and esketamine. Due to limitations in the FAERS, establishing causal links between new onset alcohol and substance misuse with either agent remains inconclusive. Possible beneficial effects on measures of SUD and AUD were observed. It is currently unclear, but possible, whether both agents have differential ameliorative effects across dimensions of SUD and AUD, which is a focus of ongoing research.

The role of KCNQ channel activators in management of major depressive disorder

Depression, a complex disorder with significant treatment challenges, necessitates innovative therapeutic approaches to address its multifaceted nature and enhance treatment outcomes. The modulation of KCNQ potassium (K+) channels, pivotal regulators of neuronal excitability and neurotransmitter release, is a promising innovative therapeutic target in psychiatry. Widely expressed across various tissues, including the nervous and cardiovascular systems, KCNQ channels play a crucial role in modulating membrane potential and regulating neuronal activity. Recent preclinical evidence suggests that KCNQ channels, particularly KCNQ3, contribute to the regulation of neuronal excitability within the reward circuitry, offering a potential target for alleviating depressive symptoms, notably anhedonia. Studies using animal models demonstrate that interventions targeting KCNQ channels can restore dopaminergic firing balance and mitigate depressive symptoms. Human studies investigating the effects of KCNQ channel activators, such as ezogabine, have shown promising results in alleviating depressive symptoms and anhedonia. The aforementioned observations underscore the therapeutic potential of KCNQ channel modulation in depression management and highlight the need and justification for phase 2 and phase 3 dose-finding studies as well as studies prespecifying symptomatic targets in depression including anhedonia.

An Immune-Enhancing Injectable Hydrogel Loaded with Esketamine and DDP Promotes Painless Immunochemotherapy to Inhibit Breast Cancer Growth

Chemotherapy is the cornerstone of triple-negative breast cancer. The poor effectiveness and severe neuropathic pain caused by it have a significant impact on the immune system. Studies confirmed that immune cells in the tumor microenvironment (TME), have critical roles in tumor immune regulation and prognosis. In this study, it is revealed that the painless administration of Esketamine, combined with Cisplatin (DDP), can exert an anti-tumor effect, which is further boosted by the hydrogel delivery system. It is also discovered that Esketamine combined with DDP co-loaded in Poloxamer Hydrogel (PDEH) induces local immunity by increasing mature Dendritic Cells (mDCs) and activated T cells in PDEH group while the regulatory T cells (Tregs) known as CD4+CD25+FoxP3+decreased significantly. Finally, , CD8+ and CD4+ T cells in the spleen exhibited a significant increase, suggesting a lasting immune impact of PDEH. This study proposes that Esketamine can serve as a painless immune modulator, enhancing an anti-tumor effect while co-loaded in poloxamer hydrogel with DDP. Along with improving immune cells in the microenvironment, it can potentially alleviate anxiety and depression. With its outstanding bio-safety profile, it offers promising new possibilities for painless clinical therapy.

Predicting treatment response to ketamine in treatment-resistant depression using auditory mismatch negativity: Study protocol

BACKGROUND

Ketamine has recently attracted considerable attention for its rapid effects on patients with major depressive disorder, including treatment-resistant depression (TRD). Despite ketamine's promising results in treating depression, a significant number of patients do not respond to the treatment, and predicting who will benefit remains a challenge. Although its antidepressant effects are known to be linked to its action as an antagonist of the N-methyl-D-aspartate (NMDA) receptor, the precise mechanisms that determine why some patients respond and others do not are still unclear.

OBJECTIVE

This study aims to understand the computational mechanisms underlying changes in the auditory mismatch negativity (MMN) response following treatment with intravenous ketamine. Moreover, we aim to link the computational mechanisms to their underlying neural causes and use the parameters of the neurocomputational model to make individual treatment predictions.

METHODS

This is a prospective study of 30 patients with TRD who are undergoing intravenous ketamine therapy. Prior to 3 out of 4 ketamine infusions, EEG will be recorded while patients complete the auditory MMN task. Depression, suicidality, and anxiety will be assessed throughout the study and a week after the last ketamine infusion. To translate the effects of ketamine on the MMN to computational mechanisms, we will model changes in the auditory MMN using the hierarchical Gaussian filter, a hierarchical Bayesian model. Furthermore, we will employ a conductance-based neural mass model of the electrophysiological data to link these computational mechanisms to their neural causes.

CONCLUSION

The findings of this study may improve understanding of the mechanisms underlying response and resistance to ketamine treatment in patients with TRD. The parameters obtained from fitting computational models to EEG recordings may facilitate single-patient treatment predictions, which could provide clinically useful prognostic information.

TRIAL REGISTRATION

Clinicaltrials.gov NCT05464264. Registered June 24, 2022.

Non-improvement predicts subsequent non-response to repeated-dose intravenous ketamine for depression: a re-analysis of a 2-week open-label study in patients with unipolar and bipolar depression

There is insufficient evidence to guide dose and frequency optimization with repeated-dose ketamine for depression. This study assessed the value of symptomatic non-improvement after the first few ketamine infusions as a predictor of overall non-response in depression for early decision-making to discontinue treatment. A total of 135 individuals with major depressive disorder or bipolar disorder experiencing a current major depressive episode were administered six repeated doses of intravenous ketamine. Depressive symptoms were assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS) at baseline, 4 h after the first infusion, and 24 h after each infusion. Improvement, partial response, and response were defined as a reduction rate of ≥ 20%, 30%, and 50% in MADRS scores, respectively. This study examined the relationship between improvement (as opposed to non-improvement after each infusion or consecutive non-improvements after the first few infusions) and partial response and response after the sixth infusion. This analysis was summarized using sensitivity, specificity, and other diagnostic test parameters. The sensitivities of improvement at 24 h post-infusion 4 and improvement at 24 h post-infusion 3, vs. three consecutive non-improvements, as predictors for overall partial response and response exceeded 90%. No significant reduction in depressive symptoms was seen in non-improvers following the remaining infusions after the above-identified point. Our study suggests that non-improvement after four infusions, or more conservatively three consecutive non-improvements after three infusions, could serve as a signal of overall non-response to repeated-dose intravenous ketamine for depression and that subsequent treatments would not be warranted.

IN Esketamine and IV Ketamine: Results of a multi-site observational study assessing the effectiveness and tolerability of two novel therapies for treatment-resistant depression

Intravenous (IV) ketamine and intranasal (IN) esketamine are novel therapies to manage treatment resistant depression within major depressive disorder (MDD-TRD). This is a multi-site observational study aiming to assess the real-world effectiveness and tolerability of these novel therapies in the management of MDD-TRD. 53 patients were referred to receive IV ketamine (n = 26, 69.23 % female, 52.81 ± 14.33 years old) or IN esketamine (n = 27, 51.85 % female, 43.93 ± 13.57 years old). Treatment effectiveness was assessed using the Montgomery and Åsberg Depression Rating Scale (MADRS) for depression severity and item 10 of the MADRS for suicidal ideation (SI). Tolerability was assessed by systematically tracking side effects and depersonalization using the 6-item Clinician administered dissociative symptom scale (CADSS-6). The data was analyzed using descriptive statistics, risk ratio and effect size. Both IV ketamine and IN esketamine significantly reduced depressive symptoms and suicidal ideation by treatment endpoint. Patients receiving IN esketamine, and patients receiving IV ketamine had a similar risk of developing side effects. All side effects reported were mild and transient. These results suggested that both IV ketamine and IN esketamine are effective in the management of depressive symptoms and were well tolerated. Therefore, the results of this study could serve to inform clinical practice.

Psilocybin in pharmacotherapy of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a chronic mental disease that affects approximately 2% of the population. Obsessions and compulsions are troublesome for patients and may disturb their everyday activities. The pathogenesis of this disease is still not fully elucidated, but dysfunctions of serotonin-, dopamine- and glutamate-mediated neurotransmission together with early maladaptive schemas seem of importance. Pharmacological treatment includes drugs affecting the serotoninergic, dopaminergic, and glutamatergic systems, such as selective serotonin reuptake inhibitors (SSRIs). Providing that up to 40% of patients with OCD are resistant to the currently available medications, there is a need for novel and effective therapies. Recent discoveries suggest that psilocybin, a non-physically addictive psychoactive substance, may ameliorate disease symptoms. When used in appropriate doses and under strict clinical control, psilocybin appears as a valuable treatment for OCD. This narrative article provides a thorough overview of OCD's etiology, current treatment options, and the emerging evidence supporting psilocybin's efficacy in managing OCD symptoms.

Update on the assessment of resistance to antidepressant treatment: Rationale for the Antidepressant Treatment History Form: Short Form-2 (ATHF-SF2)

All definitions of treatment-resistant depression (TRD) require that patients have experienced insufficient benefit from one or more adequate antidepressant trials. Thus, identifying "failed, adequate trials" is key to the assessment of TRD. The Antidepressant Treatment History Form (ATHF) was one of the first and most widely used instruments that provided objective criteria in making these assessments. The original ATHF was updated in 2018 to the ATHF-SF, changing to a checklist format for scoring, and including specific pharmacotherapy, brain stimulation, and psychotherapy interventions as potentially adequate antidepressant treatments. The ATHF-SF2, presented here, is based on the consensus of the ATHF workgroup about the novel interventions introduced since the last revision and which should/should not be considered effective treatments for major depressive episodes. This document describes the rationale for these choices and, for each intervention, the minimal criteria for determining the adequacy of treatment administration. The Supplementary Material that accompanies this article provide the Scoring Checklist, Data Collection Forms (current episode and composite of previous episodes), and Instruction Manual for the ATHF-SF2.

Rapid Antidepressant-Like Potential of Chaihu Shugan San Depends on Suppressing Glutamate Neurotransmission and Activating Synaptic Proteins in Hippocampus of Female Mice

OBJECTIVE

To explore the rapid antidepressant potential and the underlying mechanism of Chaihu Shugan San (CSS) in female mice.

METHODS

Liquid chromatography mass spectrometry (LC-MS)/MS was used to determine the content of main components in CSS to determine its stability. Female C57BL/6J mice were randomly divided into 4 groups, including control (saline), vehicle (saline), CSS (4 g/kg) and ketamine (30 mg/kg) groups. Mice were subjected to irregular stress stimulation for 4 weeks to establish the chronic mild stress (CMS) model, then received a single administration of drugs. Two hours later, the behavioral tests were performed, including open field test, tail suspension test (TST), forced swimming test (FST), novelty suppression feeding test (NSF), and sucrose preference test (SPT). Western blot analysis was used to detect the expression levels of N-methyl-D-aspartate receptor (NMDA) subtypes [N-methyl-D-aspartate receptor 1 (NR1), NR2A, NR2B], synaptic proteins [synapsin1 and post synaptic density protein 95 (PSD95)], and brain-derived neurotrophic factor (BDNF). Moreover, the rapid antidepressant effect of CSS was tested by pharmacological technologies and optogenetic interventions that activated glutamate receptors, NMDA.

RESULTS

Compared with the vehicle group, a single administration of CSS (4 g/kg) reversed all behavioral defects in TST, FST, SPT and NSF caused by CMS (P<0.05 or P<0.01). CSS also significantly decreased the expressions of NMDA subtypes (NR1, NR2A, NR2B) at 2 h in hippocampus of mice (all P<0.01). In addition, similar to ketamine, CSS increased levels of synaptic proteins and BDNF (P<0.05 or P<0.01). Furthermore, the rapid antidepressant effects of CSS were blocked by transient activation of NMDA receptors in the hippocampus (all P<0.01).

CONCLUSION

Rapid antidepressant effects of CSS by improving behavioral deficits in female CMS mice depended on rapid suppression of NMDA receptors and activation of synaptic proteins.

Rapid and long-lasting effects of subcutaneous esketamine on suicidality: An open-label study in patients with treatment-resistant depression

Therapeutics for suicide management is limited, taking weeks to work. This open-label clinical trial with 18 treatment-resistant depressive patients tested subcutaneous esketamine (8 weekly sessions) for suicidality. We noted a rapid and enduring effect of subcutaneous esketamine, lasting from one week to six months post-treatment, assessed by the Beck Inventory for Suicidality (BSI). There was an immediate drop in suicidality, 24 h following the initial dose, which persisted for seven days throughout the eight-week dosing period. Additionally, this study is the first to examine a six-month follow-up after multiple administrations of subcutaneous esketamine, finding consistently lower levels of suicidality throughout this duration. Conversely, suicidality also was measured along the 8-weeks of treatment by a psychiatrist using the Montgomery-Asberg Depression Rating Scale (MADRS), which showed significant reduction only after two treatment sessions expanding until the last session. Moreover, notably, 61% of patients achieved remission on suicidality (MADRS). These results suggest that weekly subcutaneous esketamine injections offer a cost-effective approach that induces a rapid and sustained response to anti-suicide treatment. This sets the stage for further, more controlled studies to corroborate our initial observations regarding the effects of SC esketamine on suicidality. Registered trial at: https://ensaiosclinicos.gov.br/rg/RBR-1072m6nv.

An astroglial basis of major depressive disorder: Molecular, Cellular, and Circuit Features

Major depressive disorder (MDD) is a common psychiatric disorder and has been a leading cause of disability worldwide. Astrocytes play a role in the maintenance of the function of the central nervous system (CNS), both physiologically and pathologically. Accumulated evidence indicates that the astrocyte is an important contributor to the pathophysiology of MDD including blood-brain barrier (BBB) integrity, gap junctions, gliotransmission, glutamate homeostasis, and energy metabolism. Here, we comprehensively summarize an astroglial basis for MDD based on molecular, cellular, and circuit properties, suggesting that astrocytes appear to be highly sensitive to stress and are likely to be uniquely positioned to integrate peripheral and central stress responses.

Overcoming treatment-resistant depression with machine-learning based tools: a study protocol combining EEG and clinical data to personalize glutamatergic and brain stimulation interventions (SelecTool Project)

Treatment-Resistant Depression (TRD) poses a substantial health and economic challenge, persisting as a major concern despite decades of extensive research into novel treatment modalities. The considerable heterogeneity in TRD's clinical manifestations and neurobiological bases has complicated efforts toward effective interventions. Recognizing the need for precise biomarkers to guide treatment choices in TRD, herein we introduce the SelecTool Project. This initiative focuses on developing (WorkPlane 1/WP1) and conducting preliminary validation (WorkPlane 2/WP2) of a computational tool (SelecTool) that integrates clinical data, neurophysiological (EEG) and peripheral (blood sample) biomarkers through a machine-learning framework designed to optimize TRD treatment protocols. The SelecTool project aims to enhance clinical decision-making by enabling the selection of personalized interventions. It leverages multi-modal data analysis to navigate treatment choices towards two validated therapeutic options for TRD: esketamine nasal spray (ESK-NS) and accelerated repetitive Transcranial Magnetic Stimulation (arTMS). In WP1, 100 subjects with TRD will be randomized to receive either ESK-NS or arTMS, with comprehensive evaluations encompassing neurophysiological (EEG), clinical (psychometric scales), and peripheral (blood samples) assessments both at baseline (T0) and one month post-treatment initiation (T1). WP2 will utilize the data collected in WP1 to train the SelecTool algorithm, followed by its application in a second, out-of-sample cohort of 20 TRD subjects, assigning treatments based on the tool's recommendations. Ultimately, this research seeks to revolutionize the treatment of TRD by employing advanced machine learning strategies and thorough data analysis, aimed at unraveling the complex neurobiological landscape of depression. This effort is expected to provide pivotal insights that will promote the development of more effective and individually tailored treatment strategies, thus addressing a significant void in current TRD management and potentially reducing its profound societal and economic burdens.

A replication study using the World Health Organization pharmacovigilance database (VigiBase®) to evaluate whether an association between ketamine and esketamine and alcohol and substance misuse exists

BACKGROUND AND OBJECTIVES

Ketamine and esketamine are increasingly prescribed in the treatment of resistant mood disorders and persons at risk of suicide. Ketamine is a drug of misuse with increasing non-therapeutic use in the general population. Herein, our aim was to determine whether ketamine and/or esketamine are disproportionately associated with reports of substance and/or alcohol misuse.

METHODS

Replicating a similar analysis recently conducted using the Food and Drug Administration Adverse Event Reporting System (FAERS) database, we identified cases of "alcohol problem, alcoholism, alcohol abuse, substance dependence, substance use disorder (SUD), substance abuse, drug dependence, drug use disorder and drug abuse" in association with ketamine and esketamine reported to the World Health Organization Pharmacovigilance Database (WHO VigiBase). We searched the database from inception to January 2024. The reporting odds ratio (ROR) of each of the aforementioned parameters was calculated; acetaminophen was used as the control. The numerator of the equation represents the number of cases (n) and the denominator represents the total cases of psychiatric disorders (N). Significance was obtained when the lower limit of the 95 % confidence (CI) > 1.0.

RESULTS

The RORs for ketamine was increased for most parameters (i.e., 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), respectively). With respect to esketamine, the RORs were observed to be different from ketamine insofar as we observed a reduction in the RORs for three parameters (i.e., substance abuse (0.41), drug dependence (0.083) and drug abuse (0.052), respectively). The IC025 values were significant for ketamine in cases of alcohol abuse (0.35), substance dependence (0.50), substance use disorder (2.77), substance abuse (0.83), drug dependence (0.97), drug use disorder (1.95) and drug abuse (0.94). Additionally, oxycontin showed significant IC025 values for substance use disorder (0.0014), substance abuse (0.042), and drug dependence (0.17).

CONCLUSION

Esketamine was not associated with an increased ROR for any parameter of alcohol and/or substance use disorder. Mixed results were observed with ketamine with some RORs increased and others decreased. Estimating RORs using a pharmacovigilance database does not establish causation in the case of elevated RORs and cannot be assumed to be a therapeutic effect when lower RORs were observed.

Major challenges in youth psychopathology: treatment-resistant depression. A narrative review

Major depressive disorder (MDD) represents a major health issue in adolescents and young adults, leading to high levels of disability and profoundly impacting overall functioning. The clinical presentation of MDD in this vulnerable age group may slightly differ from what can be observed in adult populations, and psychopharmacological strategies do not always lead to optimal response. Resistance to antidepressant treatment has a prevalence estimated around 40% in youths suffering from MDD and is associated with higher comorbidity rates and suicidality. Several factors, encompassing biological, environmental, and clinical features, may contribute to the emergence of treatment-resistant depression (TRD) in adolescents and young adults. Furthermore, TRD may underpin the presence of an unrecognized bipolar diathesis, increasing the overall complexity of the clinical picture and posing major differential diagnosis challenges in the clinical practice. After summarizing current evidence on epidemiological and clinical correlates of TRD in adolescents and young adults, the present review also provides an overview of possible treatment strategies, including novel fast-acting antidepressants. Despite these pharmacological agents are promising in this population, their usage is expected to rely on risk-benefit ratio and to be considered in the context of integrated models of care.

The effect and mechanism of low-dose esketamine in neuropathic pain-related depression-like behavior in rats

BACKGROUND

Clinical evidence suggests that Esketamine (ESK) is an effective treatment for depression. However, the effects of Esketamine in treating depression-like behavior induced by neuropathic pain is unclear. The underlying molecular mechanisms require further investigation to provide new therapeutic targets for the treatment of clinical neuropathic pain-related depression.

METHODS

A neuropathic pain-related depression model was established in rats with spared nerve injury (SNI). Male Sprague-Dawley rats were randomly divided into four groups: Sham Group, SNI group, SNI + Normal Saline (NS) Group and SNI + ESK5mg/kg Group. Mechanical pain thresholds were measured to assess pain sensitivity in SNI rats. On the 14th day after surgery a forced swim test and sucrose preference test were used to evaluate the depressive-like behavior of rats in each group. Further, a proteomic analysis was used to quantify differentially expressed proteins. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were analyzed to explore the main protein targets of SNI in the medial prefrontal cortex. The expression of proteins was detected by Western blotting.

RESULTS

A neuropathic pain-related depression model was established. Compared with the Sham group, the mechanical pain threshold was decreased significantly (13.2 ± 1.0 vs. 0.7 ± 0.01 g n = 8), while immobility on the forced swim test was also decreased (93.1 ± 7.4 vs. 169.5 ± 9.6 s n = 8), and sucrose preference rate was significantly increased (98.8 ± 0.3 vs. 73.1 ± 1.4n = 7) in SNI group rats. Compared with the SNI + NS group, the mechanical pain threshold was not statistically significant, while immobility on the forced swim test was clearly decreased (161.1 ± 11.6 vs. 77.9 ± 5.0 s n = 8), and sucrose preference rate was significantly increased (53.1 ± 8.9 vs. 96.1 ± 1.4n = 7) in SNI + ESK5mg/kg group rats. To further investigate the underlying mechanism, we employed proteomics to identify proteins exhibiting more than a 1.2-fold difference (P < 0.05) in expression levels within each group for subsequent analysis. Relative to the Sham group, 88 downregulated and 104 up-regulated proteins were identified in the SNI group, while 120 and 84 proteins were up- and down-regulated in the Esketamine treatment group compared with the SNI + NS group. Compared with Sham group, the expressions of mGluR5 and Homer1a were up-regulated in the medial prefrontal cortex (mPFC) in SNI group (mGluR5:0.97 ± 0.05 vs 1.47 ± 0.15, Homer1a:1.03 ± 0.06 vs 1.46 ± 0.16n = 6), and down-regulated after intervention with Esketamine (mGluR5:1.54 ± 0.11 vs 1.06 ± 0.07, Homer1a:1.51 ± 0.13 vs 1.12 ± 0.34n = 6).

CONCLUSIONS

Low-dose Esketamine appeared to relieve depression-like behavior induced by neuropathic pain. The Homer1a-mGluR5 signaling pathway might be the mechanism of antidepressant effect of Esketamine.

Implementation of a ketamine programme for treatment-resistant depression in the public health system: Lessons from the first Australian public hospital clinic

One could argue that we are living through a period of innovation and change in psychiatry unlike that seen before, with repurposed medications emerging as novel treatments. However, despite evidence of enhanced clinical outcomes and potential medium-term savings, delivering these promising interventions is resource-intensive and perceived as difficult in the public sector. Consequently, they are generally only available in the private sector, often at great cost, effectively making them inaccessible to the 'Have Nots'. The arrival of these paradigm-shifting treatments has inadvertently highlighted a growing mental health inequity. The Royal Prince Alfred Hospital's Ketamine Treatment Clinic was the first public-sector ketamine treatment clinic for complex mood disorders in Australia. Based on 3 years' experience establishing, developing and running a public-sector ketamine treatment service, we review the progress, perils and pitfalls for clinicians and health services contemplating establishing a public-sector ketamine treatment service of their own.

Number needed to treat (NNT) for ketamine and esketamine in adults with treatment-resistant depression: A systematic review and meta-analysis

BACKGROUND

Ketamine has been established as efficacious in adults living with Treatment-resistant Depression (TRD). Toward providing a quantifiable estimate of the clinical meaningfulness of the therapeutic benefit of ketamine, herein, we conduct a systematic review that aims to report the Number Needed to Treat (NNT) and the Number Needed to Harm (NNH).

METHODS

This systematic review searched Embase, Medline/Pubmed, PsycINFO and ClinicalTrials.gov from inception up to October 15th 2023, for placebo-controlled, Randomized Controlled Trials (RCTs) assessing racemic ketamine or esketamine therapy for unipolar TRD. We calculated NNT and NNH for ketamine treatments over various time points.

RESULTS

A total of 21 studies with 2042 participants were included. Racemic ketamine treatments had pooled NNTs for response of 7 at 4 h, 3 from one day to one week and 9 for studies at four weeks. Esketamine treatment was found to have a similar efficacy with an NNT of 2 at one day and 11 at four weeks. NNH values indicated low risk for ketamine treatments.

LIMITATIONS

Limitations in the data used include the possibility of functional unblinding and selective reporting bias. Moreover, the meta-analysis may have been limited in its precision by including low threshold definitions of treatment resistance (≥ 1 failed antidepressant) and low-dose ketamine treatments.

CONCLUSION

Herein, we determined that the NNT for ketamine treatment in adults living with TRD across different intervals of observation was <10. We conclude that the NNTs observed herein are highly clinically meaningful in this difficult to treat disorder.

Extended-release ketamine tablets for treatment-resistant depression: a randomized placebo-controlled phase 2 trial

Ketamine has rapid-onset antidepressant activity in patients with treatment-resistant major depression (TRD). The safety and tolerability of racemic ketamine may be improved if given orally, as an extended-release tablet (R-107), compared with other routes of administration. In this phase 2 multicenter clinical trial, male and female adult patients with TRD and Montgomery-Asberg Depression Rating Scale (MADRS) scores ≥20 received open-label R-107 tablets 120 mg per day for 5 days and were assessed on day 8 (enrichment phase). On day 8, responders (MADRS scores ≤12 and reduction ≥50%) were randomized on a 1:1:1:1:1 basis to receive double-blind R-107 doses of 30, 60, 120 or 180 mg, or placebo, twice weekly for a further 12 weeks. Nonresponders on day 8 exited the study. The primary endpoint was least square mean change in MADRS for each active treatment compared with placebo at 13 weeks, starting with the 180 mg dose, using a fixed sequence step-down closed test procedure. Between May 2019 and August 2021, 329 individuals were screened for eligibility, 231 entered the open-label enrichment phase (days 1-8) and 168 responders were randomized to double-blind treatment. The primary objective was met; the least square mean difference of MADRS score for the 180 mg tablet group and placebo was -6.1 (95% confidence interval 1.0 to 11.16, P = 0.019) at 13 weeks. Relapse rates during double-blind treatment showed a dose response from 70.6% for placebo to 42.9% for 180 mg. Tolerability was excellent, with no changes in blood pressure, minimal reports of sedation and minimal dissociation. The most common adverse events were headache, dizziness and anxiety. During the randomized phase of the study, most patient dosing occurred at home. R-107 tablets were effective, safe and well tolerated in a patient population with TRD, enriched for initial response to R-107 tablets. ClinicalTrials.gov registration: ACTRN12618001042235 .

Beyond therapeutic potential: a systematic investigation of ketamine misuse in patients with depressive disorders

Ketamine, a pharmacological agent that acts as an antagonist of the N-methyl-D-aspartate (NMDA) receptor, has garnered considerable interest because of its notable and expeditious antidepressant properties observed in individuals diagnosed with major depressive disorder (MDD) who exhibit resistance to conventional therapeutic interventions. A comprehensive and rigorous systematic review was undertaken to evaluate the prevalence of ketamine abuse undergoing ketamine treatment for depressive disorders. A comprehensive search was conducted across the electronic databases to identify pertinent studies published between 2021 and 2023. The present investigation incorporated a comprehensive range of studies encompassing the abuse or misuse of ketamine, including case reports, observational studies, and clinical trials. Data extraction and quality assessment were conducted in accordance with predetermined criteria. The findings of this systematic review demonstrate the importance of monitoring and addressing ketamine abuse in patients receiving ketamine treatment for depressive disorders like MDD. The wide range of reported prevalence rates highlights the need for standardized criteria and measures for defining and assessing ketamine abuse. This study presents a significant contribution to the field by introducing a novel screening questionnaire and assessment algorithm designed to identify and evaluate ketamine misuse among major depressive disorder (MDD) patients undergoing ketamine treatment. This innovative tool holds the potential to enhance clinical practice by providing healthcare professionals with a standardized approach to promptly detect and address ketamine misuse. The integration of this screening tool into routine care protocols can facilitate more effective monitoring and management of ketamine misuse in this population, ultimately leading to improved patient outcomes and safety.

Finding the best predictive model for hypertensive depression in older adults based on machine learning and metabolomics research

Objective

Depression is a common comorbidity in hypertensive older adults, yet depression is more difficult to diagnose correctly. Our goal is to find predictive models of depression in hypertensive patients using a combination of various machine learning (ML) methods and metabolomics.

Methods

Methods We recruited 379 elderly people aged ≥65 years from the Chinese community. Plasma samples were collected and assayed by gas chromatography/liquid chromatography-mass spectrometry (GC/LC-MS). Orthogonal partial least squares discriminant analysis (OPLS-DA), volcano diagrams and thermograms were used to distinguish metabolites. The attribute discriminators CfsSubsetEval combined with search method BestFirst in WEKA software was used to find the best predicted metabolite combinations, and then 24 classification methods with 10-fold cross-validation were used for prediction.

Results

34 individuals were considered hypertensive combined with depression according to our criteria, and 34 subjects with hypertension only were matched according to age and sex. 19 metabolites by GC-MS and 65 metabolites by LC-MS contributed significantly to the differentiation between the depressed and non-depressed cohorts, with a VIP value of more than 1 and a P value of less than 0.05. There were multiple metabolic pathway alterations. The metabolite combinations screened with WEKA for optimal diagnostic value included 12 metabolites. The machine learning methods with AUC values greater than 0.9 were bayesNet and random forests, and their other evaluation measures are also better.

Conclusion

Altered metabolites and metabolic pathways are present in older adults with hypertension combined with depression. Methods using metabolomics and machine learning performed quite well in predicting depression in hypertensive older adults, contributing to further clinical research.

Esketamine induces tripartite motif-containing protein 24 to improve cognitive dysfunction in Alzheimer's disease

Esketamine has been revealed to improve cognitive impairments under different conditions, while its function in Alzheimer's disease (AD) has not been well characterized. We expounded the effects and detailed mechanism of esketamine in triple transgenic AD (3xTg-AD) mice in the present study. The impaired spatial learning and memory retention of 3xTg-AD mice were ameliorated by esketamine, whereas tripartite motif-containing protein 24 (TRIM24) depletion reversed the ameliorative effects of esketamine in 3xTg-AD mice. Esketamine elevated the extent of PI3K and AKT phosphorylation in the hippocampus by promoting TRIM24 expression, and knockdown of TRIM24 impaired the PI3K/AKT pathway. AD-like mice had increased expression of pro-inflammatory molecules and elevated expression of GFAP and p-Tau. Esketamine reduced inflammation, but its therapeutic effect was reversed by TRIM24 knockdown. The PI3K/AKT pathway blockage exacerbated cognitive deficits and neuroinflammatory responses in mice. Thus, esketamine has the potential to improve the cognitive and memory functions of 3xTg-AD mice by repressing neuroinflammation by activating TRIM24 and the downstream PI3K/AKT pathway.

The association between ketamine and esketamine and suicidality: reports to the Food And Drug Administration Adverse Event Reporting System (FAERS)

INTRODUCTION

Replicated evidence indicates that ketamine and esketamine reduce measures of suicidality in persons with treatment-resistant depression (TRD). It remains uncertain whether individuals experience worsening of preexisting suicidality with either agent.

RESEARCH DESIGN AND METHODS

The Food and Drug Administration Adverse Event Reporting System (FAERS) database was searched from 1970 and 2019 to 30 September 2023 for reports of suicidal ideation, depression suicidal, suicidal behavior, suicidal attempt, and completed suicide in association with ketamine and esketamine exposure, respectively. We present reporting odds ratios (ROR) significance was determined when the lower limit of the 95% confidence interval (CI) exceeded 1.0. Lithium was used as the control agent.

RESULTS

Observed a higher ROR for suicidal ideation (ROR 7.58, 95% CI 6.34-9.07) and depression suicidal (ROR 14.19, 95% CI 1.80-112.07) with esketamine. Significantly lower RORs were observed for suicide attempt with ketamine (ROR 0.15, 95% CI 0.11-0.21) and esketamine (ROR 0.57, 95% CI 0.48-0.67).

CONCLUSIONS

Mixed RORs across aspects of suicidality were observed with ketamine and esketamine. Limitations of the FAERS database prevent any determination of causal effects new onset suicidality to either agent. The lower RORs for suicide attempt with ketamine and esketamine is noted but cannot be interpreted as a direct therapeutic effect.

Esketamine Combined with Dexmedetomidine to reduce Visceral Pain During elective Cesarean Section Under Combined Spinal-Epidural Anesthesia: A double-Blind Randomized Controlled Study

Purpose

We aimed to evaluate the effect of intravenous esketamine combined with dexmedetomidine as supplemental analgesia in reducing intraoperative visceral pain during elective cesarean section under combined spinal-epidural anesthesia (CSEA).

Patients and Methods

A total of 269 parturients scheduled for elective cesarean section under CSEA between May 2023 and August 2023 were assessed. The parturients were randomly allocated to receiving either intravenous infusion of 0.3-mg/kg esketamine combined with 0.5-μg/kg dexmedetomidine (group ED, n=76), 0.5-μg/kg dexmedetomidine (group D, n=76), or normal saline (group C, n=76) after umbilical cord clamping. The primary outcome was intraoperative visceral pain. Secondary outcomes included the visual analog scale (VAS) score for pain evaluation and other intraoperative complications.

Results

The incidence of visceral pain was lower in group ED [9 (12.7%)] than in group D [32 (43.8%)] and group C [36 (48.6%), P <0.0001]. The VAS score was also lower in group ED when exploring abdominal cavity [0 (0), P <0.0001] and suturing the muscle layer [0 (0), P =0.036]. The mean arterial pressure was higher in group D [83 (9) mmHg] and group ED [81 (11) mmHg] than in group C [75 (10) mmHg, P <0.0001] after solution infusion. The heart rate after infusion of the solution was lower in group D [80 (12) bpm] than in group C [86 (14) bpm] and group ED [85 (12) bpm, P = 0.016]. The incidence of transient neurologic or mental symptoms was higher in group ED compared to group C and group D (76.1% vs 18.9% vs 23.3%, P<0.0001).

Conclusion

During cesarean section, 0.3-mg/kg esketamine combined with 0.5-μg/kg dexmedetomidine can alleviate visceral traction pain and provide stable hemodynamics. Parturients receiving this regimen may experience transient neurologic or mental symptoms that can spontaneously resolve at the end of the surgery.

Spectral signatures of psilocybin, lysergic acid diethylamide (LSD) and ketamine in healthy volunteers and persons with major depressive disorder and treatment-resistant depression: A systematic review

BACKGROUND

Electrophysiologic measures provide an opportunity to inform mechanistic models and possibly biomarker prediction of response. Serotonergic psychedelics (SPs) (i.e., psilocybin, lysergic acid diethylamide (LSD)) and ketamine represent new investigational and established treatments in mood disorders respectively. There is a need to better characterize the mechanism of action of these agents.

METHODS

We conducted a systematic review investigating the spectral signatures of psilocybin, LSD, and ketamine in persons with major depressive disorder (MDD), treatment-resistant depression (TRD), and healthy controls.

RESULTS

Ketamine and SPs are associated with increased theta power in persons with depression. Ketamine and SPs are also associated with decreased spectral power in the alpha, beta and delta bands in healthy controls and persons with depression. When administered with SPs, theta power was increased in persons with MDD when administered with SPs. Ketamine is associated with increased gamma band power in both healthy controls and persons with MDD.

LIMITATIONS

The studies included in our review were heterogeneous in their patient population, exposure, dosing of treatment and devices used to evaluate EEG and MEG signatures. Our results were extracted entirely from persons who were either healthy volunteers or persons with MDD or TRD.

CONCLUSIONS

Extant literature evaluating EEG and MEG spectral signatures indicate that ketamine and SPs have reproducible effects in keeping with disease models of network connectivity. Future research vistas should evaluate whether observed spectral signatures can guide further discovery of therapeutics within the psychedelic and dissociative classes of agents, and its prediction capability in persons treated for depression.

Investigating Resistance to Antidepressants in Animal Models

Major depressive disorder is one of the most prevalent psychiatric diseases, and up to 30-40% of patients remain symptomatic despite treatment. Novel therapies are sorely needed, and animal models may be used to elucidate fundamental neurobiological processes that contribute to human disease states. We conducted a systematic review of current preclinical approaches to investigating treatment resistance with the goal of describing a path forward for improving our understanding of treatment resistant depression. We conducted a broad literature search to identify studies relevant to the preclinical investigation of treatment resistant depression. We followed PRISMA (Preferred Reporting Items for Systemic Reviews and Meta-Analyses) guidelines and included all relevant studies. We identified 467 studies in our initial search. Of these studies, we included 69 in our systematic review after applying our inclusion/exclusion criteria. We identified 10 broad strategies for investigating treatment resistance in animal models. Stress hormone administration was the most commonly used model, and the most common behavioral test was the forced swim test. We systematically identified and reviewed current approaches for gaining insight into the neurobiology underlying treatment resistant depression using animal models. Each approach has its advantages and disadvantages, but all require careful consideration of their potential limitations regarding therapeutic translation. An enhanced understanding of treatment resistant depression is sorely needed given the burden of disease and lack of effective therapies.

Risk of esketamine anesthesia on the emergence delirium in preschool children after minor surgery: a prospective observational clinical study

Emergence delirium (ED) is a common mental complication during recovery from anesthesia. However, studies on the effects of esketamine, an intravenous anesthetic for pediatrics, on ED are still lacking. This study aimed to investigate the effects of a single-dose of esketamine during anesthesia induction on ED after minor surgery in preschool children. A total of 230 children (aged 2-7 years) completed the study. The exposed group (0.46 mg kg-1: average dose of esketamine) was associated with an increased incidence of ED and a higher maximum Pediatric Anesthesia Emergence Delirium score than the non-exposed group. The length of post-anesthesia care unit stay was longer in the exposed group than the non-exposed group. In contrast, extubation time, face, legs, activity, cry, and consolability (FLACC) scores, and the proportions of rescue analgesics were comparable between the two groups. Furthermore, five factors, including preoperative anxiety scores, sevoflurane and propofol compared with sevoflurane alone for anesthesia maintenance, dezocine for postoperative analgesia, FLACC scores, and esketamine exposure, were associated with ED. In conclusion, a near-anesthetic single-dose of esketamine for anesthesia induction may increase the incidence of ED in preschool children after minor surgery. The use of esketamine in preschool children for minor surgery should be noticed during clinical practice.

Single arketamine in treatment resistant depression: Presentation of 3 cases with regard to sick-leave duration

BACKGROUND

Ketamine is the prototypal rapid-acting antidepressant (RAAD) for TRD with approved indication for esketamine-nasal spray (ESK-NS). Distinctly, arketamine (R-KET) demonstrates enhanced antidepressant effects and neuroplasticity changes compared to esketamine, with fewer dissociative side effects and abuse potential. This study focuses on R-ketamine's therapeutic implications, safety, and tolerability in TRD treatment.

METHODS

We report on a year-long follow-up of three TRD patients post-single IV R-KET administration. The study, conducted under the clinical trial PCN-101 (NCT05414422), observed these subjects for healthcare resource utilization and social support system impact. Participants, adults diagnosed with recurrent major depressive disorder without psychotic features, were observed in a year-long follow-up period for safety.

RESULTS

Case analyses revealed significant symptom reduction and improved social and vocational functioning, with reduced sick leaves and hospitalizations post-treatment. However, one case developed a substance use disorder, underscoring the need for vigilant monitoring. The study highlights R-KET's transformative potential in managing depression, indicating a shift in TRD treatment strategies towards early, aggressive interventions.

CONCLUSIONS

Despite promising findings, the study faces limitations due to its small sample size, lack of randomization, and potential observational design biases. The results, while aligning with existing ketamine research, require cautious interpretation and warrant further investigation with larger, more robust studies. This exploration of R-KET's role in home-based TRD treatment opens avenues for future research, particularly focusing on its long-term effectiveness and safety in diverse patient populations. This study is registered in clinicaltrials.gov: NCT06232291.

Combination of Acute and Maintenance Esketamine Treatment With Adjunctive Long-Term Vagus Nerve Stimulation in Difficult-to-Treat Depression

INTRODUCTION

The antidepressant effect of N-methyl-D-aspartate antagonists is often short lasting, raising the question of the best maintenance strategy, which has remained unanswered. Vagus nerve stimulation (VNS) as a treatment option for refractory and chronic major depression was shown to reduce the need for maintenance treatment sessions in patients receiving electroconvulsive therapy. To our knowledge, there are no published data on the combination of VNS and esketamine in the literature.

MATERIALS AND METHODS

This is a naturalistic prospective and retrospective observational study in patients treated with long-term VNS owing to difficult-to-treat depression. These patients also have received esketamine maintenance sessions in addition to short-term treatment. We have investigated the need for maintenance esketamine sessions per month after VNS implantation (number of sessions/number of months between visits), the change in depression severity (mean Montgomery-Asberg Depression Rating Scale [MADRS] score), and the number of hospitalizations per month (number of hospitalizations/number of postoperative observation months). Follow-up visits have been scheduled every three months after VNS implantation (follow-up period 12-24 months, mean 17).

RESULTS

All patients (n = 8, mean age 53.1 years) had severe difficult-to-treat depression (DTD) (mean MADRS at baseline 30.9). Mean number of hospitalizations per month decreased from 0.17 to 0.11 after VNS implantation (p = 0.041, T = 2.030, df = 7). Mean MADRS at 12 months was 18.3 (40.8% MADRS reduction, p = 0.008, T = 3.146, df = 7). Six of eight patients were offered maintenance esketamine treatment. Mean number of esketamine treatment sessions per month and case decreased from 2.3 at the six-month visit to 0.8 at 12 months (p = 0.076, T = 1,690, df = 5) after VNS implantation. Termination of maintenance esketamine was possible in four cases after a mean of 11.5 months.

CONCLUSIONS

Combination of esketamine and VNS was effective in patients with DTD to relieve disease severity and reduce hospitalizations. The need for esketamine treatment sessions decreased after 6 months of VNS. No safety concerns arose in this study regarding the combination treatment.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT03320304.

Increasing the bioavailability of oral esketamine by a single dose of cobicistat: A case study

Background

Intranasal esketamine is an approved drug for treatment‐resistant depression (TRD); however, it is costly and may result in specific adverse effects. In this single case study, we explored if oral esketamine can be a suitable alternative.

Methods

In collaboration with a 39‐year‐old female with TRD, we compared plasma concentration curves of intranasal (84 mg) and oral (1, 2 and 4 mg/kg) esketamine. Because oral esketamine has a relatively low bioavailability, it results in a different ratio between esketamine and its primary metabolite noresketamine. To increase the bioavailability of oral esketamine, we co‐administered a single dose of the cytochrome P‐450 (CYP) 3A4 inhibitor cobicistat (150 mg).

Results

For all doses administered, oral esketamine resulted in lower esketamine but higher noresketamine peak plasma concentrations compared with intranasal treatment. Using oral esketamine it was not possible to generate a similar esketamine plasma concentration curve as with the intranasal treatment, except when combined with cobicistat (esketamine 2 mg/kg plus cobicistat 150 mg).

Conclusions

Our findings demonstrate that cobicistat effectively increases the bioavailability of oral esketamine. Further research is required in a larger population, especially to investigate the clinical benefit of cobicistat as a booster drug for oral esketamine.

Modulation of habenular and nucleus accumbens functional connectivity by ketamine in major depression

INTRODUCTION

Major depressive disorder (MDD) is associated with dysfunctional reward processing, which involves functional circuitry of the habenula (Hb) and nucleus accumbens (NAc). Since ketamine elicits rapid antidepressant and antianhedonic effects in MDD, this study sought to investigate how serial ketamine infusion (SKI) treatment modulates static and dynamic functional connectivity (FC) in Hb and NAc functional networks.

METHODS

MDD participants (n = 58, mean age = 40.7 years, female = 28) received four ketamine infusions (0.5 mg/kg) 2-3 times weekly. Resting-state functional magnetic resonance imaging (fMRI) scans and clinical assessments were collected at baseline and 24 h post-SKI. Static FC (sFC) and dynamic FC variability (dFCv) were calculated from left and right Hb and NAc seeds to all other brain regions. Changes in FC pre-to-post SKI, and correlations with changes with mood and anhedonia were examined. Comparisons of FC between patients and healthy controls (HC) at baseline (n = 55, mean age = 32.6, female = 31), and between HC assessed twice (n = 16) were conducted as follow-up analyses.

RESULTS

Following SKI, significant increases in left Hb-bilateral visual cortex FC, decreases in left Hb-left inferior parietal cortex FC, and decreases in left NAc-right cerebellum FC occurred. Decreased dFCv between left Hb and right precuneus and visual cortex, and decreased dFCv between right NAc and right visual cortex both significantly correlated with improvements in mood ratings. Decreased FC between left Hb and bilateral visual/parietal cortices as well as increased FC between left NAc and right visual/parietal cortices both significantly correlated with improvements in anhedonia. No differences were observed between HC at baseline or over time.

CONCLUSION

Subanesthetic ketamine modulates functional pathways linking the Hb and NAc with visual, parietal, and cerebellar regions in MDD. Overlapping effects between Hb and NAc functional systems were associated with ketamine's therapeutic response.

Beyond the serotonin deficit hypothesis: communicating a neuroplasticity framework of major depressive disorder

The serotonin deficit hypothesis explanation for major depressive disorder (MDD) has persisted among clinicians and the general public alike despite insufficient supporting evidence. To combat rising mental health crises and eroding public trust in science and medicine, researchers and clinicians must be able to communicate to patients and the public an updated framework of MDD: one that is (1) accessible to a general audience, (2) accurately integrates current evidence about the efficacy of conventional serotonergic antidepressants with broader and deeper understandings of pathophysiology and treatment, and (3) capable of accommodating new evidence. In this article, we summarize a framework for the pathophysiology and treatment of MDD that is informed by clinical and preclinical research in psychiatry and neuroscience. First, we discuss how MDD can be understood as inflexibility in cognitive and emotional brain circuits that involves a persistent negativity bias. Second, we discuss how effective treatments for MDD enhance mechanisms of neuroplasticity-including via serotonergic interventions-to restore synaptic, network, and behavioral function in ways that facilitate adaptive cognitive and emotional processing. These treatments include typical monoaminergic antidepressants, novel antidepressants like ketamine and psychedelics, and psychotherapy and neuromodulation techniques. At the end of the article, we discuss this framework from the perspective of effective science communication and provide useful language and metaphors for researchers, clinicians, and other professionals discussing MDD with a general or patient audience.

Comparison of Effects of Propofol Combined with Different Doses of Esketamine for ECT in the Treatment of Depression: A Randomized Controlled Trial Protocol

Objective

Major depressive disorder (MDD) is a common mood disorder. Electroconvulsive therapy (ECT) has a significant effect on treatment-resistant MDD. Esketamine may have potential advantages in improving the efficacy of ECT, and the strong affinity of this compound for NMDAR renders it a viable therapeutic option for the management of depression. This study aims to compare the effects of different doses of esketamine combined with propofol anesthesia versus propofol anesthesia alone in ECT, aiming to provide further insights for optimizing ECT and enhancing comprehensive treatment outcomes for depression.

Study Design and Methods

This study was a prospective, randomized, controlled, double-blind trial involving subjects and evaluators. One hundred eleven patients scheduled for ECT were randomly assigned to three groups. In Group P, propofol at 1mg/kg was administered intravenously. In Group P+E, propofol at a dosage of 0.5mg/kg and esketamine at a dosage of 0.5mg/kg was administered intravenously. Patients in Group P+SE received propofol at a dosage of 0.75mg/kg and esketamine at a dosage of 0.25mg/kg. The same anesthesia protocol was used for the same patient until the end of the last treatment. The primary outcome measures were the Hamilton depression scale (HAMD) and the Patient Health Questionnaire-9 (PHQ-9), the Columbia-Suicide Severity Rating Scale (C-SSRS), and the Digit symbol substitution test (DSST). Secondary outcomes included length of hospital stay, readmission rate, hemodynamic status, recovery, and adverse events.

Discussion

This study aimed to compare the effects of propofol combined with different doses of esketamine for ECT. The results may provide a better choice for ECT anesthesia.

The Relationship Between Perioperative Use of Esketamine and Postpartum Depression Risk: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Purpose

To determine whether perioperative esketamine use decreases the risk of postpartum depression (PPD).

Methods

Online search of PubMed, Web of Science, and Embase was conducted to identify relevant studies. Key words for search included, but were not limited to, postpartum depression, esketamine, and clinical trials. The mean and standard deviation of the Edinburgh Postnatal Depression Scale (EPDS) scores were extracted from the studies as primary parameters.

Results

The literature search identified 226 articles, of which 5 met the criteria and were enrolled in the study. In total, 886 patients in the studies were taken into analysis. The EPDS scores in the esketamine group were lower than those of the control group at the early stage of puerperium (WMD=-2.05, 95% CI: -3.77, -0.34, p=0.019), whereas there was no significant difference at the middle and later stages (WMD=-1.41, 95% CI: -2.86, 0.04, p=0.056). The sensitivity analyses indicated that the result for the early stage was stable, whereas it was unreliable for the middle and later stages. The results of the Egger's test indicated no publication bias.

Conclusion

Perioperative use of esketamine contributes to a lower risk of PPD at the early stage of puerperium but not at the middle and later stages. To further verify this conclusion, more high-quality studies are required.

Facts and myths about use of esketamine for treatment-resistant depression: a narrative clinical review

Introduction and aims

Treatment-resistant depression (TRD) occurs when at least two different antidepressants, taken at the right dosage, for adequate period of time and with continuity, fail to give positive clinical effects. Esketamine, the S-enantiomer of ketamine, was recently approved for TRD treatment from U.S. Food and Drug Administration and European Medicine Agency. Despite proved clinical efficacy, many misconceptions by clinicians and patients accompany this medication. We aimed to review the most common "false myths" regarding TRD and esketemine, counterarguing with evidence-based facts.

Methods

The keywords "esketamine", "treatment resistance depression", "depression", "myth", "mythology", "pharmacological treatment", and "misunderstanding" were entered in the main databases and combined through Boolean operators.

Results

Misconceptions regarding the TRD prevalence, clinical features and predictors have been found. With respect of esketamine, criteria to start treatment, dissociative symptoms, potential addiction and aspects of administration and monitoring, were found to be affected by false beliefs by clinicians and patients.

Discussion and conclusion

TRD represents a challenging condition, requiring precise diagnosis in order to achieve patient's full recovery. Esketamine has been proved as an effective medication to treat TRD, although it requires precautions. Evidence can inform clinical practice, in order to offer this innovative treatment to all patients with TRD.

Efficacy of perioperatively application of ketamine on postoperative depressive symptoms in adult patients: A systematic review and meta-analysis with trial sequential analysis

BACKGROUND

Whether ketamine used in the perioperative period reduces the risk of postoperative depressive symptoms remains uncertain. We conducted this systematic review and meta-analysis to evaluate the clinical efficacy of ketamine in adult surgical patients.

METHODS

Two investigators independently systematically searched the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Web of Science, and PsycINFO databases using a combination of relevant Medical Subject Headings terms and free-text keywords from database inception through May 24, 2023.

RESULTS

29 studies encompassing 5327 patients were included. The pooled analysis demonstrated that the ketamine group had no significantly reduced incidence of postoperative depressive mood compared with the control group, with trial sequential analysis (TSA) inconclusive. However, postoperative depression scale scores were significantly decreased in the ketamine group.

LIMITATIONS

Most randomized controlled trials of surgical patients have included depression scale scores as the primary outcome. The incidence of postoperative depressive has been assessed as a secondary outcome or has not been assessed. In addition, non-uniform assessment scales have introduced greater heterogeneity. More rigorous methods and higher-quality evidence for further research are needed to better understand the effects of ketamine on perioperative depression in surgical anesthesia.

CONCLUSIONS

Current evidence suggests that ketamine cannot significantly decrease the incidence of postoperative depressive mood in adult surgical patients. However, ketamine can reduce postoperative depression scores. PROSPERO registration: CRD42023431566.

Guidelines for ketamine use in clinical psychiatry practice

In this editorial, we emphasise the efficacy and challenges of using ketamine in treatment-resistant depression. We highlight the need for comprehensive evidence-based guidelines to manage the use of both licensed and off-licence ketamine formulations and discuss recent efforts by Beaglehole et al to develop ketamine guidelines in New Zealand. We finally advocate for national registries to monitor ketamine therapy, ensuring its responsible and effective use in the management of depression.

Predicting non-response to ketamine for depression: An exploratory symptom-level analysis of real-world data among military veterans

Ketamine helps some patients with treatment resistant depression (TRD), but reliable methods for predicting which patients will, or will not, respond to treatment are lacking. Herein, we aim to inform prediction models of non-response to ketamine/esketamine in adults with TRD. This is a retrospective analysis of PHQ-9 item response data from 120 patients with TRD who received repeated doses of intravenous racemic ketamine or intranasal eskatamine in a real-world clinic. Regression models were fit to patients' symptom trajectories, showing that all symptoms improved on average, but depressed mood improved relatively faster than low energy. Principal component analysis revealed a first principal component (PC) representing overall treatment response, and a second PC that reflects variance across affective versus somatic symptom subdomains. We then trained logistic regression classifiers to predict overall response (improvement on PC1) better than chance using patients' baseline symptoms alone. Finally, by parametrically adjusting the classifier decision thresholds, we identified optimal models for predicting non-response with a negative predictive value of over 96 %, while retaining a specificity of 22 %. Thus, we could identify 22 % of patients who would not respond based purely on their baseline symptoms. This approach could inform rational treatment recommendations to avoid additional treatment failures.

Effects of the selective AMPA modulator NBI-1065845 on the pharmacokinetics of midazolam or ethinyl estradiol-levonorgestrel in healthy adults

This parallel-arm, phase I study investigated the potential cytochrome P450 (CYP)3A induction effect of NBI-1065845 (TAK-653), an investigational α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor potentiator in phase II development for major depressive disorder. The midazolam treatment arm received the sensitive CYP3A substrate midazolam on Day 1, followed by NBI-1065845 alone on Days 5-13; on Day 14, NBI-1065845 was administered with midazolam, then NBI-1065845 alone on Day 15. The oral contraceptive treatment arm received ethinyl estradiol-levonorgestrel on Day 1, then NBI-1065845 alone on Days 5-13; on Day 14, NBI-1065845 was administered with ethinyl estradiol-levonorgestrel, then NBI-1065845 alone on Days 15-17. Blood samples were collected for pharmacokinetic analyses. The midazolam treatment arm comprised 14 men and 4 women, of whom 16 completed the study. Sixteen of the 17 healthy women completed the oral contraceptive treatment arm. After multiple daily doses of NBI-1065845, the geometric mean ratios (GMRs) (90% confidence interval) for maximum observed concentration were: midazolam, 0.94 (0.79-1.13); ethinyl estradiol, 1.00 (0.87-1.15); and levonorgestrel, 0.99 (0.87-1.13). For area under the plasma concentration-time curve (AUC) from time 0 to infinity, the GMRs were as follows: midazolam, 0.88 (0.78-0.98); and ethinyl estradiol, 1.01 (0.88-1.15). For levonorgestrel, the GMR for AUC from time 0 to the last quantifiable concentration was 0.87 (0.78-0.96). These findings indicate that NBI-1065845 is not a CYP3A inducer and support its administration with CYP3A substrates. NBI-1065845 was generally well tolerated, with no new safety signals observed after coadministration of midazolam, ethinyl estradiol, or levonorgestrel.

Effect of Ketamine Treatment on Social Withdrawal in Autism and Autism-Like Conditions

OBJECTIVE

Ketamine and esketamine have been used in the field of psychiatry to alleviate conditions such as major depressive disorder. Our objective was to evaluate the current literature on the use of ketamine for symptoms of social withdrawal in autism spectrum disorder (ASD) and autism-like conditions.

METHODS

A comprehensive search of PubMed and Web of Science was conducted to identify literature involving the use of ketamine to treat symptoms of autism and social withdrawal. Patients with comorbid disorders were also included.

RESULTS

Two original studies were found, showing mixed results on the use of ketamine for ASD. The use of esketamine found no statistically significant results, whereas the use of intravenous ketamine was shown to alleviate symptoms of social withdrawal especially in the short term. Neither study reported a significant amount of serious adverse events. Five case reports were also included, showing decreased depressive symptoms and evidence of increased social condition.

CONCLUSIONS

Research on the use of ketamine for ASD and ASD-related conditions is limited. Evidence of improved social condition exists, but further studies should be conducted to increase sample power and test various doses and methods of administration.

Protocol for a randomised controlled trial of ketamine versus ketamine and behavioural activation therapy for adults with treatment-resistant depression in the community

INTRODUCTION

Although short-term benefits follow parenteral ketamine for treatment-resistant major depressive disorder (TR-MDD), there are challenges that prevent routine use of ketamine by clinicians. These include acute dissociative effects of parenteral ketamine, high relapse rates following ketamine dosing and the uncertain role of psychotherapy. This randomised controlled trial (RCT) seeks to establish the feasibility of evaluating repeated oral doses of ketamine and behavioural activation therapy (BAT), compared with ketamine treatment alone, for TR-MDD. We also aim to compare relapse rates between treatment arms to determine the effect size of adding BAT to oral ketamine.

METHODS AND ANALYSIS

This is a prospectively registered, two-centre, single-blind RCT. We aim to recruit 60 participants with TR-MDD aged between 18 and 65 years. Participants will be randomised to 8 weeks of oral ketamine and BAT, or 8 weeks of oral ketamine alone. Feasibility will be assessed by tracking attendance for ketamine and BAT, acceptability of treatment measures and retention to the study follow-up protocol. The primary efficacy outcome measure is the Montgomery-Asberg Depression Rating Scale (MADRS) measured weekly during treatment and fortnightly during 12 weeks of follow-up. Other outcome measures will assess the tolerability of ketamine and BAT, cognition and activity (using actigraphy). Participants will be categorised as non-responders, responders, remitters and relapsed during follow-up. MADRS scores will be analysed using a linear mixed model. For a definitive follow-up RCT study to be recommended, the recruitment expectations will be met and efficacy outcomes consistent with a >20% reduction in relapse rates favouring the BAT and ketamine arm will be achieved.

ETHICS AND DISSEMINATION

Ethics approval was granted by the New Zealand Central Health and Disability Ethics Committee (reference: 2023 FULL18176). Study findings will be reported to participants, stakeholder groups, conferences and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

UTN: U1111-1294-9310, ACTRN12623000817640p.

The Economics of Treatment for Depression

The global prevalence of depression has risen over the past three decades across all socioeconomic groups and geographic regions, with a particularly rapid increase in prevalence among adolescents (aged 12-17 years) in the United States. Depression imposes large health, economic, and societal costs, including reduced life span and quality of life, medical costs, and reduced educational attainment and workplace productivity. A wide range of treatment modalities for depression are available, but socioeconomic disparities in treatment access are driven by treatment costs, lack of culturally tailored options, stigma, and provider shortages, among other barriers. This review highlights the need for comparative research to better understand treatments' relative efficacy, cost-effectiveness, scalability, and potential heterogeneity in efficacy across socioeconomic groups and country and cultural contexts. To address the growing burden of depression, mental health policy could consider reducing restrictions on the supply of providers, implementing digital interventions, reducing stigma, and promoting healthy lifestyles.

Oral prolonged-release ketamine in treatment-resistant depression - A double-blind randomized placebo-controlled multicentre trial of KET01, a novel ketamine formulation - Clinical and safety results

INTRODUCTION

We investigated the antidepressant effects of a novel oral prolonged-release formulation of racemic ketamine (KET01) in patients suffering from treatment-resistant depression (TRD) as add-on therapy.

MATERIAL AND METHODS

Patients were randomized to an additional 160 mg/day or 240 mg/day KET01 or placebo for 14 days. The primary endpoint was change in Montgomery-Åsberg Depression Rating Scale (MADRS) scores from baseline to day 15. For treatment group comparisons, we used ANOVA with pairwise least squares mean difference tests in a mixed model repeated measures analysis.

RESULTS

Twenty-seven patients completed the double-blind protocol before trial premature termination due to poor recruitment during the COVID-19 pandemic. Mean (SD) MADRS scores on day 15 were 23 (10.32) in placebo, 25 (8.28) with 160 mg/day and 17 (10.32) with 240 mg/day KET01. MADRS change was numerically larger but statistically non-significant in the 240 mg/day KET01 group vs placebo on day 7 (-5.67; p = 00.106) and day 15 was (difference: 4.99; p = 00.15). In exploratory analysis, baseline leukocyte count correlated with response to KET01 (p = 00.01). Distribution of adverse event rates were comparable between the treatment arms. Safety analysis did not identify increased risk of suicidality, dissociation, hear rate, systolic and diastolic blood pressure associated with trial treatment.

DISCUSSION

Our results suggest that adjunctive oral administration of prolonged-release ketamine at a dose of 240 mg/day shows a positive, although statistically non-significant, trend towards antidepressant efficacy, however, the benefit could not be confirmed due to premature trial termination. Given its ease of use and low side effects, further trials are warranted to investigate this route of ketamine administration as a promising potential treatment of TRD.

IV low dose ketamine infusions for treatment resistant depression: Results from a five-year study at a free public clinic in an academic hospital

Individuals with major depressive disorder and treatment resistant depression (MDD-TRD) have limited and sometimes poorly tolerated therapeutic options. Low dose ketamine has presented promising and potent antidepressant effects in this population. To support the existent literature, we conducted a longitudinal study examining five years of real-world clinical data on the use of IV low-dose ketamine alongside standard care for MDD-TRD outpatients. For this study we collected demographic information, clinical scale scores, side effects and dropout data. The data was analyzed using descriptive statistics, effect size using Cohen's D analysis, and multivariate ANOVA (MANOVA) to determine the impact of sociodemographic variables. 71 outpatients (50.28 years old, SD: 14.26; female 74.65%) were included in the analysis. The results showed a significant reduction in depressive symptoms and suicide ideation (SI) by treatment endpoint. 54.93% of patients responded to the treatment, 78.26% experienced transient and mild side effects, and 11.27% of dropped out of the treatment. Multivariate analysis showed that the demographic variables did not impact treatment effect or tolerability. The results of this study suggest that IV low dose ketamine treatment is effective, fast-acting, and well tolerated for the management of depressive symptoms and SI in patients with MDD-TRD in naturalistic clinical practice.

Effect of intraoperative and/or postoperative esketamine administration on preventing postpartum depression: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to evaluate the impact of intraoperative and/or postoperative esketamine application on the prevention of postpartum depression (PPD). PubMed, Embase, and Web of Science were thoroughly searched for eligible randomized controlled trials (RCTs) regarding the application of esketamine for postnatal depression prevention. Nine RCTs including 1277 participants were involved in the final analysis. It was found that intraoperative and/or postoperative administration of esketamine significantly reduced the PPD incidence and the Edinburgh Postnatal Depression Scores in the early postoperative period. Meanwhile, esketamine lowered the occurrence of postoperative nausea and vomiting with no influence on other psychiatric symptoms.

Depression with comorbid borderline personality disorder - could ketamine be a treatment catalyst?

Borderline personality disorder (BPD) is diagnosed in 10-30% of patients with major depressive disorder (MDD), and the frequency of MDD among individuals with BPD reaches over 80%. The comorbidity of MDD and BPD is associated with more severe depressive symptoms and functional impairment, higher risk of treatment resistance and increased suicidality. The effectiveness of ketamine usage in treatment resistant depression (TRD) has been demonstrated in numerous studies. In most of these studies, individuals with BPD were not excluded, thus given the high co-occurrence of these disorders, it is possible that the beneficial effects of ketamine also extend to the subpopulation with comorbid TRD and BPD. However, no protocols were developed that would account for comorbidity. Moreover, psychotherapeutic interventions, which may be crucial for achieving a lasting therapeutic effect in TRD and BPD comorbidity, were not included. In the article, we discuss the results of a small number of existing studies and case reports on the use of ketamine in depressive disorders with comorbid BPD. We elucidate how, at the molecular and brain network levels, ketamine can impact the neurobiology and symptoms of BPD. Furthermore, we explore whether ketamine-induced neuroplasticity, augmented by psychotherapy, could be of use in alleviating core BPD-related symptoms such as emotional dysregulation, self-identity disturbances and self-harming behaviors. We also discuss the potential of ketamine-assisted psychotherapy (KAP) in BPD treatment. As there is no standard approach to the application of ketamine or KAP in individuals with comorbid TRD and BPD, we consider further research in the field as imperative. The priorities should include development of dedicated protocols, distinguishing subpopulations that may benefit most from such treatment and investigating factors that may influence its effectiveness and safety.