Acute effects of ketamine and esketamine on cognition in healthy subjects: A meta-analysis

Effects of subanesthetic repeated esketamine infusions on memory function and NGF in patients with depression: An open-label study

BACKGROUND

Subanesthetic ketamine is a rapidly acting antidepressant, yet the effects of ketamine on cognitive function are inconsistent. The primary objective of this study was to explore the effects of esketamine on memory function and plasma levels of nerve growth factor (NGF) in patients with depression.

METHODS

A total of 132 patients with depression completed six intravenous esketamine infusions (0.4 mg/kg) over 11 days. Depressive symptoms and neurocognitive function were assessed using the Montgomery-Asberg Depression Rating Scale (MADRS) and Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Plasma NGF levels were assayed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The mean MADRS score of depressed patients decreased from 32.11 ± 10.06 to 15.10 ± 8.62 after six infusions. Significant improvement in immediate memory, language, attention, and delayed memory were observed. NGF plasma levels increased from 226.13 ± 61.73 to 384.37 ± 56.89. Pearson's correlation analysis showed a positive correlation between memory function and NGF levels at baseline. The baseline memory function was negatively associated with the changes in NGF levels.

LIMITATION

The major limitation of this study is the open-label design.

CONCLUSIONS

Subanesthetic esketamine infusions could improve depressive symptoms and neurocognitive function. Our study showed increased plasma NGF levels in depressed patients after treatment, suggesting that NGF may play a role in the improvement of memory function by esketamine.

Ketamine use in a large global sample: Characteristics, patterns of use and emergency medical treatment

BACKGROUND

Ketamine's popularity has surged globally in the past decade, especially among young men. Emergency department visits due to its toxicity remain relatively rare, often linked to co-occurring use of other substances.

AIMS

Using data from the Global Drug Survey (GDS) 2018, this study explored the correlates associated with lifetime and past-year ketamine use, and estimated the socio-demographic characteristics, usage patterns and experiences of respondents seeking emergency medical treatment (EMT) after ketamine use.

METHODS

Secondary analysis of GDS 2018, an online cross-sectional survey on drug use patterns conducted between November 2017 and January 2018.

RESULTS

The survey received 130,761 valid responses, with 5.93% reporting lifetime ketamine use, of which 57.70% used ketamine within the past year. Predominantly, respondents were from Germany, England and Denmark. Within the past year, 8.55% met the criteria for ketamine dependence. Respondents who used ketamine in their lifetime tended to be young (mean (x̄) = 27.37 years), men, heterosexual and of white ethnicity. Younger age (x̄ = 24.84 years), gay sexual orientation, student status, past-year use of other drugs and no lifetime mental health diagnosis were associated with past-year ketamine use. Among 4477 respondents reporting past-year ketamine use, 120 adverse events were reported, with less than 0.10% prompting EMT seeking.

CONCLUSION

The study reveals frequent ketamine use but low harm occurrence, underscoring the complex interplay between ketamine use, substance use and dependence, and related factors. This underscores the need to reassess EMT priorities, implement tailored harm reduction strategies and incorporate comprehensive screening for addressing ketamine and substance dependence challenges.

Cognitive changes in patients with unipolar TRD treated with IV ketamine: A systematic review

BACKGROUND

Unipolar treatment-resistant depression (MDD-TRD) is associated with neurocognitive impairment. Ketamine, an emerging treatment for MDD-TRD, may have neurocognitive benefits, but evidence remains limited.

METHODS

We conducted a systematic search on EMBASE, Google Scholar, PsycINFO, and PubMed and included studies exploring the cognitive effects of intravenous (IV) ketamine treatment in the management of MDD-TRD following the PRISMA guidelines. We analyzed cognitive scale score changes pre- and post-IV ketamine treatment and the quality of the evidence using the Cochrane risk of bias tool and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

RESULTS

Out of 1171 identified studies, fourteen studies were included in this study. Most studies reported positive cognitive outcomes post-ketamine treatment, including improvements in processing speed, working memory, verbal and visual memory, executive function, attention, emotional processing, and auditory verbal episodic memory. Variability existed, with one study reporting negative effects on verbal memory. Overall, studies exhibited a low risk of bias.

LIMITATIONS

Several limitations impacted the results observed, including confining our scope to articles in English, heterogeneity of the included studies, small sample sizes, and the predominance of a female, Western, and Caucasian population, constraining the generalizability of the findings.

CONCLUSIONS

IV ketamine treatment shows promise in improving neurocognitive function in MDD-TRD patients. However, further research is warranted to elucidate long-term effects, control for confounders such as concomitant medications, and explore neurocognitive subgroups within the TRD population. These findings underscore the need for comprehensive assessment and management of cognitive symptoms in TRD, informing future clinical practice.

Ecotoxicological risk assessment of the novel psychoactive substance Esketamine: Emphasis on fish skeletal, behavioral, and vascular development

Novel psychoactive substances (NPS), such as Esketamine (Esket), often contaminate the aquatic ecosystems following human consumption, raising concerns about the residues and potential ecological hazards to non-target organisms. The study used zebrafish as a model organism to investigate the developmental toxicity and ecotoxicological effects of acute Esket exposure. Our findings demonstrate that exposure to Esket significantly affected the early development and angiogenesis of zebrafish embryos/larvae. The mandible length was significantly decreased, and the angles between the pharyngeal arch cartilages were narrowed compared to the control group (all P < 0.05). Additionally, Esket resulted in a decrease of 47.6-89.8 % in the number of neural crest cells (NCC). Transcriptome analysis indicated altered expression of genes associated with cartilage and osteoblast growth. Moreover, Esket significantly inhibited swimming ability in zebrafish larvae and was accompanied by behavioral abnormalities and molecular alterations in the brain. Potential mechanisms underlying Esket-induced behavioral disorders involve neurotransmitter system impairment, abnormal cartilage development and function, aberrant vascular development, as well as perturbations in oxidative stress and apoptosis signaling pathways. Notably, the dysregulation of skeleton development through the bone morphogenetic protein (BMP) signaling pathway is identified as the primary mechanistic behind Esket-induced behavioral disorder. This study enhances our understanding of Esket's ecotoxicology profile and provides a comprehensive assessment of the environmental risks associated with NPS.

Ketamine differentially affects implicit and explicit memory processes in rats

RATIONALE

Ketamine, a non-competitive NMDA receptor antagonist, produces antidepressant effects at subanesthetic doses. The therapeutic effect, however, is often accompanied by cognitive side effects, including memory impairments. Yet, the specific effects of ketamine on different processes of implicit and explicit memory remain to be elucidated.

OBJECTIVES

We examined the effect of an antidepressant dose of ketamine (10 mg/kg, IP) on the encoding, retrieval, and modulation processes of fear memory and spatial memory in adult Wistar rats.

METHODS

Ketamine was administered before the fear acquisition, retrieval, or extinction procedures in a Pavlovian fear conditioning task. In another set of experiments, it was administered before the training, probe trial, or reversal training phases of the Morris Water Maze (MWM).

RESULTS

The antidepressant dose of ketamine partially impaired fear extinction when administered before the acquisition or retrieval. In contrast, it facilitated memory modulation and decreased the escape latency in the first day of reversal training in the MWM when administered before the training or reversal training sessions. Encoding or retrieval performance in either type of memory was not affected.

CONCLUSIONS

These findings show that ketamine does not impair the acquisition or retrieval processes of cued fear or spatial memory; but exerts differential effects on memory modulation of these implicit and explicit memory paradigms, by disrupting fear extinction and facilitating reversal spatial learning.

Effect of Esketamine Nasal Spray on Cognition in Patients With Treatment-Resistant Depression: Results From Four Phase 3 Studies

BACKGROUND

While esketamine is effective in treatment-resistant depression (TRD), detailed information about the effect of esketamine on cognition is relatively scarce. This analysis assessed the effect of short-term (3 double-blind [DB] studies: DB1, DB2, and DB4) or long-term maintenance treatment (DB3) with esketamine nasal spray (ESK) compared with a placebo (PBO) combined with active-comparator, on cognition in patients with TRD.

METHODS

Patients (DB1/DB2/DB3: [18-64 years, n = 747]; DB4: [65 years or older, n = 137]) with TRD received ESK (DB1/DB2/DB3: 56/84 mg; DB4: 28/56/84 mg) or PBO+newly initiated oral antidepressant (OAD) as per treatment schedules. Cognitive assessments-Cogstate battery and Hopkins Verbal Learning Test-Revised-were administered at baseline, Day 28/early withdrawal, and follow-up visits in DB1/DB2/DB4 and at 12-week intervals in the DB3 maintenance phase. Descriptive statistics were used to analyze ESK effects on cognition with effect sizes and 95% confidence intervals to express the nature and magnitude of treatment effects relative to active-comparator+PBO. Correlation between depression severity (Montgomery-Ǻsberg Depression Rating Scale scores [MADRS]) and cognition was assessed at baseline and endpoint(s).

RESULTS

At baseline, mild-to-moderate impairment in psychomotor function, attention, and memory (working and episodic) were evident. For each DB1/DB2/DB4, group mean performance in Z-scores for ESK+OAD and OAD+PBO groups on all cognitive tests remained similar or slightly improved from baseline at endpoint (Day 28) and follow-up assessments. Similarly, in DB3 (maintenance phase), both groups generally showed improvement in cognitive performance at endpoint(s). Correlations between MADRS scores and performance on the cognitive test battery were small at baseline and endpoint(s).

CONCLUSIONS

This analysis did not identify evidence of negative effects on cognition following short-term or long-term maintenance treatment with ESK+OAD in patients with TRD.

Evidence for the Contribution of the miR-206/BDNF Pathway in the Pathophysiology of Depression

Depression is a complex disorder with substantial impacts on individual health and has major public health implications. Depression results from complex interactions between genetic and environmental factors. Epigenetic mechanisms, including DNA methylation, microRNAs (miRNAs), and histone modifications, can produce heritable phenotypic changes without a change in DNA sequence and recently were proven to mediate lasting increases in the risk of depression following exposure to adverse life events. Of these, miRNAs are gaining attention for their role in the pathogenesis of many stress-associated mental disorders, including depression. One such miRNA is microRNA-206 (miR-206), which is a critical candidate for increasing the susceptibility to stress. Although miR-206 is thought to be a typical muscle-specific miRNA, it is expressed throughout the brain, particularly in the hippocampus and prefrontal cortex. Until now, only a few studies have been conducted on rodents to understand the role of miR-206 in stress-related abnormalities in neurogenesis. However, the precise underlying molecular mechanism of miR-206-mediated depression-like behaviors remains largely unknown. Here, we reviewed recent advances in the field of biomedical and clinical research on the role of miR-206 in the pathogenesis of depression from studies using different tissues and various experimental designs and described how abnormalities in miR-206 expression in these tissues can affect neuronal functions. Moreover, we focused on studies investigating the brain-derived neurotrophic factor (BDNF) as a functional target of miR-206, where miR-206 has been implicated in the pathogenesis of depression by suppressing the expression of the BDNF. In summary, these studies confirm the existence of a tight correlation between the pathogenesis of depression and the miR-206/BDNF pathway.

Effect of intermittent subchronic MK-801 administration on dopamine synthesis capacity and responsiveness in the prefrontal cortex

AIM

The therapeutic potential of N-methyl-D-aspartate glutamate receptor (NMDAR) antagonists, particularly ketamine, in mood disorders, is linked to their modulation of dopamine dynamics in the medial prefrontal cortex (mPFC). However, conflicting effects of distinct NMDAR antagonists, like ketamine and phencyclidine, on mPFC dopamine levels stem from variances in their receptor affinity profiles. This study investigates the impact of intermittent subchronic administration of an NMDAR antagonist on dopamine synthesis capacity and responsiveness within the mPFC, focusing on Dizocilpine (MK-801), a highly selective NMDAR antagonist.

METHODS

In vivo microdialysis and high-performance liquid chromatography assessed extracellular dopamine levels in the mPFC following subchronic MK-801 treatment. Locomotor activity was measured using a computed video tracking system.

RESULTS

Intermittent subchronic MK-801 administration, followed by a 24-h withdrawal, preserved both dopamine synthesis capacity and responsiveness to MK-801 challenge in the mPFC. However, altered locomotor activity was observed, deviating from previous findings indicating impaired dopamine synthesis and responsiveness in the mPFC with twice-daily subchronic NMDAR antagonist treatment.

CONCLUSION

These findings offer crucial biochemical insights into the diverse impacts of NMDAR antagonists on dopamine dynamics and the distinct therapeutic mechanisms associated with ketamine in depression treatment. However, further investigation is imperative to pinpoint potential inconsistencies stemming from variances in drug type, dosage, or administration frequency.

Protocol for a randomised controlled trial of ketamine versus ketamine and behavioural activation therapy for adults with treatment-resistant depression in the community

INTRODUCTION

Although short-term benefits follow parenteral ketamine for treatment-resistant major depressive disorder (TR-MDD), there are challenges that prevent routine use of ketamine by clinicians. These include acute dissociative effects of parenteral ketamine, high relapse rates following ketamine dosing and the uncertain role of psychotherapy. This randomised controlled trial (RCT) seeks to establish the feasibility of evaluating repeated oral doses of ketamine and behavioural activation therapy (BAT), compared with ketamine treatment alone, for TR-MDD. We also aim to compare relapse rates between treatment arms to determine the effect size of adding BAT to oral ketamine.

METHODS AND ANALYSIS

This is a prospectively registered, two-centre, single-blind RCT. We aim to recruit 60 participants with TR-MDD aged between 18 and 65 years. Participants will be randomised to 8 weeks of oral ketamine and BAT, or 8 weeks of oral ketamine alone. Feasibility will be assessed by tracking attendance for ketamine and BAT, acceptability of treatment measures and retention to the study follow-up protocol. The primary efficacy outcome measure is the Montgomery-Asberg Depression Rating Scale (MADRS) measured weekly during treatment and fortnightly during 12 weeks of follow-up. Other outcome measures will assess the tolerability of ketamine and BAT, cognition and activity (using actigraphy). Participants will be categorised as non-responders, responders, remitters and relapsed during follow-up. MADRS scores will be analysed using a linear mixed model. For a definitive follow-up RCT study to be recommended, the recruitment expectations will be met and efficacy outcomes consistent with a >20% reduction in relapse rates favouring the BAT and ketamine arm will be achieved.

ETHICS AND DISSEMINATION

Ethics approval was granted by the New Zealand Central Health and Disability Ethics Committee (reference: 2023 FULL18176). Study findings will be reported to participants, stakeholder groups, conferences and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

UTN: U1111-1294-9310, ACTRN12623000817640p.

Studies on neurobehavioural properties of Caralluma dalzielii N.E Br. aqueous aerial parts extract in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Caralluma dalzielii (Asclepiadiaceae) is a shrub used in folkloric medicine to treat epilepsy, pain and infertility in sub-Saharan Africa. Previous studies demonstrated its analgesic, antiulcer, anticonvulsant, and anti-inflammatory activities.

AIM

This study aimed to determine the neurobehavioural properties of Caralluma dalzielii aqueous aerial parts extract (CDAE) in mice using standard experimental models.

MATERIALS AND METHODS

Neurobehavioural activities of CDAE were evaluated (100, 200, and 400 mg/kg) in Swiss Albino mice using the beam walk, staircase, hole board, object recognition, open field assay, Y-maze and forced swimming tests. Phytochemical constituents were analysed using GC-MS.

RESULTS

CDAE significantly increased the mean number of head dips, recognition index and spontaneous alternation in hole board (14.03 at 400 mg/kg and 6.01 in distilled water group; p < 0.05), object recognition (68.16% at 400 mg/kg compared with 51.66% of distilled water group) and Y maze (9.16 at 400 mg/kg as against 4.66 of distilled water group; p < 0.05) tests respectively. It decreased the rearing counts as well as the peripheral and central square crossing in the staircase (4.2 at 400 mg/kg as against 7.87 of the distilled water group; p < 0.05) and open field tests (central, 0.81; peripheral, 1.66 at 400 mg/kg as against central, 5.23; peripheral 11.83 of the distilled water control group; p < 0.05), respectively. There were no significant effects on beam walk assays and forced swim tests. The GC-MS analysis identified a hundred compounds in CDAE. Some compounds which have been reported to possess neurobehavioural activity that were identified include 3,5-Dimethylpyrazole, 2-Amino-5-methylbenzoic acid, Acetophenone, and Tetrahydropyran.

CONCLUSION

CDAE demonstrated anxiolytic, anti-hyperactivity, and memory-improving effects in mice. The extract may possess GABAergic and glutamatergic properties. More studies are needed to confirm this. Isolation of the bioactive compounds is currently ongoing to unravel the bioactive constituents present in C. dalzielii extract.

Exploring the multifaceted potential of (R)-ketamine beyond antidepressant applications

(R, S)- and (S)-ketamine have made significant progress in the treatment of treatment-resistant depression (TRD) and have become a research focus in recent years. However, they both have risks of psychomimetic effects, dissociative effects, and abuse liability, which limit their clinical use. Recent preclinical and clinical studies have shown that (R)-ketamine has a more efficient and lasting antidepressant effect with fewer side effects compared to (R, S)- and (S)-ketamine. However, a recent small-sample randomized controlled trial found that although (R)-ketamine has a lower incidence of adverse reactions in adult TRD treatment, its antidepressant efficacy is not superior to the placebo group, indicating its antidepressant advantage still needs further verification and clarification. Moreover, an increasing body of research suggests that (R)-ketamine might also have significant applications in the prevention and treatment of medical fields or diseases such as cognitive disorders, perioperative anesthesia, ischemic stroke, Parkinson's disease, multiple sclerosis, osteoporosis, substance use disorders, inflammatory diseases, COVID-19, and organophosphate poisoning. This article briefly reviews the mechanism of action and research on antidepressants related to (R)-ketamine, fully revealing its application potential and development prospects, and providing some references and assistance for subsequent expanded research.

A Meta-Analysis of Functional Neuroimaging Studies of Ketamine Administration in Healthy Volunteers

Ketamine administration leads to a psychotomimetic state when taken in large bolus doses, making it a valid model of psychosis. Therefore, understanding ketamine's effects on brain functioning is particularly relevant. This meta-analysis focused on neuroimaging studies that examined ketamine-induced brain activation at rest and during a task. Included are 10 resting-state studies and 23 task-based studies, 9 of which were measuring executive functions. Using a stringent statistical threshold (TFCE <0.05), the results showed increased activity at rest in the dorsal anterior cingulate cortex (ACC), and increased activation of the right Heschl's gyrus during executive tasks, following ketamine administration. Uncorrected results showed increased activation at rest in the right (anterior) insula and the right-fusiform gyrus, as well as increased activation during executive tasks in the rostral ACC. Rest-state studies highlighted alterations in core hubs of the salience network, while task-based studies suggested an impact on task-irrelevant brain regions. Increased activation in the rostral ACC may indicate a failure to deactivate the default mode network during executive tasks following ketamine administration. The results are coherent with alterations found in schizophrenia, which confer external validity to the ketamine model of psychosis. Studies investigating the neural mechanisms of ketamine's antidepressant action are warranted.

Apoptotic mechanism of development inhibition in zebrafish induced by esketamine

Esketamine, a widely used intravenous general anesthetic, is also employed for obstetric and pediatric anesthesia, and depression treatment. However, concerns regarding esketamine abuse have emerged. Moreover, the potential in vivo toxicity of esketamine on growth and development remains unclear. To address these concerns, we investigated the effects of esketamine exposure on developmental parameters, cell apoptosis, and gene expression in zebrafish. Esketamine exposure concentration-dependently decreased the heart rate and body length of zebrafish embryos/larvae while increasing the hatching rate and spontaneous movement frequency. Developmental retardation of zebrafish larvae, including shallow pigmentation, small eyes, and delayed yolk sac absorption, was also observed following esketamine treatment. Esketamine exposure altered the expression of apoptosis-related genes in zebrafish heads, primarily downregulating bax, caspase9, caspase3, caspase6, and caspase7. Intriguingly, BTSA1, a Bax agonist, reversed the anti-apoptotic and decelerated body growth effects of esketamine in zebrafish. Collectively, our findings suggest that esketamine may hinder embryonic development by inhibiting embryonic apoptosis via the Bax/Caspase9/Caspase3 pathway. To the best of our knowledge, this is the first study to report the lethal toxicity of esketamine in zebrafish. We have elucidated the developmental toxic effects of esketamine on zebrafish larvae and its potential apoptotic mechanisms. Further studies are warranted to evaluate the safety of esketamine in animals and humans.

Mismatch Negativity (MMN) as a Pharmacodynamic/Response Biomarker for NMDA Receptor and Excitatory/Inhibitory Imbalance-Targeted Treatments in Schizophrenia

Schizophrenia is a major mental disorder that affects approximately 0.5% of the population worldwide. Persistent negative symptoms and cognitive impairments associated with schizophrenia (CIAS) are key features of the disorder and primary predictors of long-term disability. At the neurochemical level, both CIAS and negative symptoms are potentially attributable to dysfunction or dysregulation of N-methyl-D-aspartate receptor (NMDAR)-mediated neurotransmission within cortical and subcortical brain regions. At present, there are no approved treatments for either CIAS or persistent negative symptoms. Development of novel treatments, moreover, is limited by the lack of biomarkers that can be used translationally across preclinical and early-stage clinical investigation. The present chapter describes the use of mismatch negativity (MMN) as a pharmacodynamic/response (PD/R) biomarker for early-stage clinical investigation of NMDAR targeted therapies for schizophrenia. MMN indexes dysfunction of early auditory processing (EAP) in schizophrenia. In humans, deficits in MMN generation contribute hierarchically to impaired cognition and functional outcome. Across humans, rodents, and primates, MMN has been linked to impaired NMDAR function and resultant disturbances in excitatory/inhibitory (E/I) balance involving interactions between glutamatergic (excitatory) pyramidal and GABAeric (inhibitory) local circuit neurons. In early-stage clinical trials, MMN has shown sensitivity to the acute effects of novel pharmacological treatments. These findings support use of MMN as a pharmacodynamic/response biomarker to support preclinical drug discovery and early-stage proof-of-mechanisms studies in schizophrenia and other related neuropsychiatric disorders.

Multidisciplinary development of guidelines for ketamine treatment for treatment-resistant major depression disorder for use by adult specialist mental health services in New Zealand

BACKGROUND

The evidence base for racemic ketamine treatment for treatment-resistant major depressive disorder (TRD) continues to expand, but there are major challenges translating this evidence base into routine clinical care.

AIM

To prepare guidelines for ketamine treatment of TRD that are suitable for routine use by publicly funded specialist mental health services.

METHOD

We consulted with senior leadership, clinical pharmacy, psychiatrists, nursing, service users and Māori mental health workers on issues relating to ketamine treatment. We prepared treatment guidelines taking the evidence base for ketamine treatment and the consultation into account.

RESULTS

Ketamine treatment guidance is reported. This offers two treatment pathways, including a test of ketamine responsiveness with intramuscular ketamine and the dominant use of oral ketamine for a 3-month course to maximise the opportunity for the short-term benefits of ketamine to accumulate.

CONCLUSIONS

We have responded to the challenges of translating the evidence base for ketamine treatment into a form suitable for routine care.

Arketamine for cognitive impairment in psychiatric disorders

Cognitive impairment has been observed in patients with various psychiatric disorders, including schizophrenia, major depressive disorder (MDD), and bipolar disorder (BD). Although modern therapeutic drugs can improve certain symptoms (i.e., psychosis, depression) in these patients, these drugs have not been found to improve cognitive impairment. The N-methyl-D-aspartate receptor antagonist (R,S)-ketamine has attracted attention as a rapidly acting antidepressant. In addition to its robust antidepressant effects, (R,S)-ketamine has been suggested to improve cognitive impairment in patients with MDD and BD, despite causing cognitive impairment in healthy control subjects. (R,S)-ketamine is a racemic mixture of equal amounts of (R)-ketamine (or arketamine) and (S)-ketamine (or esketamine). Arketamine has been found to have more potent antidepressant-like actions than esketamine in rodents. Interestingly, arketamine, but not esketamine, has been suggested to improve phencyclidine-induced cognitive deficits in mice. Furthermore, arketamine has been suggested to ameliorate cognitive deficits in rodent offspring after maternal immune activation. In the current article, it is proposed that arketamine has therapeutic potential for treating cognitive impairment in patients with psychiatric disorders. Additionally, the potential role of the gut-microbiome-brain axis in cognitive impairment in psychiatric disorders is discussed.

Esketamine Inhibits Cocaine-Seeking Behaviour Subsequent to Various Abstinence Conditions in Rats

BACKGROUND

Cocaine use disorder (CUD) is a relapsing brain disease caused by a chronic drug intake that involves neural mechanisms and psychological processes, including depression. Preclinical and clinical studies have demonstrated the promise of pharmacological drugs in controlling the reinstatement of cocaine by targeting the N-methyl-D-aspartate (NMDA) receptor. Recent evidence has revealed that esketamine, a (S) enantiomer of ketamine, shows a high affinity to NMDA receptors and has been used in clinical trials to treat moderate-to-severe depression.

METHODS

In the present paper, we investigated the effects of esketamine in regulating cocaine-seeking behaviour induced through the use of cocaine (10 mg/kg) or the cocaine-associated conditioned cue after a short (10 days)-lasting period of drug abstinence with extinction training, home cage or enrichment environment conditions in male rats. Furthermore, we investigated the acute effects of esketamine on locomotor activity in drug-naïve animals.

RESULTS

Esketamine (2.5-10 mg/kg) administered peripherally attenuated the reinstatement induced with cocaine priming or the drug-associated conditioned cue after different conditions of abstinence.

CONCLUSIONS

These results seem to support esketamine as a candidate for the pharmacological management of cocaine-seeking and relapse prevention; however, further preclinical and clinical research is needed to better clarify esketamine's actions in CUD.

Changes in synaptic markers after administration of ketamine or psychedelics: a systematic scoping review

Background

Ketamine and psychedelics have abuse liability. They can also induce "transformative experiences" where individuals experience enhanced states of awareness. This enhanced awareness can lead to changes in preexisting behavioral patterns which could be beneficial in the treatment of substance use disorders (SUDs). Preclinical and clinical studies suggest that ketamine and psychedelics may alter markers associated with synaptic density, and that these changes may underlie effects such as sensitization, conditioned place preference, drug self-administration, and verbal memory performance. In this scoping review, we examined studies that measured synaptic markers in animals and humans after exposure to ketamine and/or psychedelics.

Methods

A systematic search was conducted following PRISMA guidelines, through PubMed, EBSCO, Scopus, and Web of Science, based on a published protocol (Open Science Framework, DOI: 10.17605/OSF.IO/43FQ9). Both in vivo and in vitro studies were included. Studies on the following synaptic markers were included: dendritic structural changes, PSD-95, synapsin-1, synaptophysin-1, synaptotagmin-1, and SV2A.

Results

Eighty-four studies were included in the final analyses. Seventy-one studies examined synaptic markers following ketamine treatment, nine examined psychedelics, and four examined both. Psychedelics included psilocybin/psilocin, lysergic acid diethylamide, N,N-dimethyltryptamine, 2,5-dimethoxy-4-iodoamphetamine, and ibogaine/noribogaine. Mixed findings regarding synaptic changes in the hippocampus and prefrontal cortex (PFC) have been reported when ketamine was administered in a single dose under basal conditions. Similar mixed findings were seen under basal conditions in studies that used repeated administration of ketamine. However, studies that examined animals during stressful conditions found that a single dose of ketamine counteracted stress-related reductions in synaptic markers in the hippocampus and PFC. Repeated administration of ketamine also counteracted stress effects in the hippocampus. Psychedelics generally increased synaptic markers, but results were more consistently positive for certain agents.

Conclusion

Ketamine and psychedelics can increase synaptic markers under certain conditions. Heterogeneous findings may relate to methodological differences, agents administered (or different formulations of the same agent), sex, and type of markers. Future studies could address seemingly mixed results by using meta-analytical approaches or study designs that more fully consider individual differences.

An update on potential pharmacotherapies for cognitive impairment in bipolar disorder

INTRODUCTION

Cognitive impairment is a core feature of bipolar disorder (BD) that impedes recovery by preventing the return to optimal socio-occupational functioning and reducing quality of life. Presently, there are no efficacious treatments for cognitive impairment in BD, but many pharmacological interventions are being considered as they have the potential to target the underlying pathophysiology of the disorder.

AREAS COVERED

This review summarizes the available evidence for pharmacological interventions for cognitive impairment in bipolar disorder. We searched PubMed, MedLine, and PsycInfo from inception to December 1^st, 2022. Traditional treatments, such as lithium, anticonvulsants (lamotrigine), antipsychotics (aripiprazole, asenapine, cariprazine, lurasidone, and olanzapine), antidepressants (vortioxetine, fluoxetine, and tianeptine) and psychostimulants (modafinil), and emerging interventions, such as acetylcholinesterase inhibitors (galantamine and donepezil), dopamine agonists (pramipexole), erythropoietin, glucocorticoid receptor antagonists (mifepristone), immune modulators (infliximab, minocycline and doxycycline), ketamine, metabolic agents (insulin, metformin, and liraglutide), probiotic supplements, and Withania somnifera are discussed.

EXPERT OPINION

The investigation of interventions for cognitive impairment in BD is a relatively under-researched area. In the past, methodological pitfalls in BD cognition trials have also been a critical limiting factor. Expanding on the existing literature and identifying novel pharmacological and non-pharmacological treatments for cognitive impairment in BD should be a priority.

Esketamine prevents propofol-induced injection pain: Randomized controlled trial

Background: Propofol is widely used during anesthesia. However, propofol-induced injection pain (PIP) is considered an unpleasant perioperative outcome. This study aimed to investigate the efficacy of a mixture of esketamine and propofol in preventing propofol injection pain in patients undergoing general anesthesia.

Methods: This was a prospective, double-blind, multicenter, and randomized controlled trial. We included 252 adult patients with the American Society of Anesthesiologists physical status I to II who underwent surgery under general anesthesia. Patients were randomly allocated in a 1:1:1:1 ratio to four groups (n = 63 per group). Group NS received a mixture of 1% propofol (20 ml) and 0.9% normal saline (1 ml), group ESK-4 received a mixture of 1% propofol (20 ml) and esketamine 4 mg (diluted with 0.9% normal saline, 1 ml), group ESK-12 received a mixture of 1% propofol (20 ml) and esketamine 12 mg (diluted with 0.9% normal saline, 1 ml), and group ESK-20 received a mixture of 1% propofol (20 ml) and esketamine 20 mg (diluted with 0.9% normal saline, 1 ml) as sedative drugs during anesthesia. The primary outcome was the incidence and distribution of different degrees of PIP. The secondary outcomes were vital signs, characteristics of surgery and anesthesia, and adverse events.

Results: The incidence of PIP in group ESK-20 (33.3%) was significantly lower than that in groups NS, ESK-4, and ESK-12 (63.3%, 62.2%, and 49.1%, respectively; p &lt; 0.01). The incidence of moderate PIP in group NS (33.3%) and group ESK-4 (22.6%) was higher than that in groups ESK-12 (7.5%) and ESK-20 (6.7%). The incidence of severe PIP in group NS (6.7%) and group ESK-4 (9.4%) was higher than that in groups ESK-12 (1.9%) and ESK-20 (0%). There were no differences in the vital signs, characteristics of surgery and anesthesia, or adverse events between the groups.

Conclusion: Our results indicated that the esketamine–propofol admixture reduced the incidence of PIP in patients undergoing general anesthesia without severe side effects.