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

Suicidal ideation following ketamine prescription in patients with recurrent major depressive disorder: a nation-wide cohort study

Ketamine has gained attention for its effective treatment for patients with major depressive disorder (MDD) and suicidal ideation; Despite numerous studies presenting the rapid efficacy, long-term benefit in real-world populations remains poorly characterized. This is a retrospective cohort study using TriNetX US Collaborative Network, a platform aggregating electronic health records (EHRs) data from 108 million patients from 62 health care organizations in the US, and the study population includes 514,988 patients with a diagnosis of recurrent MDD who were prescribed relevant treatment in their EHRs. The prescription of ketamine was associated with significantly decreased risk of suicidal ideation compared to the prescription of other common antidepressants: HR = 0.63 (95% CI: 0.53-0.76) at 1 day - 7 days, 0.67 (95% CI: 0.59-0.77) at 1 day - 30 days, 0.69 (95% CI: 0.62-0.77) at 1 day - 90 days, 0.74 (95% CI: 0.67-0.81) at 1 day - 180 days, and 0.78 (95% CI: 0.69-0.83) at 1 day - 270 days. This trend was especially robust among adults over 24 years of age, females, males, and White patients with recurrent MDD. This study provides real-world evidence that ketamine has long-term benefits in mitigating suicidal ideation in patients with recurrent MDD. Future work should focus on optimizing dosage regimens for ketamine, understanding the mechanism, and the difference in various demographic subpopulations.

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.

The Use of Ketamine for the Treatment of Anhedonia in Depression

Anhedonia, a complex symptom rooted in deficits across reward processes, is primarily linked to depression and schizophrenia but transcends diagnostic boundaries across various mental disorders. Its presence correlates with poorer clinical outcomes, including an increased risk of suicide and diminished response to treatment. The neurobiological underpinnings of anhedonia remain incompletely understood despite advancements in biomarkers and imaging that contribute to deeper insights. Ketamine, known for its rapid-acting antidepressant properties, appears to possess antianhedonic effects through a mechanism of action not fully elucidated. This effect appears to be independent of its antidepressant properties. Explorations into alternative antianhedonic treatments have been underway, yet lingering questions persist, underscoring the imperative need for ongoing research to advance the field.

Synergistic use of deep TMS therapy with IV ketamine infusions for major depressive disorder: a pilot study

OBJECTIVE

Major Depressive Disorder (MDD) is a pervasive psychiatric condition effecting approximately 21 million adults in the U.S. (8.4%). An estimated 30-60% of patients are resistant to traditional treatment approaches (medications and talk-therapy), alluding to the need for additional options. Two promising treatment modalities include transcranial magnetic stimulation (TMS) and ketamine infusions; both have shown efficacy in standalone studies but have scarcely been investigated synergistically in the same group of participants.

METHOD

In the current study, 169 participants with treatment-resistant MDD received 36 treatments of Deep TMS-only (H1 + H7 protocols), while 66 received 36 treatments of Deep TMS (H1 + H7 protocols) and 6 IV infusions of ketamine over the course of 9 weeks. Depressive symptoms were compared pre- and -post treatment in both conditions using the PHQ-9.

RESULTS

In both treatment groups, depressive symptoms were significantly reduced from pre-to-post and there were no significant differences in response between the TMS + ketamine condition and the TMS-only condition. The TMS + ketamine condition had an 80.30% response rate (53 out of 66) and 43.42% remission rate (28 out of 66) compared to a 76.92% response (130 out of 169) and 39.64% remission (67 out of 16) in the TMS-only condition.

CONCLUSION

These results support the notion that TMS treatments yield high response rates in treatment-resistant cases; however, in this investigation there was no added benefit for including 6 sessions of IV ketamine in conjunction with TMS. Future investigations using randomized-control designs and robust outcome measures are warranted.

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.

Ketamine vs Electroconvulsive Therapy for Treatment-Resistant Depression: A Secondary Analysis of a Randomized Clinical Trial

Importance

The ELEKT-D: Electroconvulsive Therapy (ECT) vs Ketamine in Patients With Treatment Resistant Depression (TRD) (ELEKT-D) trial demonstrated noninferiority of intravenous ketamine vs ECT for nonpsychotic TRD. Clinical features that can guide selection of ketamine vs ECT may inform shared decision-making for patients with TRD.

Objective

To evaluate whether selected clinical features were associated with differential improvement with ketamine vs ECT.

Design, Setting, and Participants

This secondary analysis of an open-label noninferiority randomized clinical trial was a multicenter study conducted at 5 US academic medical centers from April 7, 2017, to November 11, 2022. Analyses for this study, which were not prespecified in the trial protocol, were conducted from May 10 to Oct 31, 2023. The study cohort included patients with TRD, aged 21 to 75 years, who were in a current nonpsychotic depressive episode of at least moderate severity and were referred for ECT by their clinicians.

Exposures

Eligible participants were randomized 1:1 to receive either 6 infusions of ketamine or 9 treatments with ECT over 3 weeks.

Main Outcomes and Measures

Association between baseline factors (including 16-item Quick Inventory of Depressive Symptomatology Self-Report [QIDS-SR16], Montgomery-Asberg Depression Rating Scale [MADRS], premorbid intelligence, cognitive function, history of attempted suicide, and inpatient vs outpatient status) and treatment response were assessed with repeated measures mixed-effects model analyses.

Results

Among the 365 participants included in this study (mean [SD] age, 46.0 [14.5] years; 191 [52.3%] female), 195 were randomized to the ketamine group and 170 to the ECT group. In repeated measures mixed-effects models using depression levels over 3 weeks and after false discovery rate adjustment, participants with a baseline QIDS-SR16 score of 20 or less (-7.7 vs -5.6 points) and those starting treatment as outpatients (-8.4 vs -6.2 points) reported greater reduction in the QIDS-SR16 with ketamine vs ECT. Conversely, those with a baseline QIDS-SR16 score of more than 20 (ie, very severe depression) and starting treatment as inpatients reported greater reduction in the QIDS-SR16 earlier in course of treatment (-8.4 vs -6.7 points) with ECT, but scores were similar in both groups at the end-of-treatment visit (-9.0 vs -9.9 points). In the ECT group only, participants with higher scores on measures of premorbid intelligence (-14.0 vs -11.2 points) and with a comorbid posttraumatic stress disorder diagnosis (-16.6 vs -12.0 points) reported greater reduction in the MADRS score. Those with impaired memory recall had greater reduction in MADRS during the second week of treatment (-13.4 vs -9.6 points), but the levels of MADRS were similar to those with unimpaired recall at the end-of-treatment visit (-14.3 vs -12.2 points). Other results were not significant after false discovery rate adjustment.

Conclusions and Relevance

In this secondary analysis of the ELEKT-D randomized clinical trial of ECT vs ketamine, greater improvement in depression was observed with intravenous ketamine among outpatients with nonpsychotic TRD who had moderately severe or severe depression, suggesting that these patients may consider ketamine over ECT for TRD.

Rapid and sustained antidepressant effects of intravenous ketamine in treatment-resistant major depressive disorder and suicidal ideation: a randomized clinical trial

BACKGROUND

Major depressive disorder (MDD) is the most disabling and burdensome mental disorder, negatively affecting an individual's quality of life and daily functioning. the current study was conducted with the aim of investigating the clinical effects of intravenous ketamine on symptoms of MDD and suicidal ideation.

METHODS

The current randomized clinical trial was carried out on 64 patients diagnosed with treatment-resistant major depressive disorder between April and August 2022. The participants were randomly assigned to two groups: the intervention group received a dose of 0.5 mg/kg of ketamine, while the control group received normal saline. The Montgomery-Asberg Depression Scale and Beck's Suicidal Ideation Scale were utilized to assess depression and suicidal ideation, respectively.

RESULTS

One hour after the administration of ketamine treatment, there was a notable and significant improvement in both depression symptoms (35.16 ± 8.13 vs. 14.90 ± 10.09) and suicidal ideation (6.74 ± 6.67 vs. 0.42 ± 1.52). Moreover, there were statistically significant differences in depression scores between the two groups at one hour, four hours, one day, three days, one week, one month, and two months after the administration of ketamine (p-value < 0.001). However, ketamine recipients frequently experienced side effects such as increased heart rate, headache, dizziness, and dissociative syndrome symptoms.

CONCLUSION

The observed rapid onset of action and sustained effect demonstrate the potential of ketamine to provide relief from depressive symptoms in a shorter timeframe compared to traditional treatment approaches. These findings contribute to the growing body of evidence supporting the use of ketamine as a valuable therapeutic option for patients with treatment-resistant depression.

IRCT REGISTRATION

IRCT registration number: IRCT20210806052096N1; IRCT URL: https://www.irct.ir/trial/62243 ; Ethical code: IR.ZUMS.REC.1400.150; Registration date: 2022-04-09.

Ethopharmacological evaluation of antidepressant-like effect of serotonergic psychedelics in C57BL/6J male mice

Serotonergic psychedelics such as psilocybin, lysergic acid diethylamide, and DOI exert a hallucinatory effect through serotonin 5-HT2A receptor (5-HT2A) activation. Recent studies have revealed that serotonergic psychedelics have therapeutic potential for neuropsychiatric disorders, including major depressive and anxiety-related disorders. However, the involvement of 5-HT2A in mediating the therapeutic effects of these drugs remains unclear. In this study, we ethopharmacologically analyzed the role of 5-HT2A in the occurrence of anxiolytic- and antidepressant-like effects of serotonergic psychedelics such as psilocin, an active metabolite of psilocybin, DOI, and TCB-2 in mice 24 h post-treatment. Mice with acute intraperitoneal psychedelic treatment exhibited significantly shorter immobility times in the forced swimming test (FST) and tail-suspension test (TST) than vehicle-treated control mice. These effects were eliminated by pretreatment with volinanserin, a 5-HT2A antagonist. Surprisingly, the decreasing immobility time in the FST in response to acute psilocin treatment was sustained for at least three weeks. In the novelty-suppressed feeding test (NSFT), the latency to feed, an indicator of anxiety-like behavior, was decreased by acute administration of psilocin; however, pretreatment with volinanserin did not diminish this effect. In contrast, DOI and TCB-2 did not affect the NSFT performance in mice. Furthermore, psilocin, DOI, and TCB-2 treatment did not affect the spontaneous locomotor activity or head-twitch response, a hallucination-like behavior in rodents. These results suggest that 5-HT2A contributes to the antidepressant effects of serotonergic psychedelics rather than anxiolytic effects.

A retrospective analysis of iv ketamine outcome on hospitalisations in an unselected psychiatric sample

OBJECTIVE

This study aims to explore the outcome with iv ketamine treatment in a real-world clinical setting, primarily measured as posttreatment days hospitalised.

METHODS

The psychiatric medical records of 46 patients having received iv ketamine on a psychiatric treatment indication between 2015 and 2018 were retrospectively examined. Analysis comparing the number and duration of hospital admissions before and after ketamine treatment as well as logistic regression analysis to investigate clinical predictors of effectiveness, were performed. To assess patients' severity of depressed symptoms records were screened for MADRS-S scores.

RESULTS

No significant difference between pre- and posttreatment hospital days (p = 0.170), or number of hospitalisations (p = 0.740) were found. The response rate was 31% and remission rate 21%. None of the predictors showed statistical significance in the logistic model.

CONCLUSION

Iv ketamine treatment showed effectiveness in reducing depressive symptoms even with complex patients in a real-world clinical setting. However, this did not translate to a reduction in hospitalisation. Highlighting the multifaceted challenges posed when implementing iv ketamine treatment in clinical practice.

Brain-derived neurotrophic factor Val66Met and CYP2B6 polymorphisms as predictors for ketamine effectiveness in patients with treatment-resistant depression

BACKGROUND

Converging lines of evidence indicate that ketamine is a rapid antidepressant for individuals with treatment-resistant depression. Hitherto, no reliable a priori predictors of ketamine response have been reported. Pharmacogenetic biomarkers have yielded mixed results regarding potential candidate genes associated with ketamine's biochemistry as reliable predictors of response.

AIMS

No studies have examined the effects of Val66Met and CYP2B6 genotypes on patients receiving repeated infusions of intravenous ketamine.

METHODS

In all, 85 participants with major depressive disorder who had previously received four infusions of intravenous ketamine were recruited to the foregoing study. Buccal swabs were collected and genotype variants across the Val66Met and CYP2B6 genes were analyzed. A repeated measures mixed linear model was used to assess change in depressive symptoms, suicidality, and anxiety, correcting for sex and age. Multiple regression was run to determine whether these genetic markers were associated with treatment efficacy for depressive severity, suicidal ideation, anxiolytic response, and degree of dissociation to intravenous ketamine.

RESULTS

Participants experienced significant overall reductions in depression, suicide, and anxiety. Overall, 25% met the response criteria and 15% met the remission criteria. However, Val66Met and CYP2B6 did not significantly predict changes in symptoms of depression, suicide, anxiety, or average dissociation.

CONCLUSIONS

This study contributes to the growing literature that ketamine efficacy is unlikely to be predicted by single genes, and a pleiotropic approach may likely be necessary for developing reliable predictors of clinical benefits.

Exploring Predictors of Ketamine Response in Adolescent Treatment-Resistant Depression

Objective: Ketamine has proved effective as a rapid-acting antidepressant agent, but treatment is not effective for everyone (approximately a quarter to a half of patients). Some adult studies have begun to investigate predictors of ketamine's antidepressant response, but no studies have examined this in adolescents with depression. Methods: We conducted a secondary data analysis of adolescents who participated in a randomized, single-dose, midazolam-controlled crossover trial of ketamine for adolescents with treatment-resistant depression. We examined the relationship between 19 exploratory demographic and clinical variables and depression symptom improvement (using the Montgomery-Åsberg Depression Rating Scale [MADRS]) at 1 and 7 days postinfusion. Results: Subjects who had fewer medication trials of both antidepressant medications and augmentation treatments were more likely to experience depression symptom improvement with ketamine. Subjects with shorter duration of their current depressive episode were more likely to experience depression symptom improvement with ketamine. Subjects currently being treated with selective serotonin reuptake inhibitor medications, and not being treated with serotonin-norepinephrine reuptake inhibitor medications, also experienced greater symptom improvement with ketamine. When receiving the midazolam control, less severe depressive symptoms, as measured by the Children's Depression Rating Scale (CDRS) (but not MADRS), and a comorbid attention-deficit/hyperactivity disorder diagnosis were associated with increased response. Conclusions: Findings should be viewed as preliminary and exploratory given the small sample size and multiple secondary analyses. Identifying meaningful predictors of ketamine response is important to inform future therapeutic use of this compound, however, considerably more research is warranted before such clinical guidance is established. The trial was registered in clinicaltrials.gov with the identifier NCT02579928.

A computational model to characterize the time-course of response to rapid antidepressant therapies

Our objective is to propose a method capable of disentangling the magnitude, the speed, and the duration or decay rate of the time course of response to rapid antidepressant therapies. To this end, we introduce a computational model of the time course of response to a single treatment with a rapid antidepressant. Numerical simulation is used to evaluate whether model parameters can be accurately estimated from observed data. Finally, we compare our computational modelling-based approach with linear mixed effects modelling in terms of their ability to detect changes in the magnitude and time-course of response to rapid antidepressant therapies in simulated randomized trials. Simulation experiments show that the parameters of our computational model can be accurately recovered using nonlinear least squares. Parameter estimation accuracy is stable over noise levels reaching as high as 25% of the true antidepressant effect magnitude. Comparison of our approach to mixed effects modelling using simulated randomized controlled trial data demonstrates an inability of linear mixed models to disentangle effect magnitude and time course, while our computational model accurately separates these response components. Our modelling approach may accurately identify the (A) magnitude, (B) speed, and (C) durability or decay rate of response to rapid antidepressant therapies. Future studies should fit this model to data from real clinical trials, and use resulting parameter estimates to uncover predictors and causes of different elements of the temporal course of antidepressant response.

EEG-vigilance regulation is associated with and predicts ketamine response in major depressive disorder

Ketamine offers promising new therapeutic options for difficult-to-treat depression. The efficacy of treatment response, including ketamine, has been intricately linked to EEG measures of vigilance. This research investigated the interplay between intravenous ketamine and alterations in brain arousal, quantified through EEG vigilance assessments in two distinct cohorts of depressed patients (original dataset: n = 24; testing dataset: n = 24). Clinical response was defined as a decrease from baseline of >33% on the Montgomery-Åsberg Depression Rating Scale (MADRS) 24 h after infusion. EEG recordings were obtained pre-, start-, end- and 24 h post- infusion, and the resting EEG was automatically scored using the Vigilance Algorithm Leipzig (VIGALL). Relative to placebo (sodium chloride 0.9%), ketamine increased the amount of low-vigilance stage B1 at end-infusion. This increase in B1 was positively related to serum concentrations of ketamine, but not to norketamine, and was independent of clinical response. In contrast, treatment responders showed a distinct EEG pattern characterized by a decrease in high-vigilance stage A1 and an increase in low-vigilance B2/3, regardless of whether placebo or ketamine had been given. Furthermore, pretreatment EEG differed between responders and non-responders with responders showing a higher percentage of stage A1 (53% vs. 21%). The logistic regression fitted on the percent of A1 stages was able to predict treatment outcomes in the testing dataset with an area under the ROC curve of 0.7. Ketamine affects EEG vigilance in a distinct pattern observed only in responders. Consequently, the percentage of pretreatment stage A1 shows significant potential as a predictive biomarker of treatment response.Clinical Trials Registration: https://www.clinicaltrialsregister.eu/ctr-search/trial/2013-000952-17/CZ Registration number: EudraCT Number: 2013-000952-17.

The rapid antidepressant effect of acupuncture on two animal models of depression by inhibiting M1-Ach receptors regulates synaptic plasticity in the prefrontal cortex

BACKGROUND

It is unclear whether acupuncture has a rapid antidepressant effect and what is the main mechanism.

METHODS

In this study, forced swimming stress test (FST) in mice were divided into five groups: control group, acupuncture group, scopolamine group, arecoline group, and acupuncture + arecoline group. Chronic unpredictable mild stress (CUMS) model rats were divided into six groups: naïve (non-CUMS) group, CUMS group, acupuncture group, scopolamine group, arecoline group, and acupuncture + arecoline group. Twenty-four hours after the end of treatment, FST was conducted in mice and rats. The expression of M1-AchR, AMPA receptors (GluR1 and GluR2), BDNF, mTOR, p-mTOR, synapsin I, and PSD95 in the prefrontal cortex was determined by western blot. The spine density of neurons in the prefrontal cortex was detected by golgi staining.

RESULTS

The results showed that acupuncture reduced the immobility time of FST in two depression models. Acupuncture inhibited the expression of M1-AchR and promoted the expression of GluR1, GluR2, BDNF, p-mTOR, synapsin I, PSD95, and increased the density of neuron dendritic spine in the prefrontal cortex.

CONCLUSIONS

The rapid antidepressant effect of acupuncture may be activating the "glutamate tide" - AMPA receptor activation - BDNF release - mTORC1 pathway activation through inhibiting the expression of M1-AchR in the prefrontal cortex, thereby increasing the expression of synaptic proteins and regulating synaptic plasticity.

Factors Associated with Antidepressant Effects of Ketamine: A Reanalysis of Double-Blind Randomized Placebo-Controlled Trial of Intravenous Ketamine for Treatment-Resistant Depression

INTRODUCTION

Predictors of treatment response to intravenous ketamine remain unclear in patients with treatment-resistant depression (TRD); therefore, this study aimed to clarify these predictors using the US National Institutes of Health database of clinical trials.

METHODS

Data from a placebo-controlled, double-blind, randomized controlled trial were used to assess the efficacy of intravenous ketamine in adult patients with TRD (NCT01920555). For the analysis, data were used from the participants who had received therapeutic doses of intravenous ketamine (i. e., 0.5 and 1.0 mg/kg). Logistic and multivariable regression analyses were conducted to explore the demographic and clinical factors associated with response to treatment or changes in the Hamilton Depression Rating Scale 6 items (HAM-D-6) total score.

RESULTS

This study included 31 patients with TRD (13 women; mean±standard deviation age, 48.4±10.9 years). Logistic regression analysis showed that the age of onset was positively correlated with treatment response after three days of ketamine administration (β=0.08, p=0.037); however, no association was observed between treatment response and age, sex, baseline HAM-D-6 total score, or dissociative score assessed with the Clinician-Administered Dissociative States Scale 40 min after ketamine infusion. Multiple regression analysis showed that no factors were correlated significantly with the percentage change in the HAM-D-6 total score three days after ketamine administration.

DISCUSSION

Later disease onset correlates with a better treatment response three days after ketamine infusion in patients with TRD. Glutamatergic signal transmission may be impaired in patients with an earlier onset of depression, resulting in decreased neuroplasticity, which diminishes ketamine response.

Anti-suicidal effects of IV ketamine in a real-world setting

The current study evaluated the effectiveness of intravenous ketamine treatment for suicidality in a community-based clinical sample of 295 outpatients (mean age=  40.37; 58.6 % male). We conducted growth mixture modeling to estimate latent classes of changes in symptoms of suicidality measured by the Concise Health Risk Tracking - Self-Report (CHRT-SR) across five infusions in a two-week course of treatment. Best-fit indices indicated three trajectory groups demonstrating non-linear, quadratic changes in CHRT-SR scores during ketamine treatment. The largest group of patients (n=  170, 57.6 %) had moderate CHRT-SR scores at baseline and showed gradual improvement during treatment. The other two groups of patients had severe CHRT-SR scores at baseline and diverged into one group with no improvement throughout treatment (n = 63, 21  %) and one group with rapid improvement (n = 62, 21 %). Of the clinical and demographic variables available and tested, only higher scores pertaining to active thoughts of death and/or plan were found to predict which of the patients with severe CHRT-SR scores at baseline would not benefit from treatment. The present study provides an important contribution to the knowledge of ketamine's effects on symptoms related to suicide over time. providing support for the possible effectiveness of ketamine in a proportion of patients.

Associations of adolescent substance use and depressive symptoms with adult major depressive disorder in the United States: NSDUH 2016-2019

BACKGROUND

Few studies have focused on the associations of adolescent substance use and depressive symptoms with adult major depressive disorder (MDD).

METHODS

Data from 168,859 adults, among which, 15,959 had experienced MDD in the past year, as indicated by a major depressive episode (MDE) marked by MDD symptoms, were from the 2016-2019 National Surveys on Drug Use and Health. Weighted multivariable logistic regression (MLR) analyses were used to determine the associations.

RESULTS

The overall MDD prevalence was 7.2 %, whereas the prevalence for adults without early onset depressive symptoms prior to age 18 was 4.6 %. Variable cluster analysis revealed that adolescent use of alcohol, cigarettes, marijuana, cocaine, hallucinogen use, and inhalants prior to age 18 were in one cluster. MLR analyses showed that the presence of depressive symptoms prior to age 18 was the major risk factor for MDD, while adolescent use of alcohol, marijuana, and inhalants prior to age 18 were associated with increased odds of MDD (p < 0.05) both in the whole data and the subset of adults without depressive symptoms prior to age 18. Adolescent use of cocaine prior to age 18 were associated with MDD only in the whole data, whereas adolescent smokeless tobacco use was associated with MDD only in those without depressive symptoms prior to age 18.

CONCLUSIONS

These findings highlight the comorbid early substance use and depressive symptoms during adolescence with adult MDD. Intervention strategies should simultaneously address early-onset substance use and depressive symptoms prior to age 18.

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

INTRODUCTION

Treatment-resistant depression (TRD) is a serious and debilitating psychiatric disorder that frequently affects older patients. Esketamine nasal spray (ESK-NS) has recently been approved as a treatment for TRD, with multiple studies establishing its efficacy and tolerability. However, the real-world effectiveness, tolerability, and safety of this treatment in older adults is still unclear.

OBJECTIVES

To evaluate the efficacy and tolerability of ESK-NS in older subjects with TRD.

METHODS

This is a post-hoc analysis of the REAL-ESK study, a multicenter, retrospective, observational study. Participants here selected were 65 years or older at baseline. The Montgomery-Åsberg Depression Rating Scale (MADRS) and the Hamilton Anxiety Rating Scale (HAM-A) were used to assess depressive and anxiety symptoms, respectively. Data were collected at three-time points: baseline, 1 month after the start of treatment (T1), and 3 months after treatment (T2).

RESULTS

The sample included older adults with TRD (n = 30). MADRS and HAM-A values decreased significantly at T1 (T0 versus T1: pholm <0.001, Cohen's d = 0.840) and T2 follow-ups (T0 versus T2: pholm <0.001, Cohen's d = 1.419). At T2, 53.3% of subjects were responders (MADRS score reduced ≥50%), while 33.33% were in remission (MADRS<10). ESK-NS-related adverse effects were in order of frequency dizziness (50%), followed by dissociation (33.3%), sedation (30%), and hypertension (13.33%). Six out of 30 participants (20%) discontinued treatment.

CONCLUSIONS

Our findings provide preliminary evidence of ESK-NS effectiveness in older adults with TRD, a highly debilitating depressive presentation. Furthermore, we observe high levels of treatment-emergent adverse events, which, in the majority of instances, did not require treatment suspension.

Individual Prediction of Optimal Treatment Allocation Between Electroconvulsive Therapy or Ketamine using the Personalized Advantage Index

Introduction

Electroconvulsive therapy (ECT) and ketamine are two effective treatments for depression with similar efficacy; however, individual patient outcomes may be improved by models that predict optimal treatment assignment. Here, we adapt the Personalized Advantage Index (PAI) algorithm using machine learning to predict optimal treatment assignment between ECT and ketamine using medical record data from a large, naturalistic patient cohort. We hypothesized that patients who received a treatment predicted to be optimal would have significantly better outcomes following treatment compared to those who received a non-optimal treatment.

Methods

Data on 2526 ECT and 235 mixed IV ketamine and esketamine patients from McLean Hospital was aggregated. Depressive symptoms were measured using the Quick Inventory of Depressive Symptomatology (QIDS) before and during acute treatment. Patients were matched between treatments on pretreatment QIDS, age, inpatient status, and psychotic symptoms using a 1:1 ratio yielding a sample of 470 patients (n=235 per treatment). Random forest models were trained and predicted differential patientwise minimum QIDS scores achieved during acute treatment (min-QIDS) scores for ECT and ketamine using pretreatment patient measures. Analysis of Shapley Additive exPlanations (SHAP) values identified predictors of differential outcomes between treatments.

Results

Twenty-seven percent of patients with the largest PAI scores who received a treatment predicted optimal had significantly lower min-QIDS scores compared to those who received a non-optimal treatment (mean difference=1.6, t=2.38, q<0.05, Cohen's D=0.36). Analysis of SHAP values identified prescriptive pretreatment measures.

Conclusions

Patients assigned to a treatment predicted to be optimal had significantly better treatment outcomes. Our model identified pretreatment patient factors captured in medical records that can provide interpretable and actionable guidelines treatment selection.

Brain-Derived Neurotrophic Factor (BDNF) as a Predictor of Treatment Response in Major Depressive Disorder (MDD): A Systematic Review

Brain-derived neurotrophic factor (BDNF) has been studied as a biomarker of major depressive disorder (MDD). Besides diagnostic biomarkers, clinically useful biomarkers can inform response to treatment. We aimed to review all studies that sought to relate BDNF baseline levels, or BDNF polymorphisms, with response to treatment in MDD. In order to achieve this, we performed a systematic review of studies that explored the relation of BDNF with both pharmacological and non-pharmacological treatment. Finally, we reviewed the evidence that relates peripheral levels of BDNF and BDNF polymorphisms with the development and management of treatment-resistant depression.

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

Treatment-resistant depression (TRD) represents a severe clinical condition with high social and economic costs. Esketamine Nasal Spray (ESK-NS) has recently been approved for TRD by EMA and FDA, but data about predictors of response are still lacking. Thus, a tool that can predict the individual patients' probability of response to ESK-NS is needed. This study investigates sociodemographic and clinical features predicting responses to ESK-NS in TRD patients using machine learning techniques. In a retrospective, multicentric, real-world study involving 149 TRD subjects, psychometric data (Montgomery-Asberg-Depression-Rating-Scale/MADRS, Brief-Psychiatric-Rating-Scale/BPRS, Hamilton-Anxiety-Rating-Scale/HAM-A, Hamilton-Depression-Rating-Scale/HAMD-17) were collected at baseline and at one month/T1 and three months/T2 post-treatment initiation. We trained three different random forest classifiers, able to predict responses to ESK-NS with accuracies of 68.53% at T1 and 66.26% at T2 and remission at T2 with 68.60% of accuracy. Features like severe anhedonia, anxious distress, mixed symptoms as well as bipolarity were found to positively predict response and remission. At the same time, benzodiazepine usage and depression severity were linked to delayed responses. Despite some limitations (i.e., retrospective study, lack of biomarkers, lack of a correct interrater-reliability across the different centers), these findings suggest the potential of machine learning in personalized intervention for TRD.

Ethopharmacological evaluation of antidepressant-like effect of serotonergic psychedelics in C57BL/6J male mice

Serotonergic psychedelics such as psilocybin, lysergic acid diethylamide, and DOI exert a hallucinatory effect through serotonin 5-HT 2A receptor (5-HT2A) activation. Recent studies have revealed that serotonergic psychedelics have therapeutic potential for neuropsychiatric disorders, including major depressive and anxiety-related disorders. However, the involvement of 5-HT2A in mediating the therapeutic effects of these drugs remains unclear. In this study, we ethopharmacologically analyzed the role of 5-HT2A in the occurrence of anxiolytic-and antidepressant-like effects of serotonergic psychedelics such as psilocin, an active metabolite of psilocybin, DOI, and TCB-2 in mice. Mice with acute intraperitoneal psychedelic treatment exhibited significantly shorter immobility times in the forced swimming test (FST) and tail-suspension test (TST) than vehicle-treated control mice 24 h post-treatment. These effects were eliminated by pretreatment with volinanserin, a 5-HT2A antagonist. Surprisingly, the decreasing immobility time in the FST in response to acute psilocin treatment was sustained for at least three weeks. In the novelty-suppressed feeding test (NSFT), the latency to feed, an indicator of anxiety-like behavior, was decreased by acute administration of psilocin; however, pretreatment with volinanserin did not diminish this effect. In contrast, DOI and TCB-2 did not affect the NSFT performance in mice. Furthermore, psilocin, DOI, and TCB-2 treatment did not affect the spontaneous locomotor activity or head-twitch response, a hallucination-like behavior in rodents. These results suggest that 5-HT2A contributes to the antidepressant effects of serotonergic psychedelics rather than an anxiolytic effects.

Efficacy and adverse effects of ketamine versus electroconvulsive therapy for major depressive disorder: A systematic review and meta-analysis

BACKGROUND

ECT is considered the fastest and most effective treatment for TRD. Ketamine seems to be an attractive alternative due to its rapid-onset antidepressant effects and impact on suicidal thoughts. This study aimed to compare efficacy and tolerability of ECT and ketamine for different depression outcomes (PROSPERO/CRD42022349220).

METHODS

We searched MEDLINE, Web of Science, Embase, PsycINFO, Google Scholar, Cochrane Library and trial registries, which were the ClinicalTrials.gov and the World Health Organization's International Clinical Trials Registry Platform, without restrictions on publication date.

SELECTION CRITERIA

randomized controlled trials or cohorts comparing ketamine versus ECT in patients with TRD.

RESULTS

Eight studies met the inclusion criteria (of 2875 retrieved). Random-effects models comparing ketamine and ECT regarding the following outcomes were conducted: a) reduction of depressive symptoms severity through scales, g = -0.12, p = 0.68; b) response to therapy, RR = 0.89, p = 0.51; c) reported side-effects: dissociative symptoms, RR = 5.41, p = 0.06; nausea, RR = 0.73, p = 0.47; muscle pain, RR = 0.25, p = 0.02; and headache, RR = 0.39, p = 0.08. Influential & subgroup analyses were performed.

LIMITATIONS

Methodological issues with high risk of bias in some of the source material, reduced number of eligible studies with high in-between heterogeneity and small sample sizes.

CONCLUSION

Our study showed no evidence to support the superiority of ketamine over ECT for severity of depressive symptoms and response to therapy. Regarding side effects, there was a statistically significant decreased risk of muscle pain in patients treated with ketamine compared to ECT.

Predictors of response and remission in patients with treatment-resistant depression: A post hoc pooled analysis of two acute trials of esketamine nasal spray

This exploratory post hoc analysis of two pooled 4-week, phase 3, double-blind, placebo- and active-controlled studies that compared esketamine nasal spray plus a newly initiated oral antidepressant (ESK+AD; n = 310) with a newly initiated oral AD plus placebo nasal spray (AD+PBO; n = 208) in patients with treatment-resistant depression (TRD) examined baseline patient demographic and psychiatric characteristics as potential predictors of response (≥50% reduction from baseline in Montgomery-Åsberg Depression Rating Scale [MADRS] total score) and remission (MADRS total score ≤12) at day 28. Overall, younger age, any employment, fewer failed ADs in the current depressive episode, and reduction in Clinical Global Impression-Severity (CGI-S) score at day 8 were significant positive predictors of response and remission at day 28. Treatment assignment was an important predictor of both response and remission. Patients treated with ESK+AD had 68% and 55% increased odds of achieving response and remission, respectively, versus those treated with AD+PBO. In the ESK+AD group, attainment of response and remission was more likely in patients who were employed, without significant anxiety at baseline, and who experienced a reduction in CGI-S score at day 8. Identification of predictors of response and remission may facilitate identification of those patients with TRD most likely to benefit from ESK+AD. Trial Registration: ClinicalTrials.gov: NCT02417064 (clinicaltrials.gov/ct2/show/NCT02417064) and NCT02418585 (clinicaltrials.gov/ct2/show/NCT02418585).

Biomarkers of ketamine's antidepressant effect: An umbrella review

Ketamine is a NMDA receptor antagonist that has a rapid acting antidepressant effect with high efficacy in treatment-resistant patients. Ketamine is a beneficial antidepressant for many individuals with depression, but not all of the patients respond, and some even exhibit symptom deterioration. The discovery of repeatable and mechanistically relevant biomarkers would address a major gap in treatment response prediction. Numerous potential peripheral biomarkers have been reported, but their current utility is unclear. We conducted an umbrella review to evaluate the biomarkers of ketamine's antidepressant effect in individuals with depression. PubMed and copus were searched using terms appropriate to each area of research, from their inception until July 2022. Five systematic reviews and meta analyses including 108 studies with 4912 participants were included. Blood-based and neuroimaging biomarkers were investigated. The results of this review indicate that ketamine can produce an anti-inflammatory effect and decrease at least one inflammatory marker following administration. Data from neuroimaging studies demonstrated that the cingulate cortex is the key locus of ketamine's action. The majority of the blood-based, neuroimaging, and neurophysiological investigations reviewed herein indicate ketamine induced normalization of major depressive disorder pathogenesis via synaptic plasticity and functional connectivity. Currently, no biomarker/biosignature is sufficiently validated for clinical utility, but several are promising. Now that ketamine is more widely available, biomarker discovery and replication should be attempted in larger, real-world populations.

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

Antidepressants require several weeks for the onset of action, a lag time that may exceed life expectancy in palliative care. Ketamine has demonstrated rapid antidepressant effects, but has been minimally studied in cancer and palliative care populations. Herein, the objective was to determine the feasibility, safety, tolerability and preliminary efficacy of intranasal racemic ketamine for major depressive disorder (MDD) in patients with advanced cancer. We conducted a single-arm, open-label phase II trial at the Princess Margaret Cancer Centre in Toronto, ON, Canada. Participants with advanced cancer with moderate to severe MDD received three flexible doses of intranasal (IN) ketamine (50−150 mg) over a one-week period. The primary efficacy outcome was an antidepressant response and remission rates as determined by the Montgomery−Åsberg Depression Rating Scale (MADRS) from baseline to the Day 8 primary endpoint. Twenty participants were enrolled in the trial, receiving at least one dose of IN ketamine, with fifteen participants receiving all three doses. The Day 8 antidepressant response (MADRS decreased by >50%) and remission (MADRS < 10 on Day 8) rates were high at 70% and 45%, respectively. Mean MADRS scores decreased significantly from baseline (mean MADRS of 31, standard deviation 7.6) to Day 8 (11 +/− 7.4) with an overall decrease of 20 points (p < 0.001). Antidepressant effects were partially sustained in the second week in the absence of additional ketamine doses, with a Day 14 mean MADRS score of 14 +/− 9.9. Common adverse effects included fatigue, dissociation, nausea, dysgeusia and headaches; almost all adverse effects were mild and transient, resolving within 2 h of each ketamine dose with one dropout related to adverse effects (negative dissociative episode). Given these promising findings, larger, controlled trials are merited.

The Glutamatergic System in Treatment-Resistant Depression and Comparative Effectiveness of Ketamine and Esketamine: Role of Inflammation?

The glutamatergic system is the primary excitatory pathway within the CNS and is responsible for cognition, memory, learning, emotion, and mood. Because of its significant importance in widespread nervous system function, it is tightly regulated through multiple mechanisms, such as glutamate recycling, microglial interactions, and inflammatory pathways. Imbalance within the glutamatergic system has been implicated in a wide range of pathological conditions including neurodegenerative conditions, neuromuscular conditions, and mood disorders including depression. Major depressive disorder (MDD) is the most common mood disorder worldwide, has a high prevalence rate, and afflicts approximately 280 million people. While there are numerous treatments for the disease, 30-40% of patients are unresponsive to treatment and deemed treatment resistant; approximately another third experience only partial improvement (World Health Organization, Depression fact sheet [Internet], 2020). Esketamine, the S-enantiomer of ketamine, was approved by the Food and Drug Administration for treatment-resistant depression (TRD) in 2019 and has offered new hope to patients. It is the first treatment targeting the glutamatergic system through a complex mechanism. Numerous studies have implicated imbalance in the glutamatergic system in depression and treatment resistance. Esketamine and ketamine principally work through inhibition of the NMDA receptor, though more recent studies have implicated numerous other mechanisms mediating the antidepressant efficacy of these agents. These mechanisms include increase in brain-derived neurotrophic factor (BDNF), activation of mammalian target of the rapamycin complex (mTORC), and reduction in inflammation. Esketamine and ketamine have been shown to decrease inflammation in numerous ways principally through reducing pro-inflammatory cytokines (e.g., TNF-α, IL-6) (Loix et al., Acta Anaesthesiol Belg 62(1):47-58, 2011; Chen et al., Psychiatry Res 269:207-11, 2018; Kopra et al., J Psychopharmacol 35(8):934-45, 2021). This anti-inflammatory effect has also been shown to be involved in the antidepressive properties of both ketamine and esketamine (Chen et al., Psychiatry Res 269:207-11, 2018; Kopra et al., J Psychopharmacol 35(8):934-45, 2021).

Association between peripheral biomarkers and clinical response to IV ketamine for unipolar treatment-resistant depression: An open label study

BACKGROUND

Major Depression is the leading cause of disability worldwide. A cohort of patients do not respond adequately to available antidepressants, leading to treatment-resistant depression (TRD). We evaluated the antidepressant efficacy of an acute intravenous ketamine treatment (0.5 mg/kg) for patients with unipolar TRD, and measured peripheral blood-based biomarkers associated with response to treatment.

METHODS

Fifteen adults diagnosed with TRD completed an open label study of ten infusions of subanesthetic ketamine over four weeks. Out of fifteen patients, blood was collected from eleven patients at three timepoints to analyze peripheral biomarkers in isolated plasma, including IL-6, IL-10, TNF-α, BDNF, and irisin. Irisin analysis was completed using an ELISA assay, and the remaining biomarkers were analyzed together simultaneously using a multiplex immunoassay.

RESULTS

Repeated ketamine infusions produced a significant decrease in total average depressive symptoms (MADRS) at all timepoints. Improvements in depressive symptoms were significant at one week, and continued to significantly decrease until two weeks, where it was maintained. Ketamine was generally well tolerated, and we observed improvements in functional impairment, anhedonia, and psychiatric symptoms, with no increases in manic symptoms. Levels of BDNF throughout treatment inversely correlated to decreases in MADRS scores, and higher levels of baseline BDNF predicted mood responses at one- and four weeks.

LIMITATIONS

The study was observational and uncontrolled, with a sample size of 15. Outpatients remained on their course of medications, unless they were pharmacological agents that have previously been identified to block ketamine's effects.

CONCLUSIONS

Ketamine may be an efficacious and safe pharmacological option for the acute treatment of patients suffering from severe TRD. BDNF has the potential to function as a prognostic biomarker for predicting response to ketamine treatments.

International pooled patient-level meta-analysis of ketamine infusion for depression: In search of clinical moderators

Depression is disabling and highly prevalent. Intravenous (IV) ketamine displays rapid-onset antidepressant properties, but little is known regarding which patients are most likely to benefit, limiting personalized prescriptions. We identified randomized controlled trials of IV ketamine that recruited individuals with a relevant psychiatric diagnosis (e.g., unipolar or bipolar depression; post-traumatic stress disorder), included one or more control arms, did not provide any other study-administered treatment in conjunction with ketamine (although clinically prescribed concurrent treatments were allowable), and assessed outcome using either the Montgomery-Åsberg Depression Rating Scale or the Hamilton Rating Scale for Depression (HRSD-17). Individual patient-level data for at least one outcome was obtained from 17 of 25 eligible trials [pooled n = 809]. Rates of participant-level data availability across 33 moderators that were solicited from these 17 studies ranged from 10.8% to 100% (median = 55.6%). After data harmonization, moderators available in at least 40% of the dataset were tested sequentially, as well as with a data-driven, combined moderator approach. Robust main effects of ketamine on acute [~24-hours; β*(95% CI) = 0.58 (0.44, 0.72); p < 0.0001] and post-acute [~7 days; β*(95% CI) = 0.38 (0.23, 0.54); p < 0.0001] depression severity were observed. Two study-level moderators emerged as significant: ketamine effects (relative to placebo) were larger in studies that required a higher degree of previous treatment resistance to federal regulatory agency-approved antidepressant medications (≥2 failed trials) for study entry; and in studies that used a crossover design. A comprehensive data-driven search for combined moderators identified statistically significant, but modest and clinically uninformative, effects (effect size r ≤ 0.29, a small-medium effect). Ketamine robustly reduces depressive symptoms in a heterogeneous range of patients, with benefit relative to placebo even greater in patients more resistant to prior medications. In this largest effort to date to apply precision medicine approaches to ketamine treatment, no clinical or demographic patient-level features were detected that could be used to guide ketamine treatment decisions.Review Registration: PROSPERO Identifier: CRD42021235630.

Blood-based biomarkers of antidepressant response to ketamine and esketamine: A systematic review and meta-analysis

(R,S)-ketamine (ketamine) and its enantiomer (S)-ketamine (esketamine) can produce rapid and substantial antidepressant effects. However, individual response to ketamine/esketamine is variable, and there are no well-accepted methods to differentiate persons who are more likely to benefit. Numerous potential peripheral biomarkers have been reported, but their current utility is unclear. We conducted a systematic review/meta-analysis examining the association between baseline levels and longitudinal changes in blood-based biomarkers, and response to ketamine/esketamine. Of the 5611 citations identified, 56 manuscripts were included (N = 2801 participants), and 26 were compatible with meta-analytical calculations. Random-effect models were used, and effect sizes were reported as standardized mean differences (SMD). Our assessments revealed that more than 460 individual biomarkers were examined. Frequently studied groups included neurotrophic factors (n = 15), levels of ketamine and ketamine metabolites (n = 13), and inflammatory markers (n = 12). There were no consistent associations between baseline levels of blood-based biomarkers, and response to ketamine. However, in a longitudinal analysis, ketamine responders had statistically significant increases in brain-derived neurotrophic factor (BDNF) when compared to pre-treatment levels (SMD [95% CI] = 0.26 [0.03, 0.48], p = 0.02), whereas non-responders showed no significant changes in BDNF levels (SMD [95% CI] = 0.05 [-0.19, 0.28], p = 0.70). There was no consistent evidence to support any additional longitudinal biomarkers. Findings were inconclusive for esketamine due to the small number of studies (n = 2). Despite a diverse and substantial literature, there is limited evidence that blood-based biomarkers are associated with response to ketamine, and no current evidence of clinical utility.

Bipolar depression: a review of treatment options

Bipolar depression (BD-D) is both common and incredibly challenging to treat. Even treated individuals with BD-D experience depression approximately 19% of the time, and subsyndromal depression an additional 18%. This stands in clear contrast to the approximately 10% of time spent in hypomania and 1% of time spent in mania. Despite this high illness burden, there remain relatively few treatment options approved by the US Food and Drug Administration for BD-D. Of the approved medications, four are second-generation antipsychotics (SGAs) and one is an SGA combined with an antidepressant. However, particularly when used long-term, antipsychotics can pose a significant risk of adverse effects, raising the clinical conundrum of weighing the risks associated with long-term antipsychotic use versus the risk of relapse when patients are off medications. Here, we review commonly used treatments for BD-D, including antipsychotics, classic mood stabilisers, electroconvulsive therapy and psychotherapy. We then address the somewhat controversial topic of antidepressant use in BD-D. Finally, we summarise emerging treatment options and highlight ongoing clinical trials. We hope this review will help compare the risks and benefits of several common and novel options for the treatment of patients with BD-D. In doing so, we also hope this review will aid the individualised selection of treatments based on each patient’s history and treatment goals.

Clinical predictors of depressive symptom remission and response after racemic ketamine and esketamine infusion in treatment-resistant depression

BACKGROUND

Major depressive disorder (MDD) is a leading cause of disability worldwide and most people do not achieve symptom remission. Treatment-resistant depression (TRD) is characterized by the failure of at least one adequate trial of a major class of antidepressant, with adequate time and dosage. We aimed to identify clinical predictors of depressive symptom remission and response 24 h and 7 days after racemic ketamine and esketamine infusions.

METHODS

A randomized, double-blind, active-controlled, non-inferiority trial using ketamine and esketamine in TRD. Individuals diagnosed with MDD according to Diagnostic and Statistical Manual of Mental Disorders version IV and fulfilling TRD criteria were recruited from March 2017 to June 2018. Participants received a single subanesthetic dose of ketamine (0.5 mg/kg) or esketamine (0.25 mg/kg) for 40 min. Depressive symptoms were assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS) and symptom remission was defined as a MADRS score ≤7 and response defined as ≥50% reduction in depressive symptom severity, 24 h and 7 days after the infusion. Clinical variables were selected based on previous clinical trials. Stepwise backward logistic regression was used, considering a confidence level of 95%.

RESULTS

61 subjects were included: 39 (63.9%) were females with a mean age of 47.2 ± 14.9. Higher number of therapeutic failures (Odds Ratio (OR) = 0.677; 95% confidence interval (CI): 0.47-0.97) and higher severity of illness (OR = 0.912; 95% CI: 0.83-0.99) were associated with fewer remissions of depressive symptoms 7 days after intervention, and with fewer response in 24 h (OR = 0.583; 95% CI: 0,40; 0,84 and OR = 0.909; 95% CI: 0,83; 0,99, respectively).

CONCLUSION

Number of treatment failures and severity of illness were predictors of fewer remissions and responses of depressive symptoms in this TRD population. Study of predictors of remission may contribute to better selection patients that may benefit from receiving ketamine.

Impulsivity as a mediator between childhood maltreatment and suicidal behavior: A systematic review and meta-analysis

Childhood maltreatment is a known risk factor for the development of suicidal behavior. Possible mediators of the association between childhood maltreatment and suicide have been analyzed. Some studies have considered impulsivity as one of these mediators, but there are no previous reviews on this topic. We, therefore, present a systematic review and mediation meta-analysis of the literature summarizing the evidence on impulsivity as a mediator of the relationship between childhood maltreatment and lifetime suicidal behavior. This review followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. The review was registered in the PROSPERO database. We searched PubMed, PsycINFO, WebOfScience, and EMBASE databases up to February 2021 to identify studies exploring the association between childhood maltreatment and suicide through impulsivity. Fourteen articles met the selection criteria and were included in the review. Seven articles could be included in the mediation meta-analysis. Impulsivity was a significant mediator of the relationship between childhood maltreatment and suicidal behavior in ten of the fourteen included studies. This result was confirmed using mediation meta-analysis (β = .06, 95% CI 0.03-0.10). Studies suggest that exposure to traumatic situations in childhood affects the proper neurobiological, cognitive, and affective development of individuals. This may increase impulsivity, which in turn would be related to an increased risk of suicide. The effects of childhood maltreatment and impulsivity may be both therapeutic targets of interest to reduce suicide rates.

Efficacy and safety of racemic ketamine and esketamine for depression: a systematic review and meta-analysis

BACKGROUND

Racemic ketamine and esketamine have demonstrated rapid antidepressant effects. We aimed to review the efficacy and safety of racemic and esketamine for depression.

RESEARCH DESIGN AND METHODS

We conducted a PRISMA-guided review for relevant randomized controlled trials of racemic or esketamine for unipolar or bipolar major depression from database inception through 2021. We conducted random-effects meta-analyses using pooled rate ratios (RRs) and Cohen's standardized mean differences (d) with their 95% confidence intervals (CI).

RESULTS

We found 36 studies (2903 participants, 57% female, 45.1 +/- 7.0 years). Nine trials used esketamine, while the rest used racemic ketamine. The overall study quality was high. Treatment with any form of ketamine was associated with improved response (RR=2.14; 95% CI, 1.72-2.66; I2=65%), remission (RR=1.64; 95% CI, 1.33-2.02; I2=39%), and depression severity (d=-0.63; 95% CI, -0.80 to -0.45; I2=78%) against placebo. Overall, there was no association between treatment with any form of ketamine and retention in treatment (RR=1.00; 95% CI, 0.99-1.01; I2<1%), dropouts due to adverse events (RR=1.56; 95% CI, 1.00-2.45; I2<1%), or the overall number of adverse events reported per participant (OR=2.14; 95% CI, 0.82-5.60; I2=62%) against placebo.

CONCLUSIONS

Ketamine and esketamine are effective, safe, and acceptable treatments for individuals living with depression.

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

BACKGROUND

Higher body mass index (BMI) has been found to predict greater antidepressant response to intravenous (IV) ketamine treatment. We evaluated the association between BMI and response to repeat-dose IV ketamine in patients with treatment-resistant depression (TRD).

METHODS

Adults (N = 230) with TRD received four infusions of IV ketamine at a community-based clinic. Changes in symptoms of depression (ie, Quick Inventory for Depressive Symptomatology-Self-Report 16; QIDS-SR16), suicidal ideation (SI; ie, QIDS-SR16 SI item), anxiety (ie, Generalized Anxiety Disorder-7 Scale), anhedonic severity (ie, Snaith-Hamilton Pleasure Scale), and functioning (ie, Sheehan Disability Scale) following infusions were evaluated. Participants were stratified by BMI as normal (18.0-24.9 kg/m2; n = 72), overweight (25-29.9 kg/m2; n = 76), obese I (30-34.9 kg/m2; n = 47), or obese II (≥35.0 kg/m2; n = 35).

RESULTS

Similar antidepressant effects with repeat-dose ketamine were reported between BMI groups (P = .261). In addition, categorical partial response (P = .149), response (P = .526), and remission (P = .232) rates were similar between the four BMI groups.

CONCLUSIONS

The findings are limited by the observational, open-label design of this retrospective analysis. Pretreatment BMI did not predict response to IV ketamine, which was effective regardless of BMI.

Population Pharmacokinetics and Pharmacodynamics of the Therapeutic and Adverse Effects of Ketamine in Patients with Treatment-Refractory Depression

We aimed to develop population pharmacokinetic/pharmacodynamic (PK/PD) models that can effectively describe ketamine and norketamine PK/PD relationships for Montgomery–Åsberg Depression Rating Scale (MADRS) scores, blood pressure (BP), and heart rate (HR) following i.v., s.c., and i.m. ketamine administration in patients with treatment‐refractory depression. Ketamine PK/PD data were collected from 21 treatment‐refractory depressed participants who received ketamine (dose titration 0.1–0.5 mg/kg as single doses) by i.v., s.c., or i.m. administration. Model development used nonlinear mixed effect modeling. Ketamine and norketamine PK were best described using two‐compartment models with first‐order absorption after s.c. and i.m. administration. Estimated ketamine bioavailability after i.m. and s.c. was ~ 64% with indistinguishable first‐order absorption rate constants. Allometric scaling of body weight on all clearance and volumes of distribution improved the model fit. The delay in the concentration‐response relationship for MADRS scores was best described using a turnover model (turnover time ~ 42 hours), whereas for the BP and HR rates this was an immediate effect model. For all PD effects, ketamine alone was superior to models with norketamine concentration linked to an effect. No covariates were identified for PD effects. The estimated half‐maximal effective concentration from the MADRS score, BP, and HR were 0.44, 468, and 7,580 ng/mL, respectively. The integrated population models were able to effectively describe the PK/PD relationships for MADRS scores, BP, and HR after i.v., s.c., and i.m. ketamine administration. These findings allow for a deeper understanding of the complex relationships between route of ketamine administration and clinical response and safety.

Functional connectivity between the habenula and default mode network and its association with the antidepressant effect of ketamine

BACKGROUND

Recently, an animal model for depression has shown that ketamine, an N-methyl- d-aspartate receptor (NMDAR) antagonist, elicits a rapid-acting antidepressant effect by blocking NMDAR-dependent bursting in the lateral habenula (Hb). However, evidence from human studies remains scarce.

METHODS

This study explored the changes of resting-state functional connectivity (FC) of the Hb in responders and nonresponders who was diagnosed with unipolar or bipolar depression before and after ketamine treatment. The response was defined as a ≥50% reduction in the total MADRS score at Day 13 (24 h following the sixth infusion) in comparison with the baseline score. Correlation analyses were performed to identify an association between symptom improvement and the signals of the significantly different brain regions detected in the above imaging analysis.

RESULTS

In the post-hoc region-of-interest analysis, an enhanced baseline FC between Hb and several hubs of the default mode network (including angulate cortex, precuneus, medial prefrontal cortex, and middle temporal cortex) was observed in responders (≥50% decrease in the Montgomery-Asberg Scale at 2 weeks) compared with nonresponders.

CONCLUSIONS

These pilot findings may suggest a potential neural mechanism by which ketamine exerts its robust antidepressant efficacy via downregulation of aberrant habenular FC with parts of the default mode network.

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

INTRODUCTION

Intranasal (IN) esketamine represents an innovative treatment for individuals with treatment resistant depression and depression with suicidal ideation and behavior. Herein, we synthesize extant long-term studies (≥ 4 weeks) regarding this treatment.

RESEARCH DESIGN AND METHODS

The interventional studies of IN esketamine in patients with depression having a study period of at least four weeks were included for our synthesis. A meta-analysis was undertaken for the efficacy and safety parameters of adjunctive IN esketamine vs IN placebo with an oral antidepressant. The data excluded from meta-analysis were synthesized narratively.

RESULTS

After pooling data from seven randomized controlled trials, treatment with adjunctive IN esketamine vs IN placebo was safe overall, and more effective at decreasing depressive symptoms (d = -0.239; 95%CI = -0.335,-0.142;p < 0.0001), with higher response (RR = 1.221; 95% CI = 1.055,1.428; p = 0.017) and remission (RR = 1.366; 95% CI = 1.182,1.578; p < 0.0001) rates. The year-long trials showed that treatment with adjunctive IN esketamine led to lower relapse rates with no considerable long-term side effects.

CONCLUSION

Intranasal esketamine was demonstrated to be safe, well tolerated, and rapidly effective in individuals with treatment resistant depression, suicidal ideation, and suicidal behavior.

Ketamine and esketamine for crisis management in patients with depression: Why, whom, and how?

Currently, only a limited number of interventions can rapidly relieve depressive symptomatology in patients with major depressive disorder or bipolar disorder experiencing extreme distress. Such crises, especially when suicide attempt or ideation is involved, are a major risk factor of suicide. Ketamine, a N-methyl-d-aspartate glutamate receptor antagonist, and its enantiomer esketamine rapidly reduce depressive symptoms in depressed patients with current suicidal ideation. Recently, esketamine has been approved for use in patients with depression at risk of suicide and for psychiatric emergency by major medical agencies in the United States and Europe, whereas ketamine is increasingly used off-label. However, there is currently limited guidance on why, when, and how to use these drugs in patients with depression to treat a crisis. In this review article, we provide a succinct overview of the cellular and molecular mechanisms of action of ketamine and esketamine, and of the functional brain changes following their administration. We also summarize the major clinical studies on ketamine and esketamine efficacy in patients experiencing a crisis (generally, suicidal ideation), and propose a profile of patients who can benefit most from such drugs, on the basis of neurobiological and clinical observations. Finally, we describe the administration mode, the efficacy and tolerability profiles, the side effect management, possible concomitant treatments and the issue of deprescribing.

Use of Staging Models for Treatment-Resistant Depression Is Not Helpful in Predicting Nonresponse to Acute Intravenous Ketamine Treatment

BACKGROUND

Some staging models for treatment-resistant depression (TRD) have been developed in the attempt to predict treatment outcome, in particular with electroconvulsive therapy. However, these models have not been tested in predicting clinical outcome of ketamine treatment. We assessed the relationship between patients' classification with different TRD staging models and subsequent nonresponse to acute intravenous ketamine treatment.

METHODS

A sample of 120 patients with TRD who received acute ketamine treatment from October 2018 to November 2020 were included. Intravenous ketamine was administered twice weekly for 3 weeks as acute treatment. Generalized linear models were fitted to examine if staging classification at baseline could predict percent change in the 16-item Quick Inventory of Depressive Symptomatology-Self Report (QIDS-SR16) scale. Potential confounders such as age, sex, and primary diagnosis were included in the models. Other generalized linear models were also fitted with the Bonferroni correction to investigate if other clinical variables of potential relevance could predict percent change in the QIDS-SR16.

RESULTS

No TRD staging model proved accurate in predicting depressive improvement after acute ketamine treatment. Clinical variables such as age (F = 6.68, P = 0.01) and history of neuromodulation therapy (F = 5.12, P = 0.03) were negatively associated with subsequent percent improvement in the QIDS-SR16 with acute ketamine treatment.

CONCLUSIONS

The efficacy of acute intravenous ketamine treatment was similar in subjects with higher and lower level of treatment resistance, using definitions based on different TRD staging models. Further exploration of ketamine treatment predictors such as age and neuromodulation therapy is warranted.

Pharmacogenomics of ketamine: A systematic review

Ketamine is a dissociative anesthetic used worldwide for anesthesia, pain management, treatment resistant depression (TRD) and suicidality. Predictors of antidepressant response and adverse effects to ketamine remain poorly understood due to contradictory results. The objective of the systematic review herein is to identify and evaluate the extant literature assessing pharmacogenomic predictors of ketamine clinical benefits and adverse effects. Electronic databases were searched from inception to July 2021 to identify relevant articles. Twelve articles involving 1,219 participants with TRD, 75 who underwent elective surgeries and received ketamine as an anesthetic, 49 with pain, and 68 healthy participants met the inclusion criteria and enrolled to this review. While identified articles reported mixed results, three predictors emerged: 1) Val66Met (rs6265) brain derived neurotrophic factor (BDNF; Met allele) was associated with reduced antidepressant and anti-suicidal effects, 2) CYP2B6*6 (e.g., CYB2B6 metabolizer) was associated with more severe dissociative effects and 3) NET allelic (rs28386840) variant were associated with greater cardiovascular complications (e.g., moderate to severe treatment emergent hypertension). Several important limitations were identified, most notably the small sample sizes and heterogeneity of study design and results. Taken together, preliminary evidence suggests the potential for pharmacogenomic testing to inform clinical practices; however, further research is needed to better determine genetic variants of greatest importance and the clinical validity of pharmacogenomics to help guide ketamine treatment planning.

Effect of ketamine on the physiological responses to combined hypoglycemic and psychophysical stress

There is evidence that hypoglycemic stress can interact with other stressors, and that ketamine can mitigate the impact of these stressors on behavior and physiology. The current study in male Sprague-Dawley rats investigated whether pre-treatment with 0, 10, or 20 mg/kg ketamine could modulate the interaction between hypoglycemia induced by 0 or 300 mg/kg 2-deoxy-D-glucose (2-DG) and the psychophysical stress of forced swimming (FSS; 6 sessions, 10 min/session) on serum concentrations of corticosterone (CORT) and the pro-inflammatory cytokine, tumor necrosis factor (TNF)-α. It was found that 2-DG enhanced the CORT response to an initial session of FSS, and this effect dissipated after multiple sessions. More importantly, animals displayed significantly higher levels of CORT and lower levels of TNF-α in response to a drug-free test swim conducted 1 week after exposure to the combined stressors, and these responses were not observed in rats that were pre-treated with ketamine. Overall, these findings indicate that ketamine has the potential to reduce the negative impact of interacting stressors on the biological reactivity of the hypothalamic-pituitary-adrenal axis and the immune system.

Safety, Tolerability, and Real-World Effectiveness of Intravenous Ketamine in Older Adults With Treatment-Resistant Depression: A Case Series

OBJECTIVE

To evaluate the safety, tolerability, and effectiveness of repeated doses of intravenous (IV) ketamine in older adults (i.e., ≥60 years of age) with treatment-resistant depression.

METHOD

In this case series, fifty-three older adults (M_age = 67, SD = 6; 57% female [n = 30]) received 4 IV ketamine infusions, administered over 1-2 weeks. Effectiveness of IV ketamine was measured using the Quick Inventory for Depressive Symptomatology-Self Report 16 (QIDS-SR16) approximately 2 days after infusions 1-3, and 1-2 weeks after infusion 4. Safety was measured as hemodynamic changes before, during, immediately after, and 20 minutes after each infusion. Tolerability was assessed via systematic reporting of treatment-emergent adverse events during and after each infusion, in addition to symptoms of dissociation measured using the Clinician Administered Dissociative States Scale. Partial response (25%-50% symptomatic improvement from baseline), response (≥50% symptomatic improvement from baseline), clinically significant improvements (≥25% symptomatic improvement from baseline), and remission rates (QIDS-SR16 ≤5) were also calculated.

RESULTS

Participants reported significant decreases in depressive symptoms (i.e., as measured by the QIDS-SR16) with repeated ketamine infusions (F(4, 92) = 7.412, p <0.001). The mean QIDS-SR16 score was 17.12 (SD = 5.33) at baseline and decreased to 12.52 (SD = 5.79) following 4 infusions. After 4 infusions, 31% (n = 8) of participants partially responded to IV ketamine, 27% (n = 7) responded, 58% (n = 15) experienced clinically significant improvements, and 10% (n = 3) met remission criteria. Thirty-six participants (69%) experienced treatment-emergent hypertension during at least 1 infusion, and 10 (19%) required intervention with an antihypertensive. Drowsiness was the most commonly reported adverse event (50% of infusions; n = 73).

CONCLUSION

Ketamine was associated with transient treatment-emergent hypertension. Response and remission rates were comparable to those reported in general adult samples. Findings are limited by the open-label, chart review nature of this study.

Does pre-treatment functioning influence response to intravenous ketamine in adults with treatment-resistant depression?

BACKGROUND

The efficacy of monoamine-based antidepressants in adults with major depressive disorder (MDD) is attenuated in persons with greater pre-treatment functional impairment. Herein, we investigated whether pre-treatment functioning in outpatients with treatment-resistant depression (TRD) moderates response to intravenous (IV) ketamine.

METHODS

Adults (N= 326; M_age = 45) with DSM-5-defined MDD or bipolar disorder and TRD received repeat-dose IV ketamine at a community-based clinic. Function was evaluated with the Sheehan Disability Scale (SDS), using total scores as well as scores on the subdomains of workplace/school, social life, and family life/home responsibilities. The primary dependent measure was change in depressive symptoms from pre-treatment to post-infusion 4, as measured by the Quick Inventory for Depressive Symptomatology-Self Report-16.

RESULTS

Total functional disability, as well as the subdomains of social life and family life/home responsibilities, significantly moderated response to IV ketamine (p = .003; p = .008; p = .008). Follow-up simple slopes analyses indicated a significant improvement in depressive symptoms across the functional domain spectrum (ps < .001). Above average functional disability (i.e., 1 SD > mean functional impairment within the sample) was associated with a greater change in depressive symptoms. Workplace function did not significantly moderate response to IV ketamine (p = .307), suggesting that individuals with significantly impaired workplace functioning may expect a similar response to ketamine as those with less workplace impairment.

CONCLUSIONS

Symptomatic benefit with IV ketamine was observed in patients with TRD and significant pre-treatment functional impairment. The foregoing result has implications for mechanism of action, cost-effectiveness, and patient selection in adults with TRD receiving IV ketamine.

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

Sleep disturbances are commonly reported in patients with treatment-resistant depression (TRD). Available data have shown that intravenous (IV) ketamine is an effective treatment for patients with TRD and growing data suggest ketamine may improve overall sleep architecture. In the present study, we evaluated whether changes in sleep symptoms mediated the anti-depressive and/or anti-suicidal effects of IV ketamine and whether improvement in sleep correlated with a higher likelihood of achieving response or remission. Adults with TRD received four infusions of IV ketamine at a community-based clinic. Total depressive symptom severity was measured with the Quick Inventory Depressive Symptoms Self-Report 16-Item (QIDS-SR₁₆ ) at baseline and was repeated across four infusions. Suicidal ideation (SI) and four sleep symptoms were measured using the SI item and the five sleep items on the QIDS-SR₁₆ . A total of 323 patients with TRD received IV ketamine. Self-reported improvements in insomnia, night-time restlessness, hypersomnia, early morning waking, and total sleep were significant partial mediators to the improvements observed in depression severity. Similarly, insomnia, night-time restlessness, early morning waking and total sleep improvements mediated the reduction of IV ketamine on SI. All sleep items, except for hypersomnia, were associated with an increased likelihood of achieving response or remission. Notably, each point improvement in total sleep score was significantly associated with achieving responder/remitter status (odds ratio 3.29, 95% confidence interval 2.00-5.41). Insomnia, sleep restlessness, early morning waking and total sleep improvements were significant mediators of antidepressant and anti-suicidal improvements in patients with TRD receiving IV ketamine.

Retracing our steps to understand ketamine in depression: A focused review of hypothesized mechanisms of action

Introduction

MDD represents a significant burden worldwide, and while a number of approved treatments exist, there are high rates of treatment resistance and refractoriness. Ketamine, an N-methyl-d-aspartate receptor (NMDAR) antagonist, is a novel, rapid-acting antidepressant, however the mechanisms underlying the efficacy of ketamine are not well understood and many other mechanisms outside of NMDAR antagonism have been postulated based on preclinical data. This focused review aims to present a summary of the proposed mechanisms of action by which ketamine functions in depressive disorders supported by preclinical data and clinical studies in humans.

Methods

A literature search was completed using the PubMed and Google Scholar databases. Results were limited to clinical trials and case studies in humans that were published in English. The findings were used to compile this article.

Results

The antidepressant effects associated with ketamine are mediated via a complex interplay of mechanisms; key steps include NMDAR blockade on γ-aminobutyric acid interneurons, glutamate surge, and subsequent activation and upregulation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor.

Discussion

Coadministration of ketamine for MDD with other psychotropic agents, for example benzodiazepines, may attenuate antidepressant effects. Limited evidence exists for these effects and should be evaluated on a case-by-case basis.

Distinct trajectories of antidepressant response to intravenous ketamine

BACKGROUND

The N-methyl-D-aspartate receptor antagonist ketamine is potentially effective in treatment resistant depression. However, its antidepressant efficacy is highly variable, and there is little information about predictors of response.

METHODS

We employed growth mixture modeling (GMM) analysis to examine specific response trajectories to intravenous (IV) ketamine (three infusions; mean dose 0.63 mg/kg, SD 0.28, range 0.30 - 2.98 mg/kg over 40 min) in 328 depressed adult outpatients referred to a community clinic. The Quick Inventory of Depressive Symptomatology-Self-Report (QIDS-SR) assessed depression severity at baseline and before each infusion, up to three infusions for four total observations.

RESULTS

GMM revealed three QIDS-SR response trajectories. There were two groups of severely depressed patients, with contrasting responses to ketamine. One group (n=135, baseline QIDS-SR=18.8) had a robust antidepressant response (final QIDS-SR=7.3); the other group (n=97, QIDS-SR=19.8) was less responsive (final QIDS-SR=15.6). A third group (n=96) was less severely depressed at baseline (QIDS-SR=11.7), with intermediate antidepressant response (final QIDS-SR=6.6). Comparisons of demographic and clinical characteristics between groups with severe baseline depression revealed higher childhood physical abuse in the group with robust ketamine response (p=0.01).

LIMITATIONS

This was a retrospective analysis on a naturalistic sample. Patients were unblinded and more heterogenous than those included in most controlled clinical trial samples. Information pertaining to traumatic events occurring after childhood and pre-existing or concurrent medical conditions that may have affected outcomes was not available.

CONCLUSIONS

Overall, ketamine's effect in patients with severe baseline depression and history of childhood maltreatment may be consistent with ketamine-induced blockade of behavioral sensitization.

Ketamine for depression

Over the last two decades, the dissociative anaesthetic agent ketamine, an uncompetitive N-Methyl-D-Aspartate (NMDA) receptor antagonist, has emerged as a novel therapy for treatment-resistant depression (TRD), demonstrating rapid and robust antidepressant effects within hours of administration. Ketamine is a racemic mixture composed of equal amounts of (S)-ketamine and (R)-ketamine. Although ketamine currently remains an off-label treatment for TRD, an (S)-ketamine nasal spray has been approved for use in TRD (in conjunction with an oral antidepressant) in the United States and Europe. Despite the promise of ketamine, key challenges including how to maintain response, concerns regarding short and long-term side-effects and the potential for abuse remain. This review provides an overview of the history of ketamine, its use in psychiatry and its basic pharmacology. The clinical evidence for the use of ketamine in depression and potential adverse effects associated with treatment are summarized. A synopsis of some of the putative neurobiological mechanisms underlying ketamine's rapid-acting antidepressant effects is provided before finally outlining future research directions, including the need to identify biomarkers for predicting response and treatment targets that may be used in the development of next-generation rapid-acting antidepressants that may lack ketamine's side-effects or abuse potential.

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

Replicated international studies have underscored the human and societal costs associated with major depressive disorder. Despite the proven efficacy of monoamine-based antidepressants in major depression, the majority of treated individuals fail to achieve full syndromal and functional recovery with the index and subsequent pharmacological treatments. Ketamine and esketamine represent pharmacologically novel treatment avenues for adults with treatment-resistant depression. In addition to providing hope to affected persons, these agents represent the first non-monoaminergic agents with proven rapid-onset efficacy in major depressive disorder. Nevertheless, concerns remain about the safety and tolerability of ketamine and esketamine in mood disorders. Moreover, there is uncertainty about the appropriate position of these agents in treatment algorithms, their comparative effectiveness, and the appropriate setting, infrastructure, and personnel required for their competent and safe implementation. In this article, an international group of mood disorder experts provides a synthesis of the literature with respect to the efficacy, safety, and tolerability of ketamine and esketamine in adults with treatment-resistant depression. The authors also provide guidance for the implementation of these agents in clinical practice, with particular attention to practice parameters at point of care. Areas of consensus and future research vistas are discussed.

Impact of impaired glucose metabolism on responses to a psychophysical stressor: modulation by ketamine

RATIONALE

There is evidence that hypoglycemia, a metabolic stressor, can negatively impact mood and motivation, and can interact with other stressors to potentiate their effects on behavior and physiology.

OBJECTIVES/METHODS

The current study in male Sprague-Dawley rats explored the interaction between impaired glucose metabolism induced by 0, 200, or 300 mg/kg 2-deoxy-D-glucose (2-DG) and a psychophysical stressor induced by forced swimming stress (FSS; 6 sessions, 10 min/session). The endpoints of interest were blood glucose levels, progressive behavioral immobility, and saccharin preference (2-bottle choice test). Furthermore, it was investigated whether pre-treatment with 0, 10, or 20 mg/kg ketamine could modify the interaction between 2-DG and FSS on these endpoints.

RESULTS

It was found that 2-DG increased blood glucose levels equally in all experimental groups, accelerated the immobile response to FSS, and suppressed saccharin preference 1 week following termination of stress exposure. As well, pre-treatment with ketamine blocked the effects of combined 2-DG and FSS on immobility and saccharin preference without affecting blood glucose levels and produced an anti-immobility effect that was observed during a drug-free test swim 1 week following administration.

CONCLUSIONS

Overall, these findings demonstrate that impaired glucose metabolism can potentiate the effects of a psychophysical stressor, and that this interaction can be modulated pharmacologically by ketamine.