Effect of Low Dose of Ketamine on Learning Memory Function in Patients Undergoing Electroconvulsive Therapy-A Randomized, Double-Blind, Controlled Clinical Study

Perspectives in treatment-resistant depression: esketamine and electroconvulsive therapy

Modern electroconvulsive therapy (ECT) and the approval of nasal esketamine for clinical use have significantly improved the approach to treatment-resistant depression (TRD), which is defined as non-response to at least two different courses of antidepressants with verified adherence to treatment, adequate dosage, and duration of treatment. The goal of this literature review is to present the newest evidence regarding efficacy and safety. Furthermore, we aim to provide an overview of future perspectives in this field of research, for example, regarding structural and molecular effects. Both treatment methods will be critically evaluated for their individual advantages, disadvantages, and response rates. Firstly, we will discuss the well-established method of ECT and its different treatment modalities. Secondly, we will discuss the properties of ketamine, the discovery of its antidepressive effects and the route to clinical approval of the esketamine nasal spray. We will comment on research settings which have evaluated intravenous ketamine against ECT. The decision-making process between esketamine nasal spray or ECT should include the assessment of contraindications, age, severity of disease, presence of psychotic symptoms, patient preference and treatment accessibility. We conclude that both treatment options are highly effective in TRD. If both are indicated, pragmatically esketamine will be chosen before ECT; however, ECT studies in ketamine non-responders are missing.

Prolonged ketamine therapy differentially rescues psychobehavioural deficits via modulation of nitro-oxidative stress and oxytocin receptors in the gut-brain-axis of chronically-stressed mice

Ketamine is an anaesthetic known to have short but rapid-acting anti-depressant effects; however, the neurobehavioural effects of its prolonged use and its role on the oxytocin system in the gut-brain axis are largely undetermined. Female BALB/c mice were either exposed to the chronic unpredictable mild stress (CUMS) paradigm for 21 days and then treated with ketamine in four doses for 14 days or exposed to CUMS and treated simultaneously in four doses of ketamine during the last two weeks of CUMS exposure. After each dose, the forced swim test was conducted to assess depressive-like behaviour. Before sacrifice, all the mice were subjected to behavioural tests to assess anxiety, memory, and social interaction. Prolonged treatment of depression with ketamine did not rescue depressive-like behaviour. It did, however, improve depression-associated anxiety-like behaviours, short-term memory and social interaction deficits when compared to the stressed untreated mice. Furthermore, ketamine treatment enhanced plasma oxytocin levels, expression of oxytocin receptors; as well as abrogated nitro-oxidative stress biomarkers in the intestinal and hippocampal tissues. Taken together, our findings indicate that while short-term use of ketamine has anti-depressant benefits, its prolonged therapeutic use does not seem to adequately resolve depressive-like behaviour in mice.

Subanesthetic Dose of Ketamine Administered Before Each Electroconvulsive Therapy Session Improves Antidepressant and Sleep Quality Outcomes: A Randomized, Controlled Trial

OBJECTIVES

The main purpose of this trial is to explore the effects of subanesthetic dose of ketamine on sleep quality and symptoms in patients with major depressive disorder undergoing bitemporal electroconvulsive therapy (ECT).

METHODS

Seventy-one patients with major depressive disorder and sleep disturbance were randomly divided into 2 groups, namely, the ECT without ketamine group (group ES), receiving routine ECT and saline (3 mL) at each ECT session, and the ECT-assisted ketamine group (group KS), which received ECT and ketamine (3 mL) at each ECT session. The 24 Hamilton Depression Rating Scale was used to assess depressive symptoms and the Chinese Pittsburgh Sleep Quality Index was used to evaluate sleep quality.

RESULTS

The patients in group KS required shorter ECT treatment sessions. Patients in group ES had lower sleep efficiency, longer sleep latency, and required more sleep medication than patients in group KS at the end of the ECT course.

CONCLUSIONS

Subanesthetic dose of ketamine improved sleep quality and enhanced ECT therapeutic effects in patients with sleep disturbance.

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.

Focal points of preanesthesia evaluations for electroconvulsive therapy in patients with depression: a retrospective analysis of clinical characteristics in nonremission

Background

This study explored the patient clinical characteristics that may affect electroconvulsive therapy (ECT) efficacy to enable improved focus during evaluations and preparation for ECT.

Methods

Patients were enrolled for ECT at the Department of Psychiatry and Anesthesiology of the First Affiliated Hospital of Chongqing Medical University from December 2017 to January 2019. The primary outcome in our study was defined as the development of nonremission. A multivariate logistic analysis was performed to identify the risk factors for nonremission.

Results

In total, 874 depressed patients were included in the study. After the ECT treatment, 255 cases (29.2%) exhibited nonremission. A multivariate logistic regression analysis of the variables was performed, and the results showed that atherosclerosis (OR 8.072, 95% CI 2.442 to 16.675; P = 0.001), COPD (OR 2.919, 95% CI 1.240 to 6.871; P = 0.014), diabetes (OR 2.202, 95% CI 1.115 to 4.348; P = 0.023) and smoking (OR 1.519, 95% CI 1.015 to 2.273; P = 0.042) were independent risk factors for nonremission.

Conclusion

In the retrospective analysis, we found that atherosclerosis, diabetes, COPD and smoking may be high-risk factors for nonremission.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01686-6.

Pharmacological interventions to diminish cognitive side effects of electroconvulsive therapy: A systematic review and meta-analysis

OBJECTIVE

The authors conducted a systematic review and meta-analysis of pharmacological interventions to diminish cognitive side effects of ECT.

METHODS

Electronic databases of Pubmed, PsycInfo, Embase and Scopus were searched from inception through 1 April, 2021, using terms for ECT (e.g. electroconvulsive therapy), cognitive outcome (e.g. cogni*) and pharmacological intervention (e.g. calcium channel blocker and general terms, like protein). Original studies with humans receiving ECT were included, which applied pharmacological interventions in comparison with placebo or no additive intervention to diminish cognitive side effects. Data quality was assessed using Risk of Bias and GRADE. Random-effects models were used. PROSPERO registration number was CRD42021212773.

RESULTS

Qualitative synthesis (systematic review) showed 52 studies reporting sixteen pharmacological intervention-types. Quantitative synthesis (meta-analysis) included 26 studies (1387 patients) describing twelve pharmacological intervention-types. Low-quality evidence of efficacy was established for memantine (large effect size) and liothyronine (medium effect size). Very low-quality evidence shows effect of acetylcholine inhibitors, piracetam and melatonin in some cognitive domains. Evidence of no efficacy was revealed for ketamine (very low-quality), herbal preparations with anti-inflammatory properties (very low to low-quality) and opioid receptor agonists (low-quality).

CONCLUSION

Memantine and liothyronine are promising for further research and future application. Quality of evidence was low because of differences in ECT techniques, study populations and cognitive measurements. These findings provide a guide for rational choices of potential pharmacological intervention research targets to decrease the burden of cognitive side effects of ECT. Future research should be more uniform in design and attempt to clarify pathophysiological mechanisms of cognitive side effects of ECT.

Ketamine in depression and electroconvulsive therapy

PURPOSE OF REVIEW

The antidepressant effect of subanesthetic doses of ketamine was recognized 20 years ago. This review briefly summarizes the current understanding of the antidepressant mechanisms and the available clinical research on the use of racemic ketamine and enantiomer esketamine for depression.

RECENT FINDINGS

The antidepressant effect of subanesthetic doses of ketamine is currently considered to be predominantly mediated by improved neuroplasticity in cortico-limbic areas in the brain. Single dose of 0.5 mg/kg of ketamine infused intravenously over 40 min, or single intranasal dose of esketamine cause rapid antidepressant and antisuicidal effects within hours of administration, and the antidepressant effect may last up to a week. Repeated administration of nasal spray esketamine is considered to prevent relapse of depression. Longitudinal studies are currently insufficient. When used in various doses for anesthetic induction for electroconvulsive therapy, ketamine improves seizure quality and may possibly diminish posttherapy cognitive impairment.

SUMMARY

A rapid onset antidepressive effect of ketamine and esketamine has been proven conclusively. The results of extensive basic science research of the mechanism of action of low-dose ketamine doses has led to an alternative hypothesis of the pathophysiology of depression and the development of a novel neurotrophic concept of depression. Further longitudinal studies are warranted to determine the safety and efficacy of repeated administration of ketamine and its analogs to prevent relapse and recurrence of depression.

Ketamine and other glutamate receptor modulators for depression in adults with unipolar major depressive disorder

BACKGROUND

Many studies have recently been conducted to assess the antidepressant efficacy of glutamate modification in mood disorders. This is an update of a review first published in 2015 focusing on the use of glutamate receptor modulators in unipolar depression.

OBJECTIVES

To assess the effects - and review the acceptability and tolerability - of ketamine and other glutamate receptor modulators in alleviating the acute symptoms of depression in people with unipolar major depressive disorder.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE, Embase and PsycINFO all years to July 2020.  We did not apply any restrictions to date, language or publication status.

SELECTION CRITERIA

Double- or single-blinded randomised controlled trials (RCTs) comparing ketamine, memantine, esketamine or other glutamate receptor modulators with placebo (pill or saline infusion), other active psychotropic drugs, or electroconvulsive therapy (ECT) in adults with unipolar major depression.

DATA COLLECTION AND ANALYSIS

Three review authors independently identified studies, assessed trial quality and extracted data. The primary outcomes were response rate (50% reduction on a standardised rating scale) and adverse events. We decided a priori to measure the efficacy outcomes at different time points and run sensitivity/subgroup analyses. Risk of bias was assessed using the Cochrane tool, and certainty of the evidence was assessed using GRADE.

MAIN RESULTS

Thirty-one new studies were identified for inclusion in this updated review. Overall, we included 64 studies (5299 participants) on ketamine (31 trials), esketamine (9), memantine (5), lanicemine (4), D-cycloserine (2), Org26576 (2), riluzole (2), atomoxetine (1), basimglurant (1), citicoline (1), CP-101,606 (1), decoglurant (1), MK-0657 (1), N-acetylcysteine (1), rapastinel (1), and sarcosine (1). Forty-eight studies were placebo-controlled, and 48 were two-arm studies. The majority of trials defined an inclusion criterion for the severity of depressive symptoms at baseline: 29 at least moderate depression; 17 severe depression; and five mild-to-moderate depression. Nineteen studies recruited only patients with treatment-resistant depression, defined as inadequate response to at least two antidepressants. The majority of studies investigating ketamine administered as a single dose, whilst all of the included esketamine studies used a multiple dose regimen (most frequently twice a week for four weeks). Most studies looking at ketamine used intravenous administration, whilst the majority of esketamine trials used intranasal routes. The evidence suggests that ketamine may result in an increase in response and remission compared with placebo at 24 hours odds ratio (OR) 3.94, 95% confidence interval (CI) 1.54 to 10.10; n = 185, studies = 7, very low-certainty evidence). Ketamine may reduce depression rating scale scores over placebo at 24 hours, but the evidence is very uncertain (standardised mean difference (SMD) -0.87, 95% CI -1.26 to -0.48; n = 231, studies = 8, very low-certainty evidence). There was no difference in the number of participants assigned to ketamine or placebo who dropped out for any reason (OR 1.25, 95% CI 0.19 to 8.28; n = 201, studies = 6, very low-certainty evidence). When compared with midazolam, the evidence showed that ketamine increases remission rates at 24 hours (OR 2.21, 95% CI 0.67 to 7.32; n = 122,studies = 2, low-certainty evidence). The evidence is very uncertain about the response efficacy of ketamine at 24 hours in comparison with midazolam, and its ability to reduce depression rating scale scores at the same time point (OR 2.48, 95% CI 1.00 to 6.18; n = 296, studies = 4,very low-certainty evidence). There was no difference in the number of participants who dropped out of studies for any reason between ketamine and placebo (OR 0.33, 95% CI 0.05 to 2.09; n = 72, studies = 1, low-certainty evidence). Esketamine treatment likely results in a large increase in participants achieving remission at 24 hours compared with placebo (OR 2.74, 95% CI 1.71 to 4.40; n = 894, studies = 5, moderate-certainty evidence). Esketamine probably results in decreases in depression rating scale scores at 24 hours compared with placebo (SMD -0.31, 95% CI -0.45 to -0.17; n = 824, studies = 4, moderate-certainty evidence). Our findings show that esketamine increased response rates, although this evidence is uncertain (OR 2.11, 95% CI 1.20 to 3.68; n = 1071, studies = 5, low-certainty evidence). There was no evidence that participants assigned to esketamine treatment dropped out of trials more frequently than those assigned to placebo for any reason (OR 1.58, 95% CI 0.92 to 2.73; n = 773, studies = 4,moderate-certainty evidence). We found very little evidence for the remaining glutamate receptor modulators. We rated the risk of bias as low or unclear for most domains, though lack of detail regarding masking of treatment in the studies reduced our certainty in the effect for all outcomes.

AUTHORS' CONCLUSIONS

Our findings show that ketamine and esketamine may be more efficacious than placebo at 24 hours. How these findings translate into clinical practice, however, is not entirely clear. The evidence for use of the remaining glutamate receptor modulators is limited as very few trials were included in the meta-analyses for each comparison and the majority of comparisons included only one study. Long term non-inferiority RCTs comparing repeated ketamine and esketamine, and rigorous real-world monitoring are needed to establish comprehensive data on safety and efficacy.

Subanesthetic dose of ketamine for the antidepressant effects and the associated cognitive impairments of electroconvulsive therapy in elderly patients-A randomized, double-blind, controlled clinical study

OBJECTIVES

We previously confirmed that low-dose ketamine, as an adjunctive anesthetic for electroconvulsive therapy (ECT) in adult patients with depression, accelerates the effects of ECT and reduces the ECT-induced learning and memory deficits. This study explored the efficacy and safety of low-dose ketamine in elderly patients with depression.

METHODS

Elderly patients with depression (N = 157) were randomly divided into two groups: propofol anesthesia group (group P) and propofol combined with ketamine anesthesia group (group KP). Patients in group KP were given low-dose ketamine (0.3 mg/kg) for each ECT treatment; patients in group P were given the same amount of normal saline. Depressive symptoms and global cognitive functions were assessed using the 24-item Hamilton Depression Rating Scale and Mini-Mental State Examination, respectively, at baseline, 1 day after the 1st, 2nd, 4th, and 6th ECT sessions, and 1 day after the end of the ECT course. ECT effects of and complications were recorded.

RESULTS

In total, 67 patients in group KP and 70 in group P completed the study. After the ECT, the response and remission rates were 82.09% and 73.13%, respectively, in group KP, and 81.43% and 68.57%, respectively, in group P; there was no statistical difference between groups. However, the incidence of cognitive function impairment was lower in group KP (10.4%) than in group P (25.7%), while different electrical dose and seizure duration were required during the course of treatment between the two groups. There was no difference in the complications of ECT between groups.

CONCLUSIONS

Low-dose ketamine is safe as an adjunct anesthetic for elderly patients subjected to ECT. It has a protective effect on cognitive function and may accelerate the antidepressant effects of ECT.

Effectiveness and Safety of Ketamine for Unipolar Depression: a Systematic Review

Major Depressive Disorder (MDD) is a common psychiatric disorder with major implications for healthcare system and socioeconomic burden. For chronic and treatment-resistant depression, Ketamine has emerged as a possible treatment option. This systematic review explores the evidence for the effectiveness and tolerability of Ketamine in patients with MDD. This systematic review was conducted following the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) checklist. Eight electronic databases were searched by using search terms: (ketamine) AND (trial OR RCT OR clinical-trial) AND (depressive OR depression OR "depressive-disorder"). After a rigorous screening process against the predetermined eligibility criteria, 35 randomized controlled trials (RCTs) were included. Quality assessment of included studies was done by using the Cochrane risk-of-bias tool for RCTs. Thirty-five RCTs are included in this review article with majority of studies from United States, Iran, and China. Intravenous (IV) Ketamine was effective in 70% (21/30) of the included studies whereas oral and Intranasal (IN) Ketamine were effective in two and three studies, respectively. The majority of studies (6/8) using Ketamine as anesthetic agent during electroconvulsive therapy (ECT) failed to show an improvement compared to the participants receiving ECT and placebo. The most common reported side effects were nausea, vomiting, dizziness, diplopia, drowsiness, dysphoria, hallucinations, and confusion. Ketamine is an effective treatment option for patients with MDD with undesirable effects when administered via oral, IV and IN routes. Ketamine agumentation of ECT requires further exploration in well-designed studies with adequate sample size. The short-lived antidepressant effect of Ketamine is a potential limitation, therefore, further studies administering multiple infusions for acute treatment and maintenance are necessary.

Effects of ketamine in electroconvulsive therapy for major depressive disorder: meta-analysis of randomised controlled trials

Background

The use of ketamine in electroconvulsive therapy (ECT) has been examined in the treatment of major depressive disorder (MDD); however, there has been no systematic review and meta-analysis of related randomised controlled trials (RCTs).

Aim

To examine the efficacy and safety of ketamine augmentation of ECT in MDD treatment.

Methods

Two reviewers searched Chinese (China National Knowledge Infrastructure and Wanfang) and English (PubMed, PsycINFO, Embase and Cochrane Library) databases from their inception to 23 July 2019. The included studies' bias risk was evaluated using the Cochrane risk of bias assessment tool. The primary outcome of this meta-analysis was improved depressive symptoms at day 1 after a single ECT treatment session. Data were pooled to calculate the standardised mean difference and risk ratio with their 95% CIs using RevMan V.5.3. We used the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach to assess the whole quality of evidence.

Results

Four RCTs (n = 239) compared ketamine alone or ketamine plus propofol (n = 149) versus propofol alone (n = 90) in patients with MDD who underwent a single ECT session. Three RCTs were considered as unclear risk with respect to random sequence generation using the Cochrane risk of bias. Compared with propofol alone, ketamine alone and the combination of ketamine and propofol had greater efficacy in the treatment of depressive symptoms at days 1, 3 and 7 after a single ECT session. Moreover, compared with propofol alone, ketamine alone and the combination of ketamine and propofol were significantly associated with increased seizure duration and seizure energy index. Compared with propofol, ketamine alone was significantly associated with increased opening-eye time. Based on the GRADE approach, the evidence level of primary and secondary outcomes ranged from very low (26.7%, 4/15) to ‘low’ (73.3%, 11/15).

Conclusion

Compared with propofol, there were very low or low evidence levels showing that ketamine alone and the combination of ketamine and propofol appeared to rapidly improve depressive symptoms of patients with MDD undergoing a single ECT session. There is a need for high-quality RCTs.

Effects of Ketamine Anesthesia on Efficacy, Tolerability, Seizure Response, and Neurocognitive Outcomes in Electroconvulsive Therapy: A Comprehensive Meta-analysis of Double-Blind Randomized Controlled Trials

Electroconvulsive therapy (ECT) remains the most effective treatment for major depressive disorder. Ketamine is an anesthetic gaining attention for its rapid antidepressant effect. Numerous randomized controlled trials have investigated the effect of ketamine anesthesia in ECT on various clinical outcomes. Previous systematic reviews have not found benefit for overall depression response, although some have found evidence of benefit early in the ECT course. Clear quantitative conclusions have not been established regarding other outcomes, particularly while only using data from high-quality studies. We aimed to examine all data from double-blind randomized controlled trials comparing ketamine to other anesthetics via meta-analysis, to make recommendations regarding ECT practice and future research. Data were extracted for depressive symptoms, seizure duration and electrical dose, neuropsychological performance, and adverse effects. Effect sizes were calculated using Hedge's g and odds ratios. Eighteen studies (n = 915) were included in the meta-analysis. Ketamine was not found to enhance improvement of depressive symptoms, either early in ECT course or at end of study. Ketamine had a large effect on increasing seizure duration both overall (Hedge's g = 0.71, P = 0.038) and in the subgroup receiving ketamine in combination with another anesthetic (Hedge's g = 0.78, P < 0.01), and on decreasing electrical dose (Hedge's g = 1.98, P = 0.039). There was no significant effect of ketamine on any individual neuropsychological domain. Ketamine was not associated with increased adverse effects, except for hypertension in patients receiving ketamine monotherapy. Significant heterogeneity was present for many outcomes, and sensitivity analyses suggested a relation to methodological variation in most cases. This study supports the finding that ketamine does not enhance ECT's antidepressant effect, including on early improvement, but provides substantial evidence for enhancing seizure duration and reducing electrical dose. No significant benefit was found on neurocognitive outcomes, but analysis was limited by small sample sizes and high heterogeneity. Ketamine is generally safe in ECT, particularly as a coanesthetic. Our findings provide meta-analytic support to the recommendations in ECT clinical guidelines for use of coadjuvant ketamine in ECT where seizures are suboptimal. Further studies targeting neurocognitive outcomes are encouraged.

Effects of Low-Dose Ketamine on the Antidepressant Efficacy and Suicidal Ideations in Patients Undergoing Electroconvulsive Therapy

OBJECTIVES

It remains controversial whether a subanesthetic dose of ketamine could modulate the antidepressant effect of electroconvulsive therapy (ECT) in patients with major depressive disorder. We investigated the effect of ketamine on accelerating the antidepressant efficacy of ECT.

METHODS

One hundred twenty-seven patients with major depressive disorder were included in this randomized, placebo-controlled, double-blind study. The study group received 0.3 mg/kg ketamine, and the control group received an isovolumetric dose of normal saline before undergoing ECT under propofol anesthesia. The main outcome was the Hamilton Depression Rating Scale score after each ECT session. Suicidal ideation (SI) was also evaluated using the Hamilton Depression Rating Scale. The response, remission, and recurrence rates were analyzed using time-to-event analysis.

RESULTS

No significant differences were found in the overall response, remission, and relapse rates between the groups (P > 0.05). The median number of ECT sessions for achieving response was 4.0 ± 0.41 in the study group and 7.0 ± 0.79 in the control group (P < 0.05). The median number of ECT sessions for achieving remission in the study and control groups was 8.0 ± 0.29 and 9.0 ± 0.48, respectively (P < 0.05). The median number of ECT sessions for achieving SI reduction in the study and control groups was 3.0 ± 0.75 and 6.0 ± 1.19, respectively (P < 0.05).

CONCLUSIONS

Low-dose ketamine (0.3 mg/kg) could modulate the antidepressant efficacy of ECT via accelerating the onset of its effects and reducing the number of ECT sessions required to obtain response, remission, and SI reduction, without influencing the relapse rates in remitting patients after ECT treatment.

Intermittent administration of low dose ketamine can shorten the course of electroconvulsive therapy for depression and reduce complications: A randomized controlled trial

This study aimed to investigate the efficacy and safety of intermittent low-dose ketamine on improving the efficacy of ECT. Patients diagnosed with Major Depressive Disorder (MDD) (n = 134) were randomized into 3 groups: routine ECT group (group E, n = 45); repeated ketamine-assisted ECT group (group RK, n = 43), and intermittent ketamine-assisted ECT group (group IK, n = 46). Patients in group RK were given ketamine at the dose of 0.3 mg/kg for each ECT treatment, patients in group IK were given ketamine once a week during ECT course. The depressive symptoms were assessed using the Hamilton Depression Rating Scale (HAM-D) at baseline, the end of ECT course, after 1 and 3 months, followed by an analysis of the psychiatric complications. Results indicated that ketamine-assisted ECT achieved a higher remission rate (P < 0.05), and no difference was observed between repeated and intermittent ketamine administrations. The total incidence rate of psychiatric complications in group RK (20.93%) was higher than that in group E (0%) and group IK (4.35%). In conclusion, intermittent administration of low dose ketamine in ECT significantly improved the effects of ECT and decreased psychiatric complications compared with repeated ketamine addition.

Ketamine and depression: a narrative review

Depression is the third leading cause of disability in the world. Depressive symptoms may be reduced within several weeks after the start of conventional antidepressants, but treatment resistance concerns one-third of patients who fail to achieve recovery. Over the last 20 years, ketamine, an antagonist of the N-methyl-D-aspartate receptor, has been described to have antidepressant properties. A literature review was conducted through an exhaustive electronic search. It was restricted to Cochrane reviews, meta-analyses, and randomized controlled trials (RCTs) of ketamine for major depressive disorder and/or bipolar disorder. This review included two Cochrane reviews, 14 meta-analyses and 15 trials. Ketamine was studied versus placebo, versus other comparators and as an anesthetic adjuvant before electroconvulsive therapy. In 14 publications, ketamine provided a rapid antidepressant effect with a maximum efficacy reached at 24 hrs. Its effect lasted for 1–2 weeks after infusion, but a longer-term effect is little reported. Ketamine does not seem to improve depressive symptoms at the end of electroconvulsive sessions. Safety and tolerability profiles with ketamine at low single dose are generally good in depressed patients. However, there is a lack of data concerning ketamine with repeated administration at higher doses. The clinical use of ketamine is increasing. Intranasal (S)-ketamine has recently been approved for depression by the Food and Drug Administration. It could be a promising treatment in depressed patients with suicidal ideation. Collectively, the level of proof of efficacy remains low and more RCTs are needed to explore efficacy and safety issues of ketamine in depression.

Adjunctive ketamine and electroconvulsive therapy for major depressive disorder: A meta-analysis of randomized controlled trials

BACKGROUND

Adjunctive ketamine with electroconvulsive therapy (ECT) has been investigated for treating major depressive disorder (MDD), but the findings have been inconsistent.

AIM

This is an updated meta-analysis of the efficacy and safety of ketamine augmentation of ECT in the treatment of MDD.

METHODS

Randomized controlled trials (RCTs) reporting on the efficacy and safety of ketamine and ECT were identified and analyzed.

RESULTS

Seventeen RCTs (n = 1,035) compared ketamine alone or ketamine plus other anesthetic drugs (n = 557) with other anesthetic agents (n = 478) in MDD patients who received ECT. Ketamine+other anesthetic drugs was superior in improving depressive symptoms over other anesthetic medications at early study time point, but not at post-ECT or end of study time points. Ketamine alone was not more efficacious in treating depressive symptoms than other anesthetic drugs at early study, post-ECT and end of study time points. Sensitivity analysis and 19 of the 20 subgroup analyses also confirmed the lack of significance of these findings. Eleven RCTs testing the effects of ketamine on neurocognitive functions with various test batteries found mixed results. Ketamine alone significantly increased blood pressure more than other anesthetic drugs in MDD treated with ECT.

CONCLUSION

Compared to other anesthetic agents, ketamine alone does not appear to improve the efficacy of ECT. However, ketamine+other anesthetic combinations may confer a short-term advantage in improving depressive symptom at the early stages of ECT.

Effect of Ketamine on LTP and NMDAR EPSC in Hippocampus of the Chronic Social Defeat Stress Mice Model of Depression

Depression is a common mental disorder that is associated with memory dysfunction. Ketamine has recently been demonstrated to be a rapid antidepressant. The mechanisms underlying how depression induces memory dysfunction and how ketamine relieves depressive symptoms remain poorly understood. This work compared three groups of male C57BL/6J mice: mice exposed to chronic social defeat stress (CSDS) to induce a depression-like phenotype, depression-like mice treated with ketamine, and control mice that were not exposed to CSDS or treated with ketamine. Spatial working memory and long term memory were assessed by spontaneous alternation Y-maze and fear conditioning tests, respectively. We used western blot to analyze the density of N-methyl-D-aspartate receptor (NMDAR) subunits in the hippocampus. We recorded long term potentiation (LTP) and NMDA receptor-mediated excitatory postsynaptic currents (EPSCs) in hippocampal slices. We observed that compared with control mice, depression-like mice had significant reductions in spatial working memory and contextual fear memory. The level of NR2B, LTP and NMDA receptor-mediated EPSCs of depression-like mice were decreased. Ketamine treatment attenuated the memory impairment, and increased the density of NR2B and the amplitude of LTP and NMDA receptor-mediated EPSCs in the hippocampus of depression-like mice. In conclusion, depression-like mice have deficits in working memory and contextual fear memory. The decrease of NR2B, LTP induction and NMDA receptor-mediated EPSCs in the hippocampus may be involved in this process. Ketamine can improve expression of NR2B, LTP induction and NMDA receptor-mediated EPSCs in the hippocampus of depression-like mice, which might be part of the reason why ketamine can alleviate the memory dysfunction induced by depression.

Ketamine in electroconvulsive therapy for depressive disorder: A systematic review and meta-analysis

Electroconvulsive therapy (ECT) is one of the most effective treatments for depressive disorder. Sub-anesthetic dose of ketamine exerts a rapid and robust antidepressive effect. However, it is still unclear whether ketamine usage in ECT is efficacious as an antidepressant. We aimed to conduct a systematic review and meta-analysis on the effects of ketamine in ECT among patients with depressive disorder. MEDLINE, EMBASE, the CENTRAL and PsycINFO for randomized controlled trials were searched to assess the effects of ketamine used in ECT until 31 Mar 2018 (PROSPERO: CRD42018081024). Sixteen studies including 928 patients were enrolled. At the end of ECT, no significant standardized mean difference (SMD) was observed in favor of the ketamine group. Depressive scores were lower in the ketamine group after 1st ECT and 3rd to 6th ECTs. The depressive scores were lower after 2nd, 3rd, 4th and 6th ECTs when the ketamine was used as an add-on anesthetic, while the depressive scores were lower after 1st ECT when ketamine alone was used. Ketamine in ECT showed no better response and remission rate, while increased adverse events, especially related to cardiovascular and psychiatric systems, during the whole ECT course. In conclusion, although ketamine used in ECT cannot reduce the depressive symptoms at the end of treatment, it could accelerate the antidepressive effect in depressive patients receiving ECT, especially in those who used ketamine as an add-on anesthetic. However, ketamine cautiously needs to be administered in ECT due to the possibility of increased risk of side effects.

Anesthetics alleviate learning and memory impairment induced by electroconvulsive shock by regulation of NMDA receptor-mediated metaplasticity in depressive rats

Along with its outstanding antidepressant effect, electroconvulsive shock (ECS) can induce learning and memory impairment. Propofol and ketamine have shown to be useful in alleviating the learning and memory impairment. Nevertheless, the mechanism still remains unclear. This study investigated the role of NMDA receptor (NMDAR)-mediated metaplasticity in the learning and memory impairment induced by ECS, as well as the neuroprotective effect of propofol and ketamine in depressive rats. Rats received ECS or ECS under anesthetics after chronic unpredictable mild stress procedure. Long-term potentiation (LTP) was tested by extracellular recording. LTD/LTP threshold was assessed by stimulation of different frequencies. Additionally, NMDAR-mediated field excitatory postsynaptic potential (fEPSP) and NMDAR input/output relationship were detected under hippocampal slice perfusion. Results showed that propofol or low-dose ketamine could partially alleviate ECS-induced LTP impairment, while propofol combined with low-dose ketamine almost reversed the LTP impairment. LTP under ECS was increased by stronger stimulation. ECS could up-regulated LTD/LTP threshold, while propofol or ketamine could down-regulate it. Moreover, ECS activated NMDAR, while propofol and ketamine could inhibit the activation of NMDAR. NMDAR input/output relationship decrease was induced by preconditioning (an analog of ECS in hippocampal slice), however, NMDAR input/output relationship increased by propofol or ketamine. In conclusion, ECS-induced cognitive impairment is caused by NMDAR-mediated metaplasticity via up-regulation of LTD/LTP threshold. Propofol or ketamine alleviates the cognitive impairment, possibly by down-regulating the threshold via inhibition of NMDAR activation induced by ECS.

Ketamine administered pregnant rats impair learning and memory in offspring via the CREB pathway

Ketamine has been reported to impair the capacity for learning and memory. This study examined whether these capacities were also altered in the offspring and investigated the role of the CREB signaling pathway in pregnant rats, subjected to ketamine-induced anesthesia. On the 14^th day of gestation (P14), female rats were anesthetized for 3 h via intravenous ketamine injection (200 mg/Kg). Morris water maze task, contextual and cued fear conditioning, and olfactory tasks were executed between the 25^th to 30^th day after birth (B25-30) on rat pups, and rats were sacrificed on B30. Nerve density and dendritic spine density were examined via Nissl’s and Golgi staining. Simultaneously, the contents of Ca²⁺/Calmodulin-Dependent Protein Kinase II (CaMKII), p-CaMKII, CaMKIV, p-CaMKIV, Extracellular Regulated Protein Kinases (ERK), p-ERK, Protein Kinase A (PKA), p-PKA, cAMP-Response Element Binding Protein (CREB), p-CREB, and Brain Derived Neurotrophic Factor (BDNF) were detected in the hippocampus. We pretreated PC12 cells with both PKA inhibitor (H89) and ERK inhibitor (SCH772984), thus detecting levels of ERK, p-ERK, PKA, p-PKA, p-CREB, and BDNF. The results revealed that ketamine impaired the learning ability and spatial as well as conditioned memory in the offspring, and significantly decreased the protein levels of ERK, p-ERK, PKA, p-PKA, p-CREB, and BDNF. We found that ERK and PKA (but not CaMKII or CaMKIV) have the ability to regulate the CREB-BDNF pathway during ketamine-induced anesthesia in pregnant rats. Furthermore, ERK and PKA are mutually compensatory for the regulation of the CREB-BDNF pathway.

Ketamine augmentation of electroconvulsive therapy to improve neuropsychological and clinical outcomes in depression (Ketamine-ECT): a multicentre, double-blind, randomised, parallel-group, superiority trial

BACKGROUND

The use of electroconvulsive therapy (ECT) is limited by concerns about its cognitive adverse effects. Preliminary evidence suggests that administering the glutamate antagonist ketamine with ECT might alleviate cognitive adverse effects and accelerate symptomatic improvement; we tested this in a randomised trial of low-dose ketamine.

METHODS

In this multicentre, randomised, parallel-group study in 11 ECT suites serving inpatient and outpatient care settings in seven National Health Service trusts in the North of England, we recruited severely depressed patients, who were diagnosed as having unipolar or bipolar depressive episodes defined as moderate or severe by DSM-IV criteria, aged at least 18 years, and were able and willing to provide written consent to participate in the study. Patients were randomly assigned (1:1) to ketamine (0·5 mg/kg intravenous bolus) or saline adjunctive to the anaesthetic for the duration of their ECT course. Patients and assessment and ECT treatment teams were masked to treatment allocation, although anaesthetists administering the study medication were not. We analysed the primary outcome, Hopkins Verbal Learning Test-Revised delayed verbal recall (HVLT-R-DR) after four ECT treatments, using a Gaussian repeated measures model in all patients receiving the first ECT treatment. In the same population, safety was assessed by adverse effect monitoring. This trial was registered with International Standard Randomised Controlled Trial Number, number ISRCTN14689382.

FINDINGS

Between early December, 2012, and mid-June, 2015, 628 patients were screened for eligibility, of whom 79 were randomly assigned to treatment (40 in the ketamine group vs 39 in the saline group). Ketamine (mean 5·17, SD 2·92), when compared with saline (5·54, 3·42), had no benefit on the primary outcome (HVLT-R-DR; difference in means -0·43 [95% CI -1·73 to 0·87]). 15 (45%) of 33 ketamine-treated patients compared with 10 (27%) of 37 patients receiving saline experienced at least one adverse event which included two (6%) of 33 patients who had ketamine-attributable transient psychological effects. Psychiatric adverse events were the most common in both groups (six [27%] of 22 adverse events in the ketamine group vs seven [54%] of 13 in the saline group).

INTERPRETATION

No evidence of benefit for ketamine was found although the sample size used was small; however, the results excluded greater than a small to moderate benefit with 95% confidence. The results do not support the use of adjunctive low-dose ketamine in routine ECT treatment.

FUNDING

National Institute for Health Research (NIHR) Efficacy and Mechanism Evaluation (EME) programme, an MRC and NIHR partnership.