Rapid and longer-term antidepressant effects of repeated-dose intravenous ketamine for patients with unipolar and bipolar depression

Exploring ketamine's reinforcement, cue-induced reinstatement, and nucleus accumbens cFos activation in male and female long evans rats

Ketamine (KET), a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist, has rapid onset of antidepressant effects in Treatment-Resistant Depression patients and repeated infusions are required to sustain its antidepressant properties. However, KET is an addictive drug, and so more preclinical and clinical research is needed to assess the safety of recurring treatments in both sexes. Thus, the aim of this study was to investigate the reinforcing properties of various doses of KET (0-, 0.125-, 0.25-, 0.5 mg/kg/infusion) and assess KET's cue-induced reinstatement and neuronal activation in both sexes of Long Evans rats. Neuronal activation was assessed using the protein expression of the immediate early gene cFos in the nucleus accumbens (Nac), an important brain area implicated in reward, reinforcement and reinstatement to most drug-related cues. Our findings show that KET has reinforcing effects in both male and female rats, albeit exclusively at the highest two doses (0.25 and 0.5 mg/kg/infusion). Furthermore, we noted sex differences, particularly at the highest dose of ketamine, with female rats displaying a higher rate of self-administration. Interestingly, all groups that self-administered KET reinstated to drug-cues. Following drug cue-induced reinstatement test in rats exposed to KET (0.25 mg/kg/infusion) or saline, there was higher cFos protein expression in KET-treated animals compared to saline controls, and higher cFos expression in the core compared to the shell subregions of the Nac. As for reinstatement, there were no notable sex differences reported for cFos expression in the Nac. These findings reveal some sex and dose dependent effects in KET's reinforcing properties and that KET at all doses induced similar reinstatement in both sexes. This study also demonstrated that cues associated with ketamine induce comparable neuronal activation in the Nac of both male and female rats. This work warrants further research into the potential addictive properties of KET, especially when administered at lower doses which are now being used in the clinic for treating various psychopathologies.

Cognitive outcomes from the randomised, active-controlled Ketamine for Adult Depression Study (KADS)

BACKGROUND

Due to its rapid antidepressant effect, ketamine has recently been clinically translated for people with treatment-resistant depression. However, its cognitive profile remains unclear, particularly with repeated and higher doses. In the present study, we report the cognitive results from a recent large multicentre randomised controlled trial, the Ketamine for Adult Depression Study (KADS).

METHODS

In this randomised, double-blind, active-controlled, parallel group, multicentre phase 3 trial study we investigated potential cognitive changes following repeated treatment of subcutaneous racemic ketamine compared to an active comparator, midazolam, over 4 weeks, which involved two cohorts; Cohort 1 involved a fixed dose treatment protocol (0.5 mg/kg ketamine), Cohort 2 involved a dose escalation protocol (0.5-0.9 mg/kg) based on mood outcomes. Participants with treatment-resistant Major Depressive Disorder (MDD) were recruited from 7 mood disorder centres and were randomly assigned to receive ketamine (Cohort 1 n = 33; Cohort 2 n = 53) or midazolam (Cohort 1 n = 35; Cohort 2 n = 53) in a 1:1 ratio. Cognitive measurements were assessed at baseline and at the end of randomised treatment.

RESULTS

Results showed that in Cohort 1, there were no differences between ketamine and midazolam in cognitive outcomes. For Cohort 2, there was similarly no difference between conditions for cognitive outcomes.

LIMITATIONS

The study included two Cohorts with different dosing regimes.

CONCLUSIONS

The findings support the cognitive safety of repeated fixed and escalating doses at least in the short-term in people with treatment resistant MDD.

Effect of Repeated Intravenous Esketamine on Adolescents With Major Depressive Disorder and Suicidal Ideation: A Randomized Active-Placebo-Controlled Trial

OBJECTIVE

Suicide is a major cause of death in adolescents with limited treatment options. Ketamine and its enantiomers have shown rapid anti-suicidal effects in adults with major depressive disorder (MDD), but their efficacy in adolescents is unknown. We conducted an active, placebo-controlled trial to determine the safety and efficacy of intravenous esketamine in this population.

METHOD

A total of 54 adolescents (aged 13-18 years) with MDD and suicidal ideation were included from an inpatient setting and randomly assigned (1:1) to receive 3 infusions of esketamine (0.25 mg/kg) or midazolam (0.02mg/kg) over 5 days, with routine inpatient care and treatment. Changes from baseline to 24 hours after the final infusion (day 6) in the scores of the Columbia Suicide Severity Rating Scale (C-SSRS) Ideation and Intensity (primary outcome) and the Montgomery-Åsberg Depression Rating Scale (MADRS, key secondary outcome) were analyzed using linear mixed models. In addition, the 4-week clinical treatment response was a key secondary outcome.

RESULTS

The mean changes in C-SSRS Ideation and Intensity scores from baseline to day 6 were significantly greater in the esketamine group than in the midazolam group (Ideation, -2.6 [SD = 2.0] vs -1.7 [SD = 2.2], p = .007; Intensity, -10.6 [SD = 8.4] vs -5.0 [SD = 7.4], p = .002), and the changes in MADRS scores from baseline to day 6 were significantly greater in the esketamine group than in the midazolam group (-15.3 [SD = 11.2] vs -8.8 [SD = 9.4], p = .004). The rates of antisuicidal and antidepressant responses at 4 weeks posttreatment were 69.2% and 61.5% after esketamine, and were 52.5% and 52.5% after midazolam, respectively. The most common adverse events in the esketamine group were nausea, dissociation, dry mouth, sedation, headache, and dizziness.

CONCLUSION

These preliminary findings indicate that 3-dose intravenous esketamine, added to routine inpatient care and treatment, was an effective and well-tolerated therapy for treating adolescents with MDD and suicidal ideation.

CLINICAL TRIAL REGISTRATION INFORMATION

A study to evaluate the efficacy and safety of Esketamine combined with oral antidepressants in the treatment of major depressive disorder with suicidal ideation; http://www.chictr.org.cn; ChiCTR2000041232.

DIVERSITY & INCLUSION STATEMENT

We worked to ensure that the study questionnaires were prepared in an inclusive way. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work. We actively worked to promote sex and gender balance in our author group.

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

BACKGROUND

Amygdala subregion-based network dysfunction has been determined to be centrally implicated in major depressive disorder (MDD). Little is known about whether ketamine modulates amygdala subarea-related networks. We aimed to investigate the relationships between changes in the resting-state functional connectivity (RSFC) of amygdala subregions and ketamine treatment and to identify important neuroimaging predictors of treatment outcomes.

METHODS

Thirty-nine MDD patients received six doses of ketamine (0.5 mg/kg). Depressive symptoms were assessed, and magnetic resonance imaging (MRI) scans were performed before and after treatment. Forty-five healthy controls underwent one MRI scan. Seed-to-voxel RSFC analyses were performed on the amygdala subregions, including the centromedial amygdala (CMA), laterobasal amygdala (LBA), and superficial amygdala subregions.

RESULTS

Abnormal RSFC between the left LBA and the left precuneus in MDD patients is related to the therapeutic efficacy of ketamine. There were significant differences in changes in bilateral CMA RSFC with the left orbital part superior frontal gyrus and in changes in the left LBA with the right middle frontal gyrus between responders and nonresponders following ketamine treatment. Moreover, there was a difference in the RSFC of left LBA and the right superior temporal gyrus/middle temporal gyrus (STG/MTG) between responders and nonresponders at baseline, which could predict the antidepressant effect of ketamine on Day 13.

CONCLUSIONS

The mechanism by which ketamine improves depressive symptoms may be related to its regulation of RSFC in the amygdala subregion. The RSFC between the left LBA and right STG/MTG may predict the response to the antidepressant effect of ketamine.

Long-term quality of life after repeated ketamine infusions in anxious and nonanxious patients with depression

BACKGROUND

There have been many studies on the benefits of repeated ketamine infusions on patients' depression but few on the impact of ketamine on patients' long-term quality of life (QoL). This study investigated long-term QoL in individuals with depression, both anxious and nonanxious.

METHODS

A total of 107 individuals with a diagnosis of depression were included in the study. The patients were evaluated on Days 0, 13 and 26 and Months 6 and 9, and they received six ketamine infusions over the course of two weeks. The World Health Organization Quality of Life-BREF (WHOQOL-BREF) Scale and the Patient Health Questionnaire-9 (PHQ-9) Scale were used to measure depressive symptoms and QoL. Linear mixed models were used to evaluate depressive symptoms and QoL during ketamine treatment.

RESULTS

A total of 67.2 % of patients were diagnosed with anxious depression. In the long term, there were no significant differences in the time-by-group interactions for general QoL (F = 0.510; P = 0.676), physical QoL (F = 2.092; P = 0.102), psychological QoL (F = 0.102; P = 0.959), social QoL (F = 2.180; P = 0.091), or environmental QoL (F = 1.849; P = 0.139) between the two groups.

LIMITATIONS

The main limitation of this study is its open-label design.

CONCLUSION

The improvement in depression symptoms and QoL following ketamine treatment was not impacted by the presence or absence of anxiety in patients who were depressed prior to treatment. Only occasionally did depressed individuals with anxiety experience a worsening of their quality of life compared to those without anxiety.

Psychedelic Therapy: A Primer for Primary Care Clinicians-Ketamine

BACKGROUND

Ketamine, an arylcyclohexylamine dissociative anesthetic agent, has evolved into a versatile therapeutic. It has a rapid-onset, well-understood cardiovascular effects and a favorable safety profile in clinical use. Its enantiomeric compound, esketamine, was approved by the Food and Drug Administration in 2019 for both treatment-resistant depression and major depressive disorder with suicidal ideation.

AREAS OF UNCERTAINTY

Research indicates dose-dependent impacts on cognition, particularly affecting episodic and working memory following both acute administration and chronic use, albeit temporarily for the former and potentially persistent for the latter. Alongside acute risks to cardiovascular stability, ketamine use poses potential liver toxicity concerns, especially with prolonged or repeated exposure within short time frames. The drug's association with "ketamine cystitis," characterized by bladder inflammation, adds to its profile of physiological risks.

THERAPEUTIC ADVANCES

Data demonstrate a single intravenous infusion of ketamine exhibits antidepressant effects within hours (weighted effect size averages of depression scores (N = 518) following a single 0.5 mg/kg infusion of ketamine is d = 0.96 at 24 hours). Ketamine is also effective at reducing posttraumatic stress disorder (PTSD) symptom severity following repeated infusions (Clinician-Administered PTSD Scale scores: -11.88 points compared with midazolam control). Ketamine also decreased suicidal ideation in emergency settings (Scale for Suicidal Ideation scores: -4.96 compared with midazolam control). Through its opioid-sparing effect, ketamine has revolutionized postoperative pain management by reducing analgesic consumption and enhancing recovery.

LIMITATIONS

Many studies indicate that ketamine's therapeutic effects may subside within weeks. Repeated administrations, given multiple times per week, are often required to sustain decreases in suicidality and depressive symptoms.

CONCLUSIONS

Ketamine's comprehensive clinical profile, combined with its robust effects on depression, suicidal ideation, PTSD, chronic pain, and other psychiatric conditions, positions it as a substantial contender for transformative therapeutic application.

Case report: Adult with bipolar disorder and autism treated with ketamine assisted psychotherapy

Background

Evidence has increased in recent years regarding the potential for ketamine to serve as a novel treatment option for a range of conditions, particularly depression (unipolar and bipolar). However, research regarding ketamine as a potential therapeutic for Autism Spectrum Disorder (ASD) is lacking, despite high overlap with bipolar depression and theoretical foundations for its use.

Case presentation

A 29-year-old man with bipolar disorder and Autism Spectrum Disorder, type 2 diabetes, presented with mood swings and suicidal thoughts, and anger outbursts occurring daily. The patient was referred by a psychiatrist due to irritability and outbursts during the previous 5 months. These outbursts were unable to be controlled by the medications prescribed, included yelling and screaming, and the patient was unable to speak with the psychiatrist. The patient underwent ketamine assisted psychotherapy with 6 initial IV infusions of ketamine over a 1 month period followed by 2 booster IV ketamine infusions. Following ketamine treatment, dramatic reductions in outbursts were observed as well as reductions in anxiety, suicidality, and depression scores.

Conclusion

This case study adds to the scant literature regarding ketamine treatment for individuals with bipolar disorder and ASD. We did not find ASD to be a contraindication for IV ketamine and ketamine assisted psychotherapy. Reductions in anger outbursts, anxiety, suicidality, and depression suggest ketamine treatment might be tailored to individuals with bipolar disorder and ASD, and additional systematized research is warranted. Although potential mechanisms of action are not clear, these data add to the discussion regarding clinical practice considerations and the potential for ketamine to improve quality of life and associated metrics.

Sex differences in the effects of repeated ketamine infusions on bone markers in patients with unipolar and bipolar depression

BACKGROUND

Patients with depression, especially women, are associated with low bone mineral density (BMD). Traditional antidepressants are associated with negative effects on BMD. Few studies have examined the effect of ketamine on BMD, and it remains unclear whether there are sex differences in the effects of ketamine on BMD in patients with depression.

METHODS

A total of 102 patients with unipolar and bipolar depression were administered six infusions of intravenous ketamine over a 12-day period. Plasma levels of eight bone markers were examined at baseline, 24 h after the sixth infusion and again 2 weeks (Days 13 and 26).

RESULTS

Linear mixed models showed all bone markers had significant time main effect (all p < 0.05). Compared with baseline, the whole sample showed increased levels of leptin and osteoprotegerin at Days 13 and 26, as well as Dickkopf-related protein 1 at Day 13, and decreased levels of osteocalcin, sclerostin, osteopontin, parathyroid hormone and fibroblast growth factor 23 at Days 13 and 26 (all p < 0.05). Females had a higher level of leptin at Days 13 and 26, and lower levels of osteocalcin and sclerostin at Day 13 than males (all p < 0.05). Increases of leptin were associated with depressive symptom improvements at Day 13 and Day 26 in females (both p < 0.05). In males, higher baseline osteocalcin levels were associated with greater depressive symptom improvement at Day 26 (β = 0.414, p = 0.009).

CONCLUSIONS

Our results suggest that repeated ketamine infusions may be associated with modulation of bone markers in patients with depression and present sex differences. Baseline osteocalcin level may be served as a predictor for the antidepressant effects of ketamine in males. Trial registration Data were derived from an open label clinical trial, which was registered at Chinese Clinical Trial Registry (ChiCTR-OOC-17012239). Registered 26 May 2017. http://www.chictr.org.cn.

The role of CD38 in inflammation-induced depression-like behavior and the antidepressant effect of (R)-ketamine

CD38 is involved in immune responses, cell proliferation, and has been identified in the brain, where it is implicated in inflammation processes and psychiatric disorders. We hypothesized that dysfunctional CD38 activity in the brain may contribute to the pathogenesis of depression. To investigate the underlying mechanisms, we used a lipopolysaccharide (LPS)-induced depression-like model and conducted behavioral tests, molecular and morphological methods, along with optogenetic techniques. We microinjected adeno-associated virus into the hippocampal CA3 region with stereotaxic instrumentation. Our results showed a marked increase in CD38 expression in both the hippocampus and cortex of LPS-treated mice. Additionally, pharmacological inhibition and genetic knockout of CD38 effectively alleviated neuroinflammation, microglia activation, synaptic defects, and Sirt1/STAT3 signaling, subsequently improving depression-like behaviors. Moreover, optogenetic activation of glutamatergic neurons of hippocampal CA3 reduced the susceptibility of mice to depression-like behaviors, accompanied by reduced CD38 expression. We also found that (R)-ketamine, which displayed antidepressant effects, was linked to its anti-inflammatory properties by suppressing increased CD38 expression and reversing synaptic defects. In conclusion, hippocampal CD38 is closely linked to depression-like behaviors in an inflammation model, highlighting its potential as a therapeutic target for antidepressant development.

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

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

Short-term cognitive effects of repeated-dose esketamine in adolescents with major depressive disorder and suicidal ideation: a randomized controlled trial

BACKGROUND

Ketamine and its enantiomer have rapid and robust effects on depressive symptom and suicidal ideation. Little is known about their cognitive effects in adolescents. We aimed to evaluate the short-term effect of esketamine on cognition in adolescents with major depressive disorder (MDD) and suicidal ideation.

METHOD

In this randomized-controlled trial, 51 participants aged 13-18 with MDD and suicidal ideation received three intravenous infusions of either esketamine (0.25 mg/kg) or midazolam (0.02 mg/kg). Four dimensions of the MATRICS Consensus Cognitive Battery (MCCB), including processing speed, working memory, verbal learning and visual learning, were assessed at Days 0, 6 and 12.

RESULTS

In the linear mixed model, a significant time main effect (F = 12.803, P < 0.001), drug main effect (F = 6.607, P = 0.013), and interaction effect (F = 3.315, P = 0.041) was found in processing speed. Other dimensions including working memory and verbal learning showed significant time main effect (all P < 0.05), but no significant drug or interaction effect (all P > 0.05). Esketamine group showed improvement in processing speed from baseline to Days 6 and 12, and working memory from baseline to Day 12 (all P < 0.05). The generalized estimation equation showed no significant association between baseline cognition and antidepressant or antisuicidal effect (both P > 0.05).

CONCLUSIONS

The present study suggested that three-dose subanesthetic esketamine infusions did not harm cognition among adolescents with MDD and suicidal ideation. Instead, esketamine may be associated with improvement in processing speed.

TRIAL REGISTRATION

This trial was registered in the Chinese Clinical Trials Registry ( http://www.chictr.org.cn , ChiCTR2000041232).

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

A role of splenic heme biosynthesis pathway in the persistent prophylactic actions of arketamine in lipopolysaccharide-treated mice

Relapse is common in remitted patients with major depressive disorder (MDD). Arketamine, an (R)-enantiomer of ketamine, has persistent prophylactic actions in an inflammatory model of depression. However, the precise mechanisms underlying these prophylactic actions remain unknown. Given the role of the brain-spleen axis in depression, we sought to identify splenic molecular targets that play a role in the prophylactic actions of arketamine. Lipopolysaccharide (LPS) (1.0 mg/kg) was administered 6 days after a single injection of arketamine (10 mg/kg) or saline. RNA-sequencing analysis found altered expression in the heme biosynthesis II pathway. Quantitative RT-PCR revealed that pretreatment with arketamine blocked increased expression of genes involved in the heme biosynthesis II pathway in LPS-treated mice, namely, 5-aminolevulinase synthase 2 (Alas2), ferrochelatase (Fech), hydroxymethylbilane synthase (Hmbs). Interestingly, there were positive correlations between the expression of these genes and spleen weight or plasma levels of pro-inflammatory cytokines. We also found higher expression of ALAS2 and FECH in the spleen from MDD patients. Pretreatment with a key intermediate precursor of heme, 5-aminolaevulinic acid (300 mg/kg/day for 3 days), caused splenomegaly, higher plasma levels of pro-inflammatory cytokines, and depression-like behavior in low-dose LPS (0.1 mg/kg)-treated mice. Interestingly, pretreatment with a heme biosynthesis inhibitor, succinyl acetone (120 mg/kg/day for 3 days), had prophylactic effects in LPS (1.0 mg/kg)-treated mice. These data suggest a novel role for the heme biosynthesis II pathway in the spleen for inflammation-related depression. Therefore, the heme biosynthesis pathway could be a new target for the prevention of relapse in MDD patients.

Efficacy of repeated intravenous esketamine in adolescents with anxious versus non-anxious depression

Background

Patients with anxious major depressive disorder (MDD) are more likely to have poorer outcomes than those with non-anxious MDD. However, the effect of esketamine on adolescents with anxious versus non-anxious MDD has remained unknown.

Aims

We compared the efficacy of esketamine in adolescents with MDD and suicidal ideation, both anxious and non-anxious.

Methods

Fifty-four adolescents with anxious (n=33) and non-anxious (n=21) MDD received three infusions of esketamine 0.25 mg/kg or active-placebo (midazolam 0.045 mg/kg) over 5 days, with routine inpatient care and treatment. Suicidal ideation and depressive symptoms were assessed using the Columbia Suicide Severity Rating Scale and the Montgomery-Åsberg Depression Rating Scale. Multiple-sample proportional tests were used to compare the differences between groups on treatment outcomes 24 hours after the final infusion (day 6, primacy efficacy endpoint) and throughout the 4-week post-treatment (days 12, 19 and 33).

Results

In subjects who received esketamine, a greater number of patients in the non-anxious group than the anxious group achieved antisuicidal remission on day 6 (72.7% vs 18.8%, p=0.015) and day 12 (90.9% vs 43.8%, p=0.013), and the non-anxious group had a higher antidepressant remission rate compared with the anxious group on day 33 (72.7% vs 26.7%, p=0.045). No significant differences in treatment outcomes were observed between the anxious and non-anxious groups at other time points.

Conclusions

Three infusions of esketamine as an adjunct to routine inpatient care and treatment had a greater immediate post-treatment antisuicidal effect in adolescents with non-anxious MDD than in those with anxious MDD; however, this benefit was temporary and was not maintained over time.

Trial registration number

ChiCTR2000041232.

Brain stimulation for treatment-resistant depression

Depression is one of the main public health problems in the world, having a high prevalence and being considered the main cause of disability. An important portion of patients does not respond to treatment with the initial trial of conventional antidepressants in the current depressive episode of moderate to severe intensity, which characterizes treatment-resistant depression. In this context, non-invasive neuromodulation procedures use an electric current or magnetic field to modulate the central nervous system, and they represent a new option for patients with treatment-resistant depression.

Ketamine and the Disinhibition Hypothesis: Neurotrophic Factor-Mediated Treatment of Depression

Ketamine is a promising alternative to traditional pharmacotherapies for major depressive disorder, treatment-resistant depression, and other psychiatric conditions that heavily contribute to the global disease burden. In contrast to the current standard of care medications for these disorders, ketamine offers rapid onset, enduring clinical efficacy, and unique therapeutic potential for use in acute, psychiatric emergencies. This narrative presents an alternative framework for understanding depression, as mounting evidence supports a neuronal atrophy and synaptic disconnection theory, rather than the prevailing monoamine depletion hypothesis. In this context, we describe ketamine, its enantiomers, and various metabolites in a range of mechanistic actions through multiple converging pathways, including N-methyl-D-aspartate receptor (NMDAR) inhibition and the enhancement of glutamatergic signaling. We describe the disinhibition hypothesis, which posits that ketamine's pharmacological action ultimately results in excitatory cortical disinhibition, causing the release of neurotrophic factors, the most important of which is brain-derived neurotrophic factor (BDNF). BDNF-mediated signaling along with vascular endothelial growth factor (VEGF) and insulin-like growth factor 1 (IGF-1) subsequently give rise to the repair of neuro-structural abnormalities in patients with depressive disorders. Ketamine's efficacious amelioration of treatment-resistant depression is revolutionizing psychiatric treatment and opening up fresh vistas for understanding the underlying causes of mental illness.

Pain mediates the improvement of social functions of repeated intravenous ketamine in patients with unipolar and bipolar depression

OBJECTIVE

Previous research has shown that ketamine can improve social functions. In addition, evidence also suggests that ketamine can alleviate pain. Herein, we propose that ketamine-induced improvements in pain and depression are partially mediated by a reduction in pain. We aimed to determine whether improvements in pain-mediated changes in psychological function were associated with ketamine treatment.

METHOD

This trial included unipolar or bipolar patients (n = 103) who received 6 intravenous infusions (0.5 mg/kg) of ketamine over 2 weeks. The severity of current depressive symptoms and social function were evaluated by the Montgomery-Åsberg Depression Scale (MADRS), Self-Rating Depression Scale (SDS) and Global Assessment Function (GAF), respectively, at baseline and on day 13 and day 26. At the same time points, the three dimensions of pain, including the sensory index, affective index and present pain intensity (PPI), were measured by the Simple McGill Pain Scale (SF-MPQ).

RESULTS

The mixed model results showed that ketamine plays an important role in improving the psychosocial functioning of patients. There was a significant decrease from baseline to the day 13 and day 26, indicating that the pain index of the patient improved significantly. Mediation analysis showed that for SDS score (coef = -5.171, 95 % CI[-6.317, -4.025]) and GAF score (coef = 1.021, 95 % CI[0.848, 1.194]), the overall effect of ketamine was observable. The overall indirect and direct effects of ketamine on social functioning were significant (SDS: direct: coef = -1949 to -2114; total indirect: from 0.594 to 0.664; GAF: from 0.399 to 0.427; total indirect: coef = 0.593 to 0.664). The MADRS total score and emotional index were important mediators of the association between ketamine treatment and improvements in subjective and objective social functioning.

CONCLUSION

Depressive symptom severity and the affective index of pain partially mediated improvements in social function after six repeated ketamine treatments among patients with bipolar or unipolar depressive disorder.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Ketamine-induced hippocampal functional connectivity alterations associated with clinical remission in major depression

OBJECTIVE

Hippocampal functional connectivity (FC) alterations, which may happen following ketamine treatment, play a key role in major depression remission. This study aims to investigate the resting-state FC changes of the hippocampus associated with clinical remission after repeated ketamine infusions.

METHODS

Forty-four major depressive patients received six intravenous ketamine (0.5 mg/kg) infusions in 12 days. The FC change of the hippocampus subregions following ketamine treatment was compared between remitters (MADRS score ≤ 10 post-treatment) and nonremitters. We also investigated whether baseline hippocampus FC predicted the antidepressant efficiency of ketamine using Receiver Operating Characteristic Curve analyses.

RESULTS

Thirty-nine patients were included in the analysis. There were significant differences in change of left rostral hippocampus FC with the right angular gyrus (the key node of the default mode network, DMN), left inferior parietal cortex and the right superior parietal cortex (parts of the dorsal attention network, dAN) between remitters and nonremitters following ketamine treatment. Specifically, while the remitters showed significantly less negative hippocampus FC than the nonremitters at baseline, the FC significantly decreased in remitters but increased in nonremitters after ketamine injections. Moreover, baseline hippocampus FC with the above three regions predicted the antidepressant effect of ketamine, with the highest predictive strength identified in the hippocampus-right angular gyrus FC (Area-Under-Curve = 0.8179, p < 0.05).

CONCLUSION

Ketamine treat depression by modulating the left rostral hippocampus resting-state FC with the DMN and dAN. The FC between the hippocampus and parts of the DMN and dAN may show promising potential in predicting remission after ketamine treatment in MDD.

Antidepressant and anti-suicidal effects of ketamine in treatment-resistant depression associated with psychiatric and personality comorbidities: A double-blind randomized trial

OBJECTIVE

To evaluate the effects of ketamine treatment on depression and suicidal ideation in treatment resistant depression (TRD) and to determine whether they are influenced by other psychiatric and personality comorbidities.

METHODS

A randomized double-blind parallel-arm controlled study on 36 patients with TRD. Patients were divided into two treatment groups: ketamine (K group) and placebo (P group). Patients in the K and P groups received one infusion of medicine per week for two weeks. All participants were assessed using the Structured Interview for the Five-Factor Personality Model (SIFFM), Hamilton Depression Rating Scale (HDRS), Suicide Probability Scale (SPS), and Symptom Checklist 90 (SCL 90).

RESULTS

After treatment, there was a significant decrease in the total HDRS and SPS scores in the K group compared to the P group, but the magnitude of response was not influenced by the presence of other psychiatric symptoms. Regression model, only receive ketamine treatment was significant factor for improve suicide and depression scores.

LIMITATIONS

lack of data on other outcomes that are important to patients (e.g., quality of life, cognition) and need for a larger sample size.

CONCLUSIONS

Ketamine infusions in TRD reduce suicidal ideation and depression despite the presence other psychiatric and personality disorders.

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.

Functional connectivity differences in the amygdala are related to the antidepressant efficacy of ketamine in patients with anxious depression

BACKGROUND

The antidepressant effects of ketamine in patients with anxious depression (AD) remain unclear. Functional connectivity (FC) differences in the amygdala have been linked to depression improvement after ketamine treatment in depressed patients, but their role in AD patients is uncertain. We investigated the correlation between depression improvement after ketamine treatment and amygdala FC in AD patients.

METHODS

Thirty-one AD patients and 18 non-anxious depression (NAD) patients received six intravenous ketamine infusions (0.5 mg/kg) over two weeks. AD patients were further divided into responders (defined as a ≥50% MADRS total score reduction on day 13) and non-responders. The FC of the amygdala subregions, including the laterobasal amygdala (LBA), centromedial amygdala (CMA), and superficial amygdala, were compared between the groups. Receiver operating characteristic curves were used to predict treatment response after ketamine infusions.

RESULTS

The baseline FC difference in the left LBA and the left precuneus between responders and non-responders among AD patients was found to be associated with depression improvement and was a significant predictor of treatment response to ketamine. A marked reduction in baseline LBA-precuneus FC after ketamine infusion was observed in responders. Unlike in patients with NAD, a lower right CMA-right middle temporal gyrus FC was found in AD patients.

LIMITATIONS

The sample size is rather small.

CONCLUSIONS

Our findings may suggest that amygdala FC is a significant predictor of treatment response to ketamine infusions in patients with AD. Further studies exploring the potential antidepressant mechanisms of ketamine may aid in the treatment of AD patients.

Antidepressant Drugs for Seizures and Epilepsy: Where do we Stand?

People with epilepsy (PWE) are more likely to develop depression and both these complex chronic diseases greatly affect health-related quality of life (QOL). This comorbidity contributes to the deterioration of the QOL further than increasing the severity of epilepsy worsening prognosis. Strong scientific evidence suggests the presence of shared pathogenic mechanisms. The correct identification and management of these factors are crucial in order to improve patients' QOL. This review article discusses recent original research on the most common pathogenic mechanisms of depression in PWE and highlights the effects of antidepressant drugs (ADs) against seizures in PWE and animal models of seizures and epilepsy. Newer ADs, such as selective serotonin reuptake inhibitors (SRRI) or serotonin-noradrenaline reuptake inhibitors (SNRI), particularly sertraline, citalopram, mirtazapine, reboxetine, paroxetine, fluoxetine, escitalopram, fluvoxamine, venlafaxine, duloxetine may lead to improvements in epilepsy severity whereas the use of older tricyclic antidepressant (TCAs) can increase the occurrence of seizures. Most of the data demonstrate the acute effects of ADs in animal models of epilepsy while there is a limited number of studies about the chronic antidepressant effects in epilepsy and epileptogenesis or on clinical efficacy. Much longer treatments are needed in order to validate the effectiveness of these new alternatives in the treatment and the development of epilepsy, while further clinical studies with appropriate protocols are warranted in order to understand the real potential contribution of these drugs in the management of PWE (besides their effects on mood).

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

The efficacy and safety of esketamine in the treatment of major depressive disorder with suicidal ideation: study protocol for a randomized controlled trial

BACKGROUND

Major depressive disorder (MDD) is a high risk factor for suicide, with up to 20% of MDD patients attempting suicide during their lifetime. Current treatments for MDD are slow onset of action, low efficiency, and the inability to control suicidal behaviors quickly and effectively. Intravenous ketamine has been shown to have a rapid but transient antidepressant effect, but there is still lack evidence on the efficacy and safety of intravenous esketamine in reducing suicidal ideation and depressive symptoms in MDD patients with suicidal ideation. We designed a study to investigate the effect of short-term repeated intravenous infusion of esketamine three times in MDD patients with suicidal ideation.

METHODS

This study features a randomized, double-blind, placebo-controlled trial (RCT) comparing short-term repeated intravenous infusions of esketamine with placebo as a supplement to conventional antidepressants with an intervention period of 6 days and one infusion every other day, followed by 4 weeks of follow-up. These methods support the examination of the efficacy, safety, tolerability, and mechanism of action of short-term repeated intravenous infusions of esketamine in MDD patients with suicidal ideation.

DISCUSSION

This is the first RCT to explore the efficacy and safety of short-term repeated infusion of esketamine on suicidal ideation and depressive symptoms in MDD patients with suicidal ideation. If proven effective and tolerated, it will provide evidence for rapid and effective treatment of suicidal ideation and depressive symptoms in MDD individuals with suicidal ideation.

TRIAL REGISTRATION

Chinese Clinical Trial Register, ChiCTR2000041232 . Registered 22 December 2020.

A century of research on psychedelics: A scientometric analysis on trends and knowledge maps of hallucinogens, entactogens, entheogens and dissociative drugs

A scientometric analysis was realized to outline clinical research on psychedelics over the last century. Web of Science Core Collection was searched up to March 18, 2022, for publications on psychedelics. Network analyses and bibliometrics were combined, to identify research themes and trends with Bibliometrix and CiteSpace. The primary aim was to measure research trends evolution over time, and the secondary aims were to identify bibliometric performance and influence networks of publications, authors, institutions, and countries. Sensitivity analyses were conducted for 2016-2022, and 2021 time periods. We included 31,687 documents (591,329 references), which aggregated into a well-structured network with credible clustering. Research productivity was split into an early less productive period mainly focusing on safety issues, and a "psychedelic renaissance" after the 1990s. Major trends were identified for hallucinogens/entheogens, entactogens, novel psychoactive substances (NPS), and on dissociative substances. There was a translational evolution from the bench to the bedside, with phase 2 and 3 trials and/or evidence synthesis in particular. The most recent trends concerned NPS, ketamine-associated brain changes, and ayahuasca-assisted psychotherapy. The USA and Canada were the most productive settings for the research overall, and more recently this geographical distribution became more prominent, reflecting legislative context/policy making. A translational evolution of psychedelics has been occurring, that has brought approval of esketamine for depression and will likely lead to approval of additional psychedelics across mental and physical conditions. Toxicology screening tools for NPS are urgently needed, which in turn might follow the same translational evolution of psychedelics in the future.

Association of anhedonia and suicidal ideation in patients with treatment-refractory depression after intravenous ketamine infusions

OBJECTIVES

Accumulating evidence suggests that the effects of ketamine administered intravenously at subanaesthetic doses on both anhedonic symptoms and suicidal ideation occur independently of depressive symptoms in major depressive disorder (MDD) and bipolar disorder (BD). This study sought to determine the relationship between anhedonia and suicidal ideation after serial ketamine infusions.

METHODS

A total of 79 subjects with either treatment-refractory MDD (n = 60) or BD (n = 19) were included in a clinical ketamine study. The Montgomery-Åsberg Depression Rating Scale (MADRS) anhedonia factor and the first five items of the Scale for Suicidal Ideations (SSI-Part I) were used to assess anhedonia symptoms and suicidal ideation, respectively.

RESULTS

At baseline, anhedonia, as measured by the MADRS, was not significantly associated with suicidal ideation or specific suicide-related ideation as measured by SSI-Part I (all p's > 0.05). Only the 'wish to die' and 'desire to make a suicide attempt' items were positively associated with anhedonia at two weeks after the sixth ketamine infusion, which was independent of the reductions in depressive symptoms (all p's < 0.05).

CONCLUSION

Anhedonia as measured by the MADRS appeared to not be positively related to suicidal ideation after serial ketamine infusions.KEY POINTSSerial ketamine (0.5 mg/kg) infusions have shown quick and dramatic antisuicidal and antianhedonic effects in patients with depression.The association between anhedonia and suicidal ideation after serial ketamine infusions is unclear.Anhedonia appeared to not be positively related to suicidal ideation after serial ketamine infusions.

(Es)Ketamine for Suicidal Ideation and Behavior: Clinical Efficacy

Suicidal ideation and behavior are among the most severe psychiatric presentations, warranting emergency room visits and psychiatric admission for higher levels of care. In the United States, suicide rates continue to climb, especially in younger patients, and the continued psychosocial stressors of the COVID-19 pandemic may further exacerbate this crisis. Suicidal ideation and behavior are core features of a major depressive episode, but there are limited treatment options to rapidly redress these life-threatening symptoms. Racemic ketamine and its S-enantiomer, esketamine, are N-methyl-D-aspartate receptor antagonists and glutamate modulators that have robust antidepressant efficacy in treatment-resistant major depressive disorder and bipolar depression. Additionally, both ketamine and esketamine have demonstrated rapid-acting antisuicidal efficacy in major mood disorders. In August 2020, this culminated in a first-in-class approval of Spravato® (intranasal esketamine) for the treatment of major depressive disorder with acute suicidal ideation and behavior. In this article, we review the literature in support of the antisuicidal efficacy of ketamine and esketamine.

Targeting NMDA Receptors in Emotional Disorders: Their Role in Neuroprotection

Excitatory glutamatergic neurotransmission mediated through N-methyl-D-Aspartate (NMDA) receptors (NMDARs) is essential for synaptic plasticity and neuronal survival. While under pathological states, abnormal NMDAR activation is involved in the occurrence and development of psychiatric disorders, which suggests a directional modulation of NMDAR activity that contributes to the remission and treatment of psychiatric disorders. This review thus focuses on the involvement of NMDARs in the pathophysiological processes of psychiatric mood disorders and analyzes the neuroprotective mechanisms of NMDARs. Firstly, we introduce NMDAR-mediated neural signaling pathways in brain function and mood regulation as well as the pathophysiological mechanisms of NMDARs in emotion-related mental disorders such as anxiety and depression. Then, we provide an in-depth summary of current NMDAR modulators that have the potential to be developed into clinical drugs and their pharmacological research achievements in the treatment of anxiety and depression. Based on these findings, drug-targeting for NMDARs might open up novel territory for the development of therapeutic agents for refractory anxiety and depression.

Influence of Effort-based Reward Training on Neuroadaptive Cognitive Responses: Implications for Preclinical Behavioral Approaches for Depressive Symptoms

Despite the presence of multiple pharmacotherapeutic options, incidence rates for depressive disorders continue to rise. Nonpharmacological approaches (e.g., cognitive and behavioral therapies) exhibit encouraging efficacy rates; however, a lack of preclinical models has prevented progress in the identification of relevant neurobiological mechanisms of these approaches. Accordingly, the effort-based reward (EBR) preclinical model exposes rats to response-outcome (R-O) contingencies and provides an opportunity to investigate behavioral clinical approaches. In the current study, male and female rats were assigned to either an EBR contingent- or noncontingent-trained group and exposed to 7 weeks of training. Neuroadaptive cognitive responses were assessed in a cognitive uncertainty task (UT) and an object pattern separation task (OPST). Although no significant effects of EBR were observed in the UT, EBR contingent-trained rats approached the novel panel in the most difficult trial of the OPST faster than the noncontingent-trained group. Additionally, female EBR contingent-trained rats exhibited increased engagement with the novel stimulus panel across all trials. Examination of brain-derived neurotrophic factor (BDNF) in the lateral habenula (LHb), a putative neurobiological target for depressive symptoms, revealed lower BDNF immunoreactivity in EBR contingent-trained rats. Females in both training groups exhibited higher dehydroepiandrosterone/cortisol (DHEA/CORT) ratios, suggesting, along with the increased engagement with novel stimulus panels, that female rats may be more responsive to EBR contingency training than males. Together, these results suggest that EBR contingency training offers promise as a preclinical rat model for behavioral therapeutic interventions for depressive symptoms leading to a clearer understanding of putative neurobiological mechanisms.

The functional connectivity of the middle frontal cortex predicts ketamine’s outcome in major depressive disorder

Background

Ketamine, a robust antidepressant, has promising potential in the treatment of major depressive disorder (MDD). However, it does not work for all MDD patients, and the mechanism underlying its anti-depressive effects is unclear. Researchers have explored the mechanisms of ketamine action in MDD patients through MRI, a technique that measures brain activity intuitively. Notably, many MRI results were inconsistent because they selected different brain regions as seeds, particularly with respect to functional connectivity (FC) analysis. To eliminate the influence of prior seeds as much as possible, we used the significantly different results in degree centrality (DC) analysis as seeds to explore the FC changes in MDD patients to identify an imaging biomarker of ketamine’s effect.

Methods

Forty-four MDD patients and 45 healthy controls (HCs) were included in the study. Patients, aged 18–65, received six intravenous ketamine injections over 12 days. Depressive symptoms were estimated and MRI scans were performed at baseline and the day after the sixth infusion. We estimated FC differences between responders, non-responders and HCs using the region that showed significant differences between responders and non-responders in DC analysis as the seed. The correlation between the MADRS changes and zFC values was performed, and the potential of zFC values to be a neuroimaging biomarker was explored using the receiver operating characteristic curve.

Result

Compared with non-responders, responders had significantly decreased DC values in the right middle frontal gyrus (MFG). In the analysis of FC using the region that showed significant differences in DC as a seed, there was a significant difference in the region of the right supplementary motor area (SMA) among responders, non-responders, and HCs. This region also overlapped with the bilateral median cingulate gyrus. In post hoc analysis, responders had higher FC than non-responders and HCs, and non-responders had lower FC than HCs. Importantly, the FC between the MFG and SMA (overlapping bilateral median cingulate gyrus) was correlated with the improvement of symptoms, which was estimated by the Mongomery-Asberg Depression Scale (MADRS). FC has the potential to be an imaging biomarker that can predict the ketamine effect in MDD patients according to the receiver operating characteristic curve analysis.

Conclusion

Our results revealed that FC between the SMG and SMA and mACC was highly correlated with depressive symptoms and has the potential to be a neuroimaging biomarker to predict the effect of ketamine in MDD.

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.

Early improvement as a predictor of final remission in patients with treatment-resistant depression receiving electroconvulsive therapy with ketofol anesthesia

OBJECTIVE

To examine whether early symptom improvement can predict eventual remission following electroconvulsive therapy (ECT) with ketamine plus propofol (ketofol) anesthesia in patients with treatment-resistant depression (TRD).

METHODS

Thirty Han Chinese subjects suffering from TRD were administered ketofol anesthesia during ECT. Remission was defined as a score of ≤7 on the 17-item Hamilton Depression Rating Scale (HAMD-17). Receiver operating characteristic (ROC) curves were applied to identify the number of ECT sessions (i.e., 1, 2, 3, or 4 ECT sessions) that had the best discriminative capacity for eventual remission. The best definition of early improvement to predict final remission was determined by using the Youden index.

RESULTS

Of the 30 patients with TRD, 16 (53.3%) and 30 (100%) were classified as remitters and responders, respectively. A 45% reduction in the HAMD-17 score after 3 ECT sessions was the optimum definition of early improvement in the prediction of eventual remission, with relatively good sensitivity (88%) and specificity (93%). Patients with than without early improvement had a greater possibility of achieving favorable ECT outcomes.

CONCLUSION

Final remission of TRD following ECT with ketofol anesthesia appeared to be predicted by early improvement, as indicated by a 45% reduction in HAMD-17 score after 3 ECT sessions.

Sex differences in ketamine's therapeutic effects for mood disorders: A systematic review

Replicated clinical trials have demonstrated rapid and robust antidepressant effects with ketamine in treatment resistant mood disorders. Sex (biological) and gender differences in therapeutic effects for any new intervention is an important consideration, however, the differential efficacy, safety and tolerability of ketamine in males versus females remains underexplored. The objective of the present systematic review is to identify and qualitatively synthesize all published clinical studies relevant to the sex differential effects of ketamine for mood disorders. A systematic search of PubMed, Medline, and PsycInfo from inception until January 20, 2021, yielded 27 reports including 1715 patients (742 males and 973 females) that met inclusion criteria. Results from the vast majority of studies (88.8%) do not support significant sex differences in antidepressant response, tolerability or safety of ketamine. Nine (33.3%) of the reports included a bioanalytical component in the analysis and only one reported on sex differences. Evidence from the present review does not support clinically or statistically significant sex differences in therapeutic effects with ketamine. Nevertheless, future studies should continue to consider sex and biological sex differences in study design and data analytic plans.

The effectiveness of repeated intravenous ketamine on subjective and objective psychosocial function in patients with treatment-resistant depression and suicidal ideation

BACKGROUND

Ketamine has rapid and robust antidepressant effects in adults with treatment-resistant depression (TRD), while its effects on functional outcomes have not been sufficiently evaluated. The aim was to evaluate the efficacy of ketamine treatment on both subjective and objective functioning, and to explore whether improvements in depressive symptom and cognition mediated changes in functioning.

METHODS

Adults (n=111) with TRD and/or suicidality received six infusions of ketamine (0.5mg/kg, thrice-weekly). Depression symptoms were assessed with the Montgomery-Asberg Depression Rating Scale (MADRS) at baseline, day 13 and day 26. Cognitive domains, including processing speed, working memory, visual learning and verbal learning were measured with the MATRICS Consensus Cognitive Battery, and subjective and objective functioning were measured with the Sheehan Disability Scale (SDS) and the Global Assessment of Functioning (GAF) at the same time-points.

RESULTS

Significant improvement was observed in SDS total score (effect size [ES]=-1.563) and GAF score (ES=1.700) during the 26-day observation. Results from path analysis indicated that reductions of the total MADRS score and improvements in processing speed aggregately significantly mediated the reductions of SDS total score (total indirect effect coef=-3.993, 95%CI [-4.9, -3.2], direct effect coef=-1.374, 95%CI [-2.4, -0.4]) as well as the increases of GAF score (total indirect effect coef=6.022, 95%CI [4.5, 7.8], direct effect coef=3.987, 95%CI [2.1, 5.8]).

CONCLUSION

Six infusions of ketamine was associated with improvements in functional outcomes in adults with TRD and/or suicidality. Depressive symptoms severity and processing speed performance were significant partial mediators of objective and subjective functioning improvements.

Repeated Yueju, But Not Fluoxetine, Induced Sustained Antidepressant Activity in a Mouse Model of Chronic Learned Helplessness: Involvement of CaMKII Signaling in the Hippocampus

OBJECTIVE

Depression is characterized with long disease length, whereas one major disadvantage of current mainstream treatment of depression is a high rate of relapse and recurrence. A sustained antidepressant activity is proposed to facilitate the prevention of relapse/recurrence. Here we compared the long-term antidepressant effect of Yueju, a traditional Chinese medicine formula, and a conventional antidepressant, fluoxetine, as well as revealing the underlying mechanism of long-term antidepressant effect of Yueju.

METHODS

Clinical long-term depression condition was modelled by using chronic learned helplessness (cLH) protocol in ICR strain mice. The short-term and long-term antidepressant effects of drugs were assessed with learned helplessness (LH), tail suspension test (TST), forced swim test (FST), and novelty-suppressed feeding (NSF) test. The expression of PKA, CaMKII signaling, and NR1, the NMDA receptor subunit, in hippocampus was determined. A CaMKII inhibitor (KN-62) was used to assess the role of CaMKII signaling in antidepressant effects of Yueju or fluoxetine.

RESULTS

In the mice exposed to chronic learned helplessness (cLH) procedure, administration of Yueju or fluoxetine for 3 weeks elicited comparable antidepressant effects, indicated by learned helplessness test, as well as TST and NSF. However, 5 days after termination of the 3-week-long drug administration, only mice previously treated with Yueju still showed the alleviation of depressive-like behaviors. At this time, the downregulation of PKA and p-CaMKII/CaMKII and upregulation of NMDA receptor subunit NR1 in the hippocampus were normalized in animals previously treated with Yueju. In contrast, none of the expressions of these proteins were changed in mice previously treated with fluoxetine. Interestingly, an administration of KN-62 blunted the antidepressant effect of Yueju.

CONCLUSION

These findings showed the sustained antidepressant efficacy of chronic treatment with routine dose of Yueju and the CaMKII signaling activation may play a critical role in the sustained antidepressant response.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Ketamine and Lamotrigine Combination in Psychopharmacology: Systematic Review

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

Nuclear factor of activated T cells 4 in the prefrontal cortex is required for prophylactic actions of (R)-ketamine

(R, S)-ketamine has prophylactic antidepressant-like effects in rodents; however, the precise molecular mechanisms underlying its action remain unknown. Using RNA-sequencing analysis, we searched novel molecular target(s) that contribute to the prophylactic effects of (R)-ketamine, a more potent enantiomer of (R, S)-ketamine. Pretreatment with (R)-ketamine (10 mg/kg, 6 days before) significantly ameliorated body weight loss, splenomegaly, and increased immobility time of forced swimming test in lipopolysaccharide (LPS: 1.0 mg/kg)-treated mice. RNA-sequencing analysis of prefrontal cortex (PFC) and subsequent IPA (Ingenuity Pathway Analysis) revealed that the nuclear factor of activated T cells 4 (NFATc4) signaling might contribute to sustained prophylactic effects of (R)-ketamine. Quantitative RT-PCR confirmed that (R)-ketamine significantly attenuated the increased gene expression of NFATc4 signaling (Nfatc4, Cd4, Cd79b, H2-ab1, H2-aa) in the PFC of LPS-treated mice. Furthermore, pretreatment with NFAT inhibitors (i.e., NFAT inhibitor and cyclosporin A) showed prophylactic effects in the LPS-treated mice. Similar to (R)-ketamine, gene knockdown of Nfatc4 gene by bilateral injection of adeno-associated virus (AAV) into the mPFC could elicit prophylactic effects in the LPS-treated mice. In conclusion, our data implicate a novel NFATc4 signaling pathway in the PFC underlying the prophylactic effects of (R)-ketamine for inflammation-related depression.

Cognitive Function Mediates the Anti-suicide Effect of Repeated Intravenous Ketamine in Adult Patients With Suicidal Ideation

OBJECTIVE

Prior research has shown that ketamine has anti-suicide effects. Additional evidence also suggests that ketamine may offer pro-cognitive effects. Herein, we propose that the anti-suicide effects of ketamine are partially mediated via pro-cognitive effects. We aimed to determine whether improvement in cognitive function mediated change in suicidal ideation was associated with ketamine treatment.

METHODS

Unipolar or bipolar depressive patients (n = 86) with suicidal ideation received six infusions of ketamine (0.5 mg/kg) over 2 weeks. The current severity of suicidal ideation and depression symptoms were assessed with the Beck Scale for Suicide Ideation (SSI) and the Montgomery-Asberg Depression Rating Scale (MADRS), respectively, at baseline, days 13 and 26. Cognitive domains, including processing speed, working memory, visual learning, and verbal learning were measured with the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery at the same time points.

RESULTS

Mediation analysis showed a significant total effect of ketamine treatment on SSI score (coef = -1.853, 95%CI [-2.2, -1.5]). The direct and total indirect (MADRS total score and any of cognitive domains) effects of ketamine on suicidal ideation both were statistically significant (direct: coef = -1.064 to -1.352; total indirect: coef = -0.501 to -0.788). MADRS total score and processing speed (but not other cognitive domains) were significant partial mediators of the association between ketamine treatment and improvements in suicidal ideation.

CONCLUSION

Depressive symptoms severity and processing speed performance partially mediated improvements in suicidal ideation after repeated ketamine infusions in persons with unipolar or bipolar depressive disorder.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Molecular mechanisms underlying the antidepressant actions of arketamine: beyond the NMDA receptor

The discovery of robust antidepressant actions exerted by the N-methyl-D-aspartate receptor (NMDAR) antagonist (R,S)-ketamine has been a crucial breakthrough in mood disorder research. (R,S)-ketamine is a racemic mixture of equal amounts of (R)-ketamine (arketamine) and (S)-ketamine (esketamine). In 2019, an esketamine nasal spray from Johnson & Johnson was approved in the United States of America and Europe for treatment-resistant depression. However, an increasing number of preclinical studies show that arketamine has greater potency and longer-lasting antidepressant-like effects than esketamine in rodents, despite the lower binding affinity of arketamine for the NMDAR. In clinical trials, non-ketamine NMDAR-related compounds did not exhibit ketamine-like robust antidepressant actions in patients with depression, despite these compounds showing antidepressant-like effects in rodents. Thus, the rodent data do not necessarily translate to humans due to the complexity of human psychiatric disorders. Collectively, the available studies indicate that it is unlikely that NMDAR plays a major role in the antidepressant action of (R,S)-ketamine and its enantiomers, although the precise molecular mechanisms underlying antidepressant actions of (R,S)-ketamine and its enantiomers remain unclear. In this paper, we review recent findings on the molecular mechanisms underlying the antidepressant actions of (R,S)-ketamine and its potent enantiomer arketamine. Furthermore, we discuss the possible role of the brain-gut-microbiota axis and brain-spleen axis in stress-related psychiatric disorders and in the antidepressant-like action of arketamine. Finally, we discuss the potential of arketamine as a treatment for cognitive impairment in psychiatric disorders, Parkinson's disease, osteoporosis, inflammatory bowel diseases, and stroke.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Plasma VEGF Concentrations and Ketamine's Effects on Suicidal Ideation in Depression With Suicidal Ideation

OBJECTIVES

Accumulating evidence supports a role for vascular endothelial growth factor (VEGF) in the pathogenesis of depression, but its relationship with the antisuicidal effects of ketamine is not clear. Our objective was to determine whether there was an association between the plasma VEGF (pVEGF) concentrations and the antisuicidal response to serial ketamine infusions.

METHODS

Six ketamine infusions (0.5 mg/kg) over a 12-day period were administered to sixty depressed individuals suffering from suicidal ideation. The Hamilton Depression Rating Scale (HAMD) suicide item, the Montgomery-Åsberg Depression Rating Scale (MADRS) suicide item, and the Beck Scale for Suicide Ideation (SSI-part I) were used to assess suicidal ideation at baseline, 1 day after the first infusion (day 1), 1 day following the last infusion (day 13), and again 2 weeks post-infusion (day 26). For this purpose, plasma was obtained at baseline, day 13 and 26.

RESULTS

The rates of antisuicidal response to ketamine were 61.7% (37/60), 81.7% (49/60), and 73.3% (44/60) at days 1, 13, and 26, respectively. The linear mixed model revealed significant time effects on suicidal ideation and pVEGF concentrations over time (all Ps < 0.05). Antisuicidal responders did not have significantly altered pVEGF concentrations compared with non-responders on day 13 and day 26 (all Ps > 0.05). No significant correlation was found between the baseline pVEGF concentration and suicidal ideation as measured by the SSI part 1, HAMD suicide item and MADRS suicide item on days 1, 13, and 26 (all ps > 0.05).

CONCLUSION

This preliminary finding does not support a role for VEGF in the antisuicidal effects of serial ketamine treatments in individuals with depression and suicidal ideation. Further research is needed to confirm and expand these findings.

A comparison of the antianhedonic effects of repeated ketamine infusions in melancholic and non-melancholic depression

OBJECTIVES

Melancholic depression may respond differently to certain treatments. The aim of this study was to compare the antianhedonic effects of six intravenous injections of 0.5 mg/kg ketamine in patients with melancholic and non-melancholic depression, which remain largely unknown.

METHODS

Individuals experiencing melancholic (n = 30) and non-melancholic (n = 105) depression were recruited and assessed for anhedonic symptoms using the Montgomery-Åsberg Depression Rating Scale (MADRS). The presence of melancholic depression was measured with the depression scale items at baseline based on DSM-5 criteria.

RESULTS

A total of 30 (22.2%) patients with depression fulfilled the DSM-5 criteria for melancholic depression. Patients with melancholic depression had a non-significant lower antianhedonic response (43.3 vs. 50.5%, t = 0.5, p > 0.05) and remission (20.0 vs. 21.0%, t = 0.01, p > 0.05) to repeated-dose ketamine infusions than those with non-melancholic depression. The melancholic group had significantly lower MADRS anhedonia subscale scores than the non-melancholic group at day 26 (p < 0.05).

CONCLUSION

After six ketamine infusions, the improvement of anhedonic symptoms was found in both patients with melancholic and non-melancholic depression, and the efficacy was similar in both groups.

The Mechanisms Behind Rapid Antidepressant Effects of Ketamine: A Systematic Review With a Focus on Molecular Neuroplasticity

The mechanism of action underlying ketamine's rapid antidepressant effects in patients with depression, both suffering from major depressive disorder (MDD) and bipolar disorder (BD), including treatment resistant depression (TRD), remains unclear. Of the many speculated routes that ketamine may act through, restoring deficits in neuroplasticity may be the most parsimonious mechanism in both human patients and preclinical models of depression. Here, we conducted a literature search using PubMed for any reports of ketamine inducing neuroplasticity relevant to depression, to identify cellular and molecular events, relevant to neuroplasticity, immediately observed with rapid mood improvements in humans or antidepressant-like effects in animals. After screening reports using our inclusion/exclusion criteria, 139 publications with data from cell cultures, animal models, and patients with BD or MDD were included (registered on PROSPERO, ID: CRD42019123346). We found accumulating evidence to support that ketamine induces an increase in molecules involved in modulating neuroplasticity, and that these changes are paired with rapid antidepressant effects. Molecules or complexes of high interest include glutamate, AMPA receptors (AMPAR), mTOR, BDNF/TrkB, VGF, eEF2K, p70S6K, GSK-3, IGF2, Erk, and microRNAs. In summary, these studies suggest a robust relationship between improvements in mood, and ketamine-induced increases in molecular neuroplasticity, particularly regarding intracellular signaling molecules.

Regulatory effects and potential therapeutic implications of alarin in depression, and arguments on its receptor

Alarin is a pleiotropic peptide involved in a multitude of putative biological activities, notably, it has a regulatory effect on depression-like behaviors. Although further elucidating research is needed, animal-based cumulative evidence has shown the antidepressant-like effects of alarin. In light of its regulatory role in depression, alarin could be used as a promising antidepressant in future treatment for depression. Nevertheless, the available information is still insufficient and the therapeutic relevance of alarin in depression is still of concern. Moreover, a plethora of studies have reported that the actions of alarin, including antidepressant activities, are mediated by a separate yet unidentified receptor, highlighting the need for more extensive research. This review focuses on the current understanding of the regulatory effects and future therapeutic relevance of alarin on depression, and the arguments on its receptors.

Efficacy and Safety of Intranasal Esketamine in Patients With Treatment-Resistant Depression and Comorbid Chronic Post-traumatic Stress Disorder: Open-Label Single-Arm Pilot Study

INTRODUCTION

Major depressive disorder (MDD) is more likely to resist to usual treatment when it is associated with post-traumatic stress disorder (PTSD). Capitalizing on the effect of ketamine in both treatment-resistant depression (TRD) and PTSD, we conducted a study in order to assess the efficacy of intranasal (IN) Esketamine in patients having TRD with comorbid PTSD.

MATERIALS AND METHODS

In this open-label, single arm, retrospective pilot study, 11 patients were treated with IN Esketamine (56 or 84 mg) with a longitudinal follow-up of 6 months. IN Esketamine was administered twice weekly during the first month, once weekly during the second month, and then once every 1 or 2 weeks. Patients were assessed with Montgomery-Åsberg Depression Rating Scale (MADRS), Patient Health Questionnaire 9 items, Global Assessment of Functioning (GAF), and Clinical Global Impression-Suicide Scale (CGI-SS).

RESULTS

We included 9 women and 2 men (mean age 47.3 ± 11.1 years). The mean (SD) MADRS scores decreased significantly from 38.6 (6.4) at baseline to 18.2 (10.03) after 6 months of IN Esketamine; 7 patients were responders and 3 patients were in remission. The percentage of patients who were moderately to severely suicidal declined from 63.6% at baseline to 27.3% after 1 month of IN Esketamine sessions. No serious adverse reactions were observed.

CONCLUSION

This study reports the outcomes of 11 severely ill patients with comorbid TRD and PTSD after IN Esketamine treatment. Esketamine significantly improved depression symptoms, suggesting that it is likely to be a treatment of choice in this specific population.

Antidepressant-like actions of the mGlu2/3 receptor antagonist TP0178894 in the chronic social defeat stress model: Comparison with escitalopram

The metabotropic glutamate 2/3 (mGlu2/3) receptor antagonists are reported to produce ketamine-like rapid-acting and sustained antidepressant-like effects in rodents. In this study, we compared the effects of single administration of the new mGlu2/3 receptor antagonist TP0178894 and the selective serotonin reuptake inhibitor (SSRI) escitalopram in the chronic social defeat stress (CSDS) model of depression, a model which has been shown to be resistant to treatment with a single dose of SSRI. In the tail suspension test and forced swimming test, high dose (3.0 mg/kg) of TP0178894 significantly attenuated the increased immobility time of these tests in CSDS susceptible mice, compared with vehicle-treated mice. In contrast, low doses (0.3 and 1.0 mg/kg) of TP0178894 and escitalopram (10 mg/kg) did not alter the increased immobility time of these two tests. In the sucrose preference test, TP0178894 (3.0 mg/kg) significantly improved the reduced sucrose preference of CSDS susceptible mice, three and seven days after a single dose. In addition, Western blot analyses showed that TP0178894 (3.0 mg/kg), but not low doses of TP0178894 and escitalopram, significantly attenuated the reduced expression of synaptic proteins [α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (GluA1) and postsynaptic density protein 95 (PSD-95)] in the prefrontal cortex from CSDS susceptible mice. This study suggests that TP0178894 shows rapid-acting and sustained antidepressant-like effects in CSDS model, as ketamine does.