A systematic review and meta-analysis of the efficacy of intravenous ketamine infusion for treatment resistant depression: January 2009 - January 2019

Therapeutic effects of 7- to 14-day subanesthetic ketamine infusions for chronic pain on standardized psychiatric measures

Background: We have previously shown that subanesthetic ketamine infusions effectively reduce refractory pain. However, the effects of ketamine infusions on comorbid conditions of depression and anxiety have not been explored in this patient population. Methods: We investigated the effects of ketamine on mood and anxiety in patients with refractory chronic pain treated with 7-14 days of subanesthetic continuous intravenous ketamine infusions, using well-validated clinical scales. Results: There was a significant 52% reduction in pain severity and 33% reduction in pain interference scores following ketamine treatment. Ketamine treatment also reduced scores on the depression module of the Patient Health Questionnaire (PHQ-9) by 28% and scores on the Generalised Anxiety and Depression Assessment (GAD-7) by 36%. Conclusion: Multiday subanesthetic ketamine infusions effectively reduce pain, anxiety and depression in patients with complex chronic pain.

Slouching towards engagement: interactions between people using psychedelics naturalistically and their healthcare providers

Introduction

There is substantial public interest in psychedelics as potential treatments for psychiatric conditions. However, most psychedelics are criminalized under federal law in the USA, so it is unclear whether use occurs with clinical support. Our objective was to assess whether naturalistic psychedelic use occurs with clinical support, interactions between those using psychedelics and healthcare providers (psychiatrist, therapist, or primary physicians), and use characteristics.

Methods

We conducted an online, anonymous, confidential, cross-sectional survey of adults reporting psychedelic use (N = 1221) through a psychedelics advocacy event and social media between 9/18/2022 and 11/5/2022. We assessed participant disclosure of psychedelic use with their psychiatric care provider (PsyCP) and/or primary care provider (PCP), desire for provider support, access to support, and rate of taking prescribed psychoactive medications alongside psychedelics.

Results

Among participants with such care providers, 22% disclosed psychedelic use to their PCP vs. 58% to their PsyCP. Participants were less confident in PCP vs. PsyCP ability to integrate psychedelics into treatment. Common reasons for nondisclosure included stigma, inadequate provider knowledge, and legal concerns. 23% reported taking psychedelics on the same day as potentially interacting psychiatric medications (e.g., anxiolytics, antidepressants). Despite 81% of participants desiring therapist support during psychedelic experiences, only 15% had received such support.

Discussion

Our results show that psychedelic use is generally disconnected from primary and psychiatric clinical care. This disconnection may result in safety issues, including inadequate screening for contraindicated conditions, lack of support during emergent adverse events, and drug interactions. Enhanced clinical education and orienting drug policy towards known harms and benefits of psychedelics is needed.

Interventional Mental Health: A Transdisciplinary Approach to Novel Psychiatric Care Delivery

Mental health disorders are among the most common health conditions in the United States. Traditional clinical treatments rely on psychiatric counseling and, in many cases, prescription medications. We propose an innovative model, Interventional Mental Health, which employs a combination of modalities through a multifaceted approach to treat conditions that have exhibited limited responsiveness to traditional methods and individuals afflicted with multiple comorbidities simultaneously. We hypothesize that creating a unique treatment algorithm combining current therapeutic modalities such as Stellate Ganglion Blocks (SGB), Transcranial Magnetic Stimulation (TMS) therapy, and ketamine therapy, within a consolidated timeframe, will yield synergistic outcomes among patients presenting with comorbid post-traumatic stress disorder (PTSD), depression, and/or anxiety.

A transdiagnostic systematic review and meta-analysis of ketamine's anxiolytic effects

BACKGROUND

Ketamine may be effective in treating symptoms of anxiety, but the time profile of ketamine's anxiolytic effect is ill-defined. This systematic review and meta-analysis investigated the anxiolytic effect of ketamine at different time points across a range of clinical settings.

METHODS

Electronic databases were searched to capture randomised control trials measuring the anxiolytic effects of ketamine in contexts including mood disorders, anxiety disorders and chronic pain. Meta-analyses were conducted using a random-effects model. The correlations between (1) improvements in mean anxiety and depression scores, and (2) peak dissociation and improvements in mean anxiety scores were also assessed.

RESULTS

In all, 14 studies met inclusion criteria. Risk of bias was high in 11 studies. Ketamine significantly reduced anxiety scores compared to placebo at acute (<12 h; standard mean difference (SMD): -1.17, 95% confidence interval (CI) [-1.89, -0.44], p < 0.01), subacute (24 h; SMD: -0.44, 95% CI [-0.65, -0.22], p < 0.01) and sustained (7-14 days; SMD: -0.40, 95% CI [-0.63, -0.17], p < 0.01) time points. Exploratory analyses revealed improvements in anxiety and depression symptoms correlated at both subacute (R2 = 0.621, p = 0.035) and sustained time points (R2 = 0.773, p = 0.021). The relationship between peak dissociation and improvement in anxiety was not significant.

CONCLUSIONS

Ketamine appears to offer rapid and sustained anxiety symptom relief across a range of clinical settings, with anxiolytic effects occurring within the first 12 h of administration and remaining effective for 1-2 weeks. Future studies could explore the effects of ketamine maintenance therapy on anxiety symptoms.

Randomized Trial of Ketamine Masked by Surgical Anesthesia in Depressed Patients

BACKGROUND

Ketamine may have antidepressant properties, but its acute psychoactive effects complicate successful masking in placebo-controlled trials.

METHODS

In a triple-masked, randomized, placebo-controlled trial, 40 adult patients with major depressive disorder were randomized to a single infusion of ketamine (0.5 mg/kg) or placebo (saline) during anesthesia as usual for routine surgery. The primary outcome was depression severity measured by the Montgomery-Åsberg Depression Rating Scale (MADRS) at 1, 2, and 3 days post-infusion. The secondary outcome was the proportion of participants with clinical response (≥50% reduction in MADRS scores) at 1, 2, and 3 days post-infusion. After all follow-up visits, participants were asked to guess which intervention they received.

RESULTS

Mean MADRS scores did not differ between groups at screening or pre-infusion baseline. The mixed-effects model showed no evidence of effect of group assignment on post-infusion MADRS scores at 1 to 3 days post-infusion (-5.82, 95% CI -13.3 to 1.64, p=0.13). Clinical response rates were similar between groups (60% versus 50% on day 1) and comparable to previous studies of ketamine in depressed populations. Secondary and exploratory outcomes did not find statistical separation of ketamine from placebo. 36.8% of participants guessed their treatment assignment correctly; both groups allocated their guesses in similar proportions. One serious adverse event occurred in each group, unrelated to ketamine administration.

CONCLUSION

In adults with major depressive disorder, a single dose of intravenous ketamine delivered during surgical anesthesia had no greater effect than placebo in acutely reducing the severity of depressive symptoms. This trial successfully masked treatment allocation in moderate-to-severely depressed patients using surgical anesthesia. While it is impractical to use surgical anesthesia for most placebo-controlled trials, future studies of novel antidepressants with acute psychoactive effects should make efforts to fully mask treatment assignment in order to minimize subject-expectancy bias. (ClinicalTrials.gov number, NCT03861988).

Ketamine for Complex Regional Pain Syndrome: A Narrative Review Highlighting Dosing Practices and Treatment Response

This is a narrative review of intravenous ketamine infusions for the treatment of complex regional pain syndrome (CRPS). It briefly covers the definition of CRPS, its epidemiology, and other treatments before introducing ketamine as the article's focus. A summary of ketamine's evidence base and its mechanisms of action is provided. The authors then review ketamine dosages reported in peer-reviewed literature for the treatment of CRPS, and their associated duration of pain relief. The observed response rates to ketamine and predictors of treatment response are also discussed.

Successful use of ketamine to treat severe depression with suicidality post-COVID-19 - A case report

Every second patient who suffers from COVID-19 experiences is at risk for depression. The treatment of severe depression with suicidal risk is challenging in patients with COVID-19 given the restrictions in access to and safety concerns with the use of electroconvulsive therapy during the COVID pandemic. Although ketamine is effective in treating depression, especially in presence of acute suicidality, to date, there are no reports on ketamine use to treat severe depression in the context of COVID-19. In this case report, we describe the success of ketamine to treat a person with severe depression and suicidality following COVID-19 infection.

The antidepressant actions of ketamine and its enantiomers

Ketamine, an N-methyl-d-aspartate receptor (NMDAR) antagonist first developed as an anesthetic, has shown significant promise as a medication with rapid antidepressant properties in treatment-resistant depression. However, concerns such as adverse side effects and potential misuse liability have limited its widespread use. Racemic ketamine has two enantiomers-(S)- and (R)-ketamine-that appear to have disparate underlying mechanisms. This brief review summarizes some of the most recent preclinical and clinical research regarding the convergent and divergent prophylactic, immediate, and sustained antidepressant effects of (S)- and (R)-ketamine while addressing potential differences in their side effect and misuse liability profiles. Preclinical research suggests divergent mechanisms underlying (S)- and (R)-ketamine, with (S)-ketamine more directly affecting mechanistic target of rapamycin complex 1 (mTORC1) signaling and (R)-ketamine more directly affecting extracellular signal-related kinase (ERK) signaling. Clinical research suggests that (R)-ketamine has a milder side effect profile than (S)-ketamine and decreases depression rating scale scores, but recent randomized, controlled trials found that it had no significant antidepressant efficacy compared to placebo, suggesting that caution is warranted in interpreting its therapeutic potential. Future preclinical and clinical research is needed to maximize the efficacy of each enantiomer, either by optimizing dose, route of administration, or administration paradigm.

Safety and tolerability of intramuscular and sublingual ketamine for psychiatric treatment in the Roots To Thrive ketamine-assisted therapy program: a retrospective chart review

Background

In the last few years, ketamine is becoming increasingly common in the treatment of mental health conditions, but there is a lack of safety data informing intramuscular and sublingual dosing in a community-focused group psychotherapy setting. The Roots To Thrive ketamine-assisted therapy (RTT-KaT) program is a unique 12-week RTT-KaT program with 12 community of practice (a form of group therapy) sessions and three ketamine medicine sessions.

Objectives

This study reports on adverse effects of intramuscular and sublingual ketamine dosing in a community group psychotherapy setting among 128 participants across four cohorts.

Design

Retrospective chart review.

Methods

A chart review of the RTT-KaT Program was performed retrospectively on four cohorts (n = 128) that participated in 448 sessions running between September 2020 and December 2021. Baseline characteristics and adverse events were captured including medication administration before, during, and after RTT-KaT sessions. Analyses by session and by individual were conducted. Chi-square test with Yates' continuity correction was used to assess side effects in subgroups from ketamine administration.

Results

RTT-KaT was well tolerated with none of the 128 participants dropping out of the program. Primarily, of the 448 sessions, 49.16% had elevated blood pressures post-KaT session by session. In terms of other adverse effects, 12.05% of participant-sessions experienced nausea, 2.52% had an episode of vomiting, 3.35% had a headache, and seven participant-sessions experienced dizziness. Analysis by individual revealed congruent findings.

Conclusion

These findings suggest good safety and tolerability for RTT-KaT among individuals seeking treatment for mental health issues. The majority of participants did not experience adverse reactions and the adverse events that were recorded involved transient symptoms that were resolved with rest and/or medications. The group therapy model described provides a comprehensive approach and presents a promising model for operating a KaT program in a community setting.

Case report: Intramuscular ketamine or intranasal esketamine as a treatment in four patients with major depressive disorder and comorbid anorexia nervosa

Introduction

A comorbid diagnosis of a depressive disorder is a negative prognostic factor for individuals with AN, and novel treatments are needed to target depressive symptoms in this population. One emerging promising treatment for depressive disorders is ketamine, although there is less research investigating the use of ketamine for alleviating depression in people with AN.

Case report

This study reports on four patients with a lifetime diagnosis of AN and a comorbid diagnosis of major depressive disorder who received either intramuscular ketamine (n = 2) or intranasal esketamine (n = 2) treatment from a private psychiatric clinic. Depressive symptomatology (PHQ-9) was measured prior to (es)ketamine administration on every dosing session and adverse effects were recorded during and after dosing. All patients reported a subjective decrease in depression, although only those administered intranasal esketamine showed a reduction in PHQ-9 depression scores over time. Number of doses ranged from 3 to 23. All patients tolerated treatment well and no serious adverse effects emerged, however nausea/vomiting was experienced by one patient on one dosing session. Weight remained stable in all cases, although notably across all patients, weight at the beginning of treatment was within a "healthy" range.

Discussion

These findings suggest that (es)ketamine may reduce depressive symptoms in people with major depressive disorder and a comorbid diagnosis of AN. Future feasibility and pilot trials are warranted in order to elicit robust data on efficacy, acceptability, safety and tolerability.

Ketamine reduces electrophysiological network activity in cortical neuron cultures already at sub-micromolar concentrations - Impact on TrkB-ERK1/2 signaling

The dissociative anesthetic ketamine regulates cortical activity in a dose-dependent manner. Subanesthetic-dose ketamine has paradoxical excitatory effects which is proposed to facilitate brain-derived neurotrophic factor (BDNF) (a ligand of tropomyosin receptor kinase B, TrkB) signaling, and activation of extracellular signal-regulated kinase 1/2 (ERK1/2). Previous data suggests that ketamine, at sub-micromolar concentrations, induces glutamatergic activity, BDNF release, and activation of ERK1/2 also on primary cortical neurons. We combined western blot analysis with multiwell-microelectrode array (mw-MEA) measurements to examine ketamine's concentration-dependent effects on network-level electrophysiological responses and TrkB-ERK1/2 phosphorylation in rat cortical cultures at 14 days in vitro. Ketamine did not cause an increase in neuronal network activity at sub-micromolar concentrations, but instead a decrease in spiking that was evident already at 500 nM concentration. TrkB phosphorylation was unaffected by the low concentrations, although BDNF elicited prominent phosphorylation response. High concentration of ketamine (10 μM) strongly reduced spiking, bursting and burst duration, which was accompanied with decreased phosphorylation of ERK1/2 but not TrkB. Notably, robust increases in spiking and bursting activity could be produced with carbachol, while it did not affect phosphorylation of TrkB or ERK1/2. Diazepam abolished neuronal activity, which was accompanied by reduced ERK1/2 phosphorylation without change on TrkB. In conclusion, sub-micromolar ketamine concentrations did not cause an increase in neuronal network activity or TrkB-ERK1/2 phosphorylation in cortical neuron cultures that readily respond to exogenously applied BDNF. Instead, pharmacological inhibition of network activity can be readily observed with high concentration of ketamine and it is associated with reduced ERK1/2 phosphorylation.

Depression roundtable: Is there a role for BoNT?

Depression can occur in the context of major depressive disorder or bipolar disorder. There are many effective and well-tolerated treatment options for most patients experiencing major depressive episodes, but for patients with treatment-resistant major depressive disorder or bipolar depression, current pharmacologic and non-pharmacologic options can be less efficacious, well tolerated, or accessible. Botulinum neurotoxin (BoNT) offers a novel approach to treating depression that is both safe and well-tolerated. Several potential mechanisms of action in depression are theorized, and studies support the efficacy of BoNT in major depression. Early data suggests that BoNT may be efficacious in bipolar depression and further study is warranted.

Bridging rapid and sustained antidepressant effects of ketamine

Acute administration of (R,S)-ketamine (ketamine) produces rapid antidepressant effects that in some patients can be sustained for several days to more than a week. Ketamine blocks N-methyl-d-asparate (NMDA) receptors (NMDARs) to elicit specific downstream signaling that induces a novel form of synaptic plasticity in the hippocampus that has been linked to the rapid antidepressant action. These signaling events lead to subsequent downstream transcriptional changes that are involved in the sustained antidepressant effects. Here we review how ketamine triggers this intracellular signaling pathway to mediate synaptic plasticity which underlies the rapid antidepressant effects and links it to downstream signaling and the sustained antidepressant effects.

Ketamine and serotonergic psychedelics: An update on the mechanisms and biosignatures underlying rapid-acting antidepressant treatment

The discovery of ketamine as a rapid-acting antidepressant spurred significant research to understand its underlying mechanisms of action and to identify other novel compounds that may act similarly. Serotonergic psychedelics (SPs) have shown initial promise in treating depression, though the challenge of conducting randomized controlled trials with SPs and the necessity of long-term clinical observation are important limitations. This review summarizes the similarities and differences between the psychoactive effects associated with both ketamine and SPs and the mechanisms of action of these compounds, with a focus on the monoaminergic, glutamatergic, gamma-aminobutyric acid (GABA)-ergic, opioid, and inflammatory systems. Both molecular and neuroimaging aspects are considered. While their main mechanisms of action differ-SPs increase serotonergic signaling while ketamine is a glutamatergic modulator-evidence suggests that the downstream mechanisms of action of both ketamine and SPs include mechanistic target of rapamycin complex 1 (mTORC1) signaling and downstream GABAA receptor activity. The similarities in downstream mechanisms may explain why ketamine, and potentially SPs, exert rapid-acting antidepressant effects. However, research on SPs is still in its infancy compared to the ongoing research that has been conducted with ketamine. For both therapeutics, issues with regulation and proper controls should be addressed before more widespread implementation. This article is part of the Special Issue on "Ketamine and its Metabolites".

Cytokine- and Vascular Endothelial Growth Factor-Related Gene-Based Genome-Wide Association Study of Low-Dose Ketamine Infusion in Patients with Treatment-Resistant Depression

BACKGROUND AND OBJECTIVE

Ketamine may work as an anti-inflammatory agent, and it increases the levels of vascular endothelial growth factor (VEGF) in patients with treatment-resistant depression. However, whether genes related to pro-inflammatory and anti-inflammatory cytokines and VEGF may predict the treatment response to ketamine remains unknown.Therefore the aim of this study was to analyze whether specific genes related to inflammatory processes and VEGF were associated with treatment response to low-dose ketamine in patients with treatment-resistant depression.

METHODS

Based on the genome data from our clinical trial, this study was a secondary analysis of candidate genes correlated with different timepoints of depressive symptoms. In total, 65 patients with treatment-resistant depression (n = 21 for ketamine 0.5 mg/kg, 20 for ketamine 0.2 mg/kg, and 24 for normal saline) were genotyped for 684,616 single nucleotide polymorphisms. Genes associated with 80 cytokines (i.e., interleukin [IL]-1, IL-6, tumor necrosis factor-α, and adiponectin) and VEGF (i.e., VEGF and VEGF receptors) were selected for the gene-based genome-wide association study on the antidepressant effect of a ketamine infusion.

RESULTS

Specific single nucleotide polymorphisms, including rs2540315 and rs75746675 in IL1R1 and rs79568085 in VEGFC, were related to the rapid (within 240 min) antidepressant effect of a ketamine infusion; specific single nucleotide polymorphisms, such as Affx-20131665 in PIGF and rs8179353, rs8179353, and rs8179353 in TNFRSF8, were associated with the sustained (up to 2 weeks) antidepressant effect of low-dose (combined 0.5 mg/kg and 0.2 mg/kg) ketamine.

CONCLUSIONS

Our findings further revealed that genes related to both anti-inflammatory and pro-inflammatory cytokines (i.e., IL-1, IL-2, IL-6, tumor necrosis factor-α, C-reactive protein, and adiponectin) and VEGF-FLK signaling predicted the treatment response to a ketamine infusion in patients with treatment-resistant depression. The synergic modulation of inflammatory and VEGF systems may contribute to the antidepressant effect of ketamine.

CLINICAL TRIAL REGISTRATION

University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) number: UMIN000016985.

Patients' recovery and non-recovery narratives after intravenous ketamine for treatment-resistant depression

BACKGROUND

Intravenous (IV) ketamine is an effective therapy for treatment-resistant depression. A large data base is confirmatory and steadily expanding. Qualitative studies can inform best practices and suggest new research directions. As part of a clinical trial designed to identify biomarkers of ketamine response, a qualitative study was conducted to characterize experiences with: receiving infusions; recovering or not recovering from depression; and beliefs about why ketamine worked or did not work.

METHODS

Adults with treatment-resistant depression received three IV ketamine infusions in a two-week period and were characterized as remitters or non-remitters via symptom reduction 24 h after the third infusion. Qualitative interviews of a subset of participants were audio recorded, transcribed verbatim, and coded using deductive and inductive methods. Themes were derived and compared across a broader construct of recovery status.

RESULTS

Of the 21 participants, nine (43 %) were characterized as having experienced remission and 12 (57 %) non-remission. Of the 12 non-remitters, five were characterized as having experienced partial recovery based on their subjective experiences, reporting substantial benefit from ketamine infusions despite non-remission status based on scale measurements. Attributions for ketamine's effects included biological and experiential mechanisms. Among non-remitters there was risk of disappointment when adding another failed treatment.

LIMITATIONS

A more diverse sample may have yielded different themes. Different patients had different amounts of time elapsed between ketamine infusions and qualitative interview.

CONCLUSIONS

Qualitative methods may enhance researchers' characterization of IV ketamine's impact on treatment-resistant depression. While requiring confirmation, patients may benefit from a preparatory milieu that prepares them for multiple recovery pathways; decouples the psychedelic experience from clinical outcomes; and addresses potential risks of another failed treatment.

Functional connectivity of the amygdala and the antidepressant and antisuicidal effects of repeated ketamine infusions in major depressive disorder

Background

Dysfunction of the amygdala is the core pathogenesis of major depressive disorder (MDD). However, it remains unclear whether ketamine treatment could modulate characteristics of amygdala-related networks. We aimed to explore the relationship between changes in the resting-state functional connectivity (RSFC) of the amygdala and the treatment of ketamine in MDD patients and to identify important neuroimaging predictors of treatment outcome.

Methods

Thirty-nine MDD patients received six subanesthetic dose infusions of ketamine. Depressive and suicidal symptoms were assessed and magnetic resonance imaging (MRI) scans were performed before and after six ketamine infusions. Forty-five healthy controls also underwent once MRI scans. Seed-based RSFC analyses were performed, focusing on the bilateral amygdala.

Results

After ketamine treatment, the RSFC between the left amygdala (LA) and the left medial superior frontal gyrus (mSFG) of MDD patients enhanced significantly, and this change was positively correlated with the reduction in depressive symptoms (r = 0.40, p = 0.012). The combination baseline RSFC of LA - right putamen and right amygdala (RA) - right putamen was related to the antidepressant and antisuicidal effects of ketamine. The combination baseline RSFC of LA - right putamen and RA - right putamen could predict the ineffective antidepressant (AUC = 0.739, p = 0.011) and antisuicidal effects of ketamine (AUC = 0.827, p = 0.001).

Conclusion

Ketamine can regulate the relevant circuits of amygdala and mSFG, and the baseline RSFC between bilateral amygdala and right putamen may be a predictor of the response of ketamine's antidepressant and antisuicidal treatment.

Clinical trial registration

https://www.chictr.org.cn/showproj.aspx?proj=20875, identifier ChiCTR-OOC-17012239.

New Psychoactive Substances: Major Groups, Laboratory Testing Challenges, Public Health Concerns, and Community-Based Solutions

Across communities worldwide, various new psychoactive substances (NPSs) continue to emerge, which worsens the challenges to global mental health, drug rules, and public health risks, as well as combats their usage. Specifically, the vast number of NPSs that are currently available, coupled with the rate at which new ones emerge worldwide, increasingly challenges both forensic and clinical testing strategies. The well-established NPS detection techniques include immunoassays, colorimetric tests, mass spectrometric techniques, chromatographic techniques, and hyphenated types. Nonetheless, mitigating drug abuse and NPS usage is achievable through extensive community-based initiatives, with increased focus on harm reduction. Clinically validated and reliable testing of NPS from human samples, along with community-driven solution, such as harm reduction, will be of great importance, especially in combating their prevalence and the use of other illicit synthetic substances. There is a need for continued literature synthesis to reiterate the importance of NPS, given the continuous emergence of illicit substances in the recent years. All these are discussed in this overview, as we performed another look into NPS, from differentiating the major groups and identifying with laboratory testing challenges to community-based initiatives.

Role of group II metabotropic glutamate receptors in ketamine's antidepressant actions

Major Depressive Disorder (MDD) is a serious neuropsychiatric disorder afflicting around 16-17 % of the global population and is accompanied by recurrent episodes of low mood, hopelessness and suicidal thoughts. Current pharmacological interventions take several weeks to even months for an improvement in depressive symptoms to emerge, with a significant percentage of individuals not responding to these medications at all, thus highlighting the need for rapid and effective next-generation treatments for MDD. Pre-clinical studies in animals have demonstrated that antagonists of the metabotropic glutamate receptor subtype 2/3 (mGlu_2/3 receptor) exert rapid antidepressant-like effects, comparable to the actions of ketamine. Therefore, it is possible that mGlu₂ or mGlu₃ receptors to have a regulatory role on the unique antidepressant properties of ketamine, or that convergent intracellular mechanisms exist between mGlu_2/3 receptor signaling and ketamine's effects. Here, we provide a comprehensive and critical evaluation of the literature on these convergent processes underlying the antidepressant action of mGlu_2/3 receptor inhibitors and ketamine. Importantly, combining sub-threshold doses of mGlu_2/3 receptor inhibitors with sub-antidepressant ketamine doses induce synergistic antidepressant-relevant behavioral effects. We review the evidence supporting these combinatorial effects since sub-effective dosages of mGlu_2/3 receptor antagonists and ketamine could reduce the risk for the emergence of significant adverse events compared with taking normal dosages. Overall, deconvolution of ketamine's pharmacological targets will give critical insights to influence the development of next-generation antidepressant treatments with rapid actions.

The Relationship Between Acute Dissociative Effects Induced by Ketamine and Treatment Response in Adolescent Patients with Treatment-Resistant Depression

Objective: Ketamine has proven effective as a rapid-acting antidepressant agent. Several adult studies have investigated the association between ketamine's acute dissociative effects and depression response, but no studies have examined the association in adolescents with treatment-resistant depression (TRD). Methods: We conducted a secondary data analysis of 16 adolescent participants who participated in a randomized, single-dose, midazolam-controlled crossover trial of ketamine in adolescents with depression. We examined the association between the acute dissociative symptoms (measured at 60 minutes following start of infusion using the Clinician-Administered Dissociative States Scale [CADSS], and its three subscales: depersonalization, derealization, amnesia) and response and depression symptom improvement at 1'day (using the Montgomery-Åsberg Depression Rating Scale). Results: Within the ketamine group, there were no significant associations between dissociation symptoms or CADSS subscale scores and magnitude of depression symptom improvement or likelihood of ketamine response. When receiving midazolam, there was no significant association between overall dissociation symptoms and magnitude or likelihood of response of depressive symptoms. Higher levels of symptoms on the 'depersonalization' CADSS subscale when receiving midazolam were associated with less improvement in depression symptoms at 1 day following infusion. Conclusions: In contrast to some adult literature, the current data do not show a relationship between acute dissociative effects and antidepressant response to ketamine in pediatric patients with TRD. Interpretation may be limited by the small sample size, reducing the power to detect small or medium associations. Future research should utilize larger samples to more definitively measure the magnitude of association between acute dissociative symptoms and later antidepressant response to ketamine and to assess the relationship to trial design (e.g., crossover vs. parallel trial, comparison condition utilized and number of infusions) within both adult and pediatric populations. ClinicalTrials.gov identifier: NCT02579928.

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.

Ketamine-assisted psychotherapy in adolescents with multiple psychiatric diagnoses

Ketamine-assisted psychotherapy is a promising new treatment for a variety of mental disorders of adolescence. There is currently an adolescent mental health crisis, with a high prevalence of disorders, diagnostic complexity, and many adolescents failing to respond to conventional treatments. While there is strong evidence for the use of ketamine in adults for a variety of treatment-refractory mental illnesses, research in adolescents is in its early stages. Ketamine-assisted psychotherapy (KAP) has been described in adults with promising results and here we present the first published cases of the use of KAP in adolescents. The four cases include adolescents aged 14-19 at the initiation of treatment, each with a variety of comorbid diagnoses including treatment-resistant depression, bipolar disorder, eating disorders, anxiety, panic, and trauma-related symptoms. They each initially received sublingual ketamine, followed by sessions with intramuscular ketamine. Their courses varied, but each had symptomatic and functional improvements, and the treatment was well-tolerated. Subjective patient reports are included. Rapid resolution of symptomatology and suffering often occurs within months as the result of the application of KAP to adolescent psychiatric care but is not inevitable. Family involvement in the treatment process appears to be essential to success. The development of this modality may have a singularly positive impact that will expand the psychiatric toolbox and its healing potency.

The potential of ketamine for posttraumatic stress disorder: a review of clinical evidence

Posttraumatic stress disorder (PTSD) is a devastating condition, for which there are few pharmacological agents, often with a delayed onset of action and poor efficacy. Trauma-focused psychotherapies are further limited by few trained providers and low patient engagement. This frequently results in disease chronicity as well as psychiatric and medical comorbidity, with considerable negative impact on quality of life. As such, off-label interventions are commonly used for PTSD, particularly in chronic refractory cases. Ketamine, an N-methyl-D-aspartate (NDMA) receptor antagonist, has recently been indicated for major depression, exhibiting rapid and robust antidepressant effects. It also shows transdiagnostic potential for an array of psychiatric disorders. Here, we synthesize clinical evidence on ketamine in PTSD, spanning case reports, chart reviews, open-label studies, and randomized trials. Overall, there is high heterogeneity in clinical presentation and pharmacological approach, yet encouraging signals of therapeutic safety, efficacy, and durability. Avenues for future research are discussed.

Acute Effects of Intravenous Sub-Anesthetic Doses of Ketamine and Intranasal Inhaled Esketamine on Suicidal Ideation: A Systematic Review and Meta-Analysis

Purpose

Suicide is a major public health concern with currently no validated and efficacious treatments approved. Preliminary evidence suggests that intravenous ketamine has rapid and sustained antidepressant effects, making it a candidate with therapeutic potential for depressed patients at risk for suicide. We conducted a meta-analysis to evaluate the efficacy of ketamine and esketamine in reducing suicidal ideation (SI), as well as their respective onset and duration of action.

Data Sources

We searched PubMed, Embase, Ovid, Cochrane, and Web of Science databases for studies published from inception to September 29, 2022.

Study Eligibility Criteria

We conducted a systematic review of all parallel randomized controlled trials (RCTs) examining the effect and duration of ketamine or esketamine on SI. Our primary outcome measure was the Suicide Scale score, which was measured using the Scale for Suicidal Ideation (SSI), Beck Scale for Suicide Ideation (BSS), Beck Depression Inventory (BDI), or Modified Scale for Suicidal Ideation (MSSI). To obtain effect sizes (Cohen's d), we calculated the difference in Suicide Scale scores before and after administration in each group.

Results

Our study showed that intravenous sub-anesthetic doses of ketamine and intranasal inhaled esketamine had a significant anti-SI effect. Specifically, ketamine produced a large degree of anti-SI effect within the 4-6 hours (Cohen's d = 1.16, 95% CI: 0.50, 1.81) and a medium-large degree in the 24 hours (Cohen's d = 0.95, 95% CI: 0.48, 1.41). Esketamine, on the other hand, produced a small-medium degree of anti-SI effect within the 4-6 hours timeframe (Cohen's d = 0.26, 95% CI: 0.09, 0.44) and the 24 hours (Cohen's d = 0.30, 95% CI: 0.17, 0.47).

Conclusion

Intravenous sub-anesthetic doses of ketamine and intranasal inhaled esketamine could reduce SI within 4 hours and last for 24 hours.

Cost-effectiveness of esketamine nasal spray compared to intravenous ketamine for patients with treatment-resistant depression in the US utilizing clinical trial efficacy and real-world effectiveness estimates

OBJECTIVE

The aim of this study was to estimate the cost-effectiveness of esketamine nasal spray relative to intravenous ketamine for patients with treatment-resistant depression (TRD) in the US.

METHODS

We used a Markov model with a 1-month cycle length, and we estimated quality-adjusted life years (QALYs), costs (2020 USD), and incremental cost-effectiveness ratios (ICER) of esketamine relative to ketamine over a 3-year time horizon, from both the healthcare sector and patient perspectives. We ran the model using efficacy estimates from both clinical trial and real-world effectiveness (RWE) data. One-way and probabilistic sensitivity analyses (PSAs) were performed to evaluate the robustness of findings.

RESULTS

Over a 3-year time horizon, the use of esketamine yielded 1.98 QALYs (RWE/clinical trial efficacy), and the use of ketamine yielded 2.03 QALYs (clinical trial efficacy) or 1.99 QALYs (RWE). Esketamine was dominated by ketamine using the healthcare perspective. ICERs were above $150,000/QALY threshold with the patient perspective. Under the healthcare perspective, PSA showed there are no scenarios where esketamine was cost-effective compared to ketamine. With the patient's perspective, the probability that esketamine was cost-effective compared to ketamine was 0.0055 (clinical trial efficacy) and 0.35 (RWE).

LIMITATIONS

The data utilized for efficacy have limitations. The time horizon may fail to capture longer-term costs and benefits.

CONCLUSIONS

In this decision analytic model evaluating esketamine versus ketamine for TRD, we found esketamine unlikely to be cost-effective under a healthcare sector perspective. Under a patient perspective, esketamine had similar effectiveness and was less costly than ketamine due to insurance coverage.

Single low-dose ketamine infusion for women with prenatal depressive symptoms undergoing cesarean delivery: A pilot randomized trial

Background

Ketamine is approved for antidepressant therapy, but evidence regarding its use in women with perinatal depression is lacking. Herein, we investigated the effects of low-dose ketamine in women with prenatal depressive symptoms and tested the feasibility of a future large randomized trial.

Methods

This was a randomized, double-blind, placebo-controlled pilot trial. Sixty-six women with prenatal depressive symptoms who were scheduled for elective cesarean delivery were randomized to receive either low-dose ketamine (0.5 mg/kg) or placebo (normal saline). The study drugs were intravenously infused over a 40-minute period after clamping the umbilical cord. The primary outcome was depression score assessed with the Edinburgh Postnatal Depression Scale at 48 h postpartum. Among other and safety outcomes, occurrence of nausea or vomiting was observed, pain intensity was assessed with the numeric rating scale. The feasibility of implementing the protocol was also evaluated.

Results

A total of 64 parturients were included in the intention-to-treat analysis. The depression score at 48 h did not differ between groups: median 9 (interquartile range 6 to 13) with ketamine vs. 8 (6 to 10) with placebo; median difference 1, 95% CI -1 to 3; P = 0.608. The pain intensity at 4 h postpartum was less severe in the ketamine group (median difference -1, 95% CI -1 to 0, P = 0.002). Among safety outcomes, intraoperative nausea or vomiting was less common in patients given ketamine (0.0% [0/33] with ketamine vs. 21.2% [7/33] with placebo, P = 0.011). Recruitment was satisfactory and the protocol was acceptable to participants and clinicians.

Conclusions

A single low-dose ketamine infusion did not decrease the depression score at 2 days, but reduced intraoperative nausea and vomiting and lowered pain intensity at 4 h after cesarean delivery among women with prenatal depressive symptoms. The study protocol is feasible for a large randomized trial.

Clinical Trial Registration

The study was registered with ClinicalTrials.gov (identifier: NCT03336541; 08/11/2017).

Safety and effectiveness of intranasal esketamine for treatment-resistant depression: a real-world retrospective study

Aim: There is limited real-world evidence for patients with treatment-resistant depression (TRD) receiving esketamine nasal spray. Methods: This retrospective cohort study used data collected from a psychiatric clinic's EHR system. Results: A total of 171 TRD patients received esketamine July 2019-June 2021. This predominantly female, white population had several mental health comorbidities and high exposure to psychiatric medications. We observed significant reductions (p < 0.001) in average PHQ-9 and GAD-7 scores from baseline (PHQ-9: mean: 16.7; SD: 5.8; GAD-7: mean: 12.0; SD: 5.8) to last available treatment (PHQ-9: mean: 12.0; SD: 6.4; GAD-7: mean: 8.7; SD: 5.6). There were no reports of serious adverse events. Conclusion: This study found a significant disease burden for patients with TRD. Esketamine appears to be well tolerated and effective in improving depression and anxiety.

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

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

Rapid-Response Treatments for Depression and Requests for Physician-Assisted Death: An Ethical Analysis

Depression is common at the end of life, and there is longstanding concern that it may affect terminally ill patients' decisions to request physician-assisted death (PAD). However, it is difficult for clinicians to determine the role of depression in a patient's PAD request. A recent case series described rapid responses to intranasal ketamine in three patients with terminal illness and comorbid depression who had requested PAD. One patient withdrew her request (which, in retrospect, had been driven by her depression) while the others maintained their requests; in all three, the rapid relief clarified the role of depression in the patients' decision-making. In addition to ketamine, there are other emerging rapid-response treatments for depression, including psilocybin with psychological support and functional connectivity-guided transcranial magnetic stimulation. We examine three key ethical implications of such treatments: their role in clarifying the decision-making capacity of depressed patients requesting PAD; the potential tension between the legal definition of irremediability in some jurisdictions and the ethical obligations of clinicians; and the likely obstacles to treatment access and their implications for equal respect for autonomy of patients.

Active mechanisms of ketamine-assisted psychotherapy: A systematic review

BACKGROUND

Few studies have evaluated the efficacy of ketamine-assisted psychotherapy (KAP) in the treatment of treatment-resistant depression (TRD) and substance use disorders (SUD).

METHODS

A systematic review of clinical trials reporting on the efficacy of KAP and discussing mechanisms of action, identified on PubMed and PsycInfo.

RESULTS

Five randomized-controlled trials reported on the efficacy of KAP treatment and discussed active mechanisms. Four of the studies treated adults with SUD and a single study treated adults with TRD. Overall, KAP had a significant positive effect on primary outcome measures compared to controls, however, the data is mixed. The study examining KAP for TRD found no benefit.

LIMITATIONS

Lack of large, replicated clinical trials. No studies actively examining mechanisms of action.

CONCLUSION

Evidence suggests that temporary neural changes caused by ketamine such as n-methyl-d-aspartate receptor (NMDAR) inhibition and increase of synaptic neuroplasticity affect treatment outcomes of KAP. Based on reports of preliminary findings, we speculate that adjunct psychotherapy, changes in perspective, and spirituality may also play a role.

Comparative study of low-dose ketamine infusion and repetitive transcranial magnetic stimulation in treatment-resistant depression: A posthoc pooled analysis of two randomized, double-blind, placebo-controlled studies

BACKGROUND

This posthoc analysis compared the antidepressant and antisuicidal effects of low-dose ketamine infusion with those of repetitive transcranial magnetic stimulation (rTMS) on treatment-resistant depression (TRD).

METHODS

In the ketamine infusion trial, 48 patients with TRD were randomized to receive a single infusion of 0.5 mg/kg ketamine or normal saline. In the rTMS trial, 105 patients were randomly assigned to intermittent theta-burst stimulation (iTBS), 10-Hz rTMS, or sham stimulation. The 17-item Hamilton Rating Scale for Depression (HDRS) was administered.

RESULTS

The antidepressant effect was prominent at Day 7 postinfusion in the ketamine group but steadily accumulated with the treatment duration from Day 7 to 14 in the iTBS and 10-Hz rTMS groups, regardless of the level of treatment resistance (all p < .01). Low-dose ketamine infusion and iTBS exerted superior effects on suicidal symptoms (HDRS item 3) than the other three groups (p < .001). The antidepressant effect of iTBS/10-Hz rTMS may persist for up to 3 months; however, the antidepressant effect of a single low-dose ketamine infusion did not persist over a month.

DISCUSSION

Both low-dose ketamine infusion and rTMS/TBS must be included in TRD treatment but may be applied in different clinical situations.

Antianhedonic effects of serial intravenous subanaesthetic ketamine in anxious versus nonanxious depression

OBJECTIVES

Patents with anxious depression have poor treatment outcomes compared to their nonanxious counterparts. Ketamine has a rapid and robust antianhedonic effect, independent of depressive symptoms. The difference in the antianhedonic effect of ketamine between patients with anxious versus nonanxious depression remains unknown.

METHODS

One hundred thirty-five Chinese individuals with anxious depression (n = 92) and nonanxious depression (n = 43) received six intravenous infusions of ketamine (0.5 mg/kg). Post hoc analyses compared changes in anhedonic symptoms, as measured by the Montgomery-Åsberg Depression Rating Scale (MADRS), between patients with anxious depression (defined by a Hamilton Depression Rating Scale Anxiety-Somatization score ≥7) and nonanxious depression.

RESULTS

In this study, 68.1 % of patients were found to have anxious depression. Anxious depressed patients were associated with a relatively lower antianhedonic response (47.8 % versus 51.2 %, p > 0.05) and remission (17.4 % versus 27.9 %, p > 0.05) than their nonanxious counterparts. When compared to baseline, a significant reduction in anhedonic symptoms was observed from the first infusion to the last infusion and 2-week follow-up in both groups (all p < 0.05). A linear mixed model did not find a significant group main effect on the MADRS anhedonia subscale scores (F = 0.5, p = 0.46).

CONCLUSION

This preliminary study shows that repeated intravenous infusions of ketamine rapidly ameliorate anhedonic symptoms in individuals experiencing anxious depression, but these individuals displayed a weaker antianhedonic response to ketamine than nonanxious depressed patients.

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

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

Pharmacogenetic and drug interaction aspects on ketamine safety in its use as antidepressant - implications for precision dosing in a global perspective

Ketamine and its enantiomer S-ketamine (esketamine) are known to produce rapid-onset antidepressant effects in major depression. Intranasal esketamine has recently come into the market as an antidepressant. Besides experience from short-term use in anesthesia and analgesia, the experience with ketamine as long-term medication is rather low. The use of ketamine and esketamine is limited due to potential neurotoxicity, psychocomimetic side effects, potential abuse and interindividual variability in treatment response including cessation of therapy. Therefore, taking a look at individual patient risks and potential underlying variability in pharmacokinetics may improve safety and dosing of these new antidepressant drugs in clinical practice. Differential drug metabolism due to polymorphic cytochrome P450 (CYP) enzymes and gene-drug interactions are known to influence the efficacy and safety of many drugs. Ketamine and esketamine are metabolized by polymorphic CYP enzymes including CYP2B6, CYP3A4, CYP2C9 and CYP2A6. In antidepressant drug therapy, usually multiple drugs are administered which are substrates of CYP enzymes, increasing the risk for drug-drug interactions (DDIs). We reviewed the potential impact of polymorphic CYP variants and common DDIs in antidepressant drug therapy affecting ketamine pharmacokinetics, and the role for dose optimization. The use of ketamine or intranasal esketamine as antidepressants demands a better understanding of the factors that may impact its metabolism and efficacy in long-term use. In addition to other clinical and environmental confounders, prior information on the pharmacodynamic and pharmacokinetic determinants of response variability to ketamine and esketamine may inform on dose optimization and identification of individuals at risk of adverse drug reactions.

The abuse liability of ketamine: A scoping review of preclinical and clinical studies

While ketamine has been used clinically over the past decades, it has only been recently shown to be a promising therapy for treatment-resistant depression (TRD). However, ketamine and related dissociative agents may also be misused recreationally, creating significant concerns for abuse liability when prescribed for depression. Although the abuse potential of ketamine is widely recognized, there is limited evidence on the differential abuse liability of ketamine enantiomers, (S)-ketamine and (R)-ketamine. The current scoping review aims to summarize the extant literature on the abuse liability of (R,S)-ketamine and the enantiomers. A systematic search was conducted on the Embase, Medline, and APA PsycInfo databases from 1947 to July 29, 2021. Clinical and preclinical studies that assessed the abuse potential of (R,S)-ketamine, (S)-ketamine, and (R)-ketamine were screened and assessed for eligibility by two independent reviewers. A total of 65 eligible studies were identified; 55 were preclinical studies and 10 were clinical studies. Only 4 preclinical studies evaluated the abuse liability of ketamine enantiomers. Available preclinical evidence suggests that (R,S)-ketamine and (S)-ketamine have greater risk for abuse compared to (R)-ketamine. (R)-ketamine, at the antidepressant-relevant doses in rodents, appears to be safe with minimal liability for abuse. Although the abuse potential of (R,S)-ketamine is well-established in animals, limited clinical studies indicate that single or repeated ketamine administrations in professionally controlled settings did not result in misuse, dependence, diversion and/or gateway activity in patients with TRD. However, most clinical studies were retrospective and did not systematically evaluate the abuse liability of ketamine via validated psychological scales/questionnaires. Future randomized controlled trials are warranted to ascertain the abuse liability of racemic, (S)- and (R)-ketamine in TRD population, especially among patients with comorbid substance use disorders.

Dysfunctional Heteroreceptor Complexes as Novel Targets for the Treatment of Major Depressive and Anxiety Disorders

Among mental diseases, major depressive disorder (MDD) and anxiety deserve a special place due to their high prevalence and their negative impact both on society and patients suffering from these disorders. Consequently, the development of novel strategies designed to treat them quickly and efficiently, without or at least having limited side effects, is considered a highly important goal. Growing evidence indicates that emerging properties are developed on recognition, trafficking, and signaling of G-protein coupled receptors (GPCRs) upon their heteromerization with other types of GPCRs, receptor tyrosine kinases, and ionotropic receptors such as N-methyl-D-aspartate (NMDA) receptors. Therefore, to develop new treatments for MDD and anxiety, it will be important to identify the most vulnerable heteroreceptor complexes involved in MDD and anxiety. This review focuses on how GPCRs, especially serotonin, dopamine, galanin, and opioid heteroreceptor complexes, modulate synaptic and volume transmission in the limbic networks of the brain. We attempt to provide information showing how these emerging concepts can contribute to finding new ways to treat both MDD and anxiety disorders.

Rapid treatments for depression: Endocannabinoid system as a therapeutic target

Current first-line treatments for major depressive disorder (MDD), i.e., antidepressant drugs and psychotherapy, show delayed onset of therapeutic effect as late as 2-3 weeks or more. In the clinic, the speed of beginning of the actions of antidepressant drugs or other interventions is vital for many reasons. Late-onset means that depression, its related disability, and the potential danger of suicide remain a threat for some patients. There are some rapid-acting antidepressant interventions, such as sleep deprivation, ketamine, acute exercise, which induce a significant response, ranging from a few hours to maximally one week, and most of them share a common characteristic that is the activation of the endocannabinoid (eCB) system. Activation of this system, i.e., augmentation of eCB signaling, appears to have anti-depressant-like actions. This article puts the idea forward that the activation of eCB signaling represents a critical mechanism of rapid-acting therapeutic interventions in MDD, and this system might contribute to the development of novel rapid-acting treatments for MDD.

Efficiently identifying individuals at high risk for treatment resistance in major depressive disorder using electronic health records

BACKGROUND

With the emergence of evidence-based treatments for treatment-resistant depression, strategies to identify individuals at greater risk for treatment resistance early in the course of illness could have clinical utility. We sought to develop and validate a model to predict treatment resistance in major depressive disorder using coded clinical data from the electronic health record.

METHODS

We identified individuals from a large health system with a diagnosis of major depressive disorder receiving an index antidepressant prescription, and used a tree-based machine learning classifier to build a risk stratification model to identify those likely to experience treatment resistance. The resulting model was validated in a second health system.

RESULTS

In the second health system, the extra trees model yielded an AUC of 0.652 (95% CI: 0.623-0.682); with sensitivity constrained at 0.80, specificity was 0.358 (95% CI: 0.300-0.413). Lift in the top quintile was 1.99 (95% CI: 1.76-2.22). Including additional data for the 4 weeks following treatment initiation did not meaningfully improve model performance.

LIMITATIONS

The extent to which these models generalize across additional health systems will require further investigation.

CONCLUSION

Electronic health records facilitated stratification of risk for treatment-resistant depression and demonstrated generalizability to a second health system. Efforts to improve upon such models using additional measures, and to understand their performance in real-world clinical settings, are warranted.

Edible Mushrooms as a Potential Component of Dietary Interventions for Major Depressive Disorder

Dietary interventions for people suffering from major depressive disorder (MDD) are an ongoing field of research. In this article, we present a comprehensive background for understanding the possibility of using edible medicinal mushrooms as an adjunctive treatment for MDD. We start with a brief history of MDD, its diagnosis, epidemiology and treatment, and the effects of diet on depression symptoms, followed by a review of neurobiological, behavioral, and clinical studies of medicinal mushrooms. We specifically highlight the results of preclinical and clinical studies on dietary supplementation with three selected mushroom species: Lion’s mane (Hericium erinaceus), Caterpillar mushroom (Cordyceps militaris), and Lingzhi/Reishi (Ganoderma lucidum). Preliminary small-sample clinical studies suggest that Lion’s mane can influence well-being of humans. In the case of Reishi, the results of clinical studies are equivocal, while in the case of Caterpillar Mushroom, such studies are underway. Edible mushrooms contain 5-hydroxy-L-tryptophan (5-HTP), which is a direct precursor of serotonin—a neurotransmitter targeted in pharmacotherapy of MDD. Therefore, in light of the well-recognized role of stress as a pathogenic factor of MDD, we also describe the neurobiological mechanisms of the interaction between stress and serotonergic neurotransmission; and summarize the current state of knowledge on dietary supplementation with 5-HTP in MDD.

Protocol for the Ketamine for Postoperative Avoidance of Depressive Symptoms (K-PASS) feasibility study: A randomized clinical trial

Background: Postoperative depressive symptoms are associated with pain, readmissions, death, and other undesirable outcomes. Ketamine produces rapid but transient antidepressant effects in the perioperative setting. Longer infusions confer lasting antidepressant activity in patients with treatment-resistant depression, but it is unknown whether a similar approach may produce a lasting antidepressant effect after surgery. This protocol describes a pilot study that will assess the feasibility of conducting a larger scale randomized clinical trial addressing this knowledge gap. Methods: This single-center, double-blind, placebo-controlled pilot trial involves the enrollment of 32 patients aged 18 years or older with a history of depression scheduled for surgery with planned intensive care unit admission. On the first day following surgery and extubation, participants will be randomized to an intravenous eight-hour infusion of either ketamine (0.5 mg kg -1 over 10 minutes followed by a continuous rate of 0.3 mg kg -1 h -1) or an equal volume of normal saline. Depressive symptoms will be quantified using the Montgomery-Asberg Depression Rating Scale preoperatively and serially up to 14 days after the infusion. To detect ketamine-induced changes on overnight sleep architecture, a wireless headband will be used to record electroencephalograms preoperatively, during the study infusion, and after infusion. The primary feasibility endpoints will include the fraction of patients approached who enroll, the fraction of randomized patients who complete the study infusion, and the fraction of randomized patients who complete outcome data collection. Conclusions: This pilot study will evaluate the feasibility of a future large comparative effectiveness trial of ketamine to reduce depressive symptoms in postsurgical patients. Registration: K-PASS is registered on ClinicalTrials.gov: NCT05233566; registered February 10, 2022.

Craving and addictive potential of esketamine as side effects?

INTRODUCTION

Esketamine was approved for adults with treatment-resistant depression (TRD) in conjunction with an oral antidepressant, and for treating depressive symptoms in adults with major depressive disorder with acute suicidal ideation or behavior. However, evidence of great efficacy and safety of esketamine is accompanied by a widespread concern regarding its addictive potential.

AREAS COVERED

A comprehensive review on the craving and addictive potential of ketamine and esketamine was carried out. In addition, a clinical case of a 34-year-old TRD woman treated with esketamine who experienced drug-seeking behaviors and craving symptomatology was described and critically discussed, with a particular focus on treatment strategies to manage craving in the short- and long term.

EXPERT OPINION

Esketamine showed great efficacy and safety in treating TRD and MDD with acute suicidal ideation or behavior. Our clinical experience demonstrated the presence of an additive potential, which has been favorably managed with slow esketamine de-titration and combination with bupropion. However, literature so far published is scant and shows contradictory findings. Therefore, it is crucial to promptly detect and manage craving symptomatology in esketamine-treated TRD patients. In our experience, the use of bupropion to counteract craving and addictive symptoms was proven to be effective and safe.

Vital Sign Changes During Intravenous Ketamine Infusions for Depression: An Exploratory Study of Prognostic Indications

PURPOSE/BACKGROUND

Subanesthetic dosing of intravenous ketamine has shown to be an effective treatment for patients with major depressive disorder. It is unknown whether sympathetic response is related to treatment outcomes. The purpose of this study is to evaluate sympathetic response to ketamine infusions as it relates to treatment outcomes.

METHODS/PROCEDURES

This retrospective study examines an outpatient population diagnosed with major depressive disorder or bipolar depression treated with ketamine infusions. Patient characteristics, depressive symptoms measured with the Patient Health Questionnaire (PHQ-9), and vital signs were retrieved by chart review. Patients (n = 145) were categorized as responders (50% reduction in PHQ-9 or less than 10 on final PHQ-9) or nonresponders. Changes in vital signs were recorded during each infusion for the initiation series.

FINDINGS/RESULTS

Ketamine responders (51.7%) showed a significant greater increase in systolic blood pressure response during the first infusion when compared with nonresponders. There was no difference seen in diastolic pressure, heart rate, or rate pressure product. Changes in vital signs for subsequent infusions also did not approach significance.

IMPLICATIONS/CONCLUSIONS

Physiologic sensitivity to the effects of ketamine may predict treatment responsiveness. Blood pressure and heart rate did not always increase. Further work should examine possible influences on physiologic responses.

The Pharmacology and Clinical Applications of Psychedelic Medicines Within Midwifery Practice

The research and use of psychedelic medicines to treat common mental health disorders has increased substantially in the past 2 decades. At the same time, knowledge is relatively uncommon among midwives regarding (1) the relative benefits of psychedelic-assisted therapy, (2) best practices associated with the delivery of psychedelic-assisted therapy, and (3) responsible integration of this potentially useful intervention into mental health treatment plans. The purpose of this review is to describe current applications of psychedelic medicines to treat common mental health disorders, to describe the current legal status of these medicines used in this context, and to explore the potential for midwifery practice in this area with further training. This article also addresses the disparities regarding LGBTQIA+ and BIPOC populations in relation to this topic and their historical exclusion from research and treatment access in this field.

The antidepressant effect and safety of non-intranasal esketamine: A systematic review

BACKGROUND

The introduction of esketamine into the field of psychiatry comes on the heels of excitement from studies on racemic ketamine. While the intranasal route has been the most studied to date, other modes of administration of esketamine may also be of interest in the management of depression.

AIMS

To systematically review the literature on non-intranasal esketamine for depression in terms of its antidepressant effect and safety.

METHODS

We searched PubMed, Embase, the Cochrane Library, and Google Scholar from inception up to February 2021. Search terms included a combination of Medical Subject Headings and text words indicative of esketamine and depression. We selected both controlled and uncontrolled studies examining non-intranasal esketamine for the treatment of depression.

RESULTS

We identified four randomized controlled trials (RCTs) on intravenous esketamine and 15 open-label studies on intravenous (n = 80), subcutaneous (n = 73), and oral (n = 5) esketamine. We found intravenous, subcutaneous, and possibly oral administration of esketamine to be effective in reducing depressive symptoms in most patients with major depressive disorder, bipolar depression, and (severe) treatment-resistant depression. Clinical response to repeated administration of esketamine persisted over the course of treatment. Esketamine was well tolerated by most patients, but open-label data indicate marked psychotomimetic symptoms in exceptional cases. The overall quality of the controlled studies was considered high, the overall quality of the uncontrolled studies low to moderate.

CONCLUSIONS

Intravenous, subcutaneous, and possibly oral esketamine may offer an effective and safe addition to the depression treatment armamentarium. However, as most included studies lacked a control group and had small sample sizes, the quality of our results is limited. Different types and formulations of ketamine remain to be compared directly.

Suicide versus Accidental Death by Autoerotic Asphyxiation in a Patient Receiving Intravenous Ketamine for Depression

Background. Clinical trials have demonstrated that subanesthetic intravenous ketamine exerts antidepressant effects lasting a week or longer postinfusion, as well as antisuicidal effects starting approximately 4 hours postinfusion and lasting 72 hours or longer. These findings have generated considerable enthusiasm within psychiatry. However, reports of treatment-emergent suicide attempts and completed suicides in some patients receiving ketamine or the ketamine enantiomer esketamine have begun to emerge. Here, we contribute to the small literature on suicide-related adverse events and ketamine with an unusual case of a patient who died either by suicide or accidental death via autoerotic asphyxiation approximately four days after a ketamine infusion. Case Presentation. The patient was a 28-year-old man with major depressive disorder, generalized anxiety disorder, panic disorder, obsessive compulsive disorder, autism spectrum disorder without intellectual disability, attention deficit hyperactivity disorder, hypothyroidism, low testosterone, and sleep apnea referred for management of treatment resistant depression. His depression briefly remitted with ketamine, and suicidality briefly disappeared. However, these improvements were short-lived. Four days after his seventh and final scheduled ketamine infusion, the patient was found dead, presumably due to autoerotic asphyxiation. Interestingly, ketamine use has been reported in association with autoerotic asphyxiation. However, given our patient’s recent severe suicidality, methods of his past suicide attempts, and family history of suicide, death from suicide seems more likely. Discussion. Here we consider the possibility of whether ketamine may have contributed to the patient’s possible suicide, either via a direct worsening of his suicidality or psychological withdrawal following cessation of treatment, given recent concerns about psychological withdrawal's potential role insuicides following esketamine treatment. Conclusions. Though we are uncertain about the patient’s cause of death, this case provides an opportunity to highlight important gaps in our understanding of the suicide-related risks of subanesthetic intravenous ketamine treatment for mood disorders and suicidality.

Ketamine as a therapeutic agent for depression and pain: mechanisms and evidence

Ketamine is an anesthetic drug which is now used to treat chronic pain conditions and psychiatric disorders, especially depression. It is an N-methyl-D-aspartate (NMDA) receptor antagonist with additional effects on α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, opioid receptors, and monoaminergic receptors. This article focuses on ketamine's role in treating depression and pain, two commonly comorbid challenging conditions with potentially shared neurobiologic circuitry. Many clinical trials have utilized intravenous or intranasal ketamine for treating depression and pain. Intravenous ketamine is more bioavailable than intranasal ketamine and both are effective for acute depressive episodes. Intravenous ketamine is advantageous for post-operative analgesia and is associated with a reduction in total opioid requirements. Few studies have treated chronic pain or concurrent depression and pain with ketamine. Larger, randomized control trials are needed to examine the safety and efficacy of intravenous vs. intranasal ketamine, ideal target populations, and optimal dosing to treat both depression and pain.