Rapid antidepressant effect of ketamine anesthesia during electroconvulsive therapy of treatment-resistant depression: comparing ketamine and propofol anesthesia

Clinical efficacy of adjunctive esketamine anesthesia in electroconvulsive therapy for major depressive disorders: A pragmatic, randomized, controlled trial

Electroconvulsive therapy (ECT) is an effective treatment for depression, and esketamine has been shown to have antidepressant effects. However, it is currently unclear whether adjunctive esketamine can enhance the clinical efficacy of ECT in real-world clinical practice. In this pragmatic clinical trial, patients with major depression were randomly assigned into two groups: patients received 0.25 mg/kg esketamine plus propofol (esketamine group) or the same volume of saline (control group) plus propofol. Results indicated that there was no difference in response and remission rates between the two groups. However, patients receiving esketamine had a higher remission rate of SI and lower psychotic scores. Patients receiving esketamine also required a lower electric dose, but the seizure duration and cognitive function were comparable between the two groups. Diastolic blood pressure increased after esketamine injection, but there was no increased risk of hypertension. Furthermore, incidence of delirium and confusion were comparable between the groups. Conclusively, adjunctive esketamine anesthesia does not provide any advantage in improving the response and remission rates of ECT. However, it can improve remission of SI and alleviate accompanying psychotic symptoms in depressive patients. With adjunctive usage, the adverse cardiovascular and neuropsychiatric events associated with esketamine appear to be tolerable.

Efficacy and safety of ketamine-assisted electroconvulsive therapy in major depressive episode: a systematic review and network meta-analysis

OBJECTIVE

To meta-analyze clinical efficacy and safety of ketamine compared with other anesthetic agents in the course of electroconvulsive therapy (ECT) in major depressive episode (MDE).

METHODS

PubMed/MEDLINE, Cochrane Library, Embase, GoogleScholar, and US and European trial registries were searched from inception through May 23, 2023, with no language limits. We included RCTs with (1) a diagnosis of MDE; (2) ECT intervention with ketamine and/or other anesthetic agents; and (3) measures included: depressive symptoms, cognitive performance, remission or response rates, and serious adverse events. Network meta-analysis (NMA) was performed to compare ketamine and 7 other anesthetic agents. Hedges' g standardized mean differences (SMDs) were used for continuous measures, and relative risks (RRs) were used for other binary outcomes using random-effects models.

RESULTS

Twenty-two studies were included in the systematic review. A total of 2322 patients from 17 RCTs were included in the NMA. The overall pooled SMD of ketamine, as compared with propofol as a reference group, was -2.21 (95% confidence interval [CI], -3.79 to -0.64) in depressive symptoms, indicating that ketamine had better antidepressant efficacy than propofol. In a sensitivity analysis, however, ketamine-treated patients had a worse outcome in cognitive performance than propofol-treated patients (SMD, -0.18; 95% CI, -0.28 to -0.09). No other statistically significant differences were found.

CONCLUSIONS

Ketamine-assisted ECT is tolerable and may be efficacious in improving depressive symptoms, but a relative adverse impact on cognition may be an important clinical consideration. Anesthetic agents should be considered based on patient profiles and/or preferences to improve effectiveness and safety of ECT use.

Comparative efficacy and tolerability of different anesthetics in electroconvulsive therapy for major depressive disorder: A systematic review and network meta-analysis

Electroconvulsive therapy (ECT) is one of the most effective treatments for major depressive disorder. Modern ECT is conducted with anesthesia, however, the optimal anesthetic agent for ECT is yet to be understood. This study is aimed to compare the effects of different anesthetic agents on antidepressant efficacy and tolerability in depressed individuals undergoing ECT. We searched MEDLINE, EMBASE, the CENTRAL and PsycINFO for randomized controlled trials from database inception until Nov 13, 2022 (PROSPERO: CRD42022375407). Global and local inconsistencies, heterogeneity and publication bias were assessed. Rankings were calculated with the surface under the cumulative ranking curve. A total of 33 studies involving 1898 patients were enrolled. Remission rates were higher for ketamine anesthesia as compared to adjunctive ketamine and propofol. In terms of ranking, ketamine was found to be first in terms of response/remission rates and depressive scores after the 1st, 3rd and 6th ECT and at the end of ECT session, while a higher incidence of adverse events was also observed. No significant advantage of any anesthetic was revealed for the cognitive function after ECT. In summary, based on current evidence, no specific anesthetic is recommended for ECT anesthesia. However, despite more side effects, ketamine monoanesthesia seems to reveal a potential benefit in improving antidepressant efficacy of ECT, and further studies are needed to investigate the relationship between anesthetic agents and the therapeutic effect of ECT.

Efficacy and Safety of Ketamine-assisted Electroconvulsive Therapy in Major Depressive Episode: A Systematic Review and Network Meta-Analysis

Objective

To meta-analyze clinical efficacy and safety of ketamine compared with other anesthetic agents in the course of electroconvulsive therapy (ECT) in major depressive episode (MDE).

Methods

PubMed/MEDLINE, Cochrane Library, Embase, GoogleScholar, and US and European trial registries were searched from inception through May 23, 2023, with no language limits. We included RCTs with (1) a diagnosis of MDE; (2) ECT intervention with ketamine and/or other anesthetic agents; and (3) measures included: depressive symptoms, cognitive performance, remission or response rates, and serious adverse events. Network meta-analysis (NMA) was performed to compare ketamine and 7 other anesthetic agents. Hedges' g standardized mean differences (SMDs) were used for continuous measures, and relative risks (RRs) were used for other binary outcomes using random-effects models.

Results

Twenty-two studies were included in the systematic review. A total of 2,322 patients from 17 RCTs were included in the NMA. The overall pooled SMD of ketamine, as compared with a propofol reference group, was -2.21 (95% confidence interval [CI], -3.79 to -0.64) in depressive symptoms, indicating that ketamine had better antidepressant efficacy than propofol. In a sensitivity analysis, however, ketamine-treated patients had a worse outcome in cognitive performance than propofol-treated patients (SMD, -0.18; 95% CI, -0.28 to -0.09). No other statistically significant differences were found.

Conclusions

Ketamine-assisted ECT is tolerable and may be efficacious in improving depressive symptoms, but a relative adverse impact on cognition may be an important clinical consideration. Anesthetic agents should be considered based on patient profiles and/or preferences to improve effectiveness and safety of ECT use.

Experimental strategies to discover and develop the next generation of psychedelics and entactogens as medicines

Research on classical psychedelics (psilocybin, LSD and DMT) and entactogen, MDMA, has produced a renaissance in the search for more effective drugs to treat psychiatric, neurological and various peripheral disorders. Psychedelics and entactogens act though interaction with 5-HT_2A and other serotonergic receptors and/or monoamine reuptake transporters. 5-HT, which serves as a neurotransmitter and hormone, is ubiquitously distributed in the brain and peripheral organs, tissues and cells where it has vasoconstrictor, pro-inflammatory and pro-nociceptive actions. Serotonergic psychedelics and entactogens have known safety and toxicity risks. For these drugs, the risks been extensively researched and empirically assessed through human experience. However, novel drug-candidates require thorough non-clinical testing not only to predict clinical efficacy, but also to address the risks they pose during clinical development and later after approval as prescription medicines. We have defined the challenges researchers will encounter when developing novel serotonergic psychedelics and entactogens. We describe screening techniques to predict clinical efficacy and address the safety/toxicity risks emerging from our knowledge of the existing drugs: 1) An early-stage, non-clinical screening cascade to pharmacologically characterise novel drug-candidates. 2) Models to detect hallucinogenic activity. 3) Models to differentiate hallucinogens from entactogens. 4) Non-clinical preclinical lead optimisation technology (PLOT) screening to select drug-candidates. 5) Modified animal models to evaluate the abuse and dependence risks of novel psychedelics in Safety Pharmacology testing. Our intention has been to design non-clinical screening strategies that will reset the balance between benefits and harms to deliver more effective and safer novel psychedelics for clinical use. This article is part of the Special Issue on 'National Institutes of Health Psilocybin Research Speaker Series'.

Ketamine for the treatment of mental health and substance use disorders: comprehensive systematic review

BACKGROUND

In the past two decades, subanaesthetic doses of ketamine have been demonstrated to have rapid and sustained antidepressant effects, and accumulating research has demonstrated ketamine's therapeutic effects for a range of psychiatric conditions.

AIMS

In light of these findings surrounding ketamine's psychotherapeutic potential, we systematically review the extant evidence on ketamine's effects in treating mental health disorders.

METHOD

The systematic review protocol was registered in PROSPERO (identifier CRD42019130636). Human studies investigating the therapeutic effects of ketamine in the treatment of mental health disorders were included. Because of the extensive research in depression, bipolar disorder and suicidal ideation, only systematic reviews and meta-analyses were included. We searched Medline and PsycINFO on 21 October 2020. Risk-of-bias analysis was assessed with the Cochrane Risk of Bias tools and A Measurement Tool to Assess Systematic Reviews (AMSTAR) Checklist.

RESULTS

We included 83 published reports in the final review: 33 systematic reviews, 29 randomised controlled trials, two randomised trials without placebo, three non-randomised trials with controls, six open-label trials and ten retrospective reviews. The results were presented via narrative synthesis.

CONCLUSIONS

Systematic reviews and meta-analyses provide support for robust, rapid and transient antidepressant and anti-suicidal effects of ketamine. Evidence for other indications is less robust, but suggests similarly positive and short-lived effects. The conclusions should be interpreted with caution because of the high risk of bias of included studies. Optimal dosing, modes of administration and the most effective forms of adjunctive psychotherapeutic support should be examined further.

Antisuicidal efficacy of ketamine infusion in suicidal patients of depressive disorder

BACKGROUND

The efficacy of ketamine in the rapid alleviation of depressive and suicidal symptoms has been observed over the past few years around the globe. Exploration of rapid antisuicidal efficacy of ketamine in Indian subpopulation can be a good preventive pharmacological option for unprecedented rise in suicides in India.

AIM

To assess efficacy of ketamine infusions on suicidal patients of depressive disorder. Severity of depression and suicidality were quantified daily over 1 week.

MATERIALS AND METHODS

This was a randomized control study, comprised sixty patients of age group 18-60 years, with a diagnosis of depressive episode, having the Modified Scale for Suicidal Ideations (MSSI) score >20 with exclusion of severe medical or surgical illness, pregnancy, and breast-feeding females. Patient were assigned to ketamine and normal saline group. Three infusions were given over 1 week on day 0, day 2, and day 4. Assessments were made at baseline using the 17-item Hamilton Depression Rating Scale (HAM-D17) and MSSI, for depression and suicidality, respectively. Assessments were repeated at 6 h after first infusion and then every day for 1 week.

RESULTS

There were significant reductions in HAM-D17 score and MSSI score within 6 h of the first dose in the ketamine group as compared to the normal saline group. Significant sustained improvement was seen on further days till 1 week in the ketamine group as compared to the normal saline group.

CONCLUSION

Ketamine might be a reasonable choice to fulfil the efficacy gap created by the delayed antisuicidal onset of standard treatments.

Intranasal esketamine: From origins to future implications in treatment-resistant depression

The approval of intranasal esketamine for treatment-resistant depression marks the next step in our understanding of and ability to treat treatment-resistant depression. The origin of ketamine is rooted in the search for a phencyclidine analog that could be used as a pre-surgical anesthetic with less emergence delirium. Following its inception, ketamine has been used in a variety of contexts. However, it was the seminal Berman et al., 2000 study, which published positive findings from the first human trial using subanesthetic intravenous ketamine for depression. Since then, a large body of research has investigated ketamine's various proposed antidepressant mechanisms of action, and the role its pharmacokinetic properties and route of administration play in producing its antidepressant effects. The results of this research were the eventual approval of intranasal esketamine for treatment-resistant depression by the U.S. Food and Drug Administration (FDA) in March 2019. By identifying and utilizing predictors of response, we can continue to refine our approach to treating treatment-resistant depression and optimize patient response to intranasal esketamine. In this article, we look at the history, pharmacology, landmark studies, and future implications of intranasal esketamine for treatment-resistant depression.

Serum BDNF levels and the antidepressant effects of electroconvulsive therapy with ketamine anaesthesia: a preliminary study

Objective

To firstly examine the relationship between serum brain-derived neurotrophic factor (BDNF) levels and antidepressant response to ketamine as an anaesthesia in electroconvulsive therapy (ECT) in Chinese patients with treatment-refractory depression (TRD).

Methods

Thirty patients with TRD were enrolled and underwent eight ECT sessions with ketamine anaesthesia (0.8 mg/kg) alone. Depression severity, response and remission were evaluated using the 17-item Hamilton Depression Rating Scale (HAMD-17). Enzyme-linked immunosorbent assay (ELISA) was applied to examine serum BDNF levels in patients with TRD at baseline and after the second, fourth and eighth ECT sessions. Baseline serum samples were also collected for 30 healthy controls.

Results

No significant differences were observed in serum BDNF levels between patients with TRD and healthy controls at baseline (p > 0.05). The remission rate was 76.7% (23/30) after the last ECT treatment, although all patients with TRD obtained antidepressant response criteria. Serum BDNF levels were not altered compared to baseline, even between remitters and nonremitters (all p > 0.05), despite the significant reduction in HAMD-17 and Brief Psychiatric Rating Scale (BPRS) scores after ECT with ketamine anaesthesia (all p < 0.05). The antidepressant effects of ECT with ketamine anaesthesia were not correlated with changes in serum BDNF levels (all p > 0.05).

Conclusion

This preliminary study indicated that serum BDNF levels do not appear to be a reliable biomarker to determine the antidepressant effects of ketamine as an anaesthesia in ECT for patients with TRD. Further studies with larger sample sizes are warranted to confirm these findings.

A comparative study of propofol, thiopentone sodium, and ketofol as induction agents for electro convulsive therapy

Background and Aims:

Thiopentone and propofol are most commonly used induction agents for electro convulsive therapy (ECT). Recently, ketofol, an admixture of propofol and ketamine, is being tried in ECT. We aimed to compare propofol, thiopentone, and ketofol as induction agents during ECT regarding their effects on ECT-induced hemodynamic changes, seizure duration and recovery parameters.

Material and Methods:

This prospective randomized double blind study was conducted in 30 patients between 18 and 65 years with ASA status I and II scheduled for ECT. All patients received all study agents for first three sessions of ECT. The observations were compiled as Group K (Inj. Ketofol i.e., Inj. propofol 0.5mg/kg % Inj. ketamine 0.5mg/kg), Group P (Inj. propofol 1mg/kg), and Group T (Inj. thiopentone 3mg/kg). Heart rate (HR) and blood pressure (systolic, diastolic, and mean) was recorded at pre op, 0, 5, 10, and 20 min after ECT. The seizure duration, time to spontaneous eye opening, andobeying verbal commands and agitation score were recorded.

Results:

Statistically significant difference was seen in HR at 10 min after delivery of shock; in systolic BP at 2 min after shock; in diastolic BP after administration of study drug and immediately after shock and in mean arterial pressure at post induction, 0and2 min after shock with group T showing higher values compared to group K and P (p < 0.05). At all other times HR andBP was comparable in all the three groups. Seizure duration was more in group T than Groups P and K although the difference was statistically insignificant. Time to spontaneous eye opening and obey verbal commands was comparable in all groups. Mean agitation score was highest in group T than Groups P& Kwith Group P showing least value (p = 0.003).

Conclusion:

Propofol and ketofol showed superior hemodynamic stability than thiopentone but comparable seizure duration and recovery parameters. Thus, propofol and ketofol can be effectively used as induction agents for ECT although propofol is associated with lesser agitation than ketofol.

Empirical ratio of the combined use of S-ketamine and propofol in electroconvulsive therapy and its impact on seizure quality

Electroconvulsive therapy (ECT) is an effective treatment for depressive disorders. In certain cases, ECT-associated anaesthesia can be improved by the use of ketofol (i.e., S-ketamine + propofol). We aimed to evaluate the empirical mixing ratio of ketofol in these cases for better clinical implementation. We retrospectively investigated n = 52 patients who received 919 ECT sessions with S-ketamine plus propofol as anaesthetic agents. Several anaesthesia and ECT-related parameters including doses of S-ketamine and propofol were analysed. The mean empirically determined S-ketamine/propofol ratio was 1.38 (SD ± 0.57) for 919 individual ECT sessions and 1.52 (SD ± 0.62) for 52 patients, respectively. The mean relative dose was 0.72 (± 0.18) mg/kg S-ketamine and 0.54 (± 0.21) mg/kg propofol. Higher propofol dose was associated with poorer seizure quality. Seizure quality and time in recovery room were significantly influenced by age. Ketofol could be an option to exploit the advantageous qualities of S-ketamine and propofol, if both doses are reduced compared with single use of S-ketamine or propofol. Patients with poor seizure quality may benefit from lower propofol doses, which are applicable by the addition of ketamine. An empirically determined mixing ratio in favour of ketamine turned out to be preferable in a clinical setting. Recovery time was primarily prolonged by higher age rather than by ketamine dose, which had previously often been associated with a prolonged monitoring time in the recovery room. These new findings could improve electroconvulsive therapy and should be replicated in a prospective manner.

Antidepressant effects of ketamine and ECT: A pilot comparison

BACKGROUND

To compare the antidepressant effects and cognitive adverse effects of intravenous ketamine infusion and Electro-convulsive therapy (ECT) in persons with severe depressive episodes.

METHODS

This assessor-blinded randomized control trial included 25 patients (either sex; 18-65 years) meeting ICD-10 criteria for severe depression (bipolar or unipolar). Patients received either ECT (n = 13) or intravenous infusions of ketamine hydrochloride (0.5 mg/kg over 45 min; n = 12) for six alternate day sessions over a period of two weeks. Severity of depression was assessed at baseline and on every alternate day of intervention using the Hamilton Depression Rating Scale (HDRS) and self-reported Beck Depression Inventory (BDI).

RESULTS

Baseline socio-demographic and clinical variables including HDRS (ECT: 25.15±6.58; Ketamine: 23.33±4.05, p = 0.418) and BDI (ECT: 37.07±6.58; Ketamine: 33.33±9.29; p = 0.254) were comparable. Repeated-measures analysis of variance revealed that ECT patients showed significantly greater reduction in HDRS (group*time interaction effect; F = 4.79; p<0.001) and BDI scores (group*time interaction effect; F = 3.83; p<0.01). ECT patients had higher response rate than ketamine patients [HDRS: ECT- 13/13(100%) vs ketamine- 8/12 (66.70%); p = 0.04]. This was true for remission as well [ECT- 12/13(92.30%) vs ketamine- 6/12(50%), p = 0.030; both HDRS and BDI]. Performance on Digit Symbol Substitution Test (as part of the Battery for ECT-Related Cognitive Deficits scale) significantly improved in ketamine patients (p = 0.02) while that in ECT patients worsened non significantly (p = 0.30).

LIMITATIONS

Relatively small sample size; higher proportion of dropouts in the Ketamine arm.

CONCLUSION

This study favoured ECT over ketamine for a better efficacy over six treatment sessions in severe depression. The results need to be replicated in larger studies.

TRIAL REGISTRATION

CTRI/2019/09/021184.

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.

A Review of Nonanesthetic Uses of Ketamine

Ketamine, a nonselective NMDA receptor antagonist, is used widely in medicine as an anesthetic agent. However, ketamine's mechanisms of action lead to widespread physiological effects, some of which are now coming to the forefront of research for the treatment of diverse medical disorders. This paper aims at reviewing recent data on key nonanesthetic uses of ketamine in the current literature. MEDLINE, CINAHL, and Google Scholar databases were queried to find articles related to ketamine in the treatment of depression, pain syndromes including acute pain, chronic pain, and headache, neurologic applications including neuroprotection and seizures, and alcohol and substance use disorders. It can be concluded that ketamine has a potential role in the treatment of all of these conditions. However, research in this area is still in its early stages, and larger studies are required to evaluate ketamine's efficacy for nonanesthetic purposes in the general population.

Ketamine and nitrous oxide: The evolution of NMDA receptor antagonists as antidepressant agents

N-methyl-d-aspartate receptor (NMDAR) antagonists, including ketamine and nitrous oxide, are currently intensely studied as rapid-acting antidepressant agents. Interestingly, both of these compounds are also drugs of abuse. Intravenous ketamine, a dissociative anesthetic that induces complex downstream effects via NMDARs, rapidly reduces depressive and suicidal symptoms in treatment-resistant depression (TRD), as demonstrated by several trials. Recently, the United States Food and Drug Administration (FDA) approved an intranasal version of ketamine (esketamine) for TRD. The United States Drug Enforcement Agency (DEA) lists ketamine as a Class III scheduled drug (moderate-low potential for physical and psychological abuse). The FDA has established a Risk Evaluation and Management Strategy (REMS) program to ensure proper drug storage, handling, dispensing, and monitoring intranasal esketamine to minimize misuse/abuse opportunities. Nitrous Oxide is a colorless, odorless, gas that has been in medical use for over 150 years. The mechanisms of action of nitrous oxide are not fully understood; however, it is known to act as a non-competitive inhibitor of NMDA-type glutamate receptors. Currently, nitrous oxide is used for inhalational general anesthesia and analgesia for short procedures. Inhaled nitrous oxide is also used recreationally, primarily by teens and young adults, but is not believed to have strong addiction potential. In contrast to ketamine, nitrous oxide is not a controlled substance and can be legally purchased without a prescription. A recent double-blind, prospective, cross-over study demonstrated that nitrous oxide reduced depressive symptoms in a group of severely ill TRD patients. Though this is a promising initial study, further investigation is needed.

Comparison of efficacy of ketamine versus thiopentone-assisted modified electroconvulsive therapy in major depression

BACKGROUND

It is well known that depression improves faster with electroconvulsive treatment (ECT) than with antidepressant medications. N-methyl-D-aspartate-receptor antagonists (ketamine) have been shown to have rapid antidepressant effects when given as an intravenous infusion. Faster recovery with ECT is likely when used with ketamine as anesthetic.

AIM

The aim of the study is to compare the outcome of modified electroconvulsive therapy (MECT) in major depressive disorder patients undergoing MECT with ketamine versus thiopentone anesthesia.

MATERIALS AND METHODS

Sixty hospitalized patients (age: 18-45 years) with major depressive disorder (Diagnostic and Statistical Manual of Mental Disorders-IV Text Revision) were randomly allocated to either of the two MECT groups (30 patients each) receiving ketamine or thiopentone as anesthetic agent. The participants were assessed on a weekly basis on Hamilton Rating Scale for Depression (HAM-D) and Beck Depression Inventory (BDI).

RESULTS

Ketamine group required significantly lesser number of MECT sessions for achieving remission and had rapid improvement in HAM-D and BDI scores compared to the thiopentone group. Furthermore, the stimulus intensity required to elicit seizures was significantly less and seizure duration was longer in ketamine group compared to the thiopentone group.

CONCLUSION

The use of ketamine for anesthesia led to rapid recovery from depressive symptoms and seems to be a better option for depressive patients, especially when a rapid response is desired.

Definition of treatment-resistant depression - Asia Pacific perspectives

BACKGROUND

The lack of uniformity in the definition of treatment resistant depression (TRD) within the Asia-Pacific (APAC) region may have implications for patient management. We aimed to characterize the most commonly used TRD definition in selected APAC countries.

METHODS

A systematic literature review of TRD definitions in APAC countries was conducted in Medline and Embase (2010-2016) and conference proceedings (2014 and 2016). TRD guidelines (APAC, Europe regional, US, or international) were also searched. An expert-panel explored APAC nuances in TRD definitions to achieve consensus for a regional-level definition.

RESULTS

Ten guidelines and 89 studies qualified for study inclusion. Among the studies, variations were observed in definitions regarding: number of antidepressants failed (range: ≥1 to ≥3), classes of antidepressants (same or different; 59% did not specify class), duration of previous treatments (range: 4-12 weeks), dosage adequacy, and consideration of adherence (yes/no; 88% of studies did not consider adherence). No TRD-specific guidelines were identified. The emerging consensus from the literature review and panel discussion was that TRD is most commonly defined as failure to ≥2 antidepressant therapies given at adequate doses, for 6-8 weeks during a major depressive episode.

LIMITATIONS

Few studies provided definitions of TRD used in daily clinical practice, and a limited number of countries were represented in the included studies and expert panel.

CONCLUSION

Attaining consensus on TRD definition may promote accurate, and possibly early detection of patients with TRD to enable appropriate intervention that may impact patient outcomes and quality of life.

Effect of different charges of modified electroconvulsive seizure on the cognitive behavior in stressed rats: Effects of GluR1 phosphorylation and CaMKIIα activity

Electroconvulsive therapy (ECT) is an efficient therapy for major depression and modern ECT requires anesthesia to enhance safety. However, the commonly used anesthetic, propofol, may weaken the treatment efficacy. A recent study confirmed that ketamine rapidly reduced the symptoms of depression in affected patients. A previous study found that electroconvulsive seizure (ECS), the animal model for ECT, under anesthesia of low-dose ketamine combined with propofol could enhance the antidepressant efficacy and improve the cognitive performance. The present study aimed to investigate the responses to different charges (0, 60, 120, 180 or 240 mC) of ECS under compound anesthetics, ketamine combined with propofol, in stressed rats and the underlying mechanisms to aid in optimization of treatment regimens. The results indicated that ECS exhibited an improved antidepressant effects at 120 mC compared with 60 mC, however, no significant differences in antidepressant effects were identified among the 120, 180 and 240 mC groups. Furthermore, rats subjected to ECS at 120 mC exhibited the best cognitive performance. The phosphorylation levels of calcium/calmodulin-dependent protein kinase IIα (CaMKIIα) at Thr286, glutamate receptor 1 (GluR1) at Ser831 and cAMP-response element-binding protein (CREB) at the Ser133 were higher in the 120-mC group compared with all other groups. These results indicated that the ECS at medium intensity (120 mC) with administration of compound anesthetics may exert an improved therapeutic effect on depression compared with other intensities (0, 60, 180 and 240 mC). The results also suggested that the improvement in cognitive function in stressed rats may be attributed to the phosphorylation of CaMKIIα (Thr286), GluR1 (Ser831) and CREB (Ser133).

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 and electroconvulsive therapy: so happy together?

PURPOSE OF REVIEW

Anesthetics, such as thiopental, methohexital, propofol and ketamine have been used to induce unconsciousness for electroconvulsive therapy (ECT), each with its advantages and disadvantages. Only until recently was it discovered that ketamine may have inherent antidepressant effects. We reviewed the side effect profile of ketamine and examined the literature for whether or not ketamine augments the antidepressant effects of ECT.

RECENT FINDINGS

Systematic reviews and meta-analyses of randomized controlled trials of the potential benefits of adding ketamine to ECT treatment have generated varied conclusions. Currently there is a lack of clear evidence that ketamine with ECT is more efficacious than ECT alone.

SUMMARY

Large, multicenter randomized controlled trials are needed to further investigate the potential advantages of adding ketamine to ECT for patients with severe or refractory depression. The addition of ketamine to ECT treatment may have some early beneficial effect in patients with acute depressive disorders. Most likely, ECT itself is responsible for lasting remission from severe depression. Ketamine's side effect profile may be undesirable in certain patient populations, and so the risks and benefits of the addition of this drug to ECT treatment must be weighed.

Ketamine-based anesthesia improves electroconvulsive therapy outcomes: a randomized-controlled study

BACKGROUND

Major depressive disorder (MDD) is a common and debilitating condition that can be challenging to treat. Electroconvulsive therapy (ECT) is currently the therapeutic gold standard for treatment-resistant MDD. We tested our hypothesis that ketamine-based anesthesia for ECT results in superior improvement in treatment-resistant MDD outcomes compared with propofol-based anesthesia.

METHODS

Patients with treatment-resistant MDD were enrolled in a randomized clinical trial with assignment to ketamine- or propofol-based anesthesia arms. Using a modified intention-to-treat analysis, we compared the median number of ECT treatments required to achieve a 50% reduction (primary outcome) and a score ≤ 10 (secondary outcome) on the Montgomery-Asberg depression rating scale (MADRS) between anesthesia groups.

RESULTS

The study was terminated as significant results were found after the first planned interim analysis with 12 patients in each of the ketamine (intervention) and propofol (control) groups. All ketamine patients achieved at least a 50% MADRS reduction after a median of two ECT treatments whereas ten propofol patients (83%) achieved the same outcome after a median of four ECT treatments. All ketamine patients and seven propofol patients (58%) achieved MDD remission (MADRS ≤ 10). Log rank tests showed that both time-to-50% reduction and remission differed significantly between groups. Adverse events and recovery time were similar between groups.

CONCLUSIONS

In this early-terminated small-sized study, ketamine-based anesthesia compared with propofol-based anesthesia provided response and remission after fewer ECT sessions.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT01935115). Registered 4 September 2013.

A randomized clinical trial of adjunctive ketamine anesthesia in electro-convulsive therapy for depression

BACKGROUND

Electroconvulsive therapy (ECT) is a rapid acting and effective treatment for both major depressive disorder (MDD) and bipolar disorder (BP). Both propofol and ketamine are commonly used anesthetic agents but recent clinical studies suggest that ketamine has rapid-acting antidepressant properties, itself, at sub-anesthetic doses.

METHODS

A total of 77 inpatients (41 MDD and 36 BP) were randomly assigned to receive ECT with propofol (1mg/kg) anesthesia or with ketamine (0.5mg/kg) plus propofol (0.5mg/kg). Depressive symptoms were assessed with the 24-item Hamilton Depression Rating Scale (HAMD-24) and Montgomery-Asberg Rating Scale (MADRS), before and after 1, 2, 4, and 6 ECT treatments, and 1-4 weeks following the last treatment. The MATRICS Consensus Cognitive Battery (MCCB) was evaluated at baseline,after the sixth ECT, and 1-4 weeks following the final ECT. Adverse effects were assessed at baseline and 4 weeks after the last treatment.

RESULTS

There were no significant differences in depressive symptoms, MCCB performance, or adverse effects between the treatment groups at any time. The electrical dose required to generate seizures in the ketamine plus propofol group was lower than that of the propofol only group at every time point. The seizure energy index and seizure duration in the ketamine plus propofol group was higher and longer than those in the propofol only group.

LIMITATIONS

The diagnoses of MDD and BP were unevenly distributed across treatment groups.

CONCLUSIONS

Ketamine plus propofol anesthesia in the ECT treatment of MDD and BP was not superior on any measure to propofol alone.

S -ketamine compared to etomidate during electroconvulsive therapy in major depression

Objective of the study was to compare two commonly used anesthetic drugs, S-ketamine and etomidate, regarding their influence on seizure characteristics, safety aspects, and outcome of electroconvulsive therapy (ECT) in major depression. Treatment data of 60 patients who underwent a total number of 13 ECTs (median) because of the severe or treatment-resistant major depressive disorder (DSM-IV) were analyzed. Etomidate, mean dosage (SD) = 0.25 (0.04) mg/kg, was used for anesthesia in 29 participants; 31 patients received S-ketamine, mean dosage (SD) = 0.96 (0.26) mg/kg. Right unilateral brief pulse ECTs were performed. The number of ECTs was individually adjusted to clinical needs, mean (SD) = 13.0 (4.3). Seizure characteristics, adverse events, and the clinical global impression (CGI) scores were compared between the both groups during ECT series. In the S-ketamine group, a lower initial seizure threshold (p = 0.014), stimulation charge (p < 0.001), higher postictal suppression (p < 0.001), EEG ictal amplitude (p = 0.04), EEG coherence (p < 0.001) and maximum heart rate (p = 0.015) were measured. Etomidate was associated with more frequent abortive seizures (p = 0.02) and restimulations (p = 0.01). The CGI scores, the number of sessions within an ECT series, and the incidence of adverse events did not differ between groups. Due to its lower initial seizure threshold, S-ketamine might hold a potential to become a clinically favorable anesthetic agent during ECT. However, the current findings should be interpreted with caution, and further prospective randomized clinical trials are required. Also, specific adverse effects profile of S-ketamine, especially with regard to the cardiovascular risk, needs to be taken into account.

A Randomized Pilot Study Comparing Ketamine and Methohexital Anesthesia for Electroconvulsive Therapy in Patients With Depression

OBJECTIVE

This randomized controlled pilot study examines the differences in response to electroconvulsive therapy (ECT) as defined by an improvement of depressive symptoms between ketamine and methohexital as the primary anesthetic agent. Adverse effects and cognitive tolerability were also examined.

METHODS

Subjects undergoing ECT for unipolar or bipolar depression were randomized to receive ketamine or methohexital as the anesthetic agent. Primary outcome measure includes the Hamilton rating scale for depression (17-item). Secondary outcome measures included the mini-mental status examination and Beck depression inventory. All ratings were conducted masked to anesthetic agent. Because of multiple outcome measures obtained over time, mixed models were used to account for the correlations among the measurements within the subjects. Because outcomes were either normally distributed or approximately normally distributed, general linear mixed models were fit with a random intercept specified.

RESULTS

A total of 21 subjects were enrolled, and 16 were randomized (methohexital, n = 8; ketamine, n = 8). The 2 treatment groups did not differ statistically in any demographic characteristic. No statistical difference was found between the ketamine and methohexital groups for an improvement in depressive symptoms (P = 0.6); however, subjects in both groups showed significant improvement in depression over time (ketamine, P < 0.0001; methohexital, P < 0.0001). Mini-mental status examination results did not differ between groups, and fatigue was reported more in subjects receiving ketamine (P = 0.03).

CONCLUSIONS

The results of this pilot study are inconclusive because they lack power to support an advantage of ketamine anesthesia compared with methohexital in ameliorating depressive symptoms for electroconvulsive therapy.

The use of ketamine in ECT anaesthesia: A systematic review and critical commentary on efficacy, cognitive, safety and seizure outcomes

OBJECTIVES

This review will discuss ECT efficacy and cognitive outcomes when using ketamine as an ECT anaesthetic compared to other anaesthetics, taking into account important moderator variables that have often not been considered to date. It will also include information on safety and other ECT outcomes (seizure threshold and quality).

METHODS

A systematic search through MEDLINE, PubMed, PsychINFO, Cochrane Databases and reference lists from retrieved articles was performed. Search terms were: "ketamine" and "Electroconvulsive Therapy", from 1995 to September 2016. Meta-analyses, randomised controlled trials, open-label and retrospective studies published in English of depressed samples receiving ECT with ketamine anaesthesia were included (n = 24).

RESULTS

Studies were heterogeneous in the clinical populations included and ECT treatment and anaesthetic methods. Frequently, studies did not report on ECT factors (i.e., pulse-width, treatment schedule). Findings regarding efficacy were mixed. Tolerance from repeated use may explain why several studies found that ketamine enhanced efficacy early in the ECT course but not at the end. The majority of studies did not comprehensively examine cognition and adverse effects were not systematically studied. Only a minority of the studies reported on seizure threshold and expression.

CONCLUSIONS

The routine use of ketamine anaesthesia for ECT in clinical settings cannot yet be recommended based on published data. Larger randomised controlled trials, taking into account moderator variables, specifically reporting on ECT parameters and systematically assessing outcomes are encouraged.

Ketamine as the anaesthetic for electroconvulsive therapy: the KANECT randomised controlled trial

BackgroundKetamine has recently become an agent of interest as an acute treatment for severe depression and as the anaesthetic for electroconvulsive therapy (ECT). Subanaesthetic doses result in an acute reduction in depression severity while evidence is equivocal for this antidepressant effect with anaesthetic or adjuvant doses. Recent systematic reviews call for high-quality evidence from further randomised controlled trials (RCTs).AimsTo establish if ketamine as the anaesthetic for ECT results in fewer ECT treatments, improvements in depression severity ratings and less memory impairment than the standard anaesthetic.MethodDouble-blind, parallel-design, RCT of intravenous ketamine (up to 2 mg/kg) with an active comparator, intravenous propofol (up to 2.5 mg/kg), as the anaesthetic for ECT in patients receiving ECT for major depression on an informal basis. (Trial registration: European Clinical Trials Database (EudraCT): 2011-000396-14 and clinicalTrials.gov: NCT01306760)ResultsNo significant differences were found on any outcome measure during, at the end of or 1 month following the ECT course.ConclusionsKetamine as an anaesthetic does not enhance the efficacy of ECT.

Significant treatment effect of add-on ketamine anesthesia in electroconvulsive therapy in depressive patients: A meta-analysis

Add-on ketamine anesthesia in electroconvulsive therapy (ECT) has been studied in depressive patients in several clinical trials with inconclusive findings. Two most recent meta-analyses reported insignificant findings with regards to the treatment effect of add-on ketamine anesthesia in ECT in depressive patients. The aim of this study is to update the current evidence and investigate the role of add-on ketamine anesthesia in ECT in depressive patients via a systematic review and meta-analysis. We performed a thorough literature search of the PubMed and ScienceDirect databases, and extracted all relevant clinical variables to compare the antidepressive outcomes between add-on ketamine anesthesia and other anesthetics in ECT. Total 16 articles with 346 patients receiving add-on ketamine anesthesia in ECT and 329 controls were recruited. We found that the antidepressive treatment effect of add-on ketamine anesthesia in ECT in depressive patients was significantly higher than that of other anesthetics (p<0.001). This significance persisted in both short-term (1-2 weeks) and moderate-term (3-4 weeks) treatment courses (all p<0.05). However, the side effect profiles and recovery time profiles were significantly worse in add-on ketamine anesthesia group than in control group. Our meta-analysis highlights the significantly higher antidepressive treatment effect of add-on ketamine in depressive patients receiving ECT compared to other anesthetics. However, clinicians need to take undesirable side effects into consideration when using add-on ketamine anesthesia in ECT in depressive patients.

Mood and neuropsychological effects of different doses of ketamine in electroconvulsive therapy for treatment-resistant depression

BACKGROUND

Treatment-resistant depression (TRD) is a growing clinical challenge. Electroconvulsive therapy (ECT) is an effective tool for TRD treatment. However, there remains a subset of patients who do not respond to this treatment with common anesthetic agent. Ketamine, a noteworthy anesthetic agent, has emerged as an augmentation to enhance the antidepressant efficacy of ECT. Trials of i.v. ketamine in TRD indicated dose-related mood enhancing efficacy. We aimed to explore anesthetic and subanesthetic concentrations of ketamine in ECT for TRD with respect to their impact on mood and neuropsychological effects.

METHODS

Ninety TRD patients (36 males, 54 females; average age, 30.6 years old) were randomly assigned to receive either ketamine (0.8mg/kg) (n=30), subanesthetic ketamine (0.5mg/kg) plus propofol (0.5mg/kg) (n=30) or propofol (0.8mg/kg) (n=30) as an anesthetic and underwent 8 ECT sessions. The primary outcome measures were the 17-item Hamilton Depression Rating Scale (HDRS-17), cognitive assessments and seizure parameters.

RESULTS

The ketamine group had an earlier improvement in HDRS-17, longer seizure duration, lower electric quantity, a higher remission rate, and a lower degree of executive cognitive impairment compared to the ketamine+propofol and propofol groups. The ketamine+propofol group showed earlier improvement in the HDRS-17, a longer seizure duration and a different seizure energy index when compared to the propofol group.

LIMITATIONS

The postoperative dissociative side effect was not assessed.

CONCLUSIONS

Both anesthetic and subanesthetic concentrations of ketamine have rapid mood enhancing actions in ECT for TRD, while anesthetic concentrations results in larger magnitudes of antidepression and cognitive protection. ECT with ketamine anesthesia might be an optimized therapy for patients with TRD.

Which anesthetic agents for ambulatory electro-convulsive therapy?

PURPOSE OF REVIEW

There have been a considerable number of research articles published in the last 10 years outlining possible advances in the provision of electro-convulsive therapy (ECT) anaesthesia. This has resulted in a range of new drugs having been proposed as useful in the ECT setting. In particular, the use of adjuvant drugs that might improve outcomes to treatment has been investigated.

RECENT FINDINGS

There is a high level of interest in ketamine and remifentanil as agents that may alter response in ECT anaesthesia, by reducing cognitive effects, and minimizing the dose of induction agent. The numbers of patients involved in current trials have been small, and it is not possible to give a definitive answer as to the usefulness of these drugs at this stage.

SUMMARY

This review covers the major recent trials involving new and emerging treatments in ECT, and brings the reader up to date with state of knowledge of ECT anaesthesia and pharmacology.

Impact comparison of ketamine and sodium thiopental on anesthesia during electroconvulsive therapy in major depression patients with drug-resistant; a double-blind randomized clinical trial

BACKGROUND

Electroconvulsive therapy (ECT) is one of the available and the most effective therapies for the treatment of resistant depression. Considering the crucial role of seizure duration on therapeutic response in patients treated with ECT, this study aimed to compare the effect of ketamine and sodium thiopental anesthesia during ECT for treatment of patients with drug-resistant major depression (DRMD).

MATERIALS AND METHODS

In a double-blind randomized clinical trial, 160 patients with DRMD were selected consequently and were assigned randomly into two groups including ketamine 0.8 mg/kg and sodium thiopental 1.5 mg/kg. The seizure duration, recovery time, and the side effects of anesthesia were evaluated after 1-h after anesthesia. Data of recovery time and complication collected in 2 nd , 4 th , 6 th , and 8 th ECT. Depression was assessed by Hamilton depression scale.

RESULTS

The results indicated that ketamine and sodium thiopental had a significant effect on the reduction of depression scores in patients with DRMD (P < 0.05). Complications such as a headache, nausea, pain at the injection site, short-term delirium, and long-term delirium were higher in ketamine group (P > 0.05). But ketamine was more effective in improvement of depression score and increasing systolic and diastolic blood pressure (P < 0.05). The mean of seizure duration showed a decreasing trend and was significant between two study groups (P < 0.05).

CONCLUSION

Anesthesia induced by ketamine during ECT therapy increased blood pressure and seizure duration. Therefore, due to lower medical complication and attack rate of seizure, ketamine is an appropriate option for anesthesia with ECT in patients with DRMD.

Augmentation Therapy With Serial Intravenous Ketamine Over 18 Months in a Patient With Treatment Resistant Depression

Major depressive disorder is a severe illness that affects 3% to 7% of adults annually in the United States. About 30% of these individuals are refractory to multiple treatment trials. Recent reports have found a significant and almost immediate improvement in depressive symptoms after single or multiple ketamine intravenous infusions (IVIs) in such patients. We present the case of A.B., a patient with treatment-resistant depression (TRD) including to subgenual deep brain stimulation, who went into remission after augmentation with 6 ketamine IVIs (0.5 mg/kg) over a 3-week period. However, she had a reemergence of depressive symptoms 4 months later and received a second series of 3 ketamine IVIs over the course of a week. A.B. again went into remission and maintained this for the next 8 months. At this time, she experienced a reemergence of depressive symptoms and was treated with the third series of ketamine IVIs (3 infusions over the course of a week). Because A.B. has now been in remission for 6 months. A.B. has received a total of 12 ketamine IVIs over the course of 18 months. No significant adverse events have occurred. To our knowledge, this is the first case of long-term ketamine efficacy as augmentation therapy in TRD over the course of 18 months. There is a need for studies examining the long-term management of TRD with IV ketamine. Guidelines for maintenance ketamine IVIs in TRD also need to be developed.

Ketamine enantiomers in the rapid and sustained antidepressant effects

Recent evidence has suggested that the N-methyl-D-aspartate receptor antagonist ketamine shows significant therapeutic effects in major depression and bipolar disorder. This effect is especially important in treatment-resistant depression and depression with suicidal ideation. In this review we explain the mechanism of action, drug efficacy, and the side effects of ketamine; the antidepressive effects of ketamine; the individual effects of ketamine isomers, R(-) ketamine and S(+) ketamine; the effects of the combination of ketamine with electroconvulsive therapy; and the possible use of ketamine in treating depression.

[Other therapeutic strategies]

Non-selective and irreversible MAOI have become as third or fourth-line strategy for the management of treatment-resistant depression. Non-selective and irreversible MAOI requires careful monitoring of drug interactions and dietary restrictions. Nutritional supplements such as omega-3 have been found to produce beneficial effects in the management of treatment-resistant depression when administered in combination with the ongoing antidepressant treatment. The glutamate antagonist ketamine has been found to produce beneficial effects in the management of treatment-resistant depression while administered alone. Dopamine and/or norepinephrine agonists, such as methylphenidate, modafinil or pramipexole, have been found to produce beneficial effects in the management of treatment-resistant depression when administered in combination with the ongoing antidepressant treatment.

A Bayesian framework systematic review and meta-analysis of anesthetic agents effectiveness/tolerability profile in electroconvulsive therapy for major depression

The aim of this study was to assess the efficacy and tolerability/acceptability of 6 anesthetic agents in ECT for depressive disorders. We systematically reviewed 14 double-blind randomized controlled trials (610 participants). Efficacy was measured by the mean scores on validated depression scales at 6 ECT (or the nearest score if not available), number of responders at the end of treatment and seizure duration. The acceptability was measured by the proportion of patients who dropped out of the allocated treatment, and the tolerability by the number of serious adverse events and post-treatment cognition assessment. After excluding the trials responsible for heterogeneity, depression scores of patients who were administered methohexital were found to be significantly more improved than those who received propofol (p = 0.001). On the contrary, those who were administered propofol had lower depression scores than those with thiopental at the end of treatment (p = 0.002). Compared to propofol, methohexital was found to be significantly associated with higher seizure duration (p = 0.018). No difference was found for the acceptability profile (all p > 0.05). In summary, ketamine and methohexital may be preferred to propofol or thiopental in regard of effectiveness in depression scores and increased seizure duration. Further studies are warranted to compare ketamine and methohexital.

Has psychiatry tamed the "ketamine tiger?" Considerations on its use for depression and anxiety

Ketamine has been available for approximately 50 years as an anesthetic agent. It is known to have potent effects on the central nervous system glutamatergic system, in particular blockade of N-methyl-D-aspartate (NMDA) receptors. Based upon pre-clinical evidence of involvement of the glutamatergic system in mood disorders, studies have been undertaken to test the antidepressant properties of ketamine. Several well-controlled studies, along with open-label case series, have established that ketamine can have rapid antidepressant effects. Additionally, data exist showing benefits of ketamine in post-traumatic stress disorder as well as obsessive compulsive disorder. However, improvements in these conditions tend to be short-lived with single infusions of ketamine. Of concern, ketamine has been associated with neurotoxicity in pre-clinical rodent models and is well-known to cause psychotomimetic effects and addiction in humans. While ketamine has been proven safe for use in sub-anesthetic doses administered once or a few times, the safety profile of prolonged use has not been established. Aspects of safety, possible mechanisms of action, and future directions of ketamine research are discussed in addition to the clinical literature on its use in psychiatric conditions.

Antidepressant drug action--From rapid changes on network function to network rewiring

There has been significant recent progress in understanding the neurobiological mechanisms of antidepressant treatments. The delayed-onset of action of monoamine-based antidepressant drugs have been associated to their ability to slowly increase synaptic plasticity and neuronal excitability via altering neurotrophic signaling (synthesis of BDNF and activation of its receptor TrkB), dematuration of GABAergic interneurons and inhibition of "breaks of plasticity". On the other hand, antidepressants rapidly regulate emotional processing that - with the help of heightened plasticity and appropriate rehabilitation - gradually lead to significant changes on functional neuronal connectivity and clinical recovery. Moreover, the discovery of rapid-acting antidepressants, most notably ketamine, has inspired interest for novel antidepressant developments with better efficacy and faster onset of action. Therapeutic effects of rapid-acting antidepressants have been linked with their ability to rapidly regulate neuronal excitability and thereby increase synaptic translation and release of BDNF, activation of the TrkB-mTOR-p70S6k signaling pathway and increased synaptogenesis within the prefrontal cortex. Thus, alterations in TrkB signaling, synaptic plasticity and neuronal excitability are shared neurobiological phenomena implicated in antidepressant responses produced by both gradually and rapid acting antidepressants. However, regardless of antidepressant, their therapeutic effects are not permanent which suggests that their effects on neuronal connectivity and network function remain unstable and vulnerable for psychosocial challenges.

Role of calcium, glutamate and NMDA in major depression and therapeutic application

Major depression is a common, recurrent mental illness that affects millions of people worldwide. Recently, a unique fast neuroprotective and antidepressant treatment effect has been observed by ketamine, which acts via the glutamatergic system. Hence, a steady accumulation of evidence supporting a role for the excitatory amino acid neurotransmitter (EAA) glutamate in the treatment of depression has been observed in the last years. Emerging evidence indicates that N-methyl-D-aspartate (NMDA), group 1 metabotropic glutamate receptor antagonists and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) agonists have antidepressant properties. Indeed, treatment with NMDA receptor antagonists has shown the ability to sprout new synaptic connections and reverse stress-induced neuronal changes. Based on glutamatergic signaling, a number of therapeutic drugs might gain interest in the future. Several compounds such as ketamine, memantine, amantadine, tianeptine, pioglitazone, riluzole, lamotrigine, AZD6765, magnesium, zinc, guanosine, adenosine aniracetam, traxoprodil (CP-101,606), MK-0657, GLYX-13, NRX-1047, Ro25-6981, LY392098, LY341495, D-cycloserine, D-serine, dextromethorphan, sarcosine, scopolamine, pomaglumetad methionil, LY2140023, LY404039, MGS0039, MPEP, 1-aminocyclopropanecarboxylic acid, all of which target this system, have already been brought up, some of them recently. Drugs targeting the glutamatergic system might open up a promising new territory for the development of drugs to meet the needs of patients with major depression.

Study protocol for the randomised controlled trial: Ketamine augmentation of ECT to improve outcomes in depression (Ketamine-ECT study)

BACKGROUND

There is a robust empirical evidence base supporting the acute efficacy of electroconvulsive therapy (ECT) for severe and treatment resistant depression. However, a major limitation, probably contributing to its declining use, is that ECT is associated with impairment in cognition, notably in anterograde and retrograde memory and executive function. Preclinical and preliminary human data suggests that ketamine, used either as the sole anaesthetic agent or in addition to other anaesthetics, may reduce or prevent cognitive impairment following ECT. A putative hypothesis is that ketamine, through antagonising glutamate receptors, protects from excess excitatory neurotransmitter stimulation during ECT. The primary aim of the ketamine-ECT study is to investigate whether adjunctive ketamine can attenuate the cognitive impairment caused by ECT. Its secondary aim is to examine if ketamine increases the speed of clinical improvement with ECT.

METHODS/DESIGN

The ketamine ECT study is a multi-site randomised, placebo-controlled, double blind trial. It was originally planned to recruit 160 moderately to severely depressed patients who had been clinically prescribed ECT. This recruitment target was subsequently revised to 100 patients due to recruitment difficulties. Patients will be randomly allocated on a 1:1 basis to receive either adjunctive ketamine or saline in addition to standard anaesthesia for ECT. The primary neuropsychological outcome measure is anterograde verbal memory (Hopkins Verbal Learning Test-Revised delayed recall task) after 4 ECT treatments. Secondary cognitive outcomes include verbal fluency, autobiographical memory, visuospatial memory and digit span. Efficacy is assessed using observer and self-report efficacy measures of depressive symptomatology. The effects of ECT and ketamine on cortical activity during cognitive tasks will be studied in a sub-sample using functional near-infrared spectroscopy (fNIRS).

DISCUSSION

The ketamine-ECT study aims to establish whether or not adjunctive ketamine used together with standard anaesthesia for ECT will significantly reduce the adverse cognitive effects observed after ECT. Potential efficacy benefits of increased speed of symptom improvement and a reduction in the number of ECT treatments required will also be assessed, as will safety and tolerability of adjunctive ketamine. This study will provide important evidence as to whether adjunctive ketamine is routinely indicated for ECT given for depression in routine NHS clinical practice.

TRIAL REGISTRATION

Current Controlled Trials: ISRCTN14689382 (assigned 30/07/2012); EudraCT Number: 2011-005476-41.

Effect of Ketamine, Thiopental and Ketamine-Thiopental Combination during Electroconvulsive Therapy for Depression

OBJECTIVE

We aimed to evaluate the effect of anaesthesia with thiopental (4 mg kg(-1)), ketamine (1 mg kg(-1)) and ketamine-thiopental (1 mg kg(-1) and 4 mg kg(-1), respectively) combination during electroconvulsive therapy (ECT) on the Hamilton Depression Rating Scale (HDRS) and Hamilton Anxiety Rating Scale (HAM-A) and haemodynamic variables in patients with resistant major depression.

METHODS

Patients with HDRS scores above 17 were included. The patients were randomly divided into three groups according to the anaesthesia used. Group 1 was given thiopental (4 mg kg(-1)), Group 2 was given ketamine (1 mg kg(-1)) and Group 3 was given ketamine (1 mg kg(-1)) and thiopental (4 mg kg(-1)). Succinylcholine (1 mg kg(-1)) was administered in all patients for muscle relaxation. HDRS and HAM-A scores were evaluated before ECT, after 3, 6. ECT and after the final ECT. Systolic and diastolic blood pressures, heart rates and oxygen saturations were recorded before and after anaesthesia induction and after the ECT procedure. Seizure duration was recorded.

RESULTS

Fifty-eight patients were included in the study. Thirty (52%) patients were male and 28 (48%) were female. The mean age was 42.7±15.8 years in Group 1, 44.8±11 years in Group 2 and 38.6±6.8 years in Group 3. In all groups, HDRS scores were reduced compared with the baseline values. There was no statistical significant difference between the groups regarding HDRS scores. HAM-A scores were higher in Group 2 and Group 3. Systolic and diastolic blood pressures and heart rate values were lower in Group 1 and the difference was statistically significant.

CONCLUSION

In this study, anaesthesia induced with thiopental, ketamine and thiopental-ketamine combination was observed to not result in a difference in ECT for patients with treatment-resistant depression. Ketamine at a dose of 1 mg kg(-1) given just before ECT did not enhance the antidepressant effect of ECT; however, anxiety scores were increased with ketamine application.

Current Status of Ketamine and Related Therapies for Mood and Anxiety Disorders

Major Depressive Disorder (MDD) is a leading cause of disability worldwide. Despite a plethora of established treatments, less than one-third of individuals with MDD achieve stable remission of symptoms. Given limited efficacy and significant lag time to onset of therapeutic action among conventional antidepressants, interest has shifted to treatments that act outside of the monoamine neurotransmitter systems (e.g., serotonin, norepinephrine, and dopamine). Preclinical and clinical research on the glutamate system has been particularly promising in this regard. Accumulating evidence shows support for a rapid antidepressant effect of ketamine - a glutamate N-methyl-d-aspartate (NMDA) receptor antagonist. The present article reviews the pharmacology, safety, and efficacy of ketamine as a novel therapeutic agent for mood and anxiety disorders. The majority of clinical trials using ketamine have been conducted in patients with treatment resistant forms of MDD; recent work has begun to examine ketamine in bipolar disorder, posttraumatic stress disorder, and obsessive-compulsive disorder. The impact of ketamine on suicidal ideation is also discussed. The current status and prospects for the identification of human biomarkers of ketamine treatment response and hurdles to treatment development are considered. We conclude by considering modulators of the glutamate system other than ketamine currently in development as potential novel treatment strategies for mood and anxiety disorders.