Pilot Randomized Controlled Trial of Titrated Subcutaneous Ketamine in Older Patients with Treatment-Resistant Depression

Fast-acting antidepressant-like effects of ketamine in aged male rats

BACKGROUND

The aging process causes anatomical and physiological changes that predispose to the development of late-life depression while reduces the efficacy of classical antidepressants. Novel fast-acting antidepressants such as ketamine might be good candidates to be explored in the context of aging, especially given the lack of previous research on its efficacy for this age period. Thus, the aim of the present study was to characterize ketamine's effects in older rats.

METHODS

The fast-acting (30 min) and repeated (7 days) antidepressant-like effects of ketamine (5 mg/kg, ip) were evaluated in 14-month-old single-housed rats through the forced-swim and novelty-suppressed feeding tests. In parallel, the modulation of neurotrophic-related proteins (i.e., mBDNF, mTOR, GSK3) was assessed in brain regions affected by the aging process, prefrontal cortex and hippocampus, as well as possible changes in hippocampal cell proliferation.

RESULTS

Acute ketamine induced a fast-acting antidepressant-like response in male aged rats, as observed by a reduced immobility in the forced-swim test, in parallel with a region-specific increase in mBDNF protein content in prefrontal cortex. However, repeated ketamine failed to induce antidepressant-like efficacy, but decreased mBDNF protein content in prefrontal cortex. The rate of hippocampal cell proliferation and/or other markers evaluated was not modulated by either paradigm of ketamine.

CONCLUSIONS

These results complement prior data supporting a fast-acting antidepressant-like effect of ketamine in rats, to further extend its efficacy to older ages. Future studies are needed to further clarify the lack of response after the repeated treatment as well as its potential adverse effects in aging.

Repeated subcutaneous esketamine on treatment-resistant depression: An open-label dose titration study

BACKGROUND

Ketamine has gained prominence as one of the most effective therapeutic options in unipolar treatment-resistant depression (TRD). However, most studies related to the antidepressant action of ketamine used intravenous (IV) or intranasal (IN) administration. The subcutaneous (SC) route of administration is a promising alternative, as it results in plasma levels comparable to IV, causes fewer side effects, and is easier and cheaper to administer than both IV and/or IN routes.

METHODS

In this context, we conducted an open-label clinical trial for investigating the efficacy and safety of 8 weekly sessions of SC esketamine in TRD patients (n = 30).

RESULTS

At the end of the treatment, a partial response rate of 26.09 %, a response rate of 52.17 % and remission rate of 34.78 % were observed, assessed by Montgomery-Åsberg Depression Rating Scale. Moreover, the self-reported depressive symptoms, as measured by the Beck Depression Inventory II (BDI-II), significantly decreased from the baseline to the final session, and the improvements were sustained throughout the week. Follow-up evaluations (BDI-II) up to the sixth month consistently showed scores lower than the baseline.

LIMITATIONS

The small sample size and the drop-out during the follow-up phase may limit the generalizability of the findings. Additionally, the absence of a control group necessitates cautious interpretation of causality.

CONCLUSIONS

This groundbreaking study, which addresses SC esketamine treatment for TRD, reported promising response and remission rates, as well as sustained antidepressant effects. It highlights the need for further research to improve and expand our knowledge of this innovative, more accessible, and cost-effective therapeutic approach.

Is lack of goal-conflict-specific rhythmicity a biomarker for treatment resistance in generalised anxiety but not social anxiety or major depression?

BACKGROUND

Anxiety and depression cause major detriment to the patient, family, and society - particularly in treatment-resistant (TR) cases, which are highly prevalent. TR prevalence may be due to current diagnoses being based not on biological measures but on symptom lists that suffer from clinical subjectivity, variation in symptom presentation, and comorbidity.

AIMS

Goal-conflict-specific rhythmicity (GCSR) measured using the Stop-Signal Task (SST) may provide the first neural biomarker for an anxiety process and disorder. This GCSR has been validated with selective drugs for anxiety. So, we proposed that GCSR could differ between TR and non-TR individuals and do so differently between those diagnoses normally sensitive to selective anxiolytics and those not.

METHODS

We recorded electroencephalograms (EEG) from 20 TR participants (4 GAD, 5 SAD and 11 MDD) and 24 non-TR participants (4 GAD, 5 SAD and 15 Comorbid GAD/MDD (GMD)) while they performed the SST.

RESULTS

There was significant positive GCSR in all groups except the GAD-TR group. GAD-TR lacked GCSR in the low-frequency range. However, TR had little effect in SAD or MDD/GMD populations with apparent increases not decreases.

CONCLUSIONS

Overall, these results suggest that GAD may occur in two forms: one resulting from excessive GCSR and so being drug sensitive, and the other resulting from some other mechanism and so being TR. In SAD and MDD groups, heightened GCSR could be a consequence rather than the cause, driven by mechanisms that are normally more sensitive to non-selective panicolytic antidepressants.

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

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

Subcutaneous ketamine reduces suicide risk and improves functioning in depression: A proof-of-concept study

This investigation explores the efficacy of subcutaneous ketamine for mitigating depressive symptoms and suicidal ideation, addressing a crucial need for rapid-onset treatments in severe depression cases. It introduces an innovative approach to administering an NMDA receptor antagonist, significantly advancing psychopharmacological methods for treating suicidal behaviors as distinct entities, even within depressive episodes. The study's objective is to assess the impact of subcutaneous ketamine on diminishing suicidal thoughts and mood symptoms during depressive episodes through a naturalistic, prospective observational design. Conducted at Hospital de Clínicas de Porto Alegre, Brazil, between 2021 and 2023, the study involved 26 patients undergoing a current depressive episode. Of these, 23 completed the acute phase of treatment, and 18 were followed up for 6 months. The treatment regimen commenced with a ketamine dose of 0.5 mg/kg, which was adjusted according to individual responses under psychiatric supervision. The findings revealed substantial decreases in Columbia Suicide Severity Rating Scale scores following multiple ketamine sessions, with most patients achieving remission after approximately eight sessions. A notable reduction in depressive symptoms was also observed. A clear dose-response relationship was established, indicating that higher doses of ketamine were associated with more significant improvements in depressive symptoms, suicidal ideation, and overall functionality. Follow-up assessments suggested that these improvements were sustained over time. The subcutaneous administration of ketamine was generally well-tolerated, with minor and short-lived side effects. The study posits that subcutaneous ketamine may present a promising solution for treating severe depression accompanied by suicidal tendencies, particularly considering its positive influence on patient functionality and well-being. This method could offer a cost-effective and accessible treatment alternative, especially relevant in settings with limited resources. Given its potential in reducing long-term disability and economic viability, the study advocates for its broader application and further validation through larger, controlled trials. Trial Registration: ClinicalTrials.gov NCT05249309.

A systematic review of the incidence of medical serious adverse events in sub-anesthetic ketamine treatment of psychiatric disorders

BACKGROUND

Limited published data exists that collates serious adverse outcomes involving ketamine as a psychiatric intervention. This systematic review assesses the reported incidence of medical serious adverse events (MSAEs), including but not limited to cardiovascular events, in patients receiving sub-anesthetic doses of ketamine for psychiatric disorders to guide practitioners during treatment planning, risk-benefit analyses, and the informed consent process.

METHODS

Pubmed database was searched for clinical trials of sub-anesthetic ketamine for psychiatric disorders in non-pregnant adult patients. Of the 2275 articles identified, 93 met inclusion criteria, over half of which were published in 2017 or later. Only studies that reported adverse events were included, and the incidence of MSAEs was calculated.

RESULTS

Of the 3756 participants who received at least one sub-anesthetic dose of ketamine, four participants experienced a MSAE, resulting in an incidence of approximately 0.1 % of individuals. The four MSAEs resolved without reported sequelae. Eighty-three percent of studies reported screening for medical illness and exclusion of high-risk patients. There were no serious cardiac adverse events or deaths observed in any participants; however, most trials' study designs excluded those with high cardiovascular complication risk.

LIMITATIONS

Most studies were small, underpowered for detecting rare MSAEs, at potential high-risk of bias of non-report of MSAEs, and limited mostly to intranasal and intravenous routes.

CONCLUSIONS

Findings suggest that with basic medical screening there is a very low incidence of MSAEs including adverse cardiac or cerebrovascular events in individuals receiving sub-anesthetic ketamine for psychiatric disorders.

Mechanism of Antidepressant Action of (2R,6R)-6-Hydroxynorketamine (HNK) and Its Compounds: Insights from Proteomic Analysis

The effects of HNK, I5, and I6 on the expression of protein in hippocampus of depressed mice were studied by isobaric tags for relative and absolute quantitation (iTRAQ) to explore the mechanism of their antidepressant action. HNK, I5, and I6 were administered intragastric administration once a day in the morning for 7 days. The drug was subsequently discontinued for 7 days (without any treatment). On the 15th day, mice in each group were given the drug (1.0, 10.0, 30.0 mg/kg) intragastric stimulation and mouse hippocampal tissues were taken to perform iTRAQ to identify differentially expressed proteins, and bioinformatics was used to analyze the functional enrichment of the differentially expressed proteins. Compared with Ctr group, the number of differentially expressed proteins in HNK, I5, and I6 treatment groups was 158, 88, and 105, respectively. The three groups shared 29 differentially expressed proteins. In addition, compared with HNK group, the number of differentially expressed proteins in I5 and I6 groups was 201 and 203, respectively. A total of 47 and 56 differentially expressed proteins were co-expressed in I5 and I6 groups. Bioinformatics analysis showed that these differentially expressed proteins mainly had the functions of binding, biocatalysis, and transport, and mainly participated in cellular process, biological regulation process, biological metabolism process, and stress reaction process. GO and KEGG pathway analysis found that these differentially expressed proteins were involved long-term potentiation, G13 pathway, platelet activation pathway, and MAPK signaling pathway. HNK, I5, and I6 antidepressants are closely related to sudden stress sensitivity, stress resistance, neurotransmitter, and metabolic pathways. This study provides a scientific basis to further elucidate the mechanism and clinical application of HNK, I5, and I6 antidepressants.

Efficacy and safety of a 4-week course of repeated subcutaneous ketamine injections for treatment-resistant depression (KADS study): randomised double-blind active-controlled trial

BACKGROUND

Prior trials suggest that intravenous racemic ketamine is a highly effective for treatment-resistant depression (TRD), but phase 3 trials of racemic ketamine are needed.

AIMS

To assess the acute efficacy and safety of a 4-week course of subcutaneous racemic ketamine in participants with TRD. Trial registration: ACTRN12616001096448 at www.anzctr.org.au.

METHOD

This phase 3, double-blind, randomised, active-controlled multicentre trial was conducted at seven mood disorders centres in Australia and New Zealand. Participants received twice-weekly subcutaneous racemic ketamine or midazolam for 4 weeks. Initially, the trial tested fixed-dose ketamine 0.5 mg/kg versus midazolam 0.025 mg/kg (cohort 1). Dosing was revised, after a Data Safety Monitoring Board recommendation, to flexible-dose ketamine 0.5-0.9 mg/kg or midazolam 0.025-0.045 mg/kg, with response-guided dosing increments (cohort 2). The primary outcome was remission (Montgomery-Åsberg Rating Scale for Depression score ≤10) at the end of week 4.

RESULTS

The final analysis (those who received at least one treatment) comprised 68 in cohort 1 (fixed-dose), 106 in cohort 2 (flexible-dose). Ketamine was more efficacious than midazolam in cohort 2 (remission rate 19.6% v. 2.0%; OR = 12.1, 95% CI 2.1-69.2, P = 0.005), but not different in cohort 1 (remission rate 6.3% v. 8.8%; OR = 1.3, 95% CI 0.2-8.2, P = 0.76). Ketamine was well tolerated. Acute adverse effects (psychotomimetic, blood pressure increases) resolved within 2 h.

CONCLUSIONS

Adequately dosed subcutaneous racemic ketamine was efficacious and safe in treating TRD over a 4-week treatment period. The subcutaneous route is practical and feasible.

Subcutaneous ketamine infusion in palliative patients for major depressive disorder (SKIPMDD)-Phase II single-arm open-label feasibility study

BACKGROUND

Ketamine at subanaesthetic dosages (≤0.5mg/kg) exhibits rapid onset (over hours to days) antidepressant effects against major depressive disorder in people who are otherwise well. However, its safety, tolerability and efficacy are not known for major depressive disorder in people with advanced life-limiting illnesses.

OBJECTIVE

To determine the feasibility, safety, tolerability, acceptability and any antidepressant signal/activity to justify and inform a fully powered study of subcutaneous ketamine infusions for major depressive disorder in the palliative setting.

METHODS

This was a single arm, open-label, phase II feasibility study (Australian New Zealand Clinical Trial Registry Number-ACTRN12618001586202). We recruited adults (≥ 18-years-old) with advanced life-limiting illnesses referred to four palliative care services in Sydney, Australia, diagnosed with major depressive disorder from any care setting. Participants received weekly subcutaneous ketamine infusion (0.1-0.4mg/kg) over two hours using individual dose-titration design. Outcomes assessed were feasibility, safety, tolerability and antidepressant activity.

RESULTS

Out of ninety-nine referrals, ten participants received ketamine and were analysed for responses. Accrual rate was 0.54 participants/month across sites with 50% of treated participants achieving ≥ 50% reduction in baseline Montgomery-Åsberg Depression Rating Scale, meeting feasibility criteria set a priori. There were no clinically relevant harms encountered.

CONCLUSIONS

A future definitive trial exploring the effectiveness of subcutaneous infusion of ketamine for major depressive disorder in the palliative care setting may be feasible by addressing identified study barriers. Individual dose-titration of subcutaneous ketamine infusions over two hours from 0.1mg/kg can be well-tolerated and appears to produce transient antidepressant signals over hours to days.

A Review of Therapeutics for Treatment-Resistant Depression in the Older Adult

One-third of older adults with depression meet criteria for treatment resistance, typically defined as a lack of response to two or more adequate trials of an antidepressant. Treatment resistance contributes to an unfavorable prognosis, compromised medical outcomes, heightened disability, accelerated cognitive decline, and an elevated risk of developing dementia. Despite this significant morbidity, evidence is sparse for how to proceed with treatment in this population. Non-pharmacologic therapy (e.g., diet, psychotherapy) can be utilized as adjunctive therapy, despite little published evidence of benefit, given that the risks are low. Pharmacotherapy trials in the treatment-resistant late-life depression population lack strong methods and external validity; however, the use of venlafaxine as monotherapy and add-on therapy, as well as lithium, bupropion, or aripiprazole as add-on therapy to standard antidepressant therapy, have enough evidence that a trial with appropriate monitoring is a prudent strategy. Electroconvulsive therapy remains a well-studied safe therapy, especially when used as maintenance treatment once an initial cycle is completed but is traditionally underutilized in the treatment-resistant late-life depression population. Ensuring non-pharmacologic and pharmacologic strategies are optimized and given a sufficient trial in those with treatment-resistant late-life depression is the best we can do for this vulnerable population.

Ketamine for the treatment of major depression: a systematic review and meta-analysis

Background

Intranasal esketamine has received regulatory approvals for the treatment of depression. Recently a large trial of repeated dose racemic ketamine also demonstrated efficacy in severe depression. However, uncertainties remain regarding comparative efficacy, dosage, and the time course of response.

Methods

In this systematic review and meta-analysis, we searched Embase, Medline, Pubmed, PsycINFO, and CENTRAL up to April 13, 2023, for randomised controlled trials (RCTs) investigating ketamine for depression. Two investigators independently assessed study eligibility and risk of bias and extracted the data on depression severity scores, response and remission rates, and all-cause dropouts. Multivariable mixed-effects meta-regressions incorporated drug formulation (racemic (Rac) or esketamine (Esket)) and dose (Low or High) as covariates. Treatment effects were assessed: immediately following the first dose, during further repeated dosing, and follow-up after the final dose of a treatment course. This study is registered with PROSPERO (CRD42021221157).

Findings

The systematic review identified 687 articles, of which 49 RCTs were eligible for analysis, comprising 3299 participants. Standardised mean differences (95% confidence intervals) immediately following the first/single treatment were moderate-high for all conditions (Rac-High: -0.73, -0.91 to -0.56; Esket-High: -0.48, -0.75 to -0.20; Rac-Low: -0.33, -0.54 to -0.12; Esket-Low: -0.55, -0.87 to -0.24). Ongoing effects during repeated dosing were significantly greater than the control for Rac-High (-0.61; -1.02 to -0.20) and Rac-Low (-0.55, -1.09 to -0.00), but not Esket-Low (-0.15, -0.49 to 0.19) or Esket-High (-0.22, -0.54 to 0.10). At follow-up effects remained significant for racemic ketamine (-0.65; -1.23 to -0.07) but not esketamine (-0.33; -0.96 to 0.31). All-cause dropout was similar between experiment and control conditions for both formulations combined (Odds Ratio = 1.18, 0.85-1.64). Overall heterogeneity varied from 5.7% to 87.6.

Interpretation

Our findings suggested that effect sizes for depression severity, as well as response and remission rates, were numerically greater for racemic ketamine than esketamine. Higher doses were more effective than low doses. Differences were evident in initial effects, ongoing treatment, and lasting effects after the final dose.

Funding

None.

A comparative analysis of antidepressant and anti-suicidal effects of repeated ketamine infusions in elderly and younger adults with depression

OBJECTIVES

This study aims to investigate the differences in safety and antidepressant effects of multi-infusion ketamine treatment between elderly and young adults with depression.

METHODS

The safety, antidepressant, and anti-suicidal effects of multi-infusion ketamine were compared between 19 elderly (≥50 years) and 116 younger (<50 years) adults with depression; all were treated with six ketamine infusions (0.5 mg/kg). Montgomery-Åsberg Depression Rating Scale (MADRS) was used to measure the depressive symptoms, and suicidal ideation was measured with Beck Scale for Suicide Ideation (SSI)-part 1, Hamilton Rating Scale for Depression (HAMD) item 3, and (MADRS) item 10. Dissociative and psychotomimetic symptoms were evaluated based on the Clinician-Administered Dissociative States Scale (CADSS) and the Brief Psychiatric Rating Scale (BPRS)-four items.

RESULTS

Multi-Ketamine infusions resulted in a lower (trend) antidepressant response (37.1 % versus 57.8 %) and antidepressant remission (15.8 % versus 47.4 %) in elderly patients with depression compared with younger patients with depression (all ps > 0.05). Interestingly, elderly patients with depression had a higher MADRS score after six ketamine infusions compared with younger patients (p = 0.04). No significant differences in SSI-part 1 scores, HAMD item 3 scores, MADRS item 10 scores, CADSS scores, and BPRS-four items scores were found between the two groups at any assessment point (all ps > 0.05).

CONCLUSION

Our study shows that repeated-dose infusions of ketamine may be a feasible treatment strategy in elderly Chinese patients with depression; however, elderly patients with depression may be less responsive to ketamine compared with younger adults with depression.

Biological factors influencing depression in later life: role of aging processes and treatment implications

Late-life depression occurring in older adults is common, recurrent, and malignant. It is characterized by affective symptoms, but also cognitive decline, medical comorbidity, and physical disability. This behavioral and cognitive presentation results from altered function of discrete functional brain networks and circuits. A wide range of factors across the lifespan contributes to fragility and vulnerability of those networks to dysfunction. In many cases, these factors occur earlier in life and contribute to adolescent or earlier adulthood depressive episodes, where the onset was related to adverse childhood events, maladaptive personality traits, reproductive events, or other factors. Other individuals exhibit a later-life onset characterized by medical comorbidity, pro-inflammatory processes, cerebrovascular disease, or developing neurodegenerative processes. These later-life processes may not only lead to vulnerability to the affective symptoms, but also contribute to the comorbid cognitive and physical symptoms. Importantly, repeated depressive episodes themselves may accelerate the aging process by shifting allostatic processes to dysfunctional states and increasing allostatic load through the hypothalamic-pituitary-adrenal axis and inflammatory processes. Over time, this may accelerate the path of biological aging, leading to greater brain atrophy, cognitive decline, and the development of physical decline and frailty. It is unclear whether successful treatment of depression and avoidance of recurrent episodes would shift biological aging processes back towards a more normative trajectory. However, current antidepressant treatments exhibit good efficacy for older adults, including pharmacotherapy, neuromodulation, and psychotherapy, with recent work in these areas providing new guidance on optimal treatment approaches. Moreover, there is a host of nonpharmacological treatment approaches being examined that take advantage of resiliency factors and decrease vulnerability to depression. Thus, while late-life depression is a recurrent yet highly heterogeneous disorder, better phenotypic characterization provides opportunities to better utilize a range of nonspecific and targeted interventions that can promote recovery, resilience, and maintenance of remission.

Ketamine study: Protocol for naturalistic prospective multicenter study on subcutaneous ketamine infusion in depressed patients with active suicidal ideation

Background

Psychiatric disorders are associated with more than 90% of reported suicide attempts worldwide, but few treatments have demonstrated a direct effect in reducing suicide risk. Ketamine, originally an anesthetic, has been shown anti-suicide effects in clinical trials designed to treat depression. However, changes at the biochemical level were assessed only in protocols of ketamine with very limited sample sizes, particularly when the subcutaneous route was considered. In addition, the inflammatory changes associated with ketamine effects and their correlation with response to treatment, dose-effect, and suicide risk warrant further investigation. Therefore, we aimed to assess whether ketamine results in better control of suicidal ideation and/or behavior in patients with depressive episodes and whether ketamine affects psychopathology and inflammatory biomarkers.

Materials and methods

We report here the design of a naturalistic prospective multicenter study protocol of ketamine in depressive episodes carried out at Hospital de Clínicas de Porto Alegre (HCPA) and Hospital Moinhos de Vento (HMV). The study was planned to recruit adult patients with Major depressive disorder (MDD) or Bipolar disorder (BD) types 1 or 2, who are currently in a depressive episode and show symptoms of suicidal ideation and/or behavior according to the Columbia-Suicide Severity Rating Scale (C-SSRS) and have been prescribed ketamine by their assistant psychiatrist. Patients receive ketamine subcutaneously (SC) twice a week for 1 month, but the frequency can be changed or the dose decreased according to the assistant physician’s decision. After the last ketamine session, patients are followed-up via telephone once a month for up to 6 months. The data will be analyzed using repeated measures statistics to evaluate the reduction in suicide risk as a primary outcome, as per C-SSRS.

Discussion

We discuss the need for studies with longer follow-ups designed to measure a direct impact on suicide risk and that additional information about the safety and tolerability of ketamine in particular subset of patients such as those with depression and ideation suicide. In line, the mechanism behind the immunomodulatory effects of ketamine is still poorly understood.

Trial registration

https://clinicaltrials.gov/, identifier NCT05249309.

Intravenous Ketamine for Late-Life Treatment-Resistant Depression: A Pilot Study of Tolerability, Safety, Clinical Benefits, and Effect on Cognition

OBJECTIVE

Evidence-based treatment options for late-life treatment-resistant depression (TRD) are limited. Ketamine is a promising treatment for TRD; however, there is a paucity of data on its safety and efficacy in older adults.

METHODS

In this pilot clinical trial, 25 adults aged ≥60 years with TRD received IV ketamine openly twice a week for 4 weeks; partial responders at the end of this acute phase were eligible to receive weekly infusions for 4 more weeks in a continuation phase. Acceptability, tolerability, and safety, including adverse and serious adverse events (AEs and SAEs), blood pressure changes, dissociation, craving, in addition to rates of depression response and remission were evaluated. The NIH Toolbox Cognitive Battery was used to assess specific measures of executive function (EF) and overall fluid cognition.

RESULTS

Completion rates were 88% for the acute phase and 100% for the continuation phase. No AEs resulted in participant discontinuation, and there were no SAEs. Treatment-emergent elevation of blood pressure, dissociation, and craving were transient and did not result in any participant discontinuation. Depressive symptoms improved significantly and 48% of participants responded. During the acute phase, the EF measures and the fluid cognition composite score improved (Cohen's d = 0.61), and these improvements were sustained in the continuation phase.

CONCLUSION

This pilot study suggests that repeated IV ketamine infusions are well-tolerated and are associated with improvement in depression and EF in older adults with TRD. These promising findings need to be confirmed and extended in a larger randomized controlled trial.

Novel and emerging treatments for major depression

Depression is common, costly, debilitating, and associated with increased risk of suicide. It is one of the leading global public health problems. Although existing available pharmacological treatments can be effective, their onset of action can take up to 6 weeks, side-effects are common, and recovery can require treatment with multiple different agents. Although psychosocial interventions might also be recommended, more effective treatments than those currently available are needed for people with moderate or severe depression. In the past 10 years, treatment trials have developed and tested many new targeted interventions. In this Review, we assess novel and emerging biological treatments for major depressive disorder, evaluate their putative brain and body mechanisms, and highlight how close each might be to clinical use.

The metabotropic glutamate receptor 5 as a biomarker for psychiatric disorders

The role of glutamate system in the etiology and pathophysiology of psychiatric disorders has gained considerable attention in the past two decades, including dysregulation of the metabotropic glutamatergic receptor subtype 5 (mGlu5). Thus, mGlu5 may represent a promising therapeutic target for psychiatric conditions, particularly stress-related disorders. Here, we describe mGlu5 findings in mood disorders, anxiety, and trauma disorders, as well as substance use (specifically nicotine, cannabis, and alcohol use). We highlight insights gained from positron emission tomography (PET) studies, where possible, and discuss findings from treatment trials, when available, to explore the role of mGlu5 in these psychiatric disorders. Through the research evidence reviewed in this chapter, we make the argument that, not only is dysregulation of mGlu5 evident in numerous psychiatric disorders, potentially functioning as a disease "biomarker," the normalization of glutamate neurotransmission via changes in mGlu5 expression and/or modulation of mGlu5 signaling may be a needed component in treating some psychiatric disorders or symptoms. Finally, we hope to demonstrate the utility of PET as an important tool for investigating mGlu5 in disease mechanisms and treatment response.

Impact of Repeated Doses of Subcutaneous Esketamine on Acute Dissociative Symptoms in Treatment-Resistant Depression

BACKGROUND

Esketamine has been approved by the US Food and Drug Administration (FDA) as an adjunctive treatment for use in conjunction with an oral antidepressant for patients with treatment-resistant depression (TRD), but dissociative symptoms are common adverse effects.

METHODS

A retrospective analysis of 394 subcutaneous esketamine injections given to 70 patients with TRD that were administered once a week during a six-week trial in conjunction with oral antidepressant therapy. Doses between 0.5 to 1.0 mg/kg were administered according to the patient's response. Dissociative symptoms were assessed using the Clinician-Administered Dissociative States Scale (CADSS) 30 and 60 min after every weekly treatment (day 1, 8, 15, 22, 29 and 36).

RESULTS

Seventy patients received a total of 394 subcutaneous esketamine injections over six weeks. Over time, the evolution of CADSS scores demonstrated a significant mean difference of CADSS at 60 min post-injection (p = 0.010) throughout the six infusions. The mean CADSS scores at 60 min on day 22, 29 and 36 were similar. There were no differences between mean CADSS scores 30 min after the injections, no clinical correlation between response and dissociative symptoms, no correlation between time and demographic and clinical characteristics and no interactions between time and combined medication.

CONCLUSIONS

Our results suggest that repeated subcutaneous esketamine doses are safe and well-tolerated regarding their acute dissociative and psychotomimetic symptoms. Symptoms usually peak at 30 min and decrease at 60 min post-injection, returning to their pretreatment levels at 120 min. Dissociative symptoms do not correlate with antidepressant response.

A unique case of very low-dose subcutaneous ketamine use: Maintenance option of ketamine for treatment-resistant depression

Numerous studies have demonstrated that low-dose subanesthetic intravenous ketamine infusion treatment leads to rapid improvement of treatment-resistant depression. The following case report describes the use of a very low-dose subcutaneous ketamine as a form of maintenance in a patient with severe treatment-resistant depression using a retrospective chart review.

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

BACKGROUND

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

RESEARCH DESIGN AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Potential advantages of ketamine over electroconvulsive therapy in the treatment of nonrefractory severe depression in older patients with multiple medical comorbidities

Depression in older adults with multiple medical comorbidities can contribute to clinical deterioration, and increased mortality. Electroconvulsive therapy (ECT) is the first-line treatment for these patients. This study aimed to evaluate the effectiveness and safety of subcutaneous (SC) ketamine as an alternative to ECT. We reviewed the medical records of all consecutive older inpatients with severe depression and multiple medical comorbidities who were referred for ECT but treated with SC ketamine over 1 year in our institution. Demographic data, DSM-5 diagnosis, MÅDRS score, and CGI score were analyzed. Twelve patients aged 67-94 years were included. All patients were rated as severely ill, 83% were women, with a mean of 12.6 (SD, 1.4) medical comorbidities. Remission was achieved in 75% of the intention-to-treat population and 100% of treatment completers. The number of sessions ranged from 1 to 6, and days until remission from 1 to 16. Patients remained without relapse for 8-28 months. SC ketamine was safe and well tolerated, and most adverse events were mild and transient. Although limited by the retrospective open-label design of the study and small sample size, our findings provide a potential new indication for ketamine: treatment of severe depression, not necessarily resistant to antidepressants, in older patients with multiple medical comorbidities, at risk of clinical deterioration, and referral for ECT. SC ketamine was highly effective in this population, with no relapse and good tolerance. Randomized controlled trials are needed to adequately test the use of ketamine in this specific group.

Acute (R,S)-Ketamine Administration Induces Sex-Specific Behavioral Effects in Adolescent but Not Aged Mice

(R,S)-ketamine is an N-methyl-D-aspartate (NMDA) receptor antagonist that was originally developed as an anesthetic. Most recently, (R,S)-ketamine has been used as a rapid-acting antidepressant, and we have reported that (R,S)-ketamine can also be a prophylactic against stress in adult mice. However, most pre-clinical studies have been performed in adult mice. It is still unknown how an acute (R,S)-ketamine injection influences behavior across the lifespan (e.g., to adolescent or aged populations). Here, we administered saline or (R,S)-ketamine at varying doses to adolescent (5-week-old) and aged (24-month-old) 129S6/SvEv mice of both sexes. One hour later, behavioral despair, avoidance, locomotion, perseverative behavior, or contextual fear discrimination (CFD) was assessed. A separate cohort of mice was sacrificed 1 h following saline or (R,S)-ketamine administration. Brains were processed to quantify the marker of inflammation Cyclooxygenase 2 (Cox-2) expression to determine whether the acute effects of (R,S)-ketamine were partially mediated by changes in brain inflammation. Our findings show that (R,S)-ketamine reduced behavioral despair and perseverative behavior in adolescent female, but not male, mice and facilitated CFD in both sexes at specific doses. (R,S)-ketamine reduced Cox-2 expression specifically in ventral CA3 (vCA3) of male mice. Notably, (R,S)-ketamine was not effective in aged mice. These results underscore the need for sex- and age-specific approaches to test (R,S)-ketamine efficacy across the lifespan.

Identification of an optimal dose of intravenous ketamine for late-life treatment-resistant depression: a Bayesian adaptive randomization trial

Evidence supporting specific therapies for late-life treatment-resistant depression (LL-TRD) is necessary. This study used Bayesian adaptive randomization to determine the optimal dose for the probability of treatment response (≥50% improvement from baseline on the Montgomery-Åsberg Depression Rating Scale) 7 days after a 40 min intravenous (IV) infusion of ketamine 0.1 mg/kg (KET 0.1), 0.25 mg/kg (KET 0.25), or 0.5 mg/kg (KET 0.5), compared to midazolam 0.03 mg/kg (MID) as an active placebo. The goal of this study was to identify the best dose to carry forward into a larger clinical trial. Response durability at day 28, safety and tolerability, and effects on cortical excitation/inhibition (E/I) ratio using resting electroencephalography gamma and alpha power, were also determined. Thirty-three medication-free US military veterans (mean age 62; range: 55-72; 10 female) with LL-TRD were randomized double-blind. The trial was terminated when dose superiority was established. All interventions were safe and well-tolerated. Pre-specified decision rules terminated KET 0.1 (N = 4) and KET 0.25 (N = 5) for inferiority. Posterior probability was 0.89 that day-seven treatment response was superior for KET 0.5 (N = 11; response rate = 70%) compared to MID (N = 13; response rate = 46%). Persistent treatment response at day 28 was superior for KET 0.5 (response rate = 82%) compared to MID (response rate = 37%). KET 0.5 had high posterior probability of increased frontal gamma power (posterior probability = 0.99) and decreased posterior alpha power (0.89) during infusion, suggesting an acute increase in E/I ratio. These results suggest that 0.5 mg/kg is an effective initial IV ketamine dose in LL-TRD, although further studies in individuals older than 75 are required.

Prophylactic (R,S)-Ketamine Is Effective Against Stress-Induced Behaviors in Adolescent but Not Aged Mice

BACKGROUND

(R,S)-ketamine, an N-methyl-D-aspartate receptor antagonist, is frequently used as an anesthetic and as a rapid-acting antidepressant. We and others have reported that (R,S)-ketamine is prophylactic against stress in adult mice but have yet to test its efficacy in adolescent or aged populations.

METHODS

Here, we administered saline or (R,S)-ketamine as a prophylactic at varying doses to adolescent (5-week-old) and aged (24-month-old) 129S6/SvEv mice of both sexes 1 week before a 3-shock contextual fear-conditioning (CFC) stressor. Following CFC, we assessed behavioral despair, avoidance, perseverative behavior, locomotion, and contextual fear discrimination. To assess whether the prophylactic effect could persist into adulthood, adolescent mice were injected with saline or varying doses of (R,S)-ketamine and administered a 3-shock CFC as a stressor 1 month later. Mice were then re-exposed to the aversive context 5 days later and administered behavioral tests as aforementioned. Brains were also processed to quantify Cyclooxygenase 2 expression as a proxy for inflammation to determine whether the prophylactic effects of (R,S)-ketamine were partially due to changes in brain inflammation.

RESULTS

Our data indicate that (R,S)-ketamine is prophylactic at sex-specific doses in adolescent but not aged mice. (R,S)-ketamine attenuated learned fear and perseverative behavior in females, reduced behavioral despair in males, and facilitated contextual fear discrimination in both sexes. (R,S)-ketamine reduced Cyclooxygenase 2 expression specifically in ventral Cornu Ammonis region 3 of male mice.

CONCLUSIONS

These findings demonstrate that prophylactic (R,S)-ketamine efficacy is sex, dose, and age dependent and will inform future studies investigating (R,S)-ketamine efficacy across the lifespan.

Effects of Sodium Benzoate, a D-Amino Acid Oxidase Inhibitor, on Perceived Stress and Cognitive Function Among Patients With Late-Life Depression: A Randomized, Double-Blind, Sertraline- and Placebo-Controlled Trial

BACKGROUND

Compared with adults with depression in the general population, elderly depressive patients are prone to poor treatment response, more side effects, and early withdrawal with current antidepressants (which principally modulate monoamines). Whether N-methyl-D-aspartate receptor enhancement can benefit treatment of late-life depression deserves study. This study aims to compare sodium benzoate (a D-amino acid oxidase inhibitor and an indirect N-methyl-D-aspartate receptor enhancer), sertraline (a selective serotonin reuptake inhibitor), and placebo in the treatment of late-life depression.

METHODS

In this randomized, double-blind trial, 117 patients with major depressive disorder aged 55 years or older received 8-week treatment of 250-1500 mg/d of sodium benzoate, 25-150 mg/d of sertraline, or placebo in 2 medical centers. The primary outcome measures were Hamilton Depression Rating Scale and Perceived Stress Scale scores.

RESULTS

Three treatments similarly decreased clinicians-rated Hamilton Depression Rating Scale scores. Compared with placebo, sodium benzoate but not sertraline substantially improved Perceived Stress Scale scores and cognitive function. Sertraline, but not benzoate, significantly reduced self-report Geriatric Depression Scale scores. Benzoate and placebo showed similar safety profiles, while sertraline was more likely to raise low-density lipoprotein than benzoate and placebo. Benzoate-treated patients were less likely to drop out than sertraline or placebo recipients.

CONCLUSIONS

Sertraline can reduce subjective depressive symptoms, while benzoate can decrease perceived stress, improve cognitive function, and enhance treatment adherence in late-life depression patients. The results show promise for D-amino acid oxidase inhibition as a novel approach for perceived stress and cognitive decline among patients with late-life depression.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03414931. Registered January 2016.

Ketamine treatment for depression: A model of care

OBJECTIVE

Ketamine and related compounds are emerging as rapidly acting therapies for treatment-resistant depression. Ketamine differs from standard antidepressants in its speed of action, specific acute and cumulative side effects, risk of dependence and regulatory requirements. However, there is currently little guidance offering translation from research studies into clinical practice. We therefore detail a comprehensive model of care for ketamine treatment of depression.

METHOD

We formulated a set of policies and procedures for a 'compassionate use' ketamine programme that developed out of our clinical research in ketamine. These policies and procedures were formulated into a detailed model of care.

RESULTS

The current Australian and New Zealand regulatory frameworks and professional bodies' recommendations regarding ketamine are detailed along with clinical governance and infrastructure considerations. We next describe a four-step model comprising initial assessment, pre-treatment, treatment and post-treatment phases. The model comprises thorough psychiatric and medical assessments examining patient suitability, a rigorous consenting process and structured safety monitoring across an acute treatment course or maintenance therapy. Our ketamine dose-titration method is detailed allowing flexible dosing of patients across a treatment course enabling individualised treatment.

CONCLUSION

The model of care aims to bridge the gap between efficacy studies and clinical care outside of research settings as ketamine and related compounds become increasingly important therapies for treatment-resistant depression.

Hallucinogen Use and Misuse in Older Adults

Hallucinogens, or psychedelics, are substances/drugs that have been used for over a millennium. The most well known are LSD, psilocybin, mescaline, and PCP. These substances may induce hallucinations as well as cause somatic and psychological symptoms. Because of the Controlled Substances Act of 1970, there has been very little research done to determine the long-term consequences or perhaps potential benefit of misuse and abuse of hallucinogens. Typically, these drugs are not abused but more often misused. Recently, there has been a renewed interest in these compounds, which may lead to possible therapeutic options.

Recreational ketamine-related deaths notified to the National Programme on Substance Abuse Deaths, England, 1997-2019

BACKGROUND

Ketamine is a phencyclidine derivative with dissociative anaesthetic properties. Increasing numbers of individuals in England take ketamine recreationally. Information on deaths arising from such use in England is presented.

METHODS

Cases were extracted on 31 January 2020 from the National Programme on Substance Abuse Deaths database, based on text searches of the cause of death, coroner's verdict and positive toxicology results for the terms 'ketamine' or 'norketamine'.

FINDINGS

During 1997-2005, there were <5 deaths p.a. in which ketamine was implicated. Numbers increased until 2009 (21), plateauing until 2016; thereafter, deaths have risen to about 30 p.a. Decedents' characteristics (N = 283): male 84.1%, mean age 31.2 (SD 10.0) years, employed 56.5%, drug use history 79.6% and living with others 60.3%. Ketamine was detected with other substances in most cases. Main (74.6%) underlying cause of death was accidental poisoning. Ketamine may have impaired judgement in other cases.

CONCLUSIONS

Although controlled, recreational ketamine use and related fatalities continue to increase. Consumers need to be more aware of the potentially fatal risks they face.

Age affects temporal response, but not durability, to serial ketamine infusions for treatment refractory depression

RATIONALE

Ketamine is a novel, rapid-acting antidepressant for treatment refractory depression (TRD); however, clinical durability is poor and treatment response trajectories vary. Little is known about which patient characteristics predict faster or more durable ketamine responses. Ketamine's antidepressant mechanism may involve modulation of glutamatergic signaling and long-term potentiation (LTP); these neuroplasticity pathways are also attenuated with older age.

OBJECTIVE

A retrospective analysis examining the impact of patient age on the speed and durability of ketamine's antidepressant effects in 49 veterans receiving serial intravenous ketamine infusions for TRD.

METHOD

The relationship between age and percent change in Beck Depression Inventory (BDI-II) scores was compared across six serial ketamine infusions (twice-weekly for 3 weeks) using a linear-mixed model.

RESULTS

A significant Age-X-Infusion number interaction (F = 3.01, p = .0274) indicated that the relationship between age and treatment response depended on infusion number. Follow-up tests showed that younger age significantly predicted greater clinical improvement at infusion #4 (t = 3.02, p = .004); this relationship was attenuated at infusion #5 (t = 1.95, p = .057) and was absent at infusion #6. Age was not a significant predictor of treatment durability, defined as percent change in BDI-II 3 weeks following infusion #6.

CONCLUSIONS

These data preliminarily suggest that younger age is associated with a faster response over six serial ketamine infusions; by infusion #6 and subsequent weeks of clinical follow-up, age no longer predicts ketamine's antidepressant activity. Age may mediate the speed but not the durability or total efficacy of ketamine treatment, suggesting that dissociable mechanisms may underlie differing aspects of ketamine's antidepressant activity.

Use of ketamine and esketamine for depression: an overview of systematic reviews with meta-analyses

PURPOSE

To summarize the evidence of efficacy and safety of the use of ketamine and esketamine for depression.

METHODS

A literature search was performed in Medline, the Cochrane Library, LILACS, and CRD until November 2020. We included systematic reviews with meta-analyses of randomized controlled trials on the use of ketamine and esketamine in adult patients with depression. Two authors independently performed the study selection and data extraction. The AMSTAR-2 tool was used to appraise the quality of included reviews.

RESULTS

A total of 118 records were identified, and 11 studies fully met the eligibility criteria. Compared to control, ketamine improved the clinical response at 40 min to 1 week and clinical remission at 80 min to 72 h, and esketamine improved both outcomes at 2 h to 4 weeks. Ketamine and esketamine also had a beneficial effect on the depression scales score and suicidality. For adverse events, oral ketamine did not show significant change compared to control, while intranasal esketamine showed difference for any events, such as dissociation, dizziness, hypoesthesia, and vertigo. Most reviews were classified as "critically low quality," and none of them declared the source of funding of the primary studies and assessed the potential impact of risk of bias in primary studies.

CONCLUSION

Ketamine and esketamine showed a significant antidepressant action within a few hours or days after administration; however, the long-term efficacy and safety are lacking. In addition, the methodological quality of the reviews was usually critically low, which may indicate the need for higher quality evidence in relation to the theme.

Ketamine in depression and electroconvulsive therapy

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

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

OBJECTIVE

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

METHOD

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

RESULTS

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

CONCLUSION

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

Molecular Basis of Late-Life Depression

Late-life depression (LLD), compared to depression at a young age, is more likely to have poor prognosis and high risk of progression to dementia. A recent systemic review and meta-analysis of the present antidepressants for LLD showed that the treatment response rate was 48% and the remission rate was only 33.7%, thus implying the need to improve the treatment with other approaches in the future. Recently, agents modulating the glutamatergic system have been tested for mental disorders such as schizophrenia, dementia, and depressive disorder. Ketamine, a noncompetitive NMDA receptor (NMDAR) antagonist, requires more evidence from randomized clinical trials (RCTs) to prove its efficacy and safety in treating LLD. The metabotropic receptors (mGluRs) of the glutamatergic system are family G-protein-coupled receptors, and inhibition of the Group II mGluRs subtypes (mGlu2 and mGlu3) was found to be as effective as ketamine in exerting rapid antidepressant activity in some animal studies. Inflammation has been thought to contribute to depression for a long time. The cytokine levels not only increase with age but also decrease serotonin. Regarding LLD, interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) released in vivo are likely to contribute to the reduced serotonin level. Brain-derived neurotrophic factor (BDNF), a growth factor and a modulator in the tropomyosin receptor kinase (Trk) family of tyrosine kinase receptors, probably declines quantitatively with age. Recent studies suggest that BDNF/TrkB decrement may contribute to learning deficits and memory impairment. In the process of aging, physiological changes in combination with geriatric diseases such as vascular diseases result in poorer prognosis of LLD in comparison with that of young-age depression. Treatments with present antidepressants have been generally unsatisfactory. Novel treatments such as anti-inflammatory agents or NMDAR agonists/antagonists require more studies in LLD. Last but not least, LLD and dementia, which share common pathways and interrelate reciprocally, are a great concern. If it is possible to enhance the treatment of LDD, dementia can be prevented or delated.

Study protocol for SKIPMDD: subcutaneous ketamine infusion in palliative care patients with advanced life limiting illnesses for major depressive disorder (phase II pilot feasibility study)

INTRODUCTION

Major depressive disorder (MDD) in people with advanced life-limiting illnesses can have significant impact on the quality-of-life of those affected. The management of MDD in the palliative care setting can be challenging as typical antidepressants may not work in time nor be tolerated due to coexisting organ dysfunctions, symptom burden and frailty. Parenteral ketamine was found to exhibit effective and rapid-onset antidepressant effect even against treatment-resistant depression in the psychiatric population. However, there is currently neither feasibility study nor available prospective study available to inform of the safety, tolerability and efficacy of such for MDD in the palliative setting.

METHODS AND ANALYSIS

This is an open-labelled, single arm, phase II pilot feasibility study involving adult patients with advanced life-limiting illnesses and MDD across four palliative care services in Australia. It has an individual dose-titration design (0.1-0.4 mg/kg) with weekly treatments of subcutaneous ketamine infusion over 2 hours. The primary outcome is feasibility. The secondary outcomes are related to the safety, tolerability and antidepressant efficacy of ketamine, participants' satisfaction in relation to the trial process and the reasons for not completing the study at various stages. The feasibility data will be reported using descriptive statistics. Meanwhile, side effects, tolerability and efficacy data will be analysed using change of assessment scores from baseline.

ETHICS AND DISSEMINATION

Ethics approval was acquired (South Western Sydney Local Health District: HREC/18/LPOOL/466). The results of this study will be submitted for publication in peer-reviewed journals and presented at relevant conferences.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trial Registry Number: ACTRN12618001586202; Pre-results.

Ketamine for depression

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

The effectiveness, safety and tolerability of ketamine for depression in adolescents and older adults: A systematic review

The majority of antidepressant medication trials have focused on adult populations (ages 18-65), with much less research in older and younger populations. Moreover, key differences in the efficacy and safety of antidepressants have been identified between these age groups. Ketamine has emerged as a promising new treatment for treatment resistant depression (TRD). The objective of this review is to summarize and synthesize the extant literature on the effectiveness, safety and tolerability of ketamine for depression in special age populations (age ≤18 and ≥ 60). Following PRISMA guidelines, a systematic review was performed, searching EMBASE, PsycInfo, and PubMed from inception through July 2020. Studies reporting the use of any ketamine formulation with variable routes of administration to treat clinically diagnosed depression in adolescents or older adults were included. Thirteen studies were included in the analysis and ten observed rapid (≤2 week latency) antidepressant effects following ketamine treatments, with better outcomes following larger, repeated doses, and in open-label rather than blinded settings. Two case reports in adolescents assessed measures of suicidal ideation and both found ketamine to effectuate rapid anti-suicidal effects. Ketamine appears to be safe and well-tolerated in adolescents and older adults. The small quantity, high heterogeneity, and generally low quality of available studies precludes statistical syntheses and significantly limits the strength of our conclusions. Preliminary proof-of-concept studies are promising, however, rigorously designed randomized controlled trials (RCTs) are still required to ascertain effectiveness, safety and tolerability in these groups.

Single Subcutaneous Ketamine Dose Followed by Oral Ketamine for Depression Symptoms in Hospice Patients: A Case Series

Management of depression symptoms in hospice patients is complicated by the fact that an appropriate trial of antidepressant therapy requires 4-6 weeks and most hospice patients receive hospice services for less than 8 weeks. Intravenously administered ketamine has been shown to produce rapid improvement in depression symptoms but is not an ideal route for hospice patients and oral ketamine appears to have a slower onset of antidepressant activity. We present a case series that illustrates the use of a single subcutaneous dose of ketamine (0.5 mg/kg) followed by daily oral ketamine (0.5 mg/kg daily) therapy to manage depression symptoms in three hospice patients. Clinical improvement of depression symptoms occurred quickly for all patients as measured by the PHQ-4, numeric ratings, and subjective reporting. A single subcutaneous dose of ketamine followed by oral therapy presents itself as an option to quickly reduce depression symptoms in hospice patients that do not also require additional pain management. Combining the use of the subcutaneous and oral routes takes advantage of the possibly faster onset, home administration, and milder side effects than intravenous dosing. Prospective studies are needed to determine which dosing strategy would be the most beneficial for hospice patients.

Meta-Analysis: Hemodynamic Responses to Sub-anesthetic Doses of Ketamine in Patients With Psychiatric Disorders

Ketamine, a medication traditionally used as an anesthetic, has increasingly been recognized as an effective treatment for psychiatric disorders. At sub-anesthetic doses (defined here as ≤ 0.5 mg/kg), ketamine treatment has been studied in patients with treatment-resistant depression (TRD), obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD), and social anxiety disorder (SAD). Transient increases in hemodynamic activity have been reported during and after ketamine treatment, which may be desirable properties in some anesthesia settings, but are generally undesirable in psychiatric settings. While ketamine doses used in psychiatry are lower than those used in anesthesia, there are published instances of early termination of psychiatric ketamine infusions due to elevations in blood pressure and heart rate. No unifying study has been conducted to examine the impact of sub-anesthetic ketamine doses on hemodynamic parameters [systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR)] in psychiatric populations and to evaluate these changes across adult age groups. Here, data from 15 articles comprising a total N = 2,252 ketamine or esketamine treatments in adult participants were used to conduct a meta-analysis of treatment-induced hemodynamic changes. Ketamine/esketamine produced modest but significant increases in the variables of interest with an average SBP increase of 12.61 mm Hg (95% CI 10.40-14.82 mm Hg, z = 11.18, p < 0.0001), average DBP increase of 8.49 mm Hg (95% CI 6.89-10.09 mmHg, z = 10.41, p < 0.0001), and average heart rate increase of 4.09 beats per minute (95% CI 0.55-7.63 BPM), z = 2.27, p = 0.0235). Stratified subgroup analysis indicated no significant differences between ketamine and esketamine effects on blood pressure. Further analysis indicated that there was no significant effect of age on ketamine-induced changes in SBP, DBP, and HR. Taken together these data show that sub-anesthetic ketamine and esketamine induce small but significant increases in hemodynamic parameters that are transient in nature in adult psychiatric populations. While these data are reassuring, it is important for each treatment case to fully explore potential cardiovascular risks prior to initiating treatment.

Recent developments in geriatric psychopharmacology

INTRODUCTION

There is a tremendous growing need to address the burden of geriatric psychiatric disorders. Recent developments relevant to geriatric psychiatry have focused on Alzheimer's disease (AD), severe/refractory depression, and cancer/end of life care.

AREAS COVERED

This is a non-systematic, narrative review (databases and websites for search: PubMed, Google Scholar, Medscape, ClinicalTrials.gov; focusing on the last 6 years), and covers developments in disease-modifying therapies for AD, diagnostic radiotracers for AD, medications for neuropsychiatric symptoms of dementia, ketamine/esketamine, psychedelics, and cannabinoids.

EXPERT OPINION

The focus of on-going trials of anti-amyloid agents has been on individuals with very early stage AD; several agents are under phase 3 investigation, and aducanumab is under FDA review. Amyloid and tau PET scans have been approved by the FDA to assist in the diagnoses of AD. Promising pharmaceuticals for neuropsychiatric symptoms of dementia include pimavanserin, brexpiprazole, escitalopram, dextromethorphan/quinidine, and lithium. Esketamine, although approved for treatment-resistant depression in general adults, failed to demonstrate efficacy in elderly patients in a phase 3 trial. There is preliminary evidence for benefit of psychedelic-assisted psychotherapy in end-of-life and cancer-related depression/anxiety. Evidence for the use of cannabinoids is currently lacking.

Cardiovascular effects of repeated subanaesthetic ketamine infusion in depression

BACKGROUND

Ketamine produces significant rapid-onset and robust antidepressant effects in patients with major depressive disorder. However, this drug also has transient cardiovascular stimulatory effects, and there are limited data about potential predictors of these cardiovascular effects.

METHODS

A total of 135 patients with unipolar and bipolar depression received a total of 741 ketamine infusions (0.5 mg/kg over 40 min). Blood pressure and pulse were monitored every 10 min during the infusions and 30 min after the infusions. Depressive, psychotomimetic and dissociative symptom severity was assessed at baseline and 4 hours after each infusion.

RESULTS

The maximum blood pressure and pulse values were observed at 30-40 min during infusions. The largest mean systolic/diastolic blood pressure increases were 7.4/6.0 mmHg, and the largest mean pulse increase was 1.9 beats per min. No significant change in blood pressure and pulse was found in the second to sixth infusions compared with the first infusion. Patients who were older (age⩾50 years), hypertensive and receiving infusions while exhibiting dissociative symptoms showed greater maximal changes in systolic and diastolic blood pressure than patients who were younger (age<50 years), normotensive and without dissociative symptoms (all p < 0.05). Hypertensive patients had less elevation of pulse than normotensive patients (p < 0.05). Ketamine dosage was positively correlated with changes in systolic and diastolic blood pressure (all p < 0.05).

CONCLUSIONS

Blood pressure and pulse elevations following subanaesthetic ketamine infusions are transient and do not cause serious cardiovascular events. Older age, hypertension, large ketamine dosage and dissociative symptoms may predict increased ketamine-induced cardiovascular effects.

A systematic review of ketamine for the treatment of depression among older adults

OBJECTIVE

To review the currently available data on the use of ketamine in the treatment of depression among older adults from randomized controlled studies.

DESIGN

Randomized controlled trials.

SETTING

Variable.

PARTICIPANTS

60 years and older with depression.

INTERVENTION

Ketamine.

MEASUREMENTS

Change in Montgomery-Asberg Depression Rating Scale (MADRS) scores.

RESULTS

Two studies met the inclusion criteria. The first study showed a significant reduction in depression symptoms with use of repeated subcutaneous ketamine administration among older adults with depression. The second study failed to achieve significance on its primary outcome measure but did show a decrease in MADRS scores with intranasal ketamine along with a higher response and remission rates in esketamine group compared with the placebo group. The adverse effects from ketamine generally lasted only a few hours and abated spontaneously. No cognitive adverse effects were noted in either trial from the use of ketamine.

CONCLUSIONS

The current evidence for use of ketamine among older adults with depression indicates some benefits with one positive and one negative trial. Although one of the trials did not achieve significance on the primary outcome measure, it still showed benefit of ketamine in reducing depressive symptoms. Ketamine was well tolerated in both studies with adverse effects being mild and transient.

Repeated subcutaneous esketamine for treatment-resistant depression: Impact of the degree of treatment resistance and anxiety comorbidity

BACKGROUND

A large number of studies indicate that subanesthetic doses of ketamine induce a fast antidepressant effect. Limited studies have investigated the subcutaneous (SC) route, and it remains unclear for whom this treatment is most suitable.

AIMS

The aim of this study was to examine the effect on depressive symptoms of repeated subanesthetic doses of SC esketamine in unipolar and bipolar treatment-resistant depression (TRD) and clinical predictors of response.

METHODS

A retrospective analysis of 70 patients who received six SC esketamine doses weekly as an adjunctive treatment was carried out. Doses started at 0.5 mg/kg and it could be titrated up to 1 mg/kg, according to response. The primary outcome was reduction in depressive symptoms. Statistical analysis to investigate clinical predictors of effectiveness included logistic regression analysis using a dependent variable of a 50% reduction in rating scale scores at the end of treatment. Comparisons between groups were made through analysis of variance and treatment effects.

RESULTS

At baseline, our sample presented with severe treatment resistance in 65.7%, as assessed by the Maudsley Staging Method (MSM), and 47.1% had anxiety disorder comorbidity. The response rate was 50%. A better outcome was predicted by mild and moderate MSM scores (OR = 3.162, p = 0.041) and anxiety disorder comorbidity (OR = 3.149, p = 0.028).

CONCLUSIONS

Our results suggest that higher levels of treatment resistance may be associated with a poor response to SC esketamine. Unlike traditional pharmacotherapies, it might benefit those with poor prognosis such as patients with depression and comorbid anxiety. Therefore, future research could investigate whether esketamine should receive a more prominent place in the treatment algorithm for TRD.

The Canadian Network for Mood and Anxiety Treatments (CANMAT) Task Force Recommendations for the Use of Racemic Ketamine in Adults with Major Depressive Disorder: Recommandations Du Groupe De Travail Du Réseau Canadien Pour Les Traitements De L'humeur Et De L'anxiété (Canmat) Concernant L'utilisation De La Kétamine Racémique Chez Les Adultes Souffrant De Trouble Dépressif Majeur

OBJECTIVE

Patients with major depressive disorder often have limited response to first-line and second-line medications; hence, novel pharmacological treatments are needed for treatment-resistant depression (TRD). Ketamine, an N-methyl-d-aspartate (NMDA) receptor antagonist, has demonstrated rapid antidepressant effects in patients with TRD. The Canadian Network for Mood and Anxiety Treatments (CANMAT) convened a task force to review the evidence for efficacy and safety of racemic ketamine and to provide recommendations for its use in clinical practice.

METHODS

A systematic review was conducted with computerized search of electronic databases up to January 31, 2020 using combinations of search terms, inspection of bibliographies, and review of other ketamine guidelines and consensus statements. The level of evidence and lines of treatment were assigned according to CANMAT criteria. Recommendations were given in question-answer format.

RESULTS

Intravenous (IV) racemic ketamine given as a single infusion has Level 1 evidence for efficacy in adults with TRD. The evidence for multiple infusions, given as an acute series or as ongoing maintenance treatment, is limited to Level 3. Adverse events associated with ketamine infusions include behavioral (e.g., dissociative symptoms) and physiological (e.g., hypertension) events. There is only Level 3 or 4 evidence for non-IV formulations of racemic ketamine. Consensus recommendations are given for clinical administration of IV ketamine including patient selection, facility and personnel issues, monitoring, and maintaining response.

CONCLUSIONS

Single-dose IV racemic ketamine is a third-line recommendation for adults with TRD. The need for repeated and maintenance ketamine infusions should be carefully assessed on a case-by-case basis with consideration of potential risks and benefits. Because of limited evidence for efficacy and risk for misuse and diversion, the use of oral and other formulations of racemic ketamine should be limited to specialists with ketamine-prescribing expertise and affiliations with tertiary or specialized centers.

Comparative efficacy of racemic ketamine and esketamine for depression: A systematic review and meta-analysis

BACKGROUND

Ketamine appears to have a therapeutic role in certain mental disorders, most notably depression. However, the comparative performance of different formulations of ketamine is less clear.

OBJECTIVES

This study aimed to assess the comparative efficacy and tolerability of racemic and esketamine for the treatment of unipolar and bipolar major depression.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

We searched PubMed, MEDLINE, Embase, PsycINFO, the Cochrane Central Register of Controlled Clinical Trials, and the Cochrane Database of Systematic Reviews for relevant studies published since database inception and December 17, 2019.

STUDY ELIGIBILITY CRITERIA

We considered randomized controlled trials examining racemic or esketamine for the treatment of unipolar or bipolar major depression.

OUTCOMES

Primary outcomes were response and remission from depression, change in depression severity, suicidality, retention in treatment, drop-outs, and drop-outs due to adverse events.

ANALYSIS

Evidence from randomized controlled trials was synthesized as rate ratios (RRs) for treatment response, disorder remission, adverse events, and withdrawals and as standardized mean differences (SMDs) for change in symptoms, via random-effects meta-analyses.

FINDINGS

24 trials representing 1877 participants were pooled. Racemic ketamine relative to esketamine demonstrated greater overall response (RR = 3.01 vs. RR = 1.38) and remission rates (RR = 3.70 vs. RR = 1.47), as well as lower dropouts (RR = 0.76 vs. RR = 1.37).

CONCLUSIONS

Intravenous ketamine appears to be more efficacious than intranasal esketamine for the treatment of depression.

Subcutaneous Ketamine in Depression: A Systematic Review

Background: Ketamine has been shown to produce a rapid and robust antidepressant effect. Though numerous routes of administration have been studied, subcutaneous (SC) has proven to be a convenient and cost-effective route making its use particularly relevant in developing countries. Here we provide a systematic review covering the use of SC racemic ketamine and esketamine in depression, including its efficacy, safety and tolerability. Methods: A systematic literature search was carried out, from inception through March, 2021, using PubMed/MEDLINE, EMBASE and Web of Science, with no limits of language. After identifying 159 potentially relevant articles, 12 articles were selected after applying our inclusion/exclusion criteria. These comprised two randomized clinical trials, five case-reports and five retrospective studies. Given the small number of studies found and their heterogeneous nature, a meta-analysis was not considered appropriate. Here we provide a synthesis of these data including participant characteristics, dose range, efficacy, safety/ tolerability. Risk of bias was accessed using the Cochrane risk of bias tool. Results: SC Ketamine was administered to unipolar and bipolar patients a single or multiple doses, weekly or twice-weekly, a dose-titration approach was made in major studies, dose ranged from 0.1 to 0.5 mg/Kg of racemic ketamine and 0.5-1 mg/Kg of esketamine. Across all studies, SC ketamine showed a rapid and robust antidepressant effect, with response/ remission rates from 50 to 100% following both single or multiple doses, with transitory side effects. Conclusion: SC racemic ketamine and esketamine in depression is a promising strategy showing beneficial efficacy and tolerability. Future studies exploring the SC route, its cost-effectiveness, and a direct comparison with IV and intranasal (IN) protocols are warranted. Systematic Review Registration: CRD42019137434.

Virtual Reality and Psychedelics for the Treatment of Psychiatric Disease: A Systematic Literature Review

OBJECTIVE

Hallucinogenic substances or psychedelic drugs have been historically used by humans worldwide for centuries, and interest grows around them because of the therapeutic potential that they pose for mental disease. Virtual Reality (VR), has been highly developed and improved in the last decade, and it is also gaining importance due to their potential as therapeutic tools. In this article, the most recent and relevant information regarding the medical applications of both VR and psychedelics was highlighted, and diverse potential therapeutic uses were explored in hope to set the ground for further research on this topic.

METHOD

A systematic literature review using the PRISMA methods was conducted in PubMed, Medline, Embase, Cochrane Library, Scopus and Web of Science, including only peer-reviewed clinical trials or case studies written in English, that address the use of psychedelics and/or VR for the treatment of psychiatric disorders and that measure the success of the therapies. A final selection of 23 manuscripts were used in this systematic review.

RESULTS

VR showed security and significant efficacy in the management of special cases of phobias (social, motion pain and spiders), eating disorder, post-traumatic stress disorder (PTSD), gambling disorder, preoperative anxiety and schizophrenia.

CONCLUSIONS

The hallucinogenic drugs evaluated exhibited positive effects in treatment of depressive and anxiety disorders, alcohol dependence and PTSD. More research is needed in order to test the effectiveness of these therapies (alone or together) in different mental illnesses and different populations.

Glutamatergic dysregulation in mood disorders: opportunities for the discovery of novel drug targets

INTRODUCTION

Recently, a considerable attention has been paid to glutamatergic conception of mood disorders. The development of new treatment strategies targeted at glutamate provides new opportunities for the treatment of mood disorders. It is expected that these novel therapeutic options will provide a fast and sustained antidepressant effect and will be better tolerated by patients than the currently available antidepressants.

AREAS COVERED

This paper discusses glutamatergic abnormalities in mood disorders and reviews novel glutamate-based drugs developed for the treatment of these disorders. We have searched the PubMed and EMBASE databases, presented the results of relevant clinical studies and also describe novel glutamate-based agents that are under investigation.

EXPERT OPINION

The glutamatergic system plays many important roles in energy metabolism of the brain and neurotransmission; therefore, any attempt to identify novel therapeutic targets within this system seems justified. The effective development of new glutamate-based drugs requires, among others, a more in-depth exploration and understanding of the anatomy, function, and localization of different glutamatergic receptors in the brain. In our opinion, novel glutamate-based antidepressants will find application in the treatment of mood disorders and present an option will be widely used in clinical practice in the future.