A preliminary study of adjunctive ketamine for treatment-resistant bipolar depression

Ketamine in neuropsychiatric disorders: an update

The discovery of ketamine as a rapid-acting antidepressant led to a new era in the development of neuropsychiatric therapeutics, one characterized by an antidepressant response that occurred within hours or days rather than weeks or months. Considerable clinical research supports the use of-or further research with-subanesthetic-dose ketamine and its (S)-enantiomer esketamine in multiple neuropsychiatric disorders including depression, bipolar disorder, anxiety spectrum disorders, substance use disorders, and eating disorders, as well as for the management of chronic pain. In addition, ketamine often effectively targets symptom domains associated with multiple disorders, such as anxiety, anhedonia, and suicidal ideation. This manuscript: 1) reviews the literature on the pharmacology and hypothesized mechanisms of subanesthetic-dose ketamine in clinical research; 2) describes similarities and differences in the mechanism of action and antidepressant efficacy between racemic ketamine, its (S) and (R) enantiomers, and its hydroxynorketamine (HNK) metabolite; 3) discusses the day-to-day use of ketamine in the clinical setting; 4) provides an overview of ketamine use in other psychiatric disorders and depression-related comorbidities (e.g., suicidal ideation); and 5) provides insights into the mechanisms of ketamine and therapeutic response gleaned from the study of other novel therapeutics and neuroimaging modalities.

Short-term ketamine use in bipolar depression: a review of the evidence for short-term treatment management

Bipolar depression constitutes a major problem in psychiatry. It correlates with high suicidality, treatment resistance, chronicity, and poor quality of life. Registered treatment for bipolar depression is limited and insufficient. There is an urgent need for implementing new therapeutic strategies. Intranasal ketamine's enantiomer-esketamine is a novel rapid-acting antidepressant with proven efficacy in treatment-resistant depression. Research on bipolar depression, although not as comprehensive, indicates that it may be a viable and safe substitute with minimal risk for mood polarity changes. Reports suggest that ketamine treatment in bipolar depression may reduce suicidal tendencies, decrease anhedonia, and alleviate anxiety. Ketamine's mood-stabilizing properties are also hypothesized. In this narrative review, we focus on ketamine use as an add-on to standard medication for the acute treatment of bipolar depression.

An Update on the Efficacy of Single and Serial Intravenous Ketamine Infusions and Esketamine for Bipolar Depression: A Systematic Review and Meta-Analysis

Ketamine has shown rapid antidepressant and anti-suicidal effects in treatment-resistant depression (TRD) with single and serial intravenous (IV) infusions, but the effectiveness for depressive episodes of bipolar disorder is less clear. We conducted an updated systematic review and meta-analysis to appraise the current evidence on the efficacy and tolerability of ketamine/esketamine in bipolar depression. A search was conducted to identify randomized controlled trials (RCTs) and non-randomized studies examining single or multiple infusions of ketamine or esketamine treatments. A total of 2657 articles were screened; 11 studies were included in the systematic review of which 7 studies were included in the meta-analysis (five non-randomized, N = 159; two RCTs, N = 33) with a mean age of 42.58 ± 13.1 years and 54.5% females. Pooled analysis from two RCTs showed a significant improvement in depression symptoms measured with MADRS after receiving a single infusion of ketamine (1-day WMD = -11.07; and 2 days WMD = -12.03). Non-randomized studies showed significant response (53%, p < 0.001) and remission rates (38%, p < 0.001) at the study endpoint. The response (54% vs. 55%) and remission (30% vs. 40%) rates for single versus serial ketamine infusion studies were similar. The affective switch rate in the included studies approximated 2.4%. Esketamine data for bipolar depression are limited, based on non-randomized, small sample-sized studies. Further studies with larger sample sizes are required to strengthen the evidence.

[Ketamine: a neuropsychotropic drug with an innovative mechanism of action]

Ketamine, a non-competitive antagonist of the N-methyl-D-aspartate-glutamate receptor (R-NMDA), has a rapid (from 24 h post-dose) and prolonged (up to one week) antidepressant effect in treatment resistant depression and in rodent models of anxiety/depression. Arguments regarding its cellular and molecular mechanisms underlying its antidepressant activity mainly come from animal studies. However, debates still persist on the structural remodeling of frontocortical/hippocampal neurons and the role of excitatory/inhibitory neurotransmitters involved in its behavioral effect. Neurochemical and behavioral changes are maintained 24 h after administration of ketamine, well beyond its plasma elimination half-life. The glutamatergic pyramidal cells of the medial prefrontal cortex are primarily implicated in the therapeutic effects of ketamine. Advances in knowledge of the consequences of R-NMDA blockade allowed to specify the underlying mechanisms involving the activation of AMPA glutamate receptors, which triggers a cascade of intracellular events dependent on the mechanistic target of rapamycin, brain-derived neurotrophic factor, and synaptic protein synthesis facilitating synaptic plasticity (number of dendritic spines, synaptogenesis). This review focuses on abnormalities of neurotransmitter systems involved in major depressive disorders, their potential impact on neural circuitry and beneficial effects of ketamine. Recent preclinical data pave the way for future studies to better clarify the mechanism of action of fast-acting antidepressant drugs for the development of novel, more effective therapies.

A synopsis of multitarget therapeutic effects of anesthetics on depression

Depression is a profound mental disorder that dampens the mood and undermines volition, which exhibited an increased incidence over the years. Although drug-based interventions remain the primary approach for depression treatment, the available medications still can't satisfy the patients. In recent years, the newly discovered therapeutic targets such as N-methyl-D-aspartate (NMDA) receptor, α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor, and tyrosine kinase B (TrkB) have brought new breakthroughs in the development of antidepressant drugs. Moreover, it has come to light that certain anesthetics possess pharmacological mechanisms intricately linked to the aforementioned therapeutic targets for depression. At present, numerous preclinical and clinical studies have explored the therapeutic effects of anesthetic drugs such as ketamine, isoflurane, N2O, and propofol, on depression. These investigations suggested that these drugs can swiftly ameliorate patients' depression symptoms and engender long-term effects. In this paper, we provide a comprehensive review of the research progress and potential molecular mechanisms of various anesthetic drugs for depression treatment. By shedding light on this subject, we aim to facilitate the development and clinical implementation of new antidepressant drugs based on anesthetic medications.

Brain-based correlates of antidepressant response to ketamine: a comprehensive systematic review of neuroimaging studies

Ketamine is an effective antidepressant, but there is substantial variability in patient response and the precise mechanism of action is unclear. Neuroimaging can provide predictive and mechanistic insights, but findings are limited by small sample sizes. This systematic review covers neuroimaging studies investigating baseline (pre-treatment) and longitudinal (post-treatment) biomarkers of responses to ketamine. All modalities were included. We performed searches of five electronic databases (from inception to April 26, 2022). 69 studies were included (with 1751 participants). There was substantial methodological heterogeneity and no well replicated biomarker. However, we found convergence across some significant results, particularly in longitudinal biomarkers. Response to ketamine was associated with post-treatment increases in gamma power in frontoparietal regions in electrophysiological studies, post-treatment increases in functional connectivity within the prefrontal cortex, and post-treatment increases in the functional activation of the striatum. Although a well replicated neuroimaging biomarker of ketamine response was not identified, there are biomarkers that warrant further investigation.

Ketamine for bipolar depression: an updated systematic review

Background

The therapeutic potential of subanesthetic doses of ketamine appears promising in unipolar depression; however, its effectiveness in treating bipolar depression (BD) remains uncertain.

Objective

This systematic review aimed to summarize findings on the use of ketamine for the treatment of BD by assessing its efficacy, safety, and tolerability.

Design

Systematic review.

Methods

We conducted a systematic review of studies that investigated the use of ketamine for adults with BD. We searched PubMed and Embase for relevant randomized-controlled trials, open-label trials, and retrospective chart analyses published from inception to 13 March 2023.

Results

Eight studies were identified [pooled n = 235; mean (SD) age: 45.55 (5.54)]. All participants who received intravenous (IV) ketamine were administered a dose of 0.5-0.75 mg/kg as an adjunctive treatment to a mood-stabilizing agent, whereas participants who received esketamine were administered a dosage ranging from 28 to 84 mg. Flexible dosing was used in real-world analyses. A total of 48% of participants receiving ketamine achieved a response (defined as ⩾50% reduction in baseline depression severity), whereas only 5% achieved a response with a placebo. Real-world studies demonstrated lower rates of response (30%) compared to the average across clinical trials (63%). Reductions in suicidal ideation were noted in some studies, although not all findings were statistically significant. Ketamine and esketamine were well tolerated in most participants; however, six participants (2% of the overall sample pool, 5 receiving ketamine) developed hypomanic/manic symptoms after infusions. Significant dissociative symptoms were observed at the 40-min mark in some trials.

Conclusion

Preliminary evidence suggests IV ketamine as being safe and effective for the treatment of BD. Future studies should focus on investigating the effects of repeated acute and maintenance infusions using a randomized study design.

The Role of Ketamine in the Treatment of Bipolar Depression: A Scoping Review

Bipolar depression remains a clinical challenge with a quarter of patients failing to respond to initial conventional treatments. Although ketamine has been extensively studied in unipolar depression, its role in bipolar disorder remains inconclusive. The aim of our scoping review was to comprehensively synthesize the current clinical literature around ketamine use in bipolar depression. A total of 10 clinical studies (5 randomized controlled trials and 5 open label studies) were selected. The preliminary evidence, albeit weak, suggests that ketamine is a promising treatment and calls for further interest from the research community. Overall, ketamine treatment appeared to be tolerable with minimal risk for manic/hypomanic switching and showed some effectiveness across parameters of depression and suicidality. Moreover, ketamine is a potential treatment agent in patients with treatment-resistant bipolar depression with promising data extracted from extant controlled trials and real-world effectiveness studies. Future studies are needed to identify ketamine's role in acute and maintenance treatment phases of bipolar depression. Moreover, future researchers should study the recurrence prevention and anti-suicidal effects of ketamine in the treatment of bipolar depression.

Treating bipolar depression with esketamine: Safety and effectiveness data from a naturalistic multicentric study on esketamine in bipolar versus unipolar treatment-resistant depression

BACKGROUND

Bipolar depression accounts for most of the disease duration in type I and type II bipolar disorder (BD), with few treatment options, often poorly tolerated. Many individuals do not respond to first-line therapeutic options, resulting in treatment-resistant bipolar depression (B-TRD). Esketamine, the S-enantiomer of ketamine, has recently been approved for treatment-resistant depression (TRD), but no data are available on its use in B-TRD.

OBJECTIVES

To compare the efficacy of esketamine in two samples of unipolar and bipolar TRD, providing preliminary indications of its effectiveness in B-TRD. Secondary outcomes included the evaluation of the safety and tolerability of esketamine in B-TRD, focusing on the average risk of an affective switch.

METHODS

Thirty-five B-TRD subjects treated with esketamine nasal spray were enrolled and compared with 35 TRD patients. Anamnestic data and psychometric assessments (Montgomery-Asberg Depression Rating Scale/MADRS, Hamilton-depression scale/HAM-D, Hamilton-anxiety scale/HAM-A) were collected at baseline (T0), at one month (T1), and three months (T2) follow up.

RESULTS

A significant reduction in depressive symptoms was found at T1 and T2 compared to T0, with no significant differences in response or remission rates between subjects with B-TRD and TRD. Esketamine showed a greater anxiolytic action in subjects with B-TRD than in those with TRD. Improvement in depressive symptoms was not associated with treatment-emergent affective switch.

CONCLUSIONS

Our results supported the effectiveness and tolerability of esketamine in a real-world population of subjects with B-TRD. The low risk of manic switch in B-TRD patients confirmed the safety of this treatment.

Ketamine as an alternative to ECT in catatonia in elderly women with bipolar disorder: A case report

The following paper described two cases of patients with catatonic depression in bipolar disorder (BD) referred to our electroconvulsive therapy (ECT) service. Both were deemed not medically fit for ECT, and were, instead, treated with intravenous (IV) ketamine. Both responded with a resolution of symptoms, returning to baseline level of functioning. During the COVID-19 pandemic, given the risks associated with providing ECT (an aerosol generating procedure) and, in the context of limited resources, ketamine therapy for catatonia is a potentially beneficial alternative or supportive treatment to ECT that merits additional research.

Real-world effectiveness of repeated ketamine infusions for treatment-resistant bipolar depression

BACKGROUND

Clinical trials have demonstrated rapid antidepressant effects with intravenous (IV) ketamine for major depressive disorder, with relatively less research specifically for bipolar depression. Herein, we describe the real-world effectiveness of repeated ketamine infusions for treatment-resistant bipolar depression.

METHODS

This study was conducted in a community clinic in Mississauga, Ontario (Canadian Rapid Treatment Centre of Excellence; Braxia Health). In this observational study (NCT04209296), patients with treatment-resistant bipolar I/II depression (n = 66) received four sub-anesthetic doses of IV ketamine (0.5-0.75 mg/kg) over a two-week period. Symptoms of depression, suicidality, anxiety, and functioning were assessed with validated self-report measures.

RESULTS

Statistically and clinically significant antidepressant effects were observed in the overall sample, as measured by the Quick Inventory for Depression Symptomatology-Self Report-16 (QIDS-SR16 ) with further reductions in depressive symptoms observed after each subsequent infusion (n = 66; mean QIDS-SR16 reduction of 6.08+/-1.39; p < 0.0001). Significant reductions of suicidal thoughts (QIDS-SR16 -Suicide Item) and anxiety (Generalized Anxiety Disorder-7) were also observed with functional improvements on the Sheehan Disability Scale (p < 0.0001 on all measures). Moreover, the response rate (QIDS-SR16 total score decrease ≥50% from baseline) was 35% and remission rate (QIDS-SR16 total score ≤5) was 20% after four infusions. Infusions were generally well tolerated with treatment-emergent hypomania observed in only three patients (4.5%) with zero cases of mania or psychosis.

CONCLUSIONS

Real-world effectiveness of IV ketamine for bipolar depression was observed. Repeated doses were associated with greater symptom reduction and adequate tolerability.

Baseline Plasma BDNF Levelsare Associated with Antianhedonic Effects of Repeated-Dose Intravenous Ketamine in Major Depressive Disorder

OBJECTIVE

Evidence has shown that brain-derived neurotrophic factor (BDNF) is associated with anhedonia symptoms in major depressive disorder (MDD) patients, while the rapid antianhedonic effects of ketamine may occur independently of depressive symptoms. To our knowledge, the relationship between plasma BDNF (pBDNF) and the effect of repeated-dose intravenous ketamine on anhedonic symptoms has not been investigated.

METHODS

Seventy-five Chinese individuals with MDD received ketamine treatments. Anhedonia and pBDNF concentrations were evaluated with a subscale of the Montgomery-Åsberg Depression Rating Scale (MADRS) and enzyme-linked immunosorbent assay (ELISA) at baseline, day 13 and day 26.

RESULTS

Baseline pBDNF levels were associated with changes in anhedonic symptoms on day 13 (r=0.30, P=0.008). Interestingly, pBDNF concentrations were associated with changes in anhedonia symptomson day 26 (r= -0.32, P=0.02). Baseline pBDNF levels were higher in antianhedonic responders than in antianhedonic nonresponders (F=4.2, P=0.04). Ketaminereduced anhedonia symptoms in antianhedonic responders compared to nonresponders on days 13 and 26 (all Ps<0.05). The baseline high BDNF group had a lower level of anhedonia than the low BDNF group on days 13 (P<0.001) and 26 (P=0.01).

CONCLUSION

Our study suggests that baseline pBDNF concentrations may predict the antianhedonic effect in individuals with MDD treated with repeated doses of ketamine.

Novel uses of ketamine in the emergency department

INTRODUCTION

: Ketamine is gaining renewed interest among healthcare providers due to its novel clinical applications in the emergency department (ED) setting.

AREAS COVERED

: This article provides a comprehensive discussion of ketamine's pharmacological properties, including safety profile and adverse effects, in addition to an overview of current evidence for ketamine (racemic formulation) in the management of ED patients with acute agitation, pain, and depression/suicide ideation.

EXPERT OPINION

: Ketamine is an effective adjunct to opioids, providing greater pain relief than morphine alone. As an analgesic agent, administration of ketamine (0.1-0.3 mg/kg IV) alone can provide analgesia similar to that of morphine in patients with acute visceral and musculoskeletal pain. Moreover, ketamine provides equal analgesic efficacy to morphine in a variety of chronic painful conditions including pain associated with cancer, vaso-occlusive pain crisis associated with sickle cell disease, and in patients with high opioid tolerance and/or opioid dependency. Available literature shows that ketamine (1-2mg/kg IV or 4-5 mg/kg IM) is a safe, rapid (<5 minutes) and effective tranquilization agent for ED patients with acute agitation. Finally, there is growing evidence that suggests ketamine may have a potential utility in the management of patients with self-harm ideation or acute depressive episodes. Intravenous infusion of ketamine (0.5 mg/kg over 40 mins) has been shown to produce an antidepressant effect and decrease in suicidal ideation within 4 hours with effects lasting up to one week.

Real-world effectiveness of ketamine in treatment-resistant depression: A systematic review & meta-analysis

Ketamine is a promising therapeutic option in treatment-resistant depression (TRD). The acute efficacy of ketamine in TRD has been demonstrated in replicated randomised-controlled trials (RCTs), but the generalizability of RCT data to real-world practice is limited. To this end, we conducted a systematic review (Search date: 25/12/2021; 1482 records identified) and meta-analysis of studies evaluating the real-world clinical effectiveness of ketamine in TRD patients. Four overlapping syntheses (Total n = 2665 patients; k = 79 studies) and 32 meta-regressions (Total n = 2050; k = 37) were conducted. All results suggest that the mean antidepressant effect is substantial (mean ± 95% CI, % responded = 45 ± 10%; p< 0.0001, % remitted = 30 ± 5.9%; p< 0.0001, Hedges g of symptomatological improvement = 1.44 ± 0.609; p < 0.0001), but the effect varies considerably among patients. The more treatment-resistant cases were found to remit less often (p < 0.01), but no such effect on response was evident (p > 0.05). Meta-regressions also confirmed that the therapeutic effect does not significantly decline with repeated treatments (p > 0.05). These results demonstrate that even the most treatment-resistant patients may benefit from ketamine, and that mid-to-long term treatment is effective in many patients.

Comparative effectiveness of repeated ketamine infusions in treating anhedonia in bipolar and unipolar depression

OBJECTIVES

Anhedonia is a common, persistent, and disabling phenomenon in patients with major depressive disorder (MDD) and bipolar depression (BD). This study was conducted to investigate the comparative effectiveness of repeated ketamine infusions in treating anhedonia in Chinese individuals suffering from MDD and BD.

METHODS

Ninety-seven individuals suffering from MDD (n = 77) or BD (n = 20) were treated with six intravenous infusions of ketamine (0.5 mg/kg) administered over 40 min. Anhedonia was measured through the Montgomery-Åsberg Depression Rating Scale (MADRS). The antianhedonic response and remission were defined as ≥ 50% and ≥ 75% reduction in MADRS anhedonia subscale score one day after the sixth infusion, respectively.

RESULTS

Anti-anhedonic response and remission rates after the sixth ketamine infusion were 48.5% (95% confidence interval =  38.3%-58.6%) and 30.9% (95% confidence interval = 21.6%-40.3%), respectively. When compared to baseline, a significant reduction in the MADRS anhedonia subscale score was observed at 4 h after the first infusion and was maintained with repeated infusions at any time point (all Ps < 0.05). The anti-anhedonic effect of ketamine did not differ between the MDD and BD groups.

CONCLUSION

This preliminary study found that repeated ketamine infusions appeared to be effective at rapidly ameliorating anhedonia, with similar efficacy in MDD and BD.

Ketamine and Lamotrigine Combination in Psychopharmacology: Systematic Review

Background and Objectives: Ketamine is a rapid-acting antidepressant with proven efficacy as an add-on agent in unipolar and bipolar treatment-resistant depression. Although many studies have been published, there is still not enough data on the effect of ketamine in combination with other medications. Particularly interesting is the combination of ketamine and lamotrigine, and its potential role in bipolar depression. The aim of this review was to identify animal and human studies in which ketamine and lamotrigine were used together in order to find out if there is scientific ground for combining ketamine and lamotrigine in the treatment of mood disorders. Directions for future studies are presented. Materials and Methods: PubMed and Web of Science were searched. Preferred Reporting Items for Systematic Reviews and Meta-Analyses PRISMA 2020 methodology was applied. Results: Seventeen studies were included for review. Animal studies using models of depression suggested a synergistic effect of ketamine and lamotrigine in combination. Studies on healthy humans showed a reduction in ketamine-induced dissociative symptoms with lamotrigine pretreatment. In a study on patients with depression, ketamine and lamotrigine did not have a stronger antidepressant effect than ketamine alone, but in this study only one ketamine infusion was administered. One case series described the antidepressant and anti-suicidal effect of the combination in two bipolar patients. Available clinical studies on patients with mood disorders did not support the hypothesis that lamotrigine reduces ketamine-induced dissociative symptoms. Conclusions: The results of the analyzed studies were not sufficient to answer any of the stated questions; however, they allowed us to delineate future research directions. The identified animal studies suggested a possible synergistic antidepressant effect of ketamine and lamotrigine. The available clinical studies were not conclusive. No controlled studies on large groups of bipolar patients with multiple ketamine infusions combined with lamotrigine treatment have been published so far. There is some evidence for the reduction of ketamine’s side effects by lamotrigine, and there are reports suggesting that lamotrigine can reduce ketamine craving. More studies with follow-up are needed in order to investigate the ketamine–lamotrigine combination in bipolar patients.

Gender differences in the antianhedonic effects of repeated ketamine infusions in patients with depression

OBJECTIVES

Subanaesthetic ketamine (0. 5 mg/kg/40 min intravenous infusion) produces rapid and robust antianhedonic effects in subjects with mood disorders, independent of other depressive symptoms. The objective of this study was to examine potential differences in rate of antianhedonic response to ketamine in males and females, which has not been previously examined.

METHODS

A total of 135 patients with depression (68 males, 67 females) who received six intravenous infusions of ketamine (0.5 mg/kg/40 min) during 2 weeks were enrolled. The anhedonia subscale of the Montgomery-Åsberg Depression Rating Scale (MADRS) was utilized to measure anhedonic symptoms. Antianhedonic remission and response were defined as ≥75 and ≥50% improvement of anhedonic symptoms at 24 h after the sixth ketamine infusion (day 13).

RESULTS

Antianhedonic response (50 vs. 47.8%, p > 0.05) and remission (26.5 vs. 14.9%, p > 0.05) rates did not differ significantly between males and females. A linear mixed model revealed a nonsignificant between-group difference in MADRS anhedonia subscale scores [F_{(1, 132.5)} = 1.1, p = 0.30]. Females reported a significantly larger reduction in anhedonic symptoms than males at the 2-week follow-up (p < 0.05).

CONCLUSION

The rates of antianhedonic response and remission to multiple ketamine infusions for the treatment of depression were similar between males and females. These findings should be verified by future studies, preferably randomized controlled trials (RCTs).

Pre-treatment Pain Symptoms Influence Antidepressant Response to Ketamine in Depressive Patients

BACKGROUND

Pain strongly coexists with depression. Ketamine has great analgesic and antidepressant effects, acting as a promising role in treating depression with pain. Few studies have evaluated impact of pain symptoms on antidepressant effect of ketamine infusions. Thus, present study investigated whether pain symptoms in individuals with depression moderate response to ketamine.

METHODS

One hundred and four individuals with major depressive disorder and bipolar depression received six intravenous infusions of ketamine. The Montgomery-Åsberg Depression Rating Scale (MADRS) was administered at baseline, the next morning after each infusion and 2 weeks (Day 26) after the last infusion. Pain symptoms were collected at baseline using the short-form McGill Pain Questionnaire (SF-MPQ).

RESULTS

The prevalence of pain in patients with depression was 48.8%. Mix model analyses showed that pre-treatment pain symptoms assessed by each domain of SF-MPQ significantly moderated antidepressant response to six infusions of ketamine from baseline to day 26 (all p < 0.05). Then follow-up simple slopes analyses suggested that all patients across groups showed a significant symptomatic improvement after ketamine infusions (all p < 0.05), and patients with severe pain (across all domains of SF-MPQ) had greater improvement in depressive symptoms than those with mild pain or non-pain (all p < 0.05).

CONCLUSION

A significant and rapid improvement in depressive symptoms was observed in patients with depression and pain after ketamine treatment. Ketamine may be a novel and promising antidepressant preferentially for the therapy of depression with severe pain.

The potential pro-cognitive effects with intravenous subanesthetic ketamine in adults with treatment-resistant major depressive or bipolar disorders and suicidality

BACKGROUND

Ketamine has rapid and robust antidepressant effects in depression, while its effects on cognitive measures are less clearly understood. This aim of the study herein is to determine whether ketamine has direct pro-cognitive effects in real-world treatment depression and/or suicidality.

METHODS

Subjects with unipolar (n = 84) and bipolar (n = 27) depression suffering treatment resistance or suicidality received six infusions of ketamine (0.5 mg/kg) during a 12-day period. Depression symptoms were assessed using the Montgomery-Asberg Depression Rating Scale at baseline, day 13 and day 26. Cognitive domains, including processing speed, working memory, visual learning and verbal learning were also measured using the MATRICS Consensus Cognitive Battery at the same time-points.

RESULTS

Significant improvement was observed in processing speed at day 13 (effect size [ES] = 0.501) and day 26 (ES = 0.654), and verbal learning at day 13 (ES = 0.362). Path analysis showed significant direct (β = 2.444, P = 0.017) and indirect (β = 1.220, P = 0.048) effect of ketamine on processing speed, indicating its improvement was partly independent of improvement in depressive symptoms. The direct effect (β = -1.963, P = 0.052) of ketamine on verbal learning was not significant, whereas the indirect effect (β = 1.386, P = 0.024) was significant, indicating treatment with ketamine indirectly improved verbal learning performance, via changes in depressive symptom.

CONCLUSION

Six infusions of ketamine have a potential mood independent pro-cognitive effect on processing speed in adults with treatment depression and/or suicidality. The potential pro-cognitive effects of ketamine provide the basis for hypothesizing that other clinical outcomes (e.g., suicidality, functional impairment) reported with ketamine treatment may be in part mediated by improvement in cognition.

Intranasal esketamine use in bipolar disorder: A case report

Over the past few years, intranasal esketamine has been FDA-approved for treatment-resistant depression as well as MDD with suicidal ideation. In the clinical trials leading to the recent FDA approvals, subjects with a diagnosis of bipolar disorder were excluded from participation in the trial. The manufacturer of intranasal esketamine states that it "has not been studied, and is not indicated, for patients with bipolar disorder." Antidepressants are commonly associated with having the potential to induce rapid cycling in patients with bipolar disorder, though the mechanism is not fully understood. This case report demonstrates the potential safety of intranasal esketamine in combination with mood stabilizer therapy in a patient diagnosed with bipolar disorder without recent history of manic or hypomanic episodes.

Ketamine for Bipolar Depression: A Systematic Review

BACKGROUND

Ketamine appears to have a therapeutic role in certain mental disorders, most notably unipolar major depressive disorder. However, its efficacy in bipolar depression is less clear. This study aimed to assess the efficacy and tolerability of ketamine for bipolar depression.

METHODS

We conducted a systematic review of experimental studies using ketamine for the treatment of bipolar depression. We searched PubMed, MEDLINE, Embase, PsycINFO, and the Cochrane Central Register for relevant studies published since each database's inception. We synthesized evidence regarding efficacy (improvement in depression rating scores) and tolerability (adverse events, dissociation, dropouts) across studies.

RESULTS

We identified 6 studies, with 135 participants (53% female; 44.7 years; standard deviation, 11.7 years). All studies used 0.5 mg/kg of add-on intravenous racemic ketamine, with the number of doses ranging from 1 to 6; all participants continued a mood-stabilizing agent. The overall proportion achieving a response (defined as those having a reduction in their baseline depression severity of at least 50%) was 61% for those receiving ketamine and 5% for those receiving a placebo. The overall response rates varied from 52% to 80% across studies. Ketamine was reasonably well tolerated; however, 2 participants (1 receiving ketamine and 1 receiving placebo) developed manic symptoms. Some participants developed significant dissociative symptoms at the 40-minute mark following ketamine infusion in 2 trials.

CONCLUSIONS

There is some preliminary evidence supporting use of intravenous racemic ketamine to treat adults with bipolar depression. There is a need for additional studies exploring longer-term outcomes and alterative formulations of ketamine.

Intravenous Ketamine Infusions in Treatment-Resistant Bipolar Depression: An Open-Label Naturalistic Observational Study

PURPOSE

Bipolar disorder is a chronic and recurrent condition often associated with treatment resistance and suicidality. There is an unmet need for effective treatment in this group of patients. Ketamine has been demonstrated to have antidepressant and antisuicidal properties in unipolar depression. Most of the available studies concern unipolar depression. Here, we present the efficacy and safety of IV ketamine as an add-on treatment in patients with bipolar I and bipolar II depression.

PATIENTS AND METHODS

Thirteen patients with treatment-resistant bipolar depression (TRBD) received eight IV infusions of 0.5 mg/kg ketamine twice a week over four weeks. This is an open-label naturalistic observational study. Ketamine is an add-on treatment. Depressive symptoms were measured with the Montgomery-Asberg Depression Rating Scale (MADRS), and manic symptoms were measured with the Young Mania Rating Scale (YMRS). Psychomimetic symptoms were assessed with the Clinician-Administered Dissociative States Scale (CADSS) and the Brief Psychiatric Rating Scale (BPRS).

RESULTS

The rates of response and remission after the seventh infusion of ketamine were 61.5% and 46.2%, respectively. A significant antisuicidal effect was observed in responders at the 7th infusion. Suicidality was measured with item 10 on the MADRS scale. The average time to respond was between 21.1 and 23.2 days to remission. There was an increase in the CADSS scores during the treatment compared to baseline and follow-up, but no differences between responders and non-responders were observed. No affective switch was observed according to the YMRS scale scores. Ketamine treatment was associated with a transient increase in arterial blood pressure. No serious adverse events, however, were observed.

CONCLUSION

This report presents the preliminary results of IV ketamine effectiveness and safety in treatment-resistant bipolar depression. The findings suggest that it is a feasible, safe and well-tolerated treatment option in this group of patients. There is a definite need for more studies in this field.

Neurocognitive effects of six ketamine infusions and the association with antidepressant effects in treatment-resistant bipolar depression: a preliminary study

Objective

The N-methyl-D-aspartate subtype glutamate receptor antagonist ketamine has rapid antidepressant and antisuicidal effects in treating treatment-resistant bipolar depression (TRBD). The neurocognitive effects of repeated ketamine infusions in TRBD are not known.

Methods

Six intravenous infusions of ketamine (0.5 mg/kg over 40 min) were administered on a Monday–Wednesday–Friday schedule during a 12-day period on 16 patients with TRBD followed by a 2-week observational period. The assessment of neurocognitive function was conducted using the MATRICS Consensus Cognitive Battery at baseline, 13 and 26 days. Tasks were designed to test speed of processing, working memory, visual learning and verbal learning.

Results

A significant improvement was found only in scores of speed of processing (F = 9.9, p = 0.001) after a 2-week observational period, which was accounted for by the improvement of depression symptoms. There were no significant changes over time in terms of working memory, visual learning and verbal learning. Pearson correlation analysis showed that the improvement of depression symptoms through six ketamine infusions was greater among TRBD patients with lower working memory at baseline (r = 0.54, p = 0.03). In multiple regression analysis, the significant correlation was still maintained (beta = 0.67, t = 2.2, p = 0.04).

Conclusion

This preliminary study indicated that six ketamine infusions were not harmful but were slightly beneficial for speed of processing in TRBD. However, this change was mainly accounted for the improvement of depression symptoms over time. Lower baseline working memory appears to be associated with greater antidepressant response after completion of six ketamine infusions in patients with TRBD.

Metabolic Risk Factors and Cardiovascular Safety in Ketamine Use for Treatment Resistant Depression

INTRODUCTION

Ketamine exhibits antidepressant properties in treatment-resistant depression (TRD) with some concern over its cardiovascular safety and tolerability issues. This paper reports on the cardiovascular safety in short-term intravenous ketamine treatment in TRD inpatients with major depressive disorder (MDD) and bipolar disorder (BP).

MATERIALS AND METHODS

The observational study population comprises 35 MDD and 14 BP subjects treated with intravenous ketamine.

RESULTS

Blood pressure (RR) and heart rate (HR) values returned to baseline within 1.5-hours post infusion with no sequelae for all study subjects. Six time points were analyzed for each infusion: 0', 15', 30', 45', 60' and 90' for RR and HR. After the infusion significant peaks in systolic (p = 0.004) and diastolic (p = 0.038) RR were seen. In concomitant medication with selective serotonin reuptake inhibitors (SSRIs), higher RR peaks (p = 0.020; p = 0.048) were seen as compared to other subjects. The decrease in HR was greater (p = 0.02) in the absence of concomitant medication with mood stabilizers as compared to subjects receiving mood stabilizing medication accompanied by the observation of a greater decrease in diastolic RR among those taking mood stabilizers (p = 0.009).

LIMITATIONS

The study may be underpowered due to the small sample size. The observations apply to an inhomogeneous TRD population in a single-site, pilot study, with no blinding and are limited to the acute administration.

CONCLUSION

The study demonstrates good safety and tolerability profile of intravenous ketamine as add-on intervention to current psychotropic medication in TRD, regardless of the MDD or BP type of mood disorders. The abatement of elevated RR and BP scores was observed in time with no sequelae nor harm. Still, cardiovascular risks appear to be more pronounced in subjects with comorbid arterial hypertension and diabetes mellitus.

Ketamine in Bipolar Disorder: A Review

Bipolar disorder (BD) is a psychiatric illness associated with high morbidity, mortality and suicide rate. It has neuroprogressive course and a high rate of treatment resistance. Hence, there is an unquestionable need for new BD treatment strategies. Ketamine appears to have rapid antidepressive and antisuicidal effects. Since most of the available studies concern unipolar depression, here we present a novel insight arguing that ketamine might be a promising treatment for bipolar disorder.