Randomized trial of ketamine masked by surgical anesthesia in patients with depression

The relationship between blinding integrity and medication efficacy in randomised-controlled trials in patients with anxiety disorders: A systematic review and meta-analysis

BACKGROUND

Blinding is thought to minimise expectancy effects and biases in double-blind randomised-controlled trials (RCTs). However, whether blinding integrity should be assessed and reported remains debated. Furthermore, it is unknown whether blinding failure influences the outcome of RCTs in anxiety disorders. We carried out a systematic review to understand whether blinding integrity is assessed and reported in anxiolytic RCTs. A secondary aim was to explore whether blinding integrity is associated with treatment efficacy.

METHOD

Our protocol was pre-registered (PROSPERO CRD42022328750). We searched electronic databases for placebo-controlled, randomised trials of medication in adults with generalised and social anxiety disorders, and in panic disorder, from 1980. We extracted data regarding blinding integrity and treatment efficacy. Risk of bias was assessed with the Cochrane risk of bias tool. Where possible, we subsequently calculated Bang's Blinding Index, and assessed the association between blinding integrity and treatment effect size.

RESULTS

Of the 248 RCTs that met inclusion criteria, we were able to obtain assessments of blinding integrity from nine (3.63%). Overall, blinding failed in five of these trials (55.56%), but blinding was intact in 80% of placebo arms. We found a significant association between reduced blinding integrity among assessors and increased treatment effect size (betas < -6.50, p's < 0.001), but this analysis involved only four studies of which two were outlying studies. In patients, we saw a non-significant trend where reduced blinding integrity in the placebo groups was associated with increased treatment efficacy, which was not present in active medication arms.

CONCLUSION

Consistent with work in other psychiatric disorders, blinding integrity is rarely reported in anxiolytic RCTs. Where it is reported, blinding appears to often fail. We found signals that suggest unblinding of clinician assessors (driven by two studies with complete unblinding), and of patients in placebo arms, might be associated with larger treatment effect sizes. We recommend that data regarding blinding integrity, along with the reasons patients and assessors offer for their beliefs regarding group allocation, are systematically collected in RCTs of anxiolytic treatment.

Suicidal ideation following ketamine prescription in patients with recurrent major depressive disorder: a nation-wide cohort study

Ketamine has gained attention for its effective treatment for patients with major depressive disorder (MDD) and suicidal ideation; Despite numerous studies presenting the rapid efficacy, long-term benefit in real-world populations remains poorly characterized. This is a retrospective cohort study using TriNetX US Collaborative Network, a platform aggregating electronic health records (EHRs) data from 108 million patients from 62 health care organizations in the US, and the study population includes 514,988 patients with a diagnosis of recurrent MDD who were prescribed relevant treatment in their EHRs. The prescription of ketamine was associated with significantly decreased risk of suicidal ideation compared to the prescription of other common antidepressants: HR = 0.63 (95% CI: 0.53-0.76) at 1 day - 7 days, 0.67 (95% CI: 0.59-0.77) at 1 day - 30 days, 0.69 (95% CI: 0.62-0.77) at 1 day - 90 days, 0.74 (95% CI: 0.67-0.81) at 1 day - 180 days, and 0.78 (95% CI: 0.69-0.83) at 1 day - 270 days. This trend was especially robust among adults over 24 years of age, females, males, and White patients with recurrent MDD. This study provides real-world evidence that ketamine has long-term benefits in mitigating suicidal ideation in patients with recurrent MDD. Future work should focus on optimizing dosage regimens for ketamine, understanding the mechanism, and the difference in various demographic subpopulations.

Repurposing General Anesthetic Drugs to Treat Depression: A New Frontier for Anesthesiologists in Neuropsychiatric Care

During the last 100 years, the role of anesthesiologists in psychiatry has focused primarily on facilitating electroconvulsive therapy and mitigating postoperative delirium and other perioperative neurocognitive disorders. The discovery of the rapid and sustained antidepressant properties of ketamine, and early results suggesting that other general anesthetic drugs (including nitrous oxide, propofol, and isoflurane) have antidepressant properties, has positioned anesthesiologists at a new frontier in the treatment of neuropsychiatric disorders. Moreover, shared interest in understanding the biologic underpinnings of anesthetic drugs as psychotropic agents is eroding traditional academic boundaries between anesthesiology and psychiatry. This article presents a brief overview of anesthetic drugs as novel antidepressants and identifies promising future candidates for the treatment of depression. The authors issue a call to action and outline strategies to foster collaborations between anesthesiologists and psychiatrists as they work toward the common goals of repurposing anesthetic drugs as antidepressants and addressing mood disorders in surgical patients.

Nitric Oxide Donor Sodium Nitroprusside Reduces Racemic Ketamine-But Not Esketamine-Induced Pain Relief

The anesthetic, analgesic and antidepressant drug ketamine produces dissociation with symptoms of psychosis and anxiety, an effect attributed to neuronal nitric oxide depletion following N-methyl-d-aspartate blockade. There is evidence that dissociation induced by racemic ketamine, containing both ketamine enantiomers (S- and R-ketamine) but not esketamine (the S-isomer) is inhibited by nitric oxide (NO) donor sodium nitroprusside (SNP). We tested whether a similar intervention would reduce racemic and esketamine-induced analgesia in a randomized double-blind placebo-controlled trial. Seventeen healthy volunteers were treated with 0.5 μg.kg-1.min-1 SNP or placebo during a 3-h infusion of escalating doses of racemic ketamine (total dose 140 mg) or esketamine (70 mg). Pain pressure threshold (PPT) and arterial blood samples for measurement of S- and R-ketamine and their metabolites, S- and R-norketamine, were obtained. The data were analyzed with a population pharmacokinetic-pharmacodynamic model that incorporated the measured S- and R- ketamine and S- and R-norketamine isomers as input and PPT as output to the model. The potency of the 2 formulations in increasing PPT from baseline by 100% was 0.47 ± 0.12 (median ± standard error of the estimate) nmol/mL for esketamine and 0.62 ± 0.19 nmol/mL for racemic ketamine, reflecting the 52 ± 27% lower analgesic potency of R-ketamine versus S-ketamine. Modeling showed that SNP had no effect on S-ketamine potency but abolished the R-ketamine analgesic effect. Similar observations were made for S- and R-norketamine. Since SNP had no effect on S-ketamine analgesia, we conclude that SNP interacts on R-ketamine nociceptive pathways, possibly similar to its effects on R-ketamine activated dissociation pathways.

Prevalence and characteristics of preoperative patients with depression

BACKGROUND

Within the perioperative period, depression-related diagnoses are associated with postoperative complications. We developed a perioperative depression screening programme to assess disease prevalence and feasibility for intervention.

METHODS

Adult patients in multiple surgical departments at a single academic centre were screened for depression via the electronic health record patient portal or preoperative anaesthesia clinic before surgery, using the Patient Health Questionnaire (PHQ)-2 and -8. We utilised a broad method, screening all patients, and a focused method, only screening patients with a history of depression. Logistic regression was used to identify characteristics associated with clinically significant depression (PHQ-8 ≥10). Symptomatic patients were administered a brief psychoeducational intervention and referred for mental health services.

RESULTS

A total of 3735 patients were identified by the broad and focused screens, of whom 2940 (79%) returned PHQ-2 data and were included in analysis. The broad screen (N=1216) found 46 (4%) patients who reported symptoms of moderate or greater severity. The focused screen (N=1724) found 242 (14%) patients with symptoms of moderate or greater severity and over all higher rates of depression across the symptom severity scale. Using the total screened pool, logistic regression identified a history of depression as the strongest associated patient characteristic variable but this did not capture most cases. Finally, we found that 66% of patients who were contacted about mental health services accepted referrals or sought outside care.

CONCLUSIONS

At least 4% of preoperative patients have clinically significant symptoms of depression, most of whom do not have a chart history of depression.

Ketamine in the effective management of chronic pain, depression, and posttraumatic stress disorder for Veterans: A meta-analysis and systematic review

Introduction

Ketamine has emerged as a promising treatment alternative for the management of chronic pain. Despite encouraging findings in civilian populations, and favourable results from trials examining its efficacy in military populations, there is still a dearth of information pointing to optimal specifications related to ketamine administration for pain, depression, and posttraumatic stress disorder (PTSD) in military populations. This meta-analysis and systematic review synthesised available evidence on the effectiveness, tolerability, and feasibility of ketamine in the management of chronic pain and mental health conditions in military populations.

Methods

This review followed the Cochrane's Guide for systematic reviews of interventions and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) as frameworks for data collection and synthesis.

Results

A total of 11 studies and 22 independent samples were retained for data analyses. Across samples, improvements in pain, depression, and PTSD outcomes were evident, with the use of ketamine leading to significant reductions, g = 1.76, SE = 0.19, 95% CI (1.39, 2.13), Z = 9.26, p <.001. These effect sizes were robust with moderate-to-large effects. In addition, the reductions in symptoms were observed in both active-duty and Veteran groups, and for different routes of ketamine administration, frequencies of ketamine administration, duration of ketamine treatments, dosage, study design, and allowance for concurrent treatments.

Discussion

This review provides a preliminary synthesis of available evidence which suggests that ketamine may be a potential option for the treatment of depression, PTSD, and chronic pain in military populations. The viability of ketamine as an alternative treatment may be particularly impactful for those who are treatment resistant, experience chronic symptoms, and/or have exhausted conventional treatments. More research is warranted in order verify the findings presented in this review.

(R)-(-)-Ketamine: The Promise of a Novel Treatment for Psychiatric and Neurological Disorders

NMDA receptor antagonists have potential for therapeutics in neurological and psychiatric diseases, including neurodegenerative diseases, epilepsy, traumatic brain injury, substance abuse disorder (SUD), and major depressive disorder (MDD). (S)-ketamine was the first of a novel class of antidepressants, rapid-acting antidepressants, to be approved for medical use. The stereoisomer, (R)-ketamine (arketamine), is currently under development for treatment-resistant depression (TRD). The compound has demonstrated efficacy in multiple animal models. Two clinical studies disclosed efficacy in TRD and bipolar depression. A study by the drug sponsor recently failed to reach a priori clinical endpoints but post hoc analysis revealed efficacy. The clinical value of (R)-ketamine is supported by experimental data in humans and rodents, showing that it is less sedating, does not produce marked psychotomimetic or dissociative effects, has less abuse potential than (S)-ketamine, and produces efficacy in animal models of a range of neurological and psychiatric disorders. The mechanisms of action of the antidepressant effects of (R)-ketamine are hypothesized to be due to NMDA receptor antagonism and/or non-NMDA receptor mechanisms. We suggest that further clinical experimentation with (R)-ketamine will create novel and improved medicines for some of the neurological and psychiatric disorders that are underserved by current medications.

Expectancy Effects in Psychedelic Trials

Clinical trials of psychedelic compounds like psilocybin, lysergic acid diethylamide (LSD), and N,N-dimethyltrptamine (DMT) have forced a reconsideration of how nondrug factors, such as participant expectations, are measured and controlled in mental health research. As doses of these profoundly psychoactive substances increase, so does the difficulty in concealing the treatment condition in the classic double-blind, placebo-controlled trial design. As widespread public enthusiasm for the promise of psychedelic therapy grows, so do questions regarding whether and how much trial results are biased by positive expectancy. First, we review the key concepts related to expectancy and its measurement. Then, we review expectancy effects that have been reported in both micro- and macrodose psychedelic trials from the modern era. Finally, we consider expectancy as a discrete physiological process that can be independent of, or even interact with, the drug effect. Expectancy effects can be harnessed to improve treatment outcomes and can also be actively managed in controlled studies to enhance the rigor and generalizability of future psychedelic trials.

A retrospective analysis of iv ketamine outcome on hospitalisations in an unselected psychiatric sample

OBJECTIVE

This study aims to explore the outcome with iv ketamine treatment in a real-world clinical setting, primarily measured as posttreatment days hospitalised.

METHODS

The psychiatric medical records of 46 patients having received iv ketamine on a psychiatric treatment indication between 2015 and 2018 were retrospectively examined. Analysis comparing the number and duration of hospital admissions before and after ketamine treatment as well as logistic regression analysis to investigate clinical predictors of effectiveness, were performed. To assess patients' severity of depressed symptoms records were screened for MADRS-S scores.

RESULTS

No significant difference between pre- and posttreatment hospital days (p = 0.170), or number of hospitalisations (p = 0.740) were found. The response rate was 31% and remission rate 21%. None of the predictors showed statistical significance in the logistic model.

CONCLUSION

Iv ketamine treatment showed effectiveness in reducing depressive symptoms even with complex patients in a real-world clinical setting. However, this did not translate to a reduction in hospitalisation. Highlighting the multifaceted challenges posed when implementing iv ketamine treatment in clinical practice.

Optimizing Antidepressant Efficacy: Multimodal Neuroimaging Biomarkers for Prediction of Treatment Response

Major depressive disorder (MDD) is a common and often severe condition that profoundly diminishes quality of life for individuals across ages and demographic groups. Unfortunately, current antidepressant and psychotherapeutic treatments exhibit limited efficacy and unsatisfactory response rates in a substantial number of patients. The development of effective therapies for MDD is hindered by the insufficiently understood heterogeneity within the disorder and its elusive underlying mechanisms. To address these challenges, we present a target-oriented multimodal fusion framework that robustly predicts antidepressant response by integrating structural and functional connectivity data (sertraline: R2 = 0.31; placebo: R2 = 0.22). Through the model, we identify multimodal neuroimaging biomarkers of antidepressant response and observe that sertraline and placebo show distinct predictive patterns. We further decompose the overall predictive patterns into constitutive network constellations with generalizable structural-functional co-variation, which exhibit treatment-specific association with personality traits and behavioral/cognitive task performance. Our innovative and interpretable multimodal framework provides novel insights into the intricate neuropsychopharmacology of antidepressant treatment and paves the way for advances in precision medicine and development of more targeted antidepressant therapeutics.

Rethinking ketamine as a panacea: adverse effects on oxygenation and postoperative outcomes

Ketamine is receiving renewed interest in perioperative medicine as an anaesthetic adjunct and a treatment for chronic conditions, including depression. Ketamine's complex pharmacologic profile results not only in several desirable effects, such as anaesthesia and analgesia, but also multiple adverse effects affecting the central nervous, cardiovascular, and respiratory systems. In addition to defining patient-centred outcomes in future clinical studies on the perioperative uses of ketamine, careful monitoring for its numerous adverse effects will be paramount.

Cortical thickness of the posterior cingulate cortex is associated with the ketamine-induced altered sense of self: An ultra-high field MRI study

Subanesthetic doses of ketamine induce an antidepressant effect within hours in individuals with treatment-resistant depression while it furthermore induces immediate but transient psychotomimetic effects. Among these psychotomimetic effects, an altered sense of self has specifically been associated with the antidepressant response to ketamine as well as psychedelics. However, there is plenty of variation in the extent of the drug-induced altered sense of self experience that might be explained by differences in basal morphological characteristics, such as cortical thickness. Regions that have been previously associated with a psychedelics-induced sense of self and with ketamine's mechanism of action, are the posterior cingulate cortex (PCC) and the pregenual anterior cingulate cortex (pgACC). In this randomized, placebo-controlled, double-blind cross-over magnetic resonance imaging study, thirty-five healthy male participants (mean age ± standard deviation (SD) = 25.1 ± 4.2 years) were scanned at 7 T. We investigated whether the cortical thickness of two DMN regions, the PCC and the pgACC, are associated with disembodiment and experience of unity scores, which were used to index the ketamine-induced altered sense of self. We observed a negative correlation between the PCC cortical thickness and the disembodiment scores (R = -0.54, p < 0.001). In contrast, no significant association was found between the pgACC cortical thickness and the ketamine-induced altered sense of self. In the context of the existing literature, our findings highlight the importance of the PCC as a structure involved in the mechanism of ketamine-induced altered sense of self that seems to be shared with different antidepressant agents with psychotomimetic effects operating on different classes of transmitter systems.

The mechanistic divide in psychedelic neuroscience: An unbridgeable gap?

In recent years, psychedelics have generated considerable excitement and interest as potential novel therapeutics for an array of conditions, with the most advanced evidence base in the treatment of certain severe and/or treatment-resistant psychiatric disorders. An array of clinical and pre-clinical evidence has informed our current understanding of how psychedelics produce profound alterations in consciousness. Mechanisms of psychedelic action include receptor binding and downstream cellular and transcriptional pathways, with long-term impacts on brain structure and function-from the level of single neurons to large-scale circuits. In this perspective, we first briefly review and synthesize separate lines of research on potential mechanistic processes underlying the acute and long-term effects of psychedelic compounds, with a particular emphasis on highlighting current theoretical models of psychedelic drug action and their relationships to therapeutic benefits for psychiatric and brain-based disorders. We then highlight an existing area of ongoing controversy we argue is directly informed by theoretical models originating from disparate levels of inquiry, and we ultimately converge on the notion that bridging the current chasm in explanatory models of psychedelic drug action across levels of inquiry (molecular, cellular, circuit, and psychological/behavioral) through innovative methods and collaborative efforts will ultimately yield the comprehensive understanding needed to fully capitalize on the potential therapeutic properties of these compounds.

Sub-anesthetic dose of esketamine decreases postoperative opioid self-administration after spine surgery: a retrospective cohort analysis

The use of intraoperative sub-anesthetic esketamine for postoperative analgesia is controversial. In this study, the impact of sub-anesthetic esketamine on postoperative opioid self-administration was determined. Patients who underwent spinal surgery with patient-controlled analgesia (PCA) from January 2019 to December 2021 were respectively screened for analysis. Postoperative PCA was compared between patients who received a sub-anesthetic esketamine dose and patients who were not treated with esketamine (non-esketamine group) with or without propensity score matching. Negative binomial regression analysis was used to identify factors associated with postoperative PCA. Patients who received intraoperative sub-anesthetic esketamine self-administered less PCA (P = 0.001). Azasetron, esketamine, and dexamethasone lowered the self-administration of PCA (IRR with 95% confidential interval, 0.789 [0.624, 0.993]; 0.581 [0.458, 0.741]; and 0.777 [0.627, 0.959], respectively). Fixation surgery and drinking were risk factors for postoperative PCA (1.737 [1.373, 2.188] and 1.332 [1.032, 1.737] for fixation surgery and drinking, respectively). An intraoperative sub-anesthetic dose of esketamine decreases postoperative opioid self-administration. Azasetron and dexamethasone also decrease postoperative opioid consumption. The study is registered at www.chictr.org.cn (ChiCTR2300068733).

Synthetic surprise as the foundation of the psychedelic experience

Psychedelic agents, such as LSD and psilocybin, induce marked alterations in consciousness via activation of the 5-HT2A receptor (5-HT2ARs). We hypothesize that psychedelics enforce a state of synthetic surprise through the biased activation of the 5-HTRs system. This idea is informed by recent insights into the role of 5-HT in signaling surprise. The effects on consciousness, explained by the cognitive penetrability of perception, can be described within the predictive coding framework where surprise corresponds to prediction error, the mismatch between predictions and actual sensory input. Crucially, the precision afforded to the prediction error determines its effect on priors, enabling a dynamic interaction between top-down expectations and incoming sensory data. By integrating recent findings on predictive coding circuitry and 5-HT2ARs transcriptomic data, we propose a biological implementation with emphasis on the role of inhibitory interneurons. Implications arise for the clinical use of psychedelics, which may rely primarily on their inherent capacity to induce surprise in order to disrupt maladaptive patterns.

Making Sense of Psychedelics in the CNS

For centuries, ancient lineages have consumed psychedelic compounds from natural sources. In the modern era, scientists have since harnessed the power of computational tools, cellular assays, and behavioral metrics to study how these compounds instigate changes on molecular, cellular, circuit-wide, and system levels. Here, we provide a brief history of psychedelics and their use in science, medicine, and culture. We then outline current techniques for studying psychedelics from a pharmacological perspective. Finally, we address known gaps in the field and potential avenues of further research to broaden our collective understanding of physiological changes induced by psychedelics, the limits of their therapeutic capabilities, and how researchers can improve and inform treatments that are rapidly becoming accessible worldwide.