Treatment-resistant depression: therapeutic trends, challenges, and future directions

Efficacy of amisulpride for depressive symptoms in individuals with mental disorders: A systematic review and meta-analysis

BACKGROUND

Depressive symptoms occur in several psychiatric disorders, often in the absence of a formal diagnosis of depression. We aimed to evaluate the efficacy and the tolerability of amisulpride, both alone and as augmentation therapy, in the treatment of depressive symptoms in individuals with any major psychiatric disorder.

METHODS

We searched PubMed, Embase, PsycINFO, GreyLit, OpenGrey and ProQuest up to March 2020 for randomised controlled trials focussing on the treatment of an acute depressive episode in any major psychiatric disorder. A random-effect meta-analysis was performed to synthesize the findings on depressive symptoms (primary outcome), response rate and tolerability.

RESULTS

We retrieved 11 studies including 2065 patients with a diagnosis of dysthymia (eight studies), major depression (one study) or schizophrenia (two studies). Amisulpride 50 mg/day was associated with a larger reduction of depressive symptoms compared to placebo (standardised mean difference [SMD] = -0.70, CI 95% -0.92, -0.49; I²  = 0.0%), and was found to be comparable to selective serotonin reuptake inhibitors (SSRIs; SMD = -0.08, CI 95% -0.23, 0.06, I²  = 0.0%), amineptine, imipramine and amitriptyline in the treatment of dysthymia (three studies, not pooled). In individuals with schizophrenia, amisulpride administered at higher doses (>400 mg/day) was comparable to olanzapine and risperidone (two studies, not pooled). In terms of tolerability, amisulpride was superior to placebo for dysthymia (odds ratio [OR] = 3.94, CI 95% 1.07, 14.48; I²  = 0.0) and comparable with SSRIs (OR = 0.94, CI 95% 0.55, 1.62; I²  = 0.0%).

CONCLUSION

Treatment with amisulpride could be a valid choice for selected individuals with dysthymia or depressive symptoms in the context of schizophrenia. More studies on the efficacy and tolerability of amisulpride are needed to draw firm conclusions on its potential benefits in other psychiatric disorders.

Investigating the Role of Leukocyte Telomere Length in Treatment-Resistant Depression and in Response to Electroconvulsive Therapy

Psychiatric disorders seem to be characterized by premature cell senescence. However, controversial results have also been reported. In addition, the relationship between accelerated aging and treatment-resistance has scarcely been investigated. In the current study, we measured leukocyte telomere length (LTL) in 148 patients with treatment-resistant depression (TRD, 125 with major depressive disorder, MDD, and 23 with bipolar disorder, BD) treated with electroconvulsive therapy (ECT) and analyzed whether LTL was associated with different response profiles. We also compared LTL between patients with TRD and 335 non-psychiatric controls. For 107 patients for which genome-wide association data were available, we evaluated whether a significant overlap among genetic variants or genes associated with LTL and with response to ECT could be observed. LTL was negatively correlated with age (Spearman’s correlation coefficient = −0.25, p < 0.0001) and significantly shorter in patients with treatment-resistant MDD (Quade’s F = 35.18, p < 0.0001) or BD (Quade’s F = 20.84, p < 0.0001) compared to controls. Conversely, baseline LTL was not associated with response to ECT or remission. We did not detect any significant overlap between genetic variants or genes associated with LTL and response to ECT. Our results support previous findings suggesting premature cell senescence in patients with severe psychiatric disorders and suggest that LTL could not be a predictive biomarker of response to ECT.

Plant-based dietary quality and depressive symptoms in Australian vegans and vegetarians: a cross-sectional study

Plant-based dietary patterns (vegan and vegetarian) are often considered 'healthy' and have been associated with broad health benefits, including decreased risk of obesity and ill health (cardiovascular disease, blood glucose and type II diabetes). However, the association between plant-based diets and mood disorders such as depression remains largely equivocal. This cross-sectional study of 219 adults aged 18-44 (M=31.22, SD=7.40) explored the associations between an estimate of overall plant-based diet quality and depression in vegans (n=165) and vegetarians (n=54). Overall plant-based diet quality was associated with depressive symptoms in vegans and vegetarians F(1, 215)=13.71, p<0.001 accounting for 6% of the variation in depressive symptoms. For those without depression, higher diet quality was protective against depressive symptoms F(1, 125)=6.49, p=0.012. Conversely, for those with depression no association with diet quality was found F(1, 89)=0.01, p=0.963. These findings suggest that a high-quality plant-based diet may be protective against depressive symptoms in vegans and vegetarians. In line with emerging research between food and mental health, higher-quality dietary patterns are associated with a reduced risk of depressive symptoms. Given the rapidly increasing rate of vegan and vegetarian food products within Australia, understanding the potential mechanisms of effects through which a plant-based diet may influence depressive symptoms is required.

Kir4.1 Dysfunction in the Pathophysiology of Depression: A Systematic Review

A serotonergic dysfunction has been largely postulated as the main cause of depression, mainly due to its effective response to drugs that increase the serotonergic tone, still currently the first therapeutic line in this mood disorder. However, other dysfunctional pathomechanisms are likely involved in the disorder, and this may in part explain why some individuals with depression are resistant to serotonergic therapies. Among these, emerging evidence suggests a role for the astrocytic inward rectifier potassium channel 4.1 (Kir4.1) as an important modulator of neuronal excitability and glutamate metabolism. To discuss the relationship between Kir4.1 dysfunction and depression, a systematic review was performed according to the PRISMA statement. Searches were conducted across PubMed, Scopus, and Web of Science by two independent reviewers. Twelve studies met the inclusion criteria, analyzing Kir4.1 relationships with depression, through in vitro, in vivo, and post-mortem investigations. Increasing, yet not conclusive, evidence suggests a potential pathogenic role for Kir4.1 upregulation in depression. However, the actual contribution in the diverse subtypes of the disorder and in the comorbid conditions, for example, the epilepsy-depression comorbidity, remain elusive. Further studies are needed to better define the clinical phenotype associated with Kir4.1 dysfunction in humans and the molecular mechanisms by which it contributes to depression and implications for future treatments.

Sex-based changes in rat brain serotonin and behavior in a model of altitude-related vulnerability to treatment-resistant depression

RATIONALE

Rates of depression and suicide increase with altitude. In our animal model, rats housed at moderate altitude vs. at sea level exhibit increased depressive symptoms in the forced swim test (FST) and lack of response to selective serotonin reuptake inhibitors (SSRIs). Depression and SSRI resistance are linked to disrupted serotonergic function, and hypobaric hypoxia may reduce the oxygen-dependent synthesis of serotonin. We therefore tested brain serotonin in rats housed at altitude.

METHODS

Sprague-Dawley rats were housed at altitude (4,500 ft, 10,000 ft) vs. sea level for 7-36 days. Brain serotonin was measured by ELISA, or behavior evaluated in the FST, sucrose preference (SPT), or open-field tests (OFT).

RESULTS

After 2 weeks at 4,500 ft or 10,000ft vs. sea level, serotonin levels decreased significantly at altitude in the female prefrontal cortex, striatum, hippocampus, and brainstem, but increased with altitude in the male hippocampus and brainstem. Female brain serotonin decreased from 7 to 36 days at 4,500 ft, but males did not vary. At 2 weeks and 24 days, females at altitude exhibit lower brain serotonin and increased depressive symptoms in the FST and SPT, with motor behavior unaltered. In males, serotonin, passive coping in the FST and OFT immobility increased with altitude at 2 weeks, but not at 24 days. Male SPT behavior did not change with altitude.

CONCLUSIONS

Females may be more vulnerable to depressive symptoms at altitude, while males may be resilient. Chronic hypoxic stress at altitudes as low as 4,500 ft may cause a brain serotonin imbalance to worsen vulnerability to depression and SSRI resistance, and potentially worsen suicide risk.

A partial least squares and artificial neural network study for a series of arylpiperazines as antidepressant agents

Depression affects more than 300 million people around the world and can lead to suicide. About 30% of patients on treatment for depression drop out of therapy due to side effects or to latency time associated to therapeutic effects. 5-HT receptor, known as serotonin, is considered the key in depression treatment. Arylpiperazine compounds are responsible for several pharmacological effects and are considered as ligands in serotonin receptors, such as the subtype 5-HT_2a. Here, in silico studies were developed using partial least squares (PLSs) and artificial neural networks (ANNs) to design new arylpiperazine compounds that could interact with the 5-HT_2a receptor. First, molecular and electronic descriptors were calculated and posteriorly selected from correlation matrixes and genetic algorithm (GA). Then, the selected descriptors were used to construct PLS and ANN models that showed to be robust and predictive. Lastly, new arylpiperazine compounds were designed and their biological activity values were predicted by both PLS and ANN models. It is worth to highlight compounds G5 and G7 (predicted by the PLS model) and G3 and G15 (predicted by the ANN model), whose predicted pIC₅₀ values were as high as the three highest values from the arylpiperazine original set studied here. Therefore, it can be asserted that the two models (PLS and ANN) proposed in this work are promising for the prediction of the biological activity of new arylpiperazine compounds and may significantly contribute to the design of new drugs for the treatment of depression.

Neuroprotective Effects and Therapeutic Potential of Transcorneal Electrical Stimulation for Depression

Transcorneal electrical stimulation (TES) has emerged as a non-invasive neuromodulation approach that exerts neuroprotection via diverse mechanisms, including neurotrophic, neuroplastic, anti-inflammatory, anti-apoptotic, anti-glutamatergic, and vasodilation mechanisms. Although current studies of TES have mainly focused on its applications in ophthalmology, several lines of evidence point towards its putative use in treating depression. Apart from stimulating visual-related structures and promoting visual restoration, TES has also been shown to activate brain regions that are involved in mood alterations and can induce antidepressant-like behaviour in animals. The beneficial effects of TES in depression were further supported by its shared mechanisms with FDA-approved antidepressant treatments, including its neuroprotective properties against apoptosis and inflammation, and its ability to enhance the neurotrophic expression. This article critically reviews the current findings on the neuroprotective effects of TES and provides evidence to support our hypothesis that TES possesses antidepressant effects.

The role of meningeal populations of type II innate lymphoid cells in modulating neuroinflammation in neurodegenerative diseases

Recent research into meningeal lymphatics has revealed a never-before appreciated role of type II innate lymphoid cells (ILC2s) in modulating neuroinflammation in the central nervous system (CNS). To date, the role of ILC2-mediated inflammation in the periphery has been well studied. However, the exact distribution of ILC2s in the CNS and therefore their putative role in modulating neuroinflammation in neurodegenerative diseases such as Alzheimer's disease (AD), multiple sclerosis (MS), Parkinson's disease (PD), and major depressive disorder (MDD) remain highly elusive. Here, we review the current evidence of ILC2-mediated modulation of neuroinflammatory cues (i.e., IL-33, IL-25, IL-5, IL-13, IL-10, TNFα, and CXCL16-CXCR6) within the CNS, highlight the distribution of ILC2s in both the periphery and CNS, and discuss some challenges associated with cell type-specific targeting that are important for therapeutics. A comprehensive understanding of the roles of ILC2s in mediating and responding to inflammatory cues may provide valuable insight into potential therapeutic strategies for many dementia-related disorders.

Prevalence of Pre-existing Conditions Relevant for Adverse Events and Potential Drug-Drug Interactions Associated with Augmentation Therapies Among Patients with Treatment-Resistant Depression

INTRODUCTION

Pre-existing conditions relevant for adverse events (AE) and the potential for drug-drug interactions (DDIs) may limit safe pharmacotherapeutic augmentation options for patients with major depressive disorder (MDD). This concern may be heightened among patients with treatment-resistant depression (TRD), who often have comorbid medical disorders.

METHODS

Adults with MDD and ≥ 1 antidepressant claim within the first observed major depressive episode were identified in the MarketScan® Databases. Those initiating a new regimen after two regimens at adequate dose and duration were considered to have TRD. The index date was defined at TRD onset or on a random antidepressant claim among patients with non-TRD MDD. Pre-existing conditions 12 months pre-index and potential DDIs 3 months pre/post-index associated with specific non-antidepressant augmentation therapies, including atypical antipsychotics (APs), buspirone, psychostimulants, anticonvulsants, thyroid hormone, and lithium were compared between 1:1 matched TRD and non-TRD MDD cohorts.

RESULTS

Overall, 3414 patients with TRD and non-TRD MDD (mean age 39.7 years, 69% female) were matched. Relative to non-TRD MDD, patients with TRD had 33% higher likelihood of ≥ 1 pre-existing condition relevant for AEs listed in product labels of non-antidepressant augmentation therapies (p < 0.001). Patients with TRD vs. non-TRD MDD had 12.9 and 6.4 times higher likelihood of ≥ 2 and ≥ 3 DDIs, respectively, based on their medication regimen (all p < 0.001).

CONCLUSION

Pre-existing conditions relevant for listed AEs and potential DDIs limit safe augmentation options in MDD, particularly among patients with TRD. Payer prior authorization policies requiring several augmentation therapy trials to access novel treatments may complicate clinical management of this population.

Sequencing the serotonergic neuron translatome reveals a new role for Fkbp5 in stress

Serotonin is a key mediator of stress, anxiety, and depression, and novel therapeutic targets within serotonin neurons are needed to combat these disorders. To determine how stress alters the translational profile of serotonin neurons, we sequenced ribosome-associated RNA from these neurons after repeated stress in male and female mice. We identified numerous sex- and stress-regulated genes. In particular, Fkbp5 mRNA, which codes for the glucocorticoid receptor co-chaperone protein FKBP51, was consistently upregulated in male and female mice following stress. Pretreatment with a selective FKBP51 inhibitor into the dorsal raphe prior to repeated forced swim stress decreased resulting stress-induced anhedonia. Our results support previous findings linking FKBP51 to stress-related disorders and provide the first evidence suggesting that FKBP51 function may be an important regulatory node integrating circulating stress hormones and serotonergic regulation of stress responses.

A narrative review on invasive brain stimulation for treatment-resistant depression

While most patients with depression respond to pharmacotherapy and psychotherapy, about one-third will present treatment resistance to these interventions. For patients with treatment-resistant depression (TRD), invasive neurostimulation therapies such as vagus nerve stimulation, deep brain stimulation, and epidural cortical stimulation may be considered. We performed a narrative review of the published literature to identify papers discussing clinical studies with invasive neurostimulation therapies for TRD. After a database search and title and abstract screening, relevant English-language articles were analyzed. Vagus nerve stimulation, approved by the U.S. Food and Drug Administration as a TRD treatment, may take several months to show therapeutic benefits, and the average response rate varies from 15.2-83%. Deep brain stimulation studies have shown encouraging results, including rapid response rates (> 30%), despite conflicting findings from randomized controlled trials. Several brain regions, such as the subcallosal-cingulate gyrus, nucleus accumbens, ventral capsule/ventral striatum, anterior limb of the internal capsule, medial-forebrain bundle, lateral habenula, inferior-thalamic peduncle, and the bed-nucleus of the stria terminalis have been identified as key targets for TRD management. Epidural cortical stimulation, an invasive intervention with few reported cases, showed positive results (40-60% response), although more extensive trials are needed to confirm its potential in patients with TRD.

Striatal Shati/Nat8l-BDNF pathways determine the sensitivity to social defeat stress in mice through epigenetic regulation

The global number of patients with depression increases in correlation to exposure to social stress. Chronic stress does not trigger depression in all individuals, as some remain resilient. The underlying molecular mechanisms that contribute to stress sensitivity have been poorly understood, although revealing the regulation of stress sensitivity could help develop treatments for depression. We previously found that striatal Shati/Nat8l, an N-acetyltransferase, was increased in a depression mouse model. We investigated the roles of Shati/Nat8l in stress sensitivity in mice and found that Shati/Nat8l and brain-derived neurotrophic factor (BDNF) levels in the dorsal striatum were increased in stress-susceptible mice but not in resilient mice exposed to repeated social defeat stress (RSDS). Knockdown of Shati/Nat8l in the dorsal striatum induced resilience to RSDS. In addition, blockade of BDNF signaling in the dorsal striatum by ANA-12, a BDNF-specific receptor tropomyosin-receptor-kinase B (TrkB) inhibitor, also induced resilience to stress. Shati/Nat8l is correlated with BDNF expression after RSDS, and BDNF is downstream of Shati/Nat8l pathways in the dorsal striatum; Shati/Nat8l is epigenetically regulated by BDNF via histone acetylation. Our results demonstrate that striatal Shati/Nat8l-BDNF pathways determine stress sensitivity through epigenetic regulation. The striatal Shati/Nat8l-BDNF pathway could be a novel target for treatments of depression and could establish a novel therapeutic strategy for depression patients.

Sex-Based Impact of Creatine Supplementation on Depressive Symptoms, Brain Serotonin and SSRI Efficacy in an Animal Model of Treatment-Resistant Depression

Background: Rates of major depressive disorder (MDD) increase with living at altitude. In our model, rats housed at moderate altitude (in hypobaric hypoxia) exhibit increased depression-like behavior, altered brain serotonin and a lack of antidepressant response to most selective serotonin reuptake inhibitors (SSRIs). A forebrain deficit in the bioenergetic marker creatine is noted in people living at altitude or with MDD. Methods: Rats housed at 4500 ft were given dietary creatine monohydrate (CRMH, 4% w/w, 5 weeks) vs. un-supplemented diet, and impact on depression-like behavior, brain bioenergetics, serotonin and SSRI efficacy assessed. Results: CRMH significantly improved brain creatine in a sex-based manner. At altitude, CRMH increased serotonin levels in the female prefrontal cortex and striatum but reduced male striatal and hippocampal serotonin. Dietary CRMH was antidepressant in the forced swim test and anti-anhedonic in the sucrose preference test in only females at altitude, with motor behavior unchanged. CRMH improved fluoxetine efficacy (20 mg/kg) in only males at altitude: CRMH + SSRI significantly improved male striatal creatine and serotonin vs. CRMH alone. Conclusions: Dietary CRMH exhibits sex-based efficacy in resolving altitude-related deficits in brain biomarkers, depression-like behavior and SSRI efficacy, and may be effective clinically for SSRI-resistant depression at altitude. This is the first study to link CRMH treatment to improving brain serotonin.

Efficacy and Safety of Seltorexant as Adjunctive Therapy in Major Depressive Disorder: A Phase 2b, Randomized, Placebo-Controlled, Adaptive Dose-Finding Study

BACKGROUND

Seltorexant, a selective antagonist of human orexin-2 receptors, demonstrated antidepressant effects in a previous exploratory study in patients with major depressive disorder (MDD).

METHODS

To replicate and extend this observation, a double-blind, adaptive dose-finding study was performed in patients with MDD who had an inadequate response to 1-3 selective serotonin/serotonin-norepinephrine reuptake inhibitors in the current episode. Patients were randomized (2:1:1) to placebo or seltorexant (20 mg or 40 mg) once-daily, administered adjunctively to the antidepressant the patient had been receiving at screening. After an interim analysis (6 weeks post-randomization of 160th patient), newly recruited patients randomly received (3:3:1) placebo or seltorexant 10 mg or 20 mg; the 40-mg dose was no longer assigned. Patients were stratified by baseline Insomnia Severity Index (ISI) scores (ISI ≥ 15 vs < 15). The primary endpoint was change from baseline Montgomery-Åsberg Depression Rating Scale (MADRS) total score at week 6.

RESULTS

Mixed-Model for Repeated Measures analysis showed a greater improvement in MADRS total score in the seltorexant 20-mg group vs placebo at weeks 3 and 6; least-square means difference (90% CI): -4.5 (-6.96; -2.07), P = .003; and -3.1 (-6.13; -0.16), P = .083, respectively. The improvement in MADRS score at week 6 for seltorexant 20 mg was greater in patients with baseline ISI ≥ 15 vs those with ISI < 15; least-square means difference (90% CI) vs placebo: -4.9 (-8.98; -0.80) and -0.7 (-5.16; 3.76), respectively. The most common (≥5%) adverse events with seltorexant were somnolence, headache, and nausea.

CONCLUSIONS

A clinically meaningful reduction of depressive symptoms was observed for seltorexant 20 mg. In the subset of patients with sleep disturbance (ISI ≥ 15), a larger treatment difference between seltorexant 20 mg and placebo was observed, warranting further investigation. No new safety signal was identified.

REGISTRATION

ClinicalTrials.gov Identifier: NCT03227224.

PREVIOUS PRESENTATION

Poster presented at 58th Annual Meeting of American College of Neuropsychopharmacology (ACNP), December 8-11, 2019, Orlando, FL.

Synthesis and Evaluation of the Antidepressant-like Properties of HBK-10, a Novel 2-Methoxyphenylpiperazine Derivative Targeting the 5-HT1A and D2 Receptors

The increasing number of patients reporting depressive symptoms requires the design of new antidepressants with higher efficacy and limited side effects. As our previous research showed, 2-methoxyphenylpiperazine derivatives are promising candidates to fulfill these criteria. In this study, we aimed to synthesize a novel 2-methoxyphenylpiperazine derivative, HBK-10, and investigate its in vitro and in vivo pharmacological profile. After assessing the affinity for serotonergic and dopaminergic receptors, and serotonin transporter, we determined intrinsic activity of the compound at the 5-HT_1A and D₂ receptors. Next, we performed behavioral experiments (forced swim test, tail suspension test) to evaluate the antidepressant-like activity of HBK-10 in naïve and corticosterone-treated mice. We also assessed the safety profile of the compound. We showed that HBK-10 bound strongly to 5-HT_1A and D₂ receptors and presented antagonistic properties at these receptors in the functional assays. HBK-10 displayed the antidepressant-like effect not only in naïve animals, but also in the corticosterone-induced mouse depression model, i.e., chronic administration of HBK-10 reversed corticosterone-induced changes in behavior. Moreover, the compound’s sedative effect was observed at around 26-fold higher doses than the antidepressant-like ones. Our study showed that HBK-10 displayed a favorable pharmacological profile and may represent an attractive putative treatment candidate for depression.

Acupuncture Treatment for Social Defeat Stress

Depression is a mood disorder characterized by disordered affect, thoughts, cognition, and behavior. Antidepressant therapy is often the primary treatment for depression. However, antidepressant therapy may cause unwanted side effects, and its effects are slow. Therefore, some patients are seeking alternative treatments for depression, such as acupuncture. However, there are many unclear points regarding the mechanism of the effect of acupuncture on depression. In recent years, we have reported that acupuncture improves the symptoms of mild depression induced by water-immersion stress in a rat model and depression induced by forced swimming in a mouse model. In this study, we examined the effect of acupuncture on the symptoms of social defeat stress (SDS)-induced depression in mice that most closely resemble human symptoms. In this study, we investigated the preventive and therapeutic effects of acupuncture as part of GV20 “Bai-Hui” and Ex-HN3 “Yintang” on model mice with depression induced by SDS. To examine the mechanism of the preventive and therapeutic effects of acupuncture on depression model mice, we examined the expression of neurotrophic factors in the brains of SDS mice. Two weeks of simultaneous acupuncture stimulation as part of GV20 and Ex-HN3 restored SDS-reduced brain-derived neurotrophic factor (BDNF), neurotrophin (NT)-3, and NT-4/5 expression, which was not observed with antidepressants. In contrast, acupuncture stimulation suppressed nerve growth factor (NGF) expression induced by SDS. These results suggest that acupuncture treatment could be effective in correcting the imbalance in the expression of neurotrophic factors. Furthermore, the effects of acupuncture on the expression of neurotrophic factors appear earlier than those of antidepressants, suggesting that it may be a useful treatment for depression.

Escitalopram Targets Oxidative Stress, Caspase-3, BDNF and MeCP2 in the Hippocampus and Frontal Cortex of a Rat Model of Depression Induced by Chronic Unpredictable Mild Stress

In recent years, escitalopram (ESC) has been suggested to have different mechanisms of action beyond its well known selective serotonin reuptake inhibition. The aim of this study is to investigate the effects of escitalopram on oxidative stress, apoptosis, brain-derived neurotrophic factor (BDNF), Methyl-CpG-binding protein 2 (MeCP2), and oligodendrocytes number in the brain of chronic unpredictable mild stress-induced depressed rats. The animals were randomised in four groups (8 in each group): control, stress, stress + ESC 5 and stress + ESC 5/10. ESC was administered for 42 days in a fixed dose (5 mg/kg b.w.) or in an up-titration regimen (21 days ESC 5 mg/kg b.w. then 21 days ESC 10 mg/kg b.w.). Sucrose preference test (SPT) and elevated plus maze (EPM) were also performed. ESC improved the percentage of sucrose preference, locomotion and anxiety. ESC5/10 reduced the oxidative damage in the hippocampus and improved the antioxidant defence in the hippocampus and frontal lobe. ESC5/10 lowered caspase 3 activity in the hippocampus. Escitalopram had a modulatory effect on BDNF and the number of oligodendrocytes in the hippocampus and frontal lobe and also improved the MeCP2 expressions. The results confirm the multiple pathways implicated in the pathogenesis of depression and suggest that escitalopram exerts an antidepressant effect via different intricate mechanisms.

Exploring CNS effects of American traditional medicines using zebrafish models

Although American traditional medicine (ATM) has been practiced for millennia, its complex multi-target mechanisms of therapeutic action remain poorly understood. Animal models are widely used to elucidate the therapeutic effects of various ATMs, including their modulation of brain and behavior. Complementing rodent models, the zebrafish (Danio rerio) is a promising novel organism in translational neuroscience and neuropharmacology research. Here, we emphasize the growing value of zebrafish for testing neurotropic effects of ATMs and outline future directions of research in this field. We also demonstrate the developing utility of zebrafish as complementary models for probing CNS mechanisms of ATM action and their potential to treat brain disorders.

Merging the Multi-Target Effects of Kleeb Bua Daeng, a Thai Traditional Herbal Formula in Unpredictable Chronic Mild Stress-Induced Depression

Major depressive disorder (MDD) is a common and debilitating psychiatric disease characterized by persistent low mood, lack of energy, hypoactivity, anhedonia, decreased libido, and impaired cognitive and social functions. However, the multifactorial etiology of MDD remains largely unknown due the complex interaction between genetics and environment involved. Kleeb Bua Daeng (KBD) is a Thai traditional herbal formula that has been used to promote brain health. It consists of a 1:1:1 ratio of the aerial part of Centella asiatica, Piper nigrum fruit, and the petals of Nelumbo nucifera. According to the pharmacological activities of the individual medicinal plants, KBD has good potential as a treatment for MDD. The present study investigated the antidepressant activity of KBD in an unpredictable chronic mild stress (UCMS) mouse model. Daily administration of KBD to UCMS mice ameliorated both anhedonia, by increasing 2% sucrose intake, and hopeless behavior, by reducing immobility times in the forced swimming test (FST) and tail suspension test (TST) without any effect on locomotor activity. The mechanism of KBD activity was multi-modal. KBD promoted neurogenesis by upregulation of brain-derived neurotrophic factor (BDNF) and cyclic AMP-responsive element binding (CREB) mRNA expression in the frontal cortex and hippocampus. Daily treatment with KBD significantly reversed UCMS-induced HPA axis dysregulation by upregulating the glucocorticoid receptor (GR) while downregulating serum- and glucocorticoid-inducible kinase 1 (SGK1) and FK506 binding protein 5 (FKBP5) mRNA expression. KBD treatment also normalized proinflammatory cytokine expression including tumor necrosis factor-alpha (TNF-α), and interleukin (IL)-1β and IL-6. KBD and its component extracts also exhibited an inhibitory effect in vitro on monoamine oxidase (MAO) A and B. The multiple antidepressant actions of KBD emphasize its potential as an effective, novel treatment for MDD.

P11 (S100A10) as a potential predictor of ketamine response in patients with SSRI-resistant depression

BACKGROUND

Ketamine can act as antidepressant in patients with major depressive disorder (MDD) who are treatment-resistant. P11 has been implicated in ketamine's mechanism of action and proposed as biomarker for treatment response to other antidepressants. This study explores the effect of ketamine on peripheral p11 and the potential role for p11 as response marker for ketamine treatment.

METHODS

Thirty Selective Serotonin Reuptake Inhibitor resistant MDD patients were randomized to either 0.5 mg/kg ketamine or placebo intravenous treatment. Using multicolor Flow Cytometry, peripheral p11 levels were measured before and 1-2 days after treatment.

RESULTS

P11 levels were decreased within the ketamine group in both cytotoxic T cell and T helper cells populations, although this did not significantly differ from changes seen in the placebo group. Baseline p11 levels in cytotoxic T cells were significantly correlated with antidepressant response to ketamine treatment.

LIMITATIONS

This study was part of a larger study examining the effect of ketamine on the serotonin system in MDD patients, therefore the number of study subjects was limited to that of the primary study.

CONCLUSIONS

High baseline p11 levels in cytotoxic T cells were associated with a stronger reduction of depressive symptoms in MDD patients after ketamine treatment. Future studies should confirm if peripheral p11 levels could be used as a predictor of ketamine treatment response.

Exploring real-world evidence to uncover unknown drug benefits and support the discovery of new treatment targets for depressive and bipolar disorders

BACKGROUND

Major depressive and bipolar disorders are associated with impaired quality of life and high economic burden. Although progress has been made in our understanding of the underlying pathophysiology and the development of novel pharmacological treatments, a large unmet need remains for finding effective treatment options. The purpose of this study was to identify potential new mechanisms of actions or treatment targets that could inform future research and development opportunities for major depressive and bipolar disorders.

METHODS

A self-controlled cohort study was conducted to examine associations between 1933 medications and incidence of major depressive and bipolar disorders across four US insurance claims databases. Presence of incident depressive or bipolar disorders were captured for each patient prior to or after drug exposure and incident rate ratios were calculated. Medications that demonstrated ≥50% reduction in risk for both depressive and bipolar disorders within two or more databases were evaluated as potential treatment targets.

RESULTS

Eight medications met our inclusion criteria, which fell into three treatment groups: drugs used in substance use disorders; drugs that affect the cholinergic system; and drugs used for the management of cardiovascular-related conditions.

LIMITATIONS

This study was not designed to confirm a causal association nor inform current clinical practice. Instead, this research and the methods employed intended to be hypothesis generating and help uncover potential treatment pathways that could warrant further investigation.

CONCLUSIONS

Several potential drug targets that could aid further research and discovery into novel treatments for depressive and bipolar disorders were identified.

Practical recommendations for the management of treatment-resistant depression with esketamine nasal spray therapy: Basic science, evidence-based knowledge and expert guidance

OBJECTIVES

Despite the available therapies for treatment-resistant depression (TRD), there are a limited number that are evidence-based and effective in this hard-to-treat population. Esketamine nasal spray, an intranasal N-methyl-d-aspartate (NMDA) glutamate receptor antagonist, is a novel, fast-acting option in this patient population. This manuscript provides expert guidance on the practicalities of using esketamine nasal spray.

METHODS

A group of six European experts in major depressive disorder (MDD) and TRD, with clinical experience of treating patients with esketamine nasal spray, first generated practical recommendations, before editing and voting on these to develop consensus statements during an online meeting.

RESULTS

The final consensus statements encompass not only pre-treatment considerations for patients with TRD, but also specific guidelines for clinicians to consider during and post-administration of esketamine nasal spray.

CONCLUSIONS

Esketamine nasal spray is a novel, fast-acting agent that provides an additional treatment option for patients with TRD who have previously failed several therapies. The guidance here is based on the authors' experience and the available literature; however, further real-world use of esketamine nasal spray will add to existing knowledge. The recommendations offer practical guidance to clinicians who are unfamiliar with esketamine nasal spray.

Comparative Efficacy and Acceptability of Anti-inflammatory Agents on Major Depressive Disorder: A Network Meta-Analysis

Background: With the growing importance of research about the association between neuroinflammation and major depressive disorder (MDD), anti-inflammatory agents have been used as a new antidepressant therapy in clinical practice. We conducted a network meta-analysis (NMA) with up-to-date evidence to compare different anti-inflammatory agents for improving the treatment of MDD patients.

Methods: To identify eligible randomized clinical trials, four databases (i.e, the Cochrane Library, Web of Science, PubMed and Embase) were searched from inception date to May 31, 2020. Anti-inflammatory agents were defined as non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, cytokine inhibitors, statins, pioglitazone, minocycline, N-acetylcysteine (NAC) and omega-3 fatty acid (Omega-3 FA). The main outcomes of this NMA were efficacy, acceptability and remission rate. Risk ratio (RR) was adopted for dichotomous outcomes, and the confidence interval (CI) was set at 95%. STATA 14.0 and R 3.6.3 were used to conduct the NMA. The study protocol was registered with PROSPERO (CRD42020182531).

Results: A total of 39 studies, involving 2871 participants, were included in quantitative data synthesis. For efficacy, NSAIDs (RR=0.50, 95%CI: 0.26-0.73) and pioglitazone (RR=0.45, 95%CI: 0.20-0.84) were more favorable than placebo. With respect to acceptability, NSAIDs were more acceptable than placebo (RR=0.89, 95%CI: 0.77-0.99) and minocycline (RR=1.22, 95%CI: 1.03-1.49). For remission, NSAIDs were more superior than placebo (RR=0.48, 95%CI: 0.27-0.79) and Omega-3 FA (RR=2.01, 95%CI: 1.09-3.90), while NACs were more favorable than placebo (RR=0.39, 95%CI: 0.13-0.99). Based on the surface under the cumulative ranking curve (SUCRA) value, corticosteroids (0.86) were the best anti-inflammatory agent for MDD patients in terms of efficacy, but the head-to-head comparisons for the efficacy of glucocorticoids and other agents were not statistically significant. As for acceptability, NSAIDs (0.81) were much better than other anti-inflammatory agents. Besides, NAC (0.80) was the best anti-inflammatory agent in the terms of remission.

Conclusions: In summary, we found that corticosteroids were more superior than other agents in terms of efficacy according to the SUCRA value. However, this result must be interpreted with caution because the head-to-head comparisons for the efficacy of glucocorticoids and other agents did not reach statistical significance. NSAIDs were recommended for acceptability and NAC for remission rate.

Real-world evidence from a European cohort study of patients with treatment resistant depression: Treatment patterns and clinical outcomes

BACKGROUND

Treatment resistant depression (TRD) characterizes a subgroup of 10-30% of patients with major depressive disorder, and is associated with considerable morbidity and mortality. A consensus treatment for TRD does not exist, which often leads to wide variations in treatment strategies. Real-world studies on treatment patterns and outcomes in TRD patients in Europe are lacking and could help elucidate current treatment strategies and their efficacy.

METHODS

This non-interventional cohort study of patients with TRD (defined as treatment failure on ≥2 oral antidepressants given at adequate dose and duration) with moderate to severe depression collected real-world data on treatment patterns and outcomes in several European countries. Patients were started on a new treatment for depression according to routine clinical practice.

RESULTS

Among 411 patients enrolled, after 6 months, only 16.7% achieved remission and 73.5% showed no response. At Month 12, while 19.2% achieved remission and 69.2% showed no response, 33.3% of those in remission at Month 6 were no longer in remission. Pharmacological treatments employed were heterogenous; 54 different drugs were recorded at baseline, and the top 5 treatment types according to drug classes accounted for 40.0% of patients. Even though remission rates were very low, at Month 12, 60.0% of patients had not changed treatment since enrolment.

CONCLUSIONS

The heterogeneity of treatments highlights a lack of consensus. Moreover, despite low response rates, patients often remained on treatments for substantial periods of time. These data further support existence of an unmet treatment need for TRD patients in Europe.

Role of the Pharmacist in Managing Treatment-Resistant Depression: A Focus on Ketamine

The impact of depression is well described in the literature, and it is most prominent in patients who have trialed multiple treatments. Treatment-resistant depression (TRD) is particularly debilitating, and it is associated with significant morbidity and mortality. Despite this, there seems to be therapeutic inertia in adopting novel therapies in current practice. Ketamine is an N-methyl-D-aspartate receptor antagonist and anesthetic agent which has recently been shown to be effective in the management of TRD when administered intravenously or intranasally. The treatments, however, are not easily accessible due to restrictions in prescribing and dispensing, high costs, and the slow uptake of evidence-based practice involving ketamine within the Canadian healthcare system. Given the limited treatment options for TRD, novel approaches should be considered and adopted into practice, and facilitated by a multi-disciplinary approach. Pharmacists play a critical role in ensuring access to quality care. This includes dissemination of evidence supporting pharmacological treatments and facilitating translation into current practice. Pharmacists are uniquely positioned to collaborate with prescribers and assess novel treatment options, such as ketamine, address modifiable barriers to treatment, and triage access to medications during transitions of care. Extending the reach of these novel psychiatric treatments in both tertiary and primary care settings creates an emerging role for pharmacists in the collaborative effort to better manage treatment-resistant depression.

Deep Brain Stimulation for Refractory Depression, Obsessive-Compulsive Disorder and Addiction

Background

Depression, Obsessive-compulsive Disorder (OCD), and addiction are the leading disabling psychiatric conditions with huge health care and psychosocial burden besides increased morbidity and mortality. Deep brain stimulation (DBS) for depression, OCD, and addiction is increasingly explored and is quite challenging. We present a brief review of the pertinent literature of DBS for depression, OCD, and addiction and present the status and challenges.

Objective

The aim of this study was to review the current status and challenges with the DBS for Depression, Obsessive-compulsive Disorder (OCD), and addiction.

Method

The pertinent brief literature was reviewed in reference to the DBS for Depression, Obsessive-compulsive Disorder (OCD), and addiction.

Results

To date, OCD is the only psychiatric condition approved for DBS therapy (under humanitarian device exemption). Although the initial encouraging results of DBS in depression were encouraging but the two larger multicenter clinical trials failed to meet the primary objective. Further evaluation and studies are ongoing. Similarly, the initial results of DBS for addiction are encouraging; however, the experience is limited.

Conclusion

DBS for depression, OCD, and addiction seem challenging but promising. Further refinement of the target and evaluation in a larger and controlled setting is needed, specifically for depression and addiction.

Synthesis and biological evaluation of 1-(4-(piperazin-1-yl)phenyl)pyridin-2(1H)-one derivatives as potential SSRIs

A series of novel 1-(4-(piperazin-1-yl)phenyl)pyridin-2(1H)-one derivatives were synthesized and evaluated for their serotonin (5-HT) reuptake inhibitory activity. The results in vitro indicated that most of the evaluated compounds displayed potent 5-HT reuptake inhibition. The most promising compound A20 was stable in human liver microsomes and possessed good pharmacokinetic properties. Antidepressant study in vivo of the compound A20 showed that A20 could potently antagonize the p-chloroamphetamine (PCA)-induced depletion of serotonin in hypothalamus and reduce immobility times in the rat forced swimming test (FST).

Recent Advances in the Synthesis of the Antidepressant Paroxetine

Paroxetine is a potent inhibitor of serotonin reuptake and is widely prescribed for the treatment of depression and other neurological disorders. The synthesis of paroxetine and the possibility to prepare derivatives with a specific substitution pattern that may allow their use as biological probes is an attractive topic especially for medicinal chemists engaged in neurosciences research. Considering the extensive work that was developed in the last decade on the total synthesis of paroxetine, this review summarizes the most important contributions in this field, organized according to the reagent that was used as a starting material. Most of the methods allowed to prepare paroxetine in 4-9 steps with an overall yield of 9-66%. Despite the progress made in this area, there is still room for improvement, searching for new eco-friendly and sustainable synthetic alternatives.

The effects of perinatal fluoxetine exposure on emotionality behaviours and cortical and hippocampal glutamatergic receptors in female Sprague-Dawley and Wistar-Kyoto rats

RATIONALE

There is increasing concern regarding the use of selective serotonin reuptake inhibitors (SSRIs) in pregnancy. Animal studies repeatedly show increased anxiety- and depressive-like behaviours in offspring exposed perinatally to SSRIs, however much of this research is in male offspring.

OBJECTIVES

The primary aim of this study was to investigate the effects of perinatal SSRI exposure on emotionality-related behaviours in female offspring and associated glutamatergic markers, in Sprague-Dawley (SD) rats and in the Wistar-Kyoto (WKY) rat model of depression. Secondly, we sought to investigate the glutamatergic profile of female WKY rats that may underlie their depressive- and anxiety-like phenotype.

METHODS

WKY and SD rat dams were treated with the SSRI, fluoxetine (FLX; 10 mg/kg/day), or vehicle, throughout gestation and lactation (5 weeks total). Female adolescent offspring underwent behaviour testing followed by quantitative immunoblot of glutamatergic markers in the prefrontal cortex and ventral hippocampus.

RESULTS

Naïve female WKY offspring displayed an anxiety-like and depressive-like phenotype as well as reductions in NMDA and AMPA receptor subunits and PSD-95 in both ventral hippocampus and prefrontal cortex, compared to SD controls. Perinatal FLX treatment increased anxiety-like and forced swim immobility behaviours in SD offspring but did not influence behaviour in female WKY offspring using these tests. Perinatal FLX exposure did not influence NMDA or AMPA receptor subunit expression in female WKY or SD offspring; it did however have restricted effects on group I mGluR expression in SD and WKY offspring and reduce the glutamatergic synaptic scaffold, PSD-95.

CONCLUSION

These findings suggest female offspring of the WKY strain display deficits in glutamatergic markers which may be related to their depressive- and anxiety-like phenotype. While FLX exposed SD offspring displayed increases in anxiety-like and depressive-like behaviours, further studies are needed to assess the potential impact of developmental FLX exposure on the behavioural phenotype of female WKY rats.

Rice bran, an off-shoot to newer therapeutics in neurological disorders

Normal brain functioning involves the interaction of interconnected molecular and cellular activities, which appear to alter normal to abnormal brain functioning when worsened, contributing to the emergence of neurological disorders. There are currently millions of people who are living with brain disorders globally and this will rise if suitable prevention strategies are not explored. Nutraceutical intended to treat numerous health goals with little adverse effect possible together can be more beneficial than pharmaceutical monotherapy for fostering balanced brain functioning. Nutraceutical provides a specific composition of effective macronutrients and micronutrients that are difficult to synthesize in the laboratory. Numerous elements of rice fibers in rice bran are characterized as natural anti-oxidant and having potential anti-inflammatory activity. The rice bran captures interest among the researchers as it is widespread, affordable, and rich in nutrients including protein, fat, carbohydrates, bioactive components, and dietary fiber. This review covers the neuroprotective multiplicity of rice bran and its constituents to deter pathological conditions of the brain and to facilitate balanced brain functioning at the same time.

The relationship between depressive symptoms, general psychopathology, and well-being in patients with major depressive disorder

OBJECTIVE

In mental health care, treatment effects are commonly monitored by symptom severity measures. This study aimed to investigate the relationship between symptom severity and well-being in the treatment of patients with major depressive disorder (MDD).

METHODS

Adult MDD outpatients (n = 77) were administered the Quick Inventory of Depressive Symptomatology-Self-Report (QIDS-SR), the Outcome Questionnaire (OQ-45), and the Mental Health Continuum-Short Form (MHC-SF) before treatment and 6 months later.

RESULTS

Symptom severity correlated moderately with well-being at baseline and strongly at follow-up. Reliable change index scores showed improvement on the QIDS-SR, OQ-45, and MHC-SF in 65%, 59%, and 40%, respectively. A quarter of patients improved in symptom severity but not well-being (Inventory of Depressive Symptomatology-Self-Report [IDS-SR]: 25%; OQ-45: 24%).

CONCLUSION

Findings suggest that symptom severity and subjective well-being are related, but distinct concepts. Several reasons for the stronger improvements in symptoms than in well-being are discussed.

Phloridzin ameliorates type 2 diabetes-induced depression in mice by mitigating oxidative stress and modulating brain-derived neurotrophic factor

PURPOSE

Type 2 diabetes (T2D) is linked with depression due to insulin resistance, oxidative stress and disruption of neurotrophic factors. We evaluated potential benefits of phloridzin in ameliorating depressive symptoms in T2D.

METHODS

Adult male Swiss-albino mice (25-30 g) on high-fat-diet (HFD) for 2 weeks were administered with streptozotocin (STZ; 35 mg/kg, intraperitoneal) to induce T2D. Seven days after STZ administration, diabetic mice on HFD were distributed into different groups. Animals were subjected daily to oral treatment of saline (0.25 ml), fluoxetine (10-20 mg/kg) or phloridzin (10-20 mg/kg) for a period of 4 weeks. One hour after last dose, the immobility time of animals was evaluated in forced swim test (FST) and tail suspension test (TST). To further confirm the mechanisms involved in antidepressant effect of phloridzin, biochemical parameters like brain derived neurotropic factor (BDNF), glutathione (GSH), extracellular signal-regulated kinase (ERK), tyrosine receptor kinase B (TrkB) and cAMP-response element binding protein (CREB) were estimated in the brain.

RESULTS

Animals with T2D showed a significant increase in immobility as compared to control in FST and TST. However, 4 weeks administration of fluoxetine or phloridzin attenuated this effect. A significant decline in GSH, BDNF, TrkB, CREB and ERK levels were noticed in the brain of mice with T2D. These changes were also attenuated by administration of phloridzin.

CONCLUSIONS

Phloridzin may ameliorates T2D-induced depression by mitigating the oxidative stress, and up-regulation of neurotrophins in the brain. Therefore, phloridzin can be used as a therapeutic intervention for the management of depression co-morbid with T2D.

Targeting 2-arachidonoylglycerol signalling in the neurobiology and treatment of depression

The endocannabinoid 2-arachidonoylglycerol (2-AG) is an atypical neurotransmitter synthesized on demand in response to a wide range of stimuli, including exposure to stress. Through the activation of cannabinoid receptors, 2-AG can interfere with excitatory and inhibitory neurotransmission in different brain regions and modulate behavioural, endocrine and emotional components of the stress response. Exposure to chronic or intense unpredictable stress predisposes to maladaptive behaviour and is one of the main risk factors involved in developing mood disorders, such as major depressive disorder (MDD). In this review, we describe the molecular mechanisms involved in 2-AG signalling in the brain of healthy and stressed animals and discuss how such mechanisms could modulate stress adaptation and susceptibility to depression. Furthermore, we review preclinical evidence indicating that the pharmacological modulation of 2-AG signalling stands as a potential new therapeutic target in treating MDD. Particular emphasis is given to the pharmacological augmentation of 2-AG levels by monoacylglycerol lipase (MAGL) inhibitors and the modulation of CB2 receptors.

Effect of neuropsychiatric medications on mitochondrial function: For better or for worse

Individuals with mitochondrial disease often present with psychopathological comorbidity, and mitochondrial dysfunction has been proposed as the underlying pathobiology in various psychiatric disorders. Several studies have suggested that medications used to treat neuropsychiatric disorders could directly influence mitochondrial function. This review provides a comprehensive overview of the effect of these medications on mitochondrial function. We collected preclinical information on six major groups of antidepressants and other neuropsychiatric medications and found that the majority of these medications either positively influenced mitochondrial function or showed mixed effects. Only amitriptyline, escitalopram, and haloperidol were identified as having exclusively adverse effects on mitochondrial function. In the absence of formal clinical trials, and until such trials are completed, the data from preclinical studies reported and discussed here could inform medication prescribing practices for individuals with psychopathology and impaired mitochondrial function in the underlying pathology.

A retrospective examination of care pathways in individuals with treatment-resistant depression

BACKGROUND

Individuals with treatment-resistant depression (TRD) experience a high burden of illness. Current guidelines recommend a stepped care approach for treating depression, but the extent to which best-practice care pathways are adhered to is unclear.

AIMS

To explore the extent and nature of 'treatment gaps' (non-adherence to stepped care pathways) experienced by a sample of patients with established TRD (non-response to two or more adequate treatments in the current depressive episode) across three cities in the UK.

METHOD

Five treatment gaps were considered and compared with guidelines, in a cross-sectional retrospective analysis: delay to receiving treatment, lack of access to psychological therapies, delays to medication changes, delays to adjunctive (pharmacological augmentation) treatment and lack of access to secondary care. We additionally explored participant characteristics associated with the extent of treatment gaps experienced.

RESULTS

Of 178 patients with TRD, 47% had been in the current depressive episode for >1 year before initiating antidepressants; 53% had received adequate psychological therapy. A total of 47 and 51% had remained on an unsuccessful first and second antidepressant trial respectively for >16 weeks, and 24 and 27% for >1 year before medication switch, respectively. Further, 54% had tried three or more antidepressant medications within their episode, and only 11% had received adjunctive treatment.

CONCLUSIONS

There appears to be a considerable difference between treatment guidelines for depression and the reality of care received by people with TRD. Future research examining representative samples of patients could determine recommendations for optimising care pathways, and ultimately outcomes, for individuals with this illness.

Retracing our steps to understand ketamine in depression: A focused review of hypothesized mechanisms of action

Introduction

MDD represents a significant burden worldwide, and while a number of approved treatments exist, there are high rates of treatment resistance and refractoriness. Ketamine, an N-methyl-d-aspartate receptor (NMDAR) antagonist, is a novel, rapid-acting antidepressant, however the mechanisms underlying the efficacy of ketamine are not well understood and many other mechanisms outside of NMDAR antagonism have been postulated based on preclinical data. This focused review aims to present a summary of the proposed mechanisms of action by which ketamine functions in depressive disorders supported by preclinical data and clinical studies in humans.

Methods

A literature search was completed using the PubMed and Google Scholar databases. Results were limited to clinical trials and case studies in humans that were published in English. The findings were used to compile this article.

Results

The antidepressant effects associated with ketamine are mediated via a complex interplay of mechanisms; key steps include NMDAR blockade on γ-aminobutyric acid interneurons, glutamate surge, and subsequent activation and upregulation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor.

Discussion

Coadministration of ketamine for MDD with other psychotropic agents, for example benzodiazepines, may attenuate antidepressant effects. Limited evidence exists for these effects and should be evaluated on a case-by-case basis.

Gut microbiota in mental health and depression: role of pre/pro/synbiotics in their modulation

The microbiome residing in the human gut performs a wide range of biological functions. Recently, it has been elucidated that a change in dietary habits is associated with alteration in the gut microflora which results in increased health risks and vulnerability towards various diseases. Falling in line with the same concept, depression has also been shown to increase its prevalence around the globe, especially in the western world. Various research studies have suggested that changes in the gut microbiome profile further result in decreased tolerance of stress. Although currently available medications help in relieving the symptoms of depressive disorders briefly, these drugs are not able to completely reverse the multifactorial pathology of depression. The discovery of the communication pathway between gut microbes and the brain, i.e. the Gut-Brain Axis, has led to new areas of research to find more effective and safer alternatives to current antidepressants. The use of probiotics and prebiotics has been suggested as being effective in various preclinical studies and clinical trials for depression. Therefore, in the present review, we address the new antidepressant mechanisms via gut microbe alterations and provide insight into how these can provide an alternative to antidepressant therapy without the side effects and risk of adverse drug reactions.

Ketamine for depression

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

Using a machine learning approach to investigate factors associated with treatment-resistant depression among adults with chronic non-cancer pain conditions and major depressive disorder

OBJECTIVE

Presence of chronic non-cancer pain conditions (CNPC) among adults with major depressive disorder (MDD) may reduce benefits of antidepressant therapy, thereby increasing the possibility of treatment resistance. This study sought to investigate factors associated with treatment-resistant depression (TRD) among adults with MDD and CNPC using machine learning approaches.

METHODS

This retrospective cohort study was conducted using a US claims database which included adults with newly diagnosed MDD and CNPC (January 2007-June 2017). TRD was identified using a clinical staging algorithm for claims data. Random forest (RF), a machine learning method, and logistic regression was used to identify factors associated with TRD. Initial model development included 42 known and/or probable factors that may be associated with TRD. The final refined model included 20 factors.

RESULTS

Included in the sample were 23,645 patients (73% female mean age: 55 years; 78% with ≥2 CNPC, and 91% with joint pain/arthritis). Overall, 11.4% adults (N = 2684) met selected criteria for TRD. The five leading factors associated with TRD were the following: mental health specialist visits, polypharmacy (≥5 medications), psychotherapy use, anxiety, and age. Cross-validated logistic regression model indicated that those with TRD were younger, more likely to have anxiety, mental health specialist visits, polypharmacy, and psychotherapy use with adjusted odds ratios (AORs) ranging from 1.93 to 1.27 (all ps < .001).

CONCLUSION

Machine learning identified several factors that warrant further investigation and may serve as potential targets for clinical intervention to improve treatment outcomes in patients with TRD and CNPC.

Chronic Mild Stress and Venlafaxine Treatment Were Associated with Altered Expression Level and Methylation Status of New Candidate Inflammatory Genes in PBMCs and Brain Structures of Wistar Rats

Preclinical studies conducted to date suggest that depression could be elicited by the elevated expression of proinflammatory molecules: these play a key role in the mediation of neurochemical, neuroendocrine and behavioral changes. Thus, this study investigates the effect of chronic mild stress (CMS) and administration of venlafaxine (SSRI) on the expression and methylation status of new target inflammatory genes: TGFA, TGFB, IRF1, PTGS2 and IKBKB, in peripheral blood mononuclear cells (PMBCs) and in selected brain structures of rats. Adult male Wistar rats were subjected to the CMS and further divided into matched subgroups to receive vehicle or venlafaxine. TaqMan gene expression assay and methylation-sensitive high-resolution melting (MS-HRM) were used to evaluate the expression of the genes and the methylation status of their promoters, respectively. Our results indicate that both CMS and chronic treatment with venlafaxine were associated with changes in expression of the studied genes and their promoter methylation status in PMBCs and the brain. Moreover, the effect of antidepressant administration clearly differed between brain structures. Summarizing, our results confirm at least a partial association between TGFA, TGFB, IRF1, PTGS2 and IKBKB and depressive disorders.

Neuroimmunology of depression

Depression is one of the leading causes of disability worldwide and a major contributor to the global burden of disease, yet the cellular and molecular etiology of depression remain largely unknown. Major Depressive Disorder (MDD) is associated with a variety of chronic physical inflammatory and autoimmune disorders, and mood disorders may act synergistically with other medical disorders to worsen patient outcomes. Here, we outline the neuroimmune complement, explore the evidence for altered immune system function in MDD, and present some of the potential mechanisms by which immune cells and molecules may drive the onset and course of MDD. These include pro-inflammatory signaling, alterations in the hypothalamic-pituitary-adrenal axis, dysregulation of the serotonergic and noradrenergic neurotransmitter systems, neuroinflammation, and meningeal immune dysfunction. Finally, we discuss the interactions between current antidepressants and the immune system and propose the possibility of immunomodulatory drugs as potential novel antidepressant treatments.

Bacterial Extracellular Vesicles and the Gut-Microbiota Brain Axis: Emerging Roles in Communication and Potential as Therapeutics

Bacterial extracellular vesicles (BEVs) have emerged as candidate signaling vectors for long-distance interkingdom communication within the gut-microbiota brain axis. Most bacteria release these nanosized vesicles, capable of signaling to the brain via their abundant protein and small RNA cargo, possibly directly via crossing the blood-brain barrier. BEVs have been shown to regulate brain gene expression and induce pathology at most stages of neuroinflammation and neurodegeneration, and thus they may play a causal role in diseases such as Alzheimer's, Parkinson's, and depression/anxiety. On the other hand, BEVs have intrinsic therapeutic properties that may be relevant to probiotic therapy and can also be engineered to function as drug delivery vehicles and vaccines. Thus, BEVs may be both a cause of and solution to neuropathological conditions. In this review, current knowledge of the physiological roles of BEVs as well as state of the art pertaining to the development of therapeutic BEVs in the context of the microbiome-gut-brain axis are summarized.

A Novel CYP2C-Haplotype Associated With Ultrarapid Metabolism of Escitalopram

Escitalopram is one of the most commonly used antidepressant drugs but exhibits a substantial interindividual variation in clinical response. A key factor underlying response differences is the polymorphic nature of the CYP2C19 gene encoding the major enzyme responsible for escitalopram metabolism. Although pre-emptive CYP2C19 genotyping may improve escitalopram treatment outcome by dose individualization, much of the interindividual variability cannot be assigned to the currently known CYP2C19 gene variants. The aim of the present study was to search for novel CYP2C-haplotypes for better genetic prediction of escitalopram metabolism. First, the CYP2C18/CYP2C19 locus was sequenced from gDNA obtained from 24 patients previously genotyped as CYP2C19*1/*1 showing consistently low serum concentrations of escitalopram (< 25 nM/10 mg). Three new haplotypes of the CYP2C locus (CYP2C:TG, CYP2C:TA, and CYP2C:CG) were here identified, and their functional roles were evaluated using gDNA from 875 previously genotyped escitalopram-treated patients. The CYP2C:CG and CYP2C:TA haplotypes had no significant impact on escitalopram concentration. Based on the estimated effects of the novel CYP2C-haplotypes on escitalopram exposure, the predicted serum concentrations of escitalopram in homozygous CYP2C:TG and CYP2C19*17 carriers were 24.8% and 17.3% lower compared with the baseline (CYP2C:CG and CYP2C:TA), respectively. In conclusion, a novel CYP2C-haplotype defined by rs2860840T and rs11188059G associated with ultrarapid metabolism of escitalopram was identified. Further studies should clarify the genetic basis for the enhanced escitalopram metabolism and the impact of the CYP2C:TG haplotype on the metabolism of other CYP2C19 substrates like omeprazole, voriconazole, and clopidogrel.

Investigation of Diagnostic Proteins by 2D Electrophoresis in Major Depression Model Induced by Forced Swim Test in Rats

BACKGROUND

Aside from its pervasiveness, whereby it affects as much as 20% of the world's population, depression continues to be one of the most crucial psychiatric problems due to the loss of power it causes by disrupting daily life functioning, containing economic consequences, and having a high suicidal tendency. Major depression (MD) is a systemic and multifactorial disorder involving complex interactions between genetic predisposition and disturbances of various molecular pathways.

OBJECTIVES

In our current study, we aimed to identify the proteins obtained from serum samples that change during depression with the MD model.

METHODS

The MD model was applied through the forced swim test in rats. 14 Winstar Albino male rats were divided into two equal groups as follows: depression and control groups. Serum samples were separated by chromatographic methods and then compared with two-dimensional (2D) electrophoresis.

RESULTS

A total of 9 potential diagnostic protein sequences were identified, which were distinguished with computer software. During the last phase of the study, the Matrix-Assisted Laser Desorption/ Ionization - Time of Flight (MALDI-TOF) analysis, the previous expression sequences identified among the groups were determined and classified. By comparing protein expressions, it was concluded that 9 different points could be used together as a potential biomarker.

CONCLUSION

Results can help us identify a new diagnostic system that can be used to diagnose MD.

The Genetics of Major Depression: Perspectives on the State of Research and Opportunities for Precision Medicine

Major depression (MD) is a leading cause of disability worldwide; it arises from the action and interaction between genetic and environmental factors, and is often comorbid with other psychiatric and medical conditions. To date, upwards of 100 genetic loci have been associated with MD, giving clues to biological underpinnings. Although recent progress has yielded modest insight into the genetic architecture of MD, most studies have been in populations with European ancestry, seriously limiting precision medicine efforts. Broadening diversity of study populations will empower genomic research by expanding discovery and enhancing our understanding of the role of genomic variation in disease etiology. To fully realize the potential of pharmacogenetics and precision medicine, we will need to address the major gaps in our knowledge of the genetic and environmental risk architecture of MD across ancestries, including sex differences, to improve etiologic understanding, diagnosis, prevention, and treatment for all.

Preventive and Therapeutic Spermidine Treatment Attenuates Acute Colitis in Mice

Inflammatory bowel disease (IBD) is associated with acute and chronic inflammation of the gastrointestinal tract and has emerged to be a global disease. Spermidine, a natural polyamine, plays a critical role in maintaining cellular homeostasis. Herein, we investigated the impact and mechanism of spermidine on both dextran sulfate sodium (DSS)- and 2,4,6-trinitrobenzenesulfonic acid solution (TNBS)-induced colitis in mice. We found that spermidine exerted protective effects against acute colitis, evidenced by reduced disease activity index (DAI) and colonic inflammation, increased colonic length, and upregulated tight junction proteins in these two colitis models. Importantly, spermidine exerted significant therapeutic and preventive effects against DSS-induced colitis. Pre- and post-treatment with spermidine reduced the expression of proinflammatory cytokines, phosphorylation of (nuclear factor-κB) NF-κB and (mitogen-activated protein kinase) MAPK, and the activation of F4/80 macrophages and T cells in the colon. Furthermore, spermidine upregulated M2 macrophage markers, whereas it downregulated M1 markers in the inflamed colons. In parallel, spermidine reduced M1 pro-inflammatory markers and enhanced M2 anti-inflammatory genes in RAW264.7 cells. These results revealed that spermidine-ameliorated colitis might be through the regulation of M1/M2 macrophage polarization. In addition, spermidine treatment also alleviated LPS/TNF-α-induced inflammation in Caco-2 cells. Taken together, spermidine prevented and reversed colonic inflammation in colitis mice and might be a promising candidate for IBD intervention.

Exosomes: A Novel Therapeutic Paradigm for the Treatment of Depression

Extracellular vesicles (EVs) of endocytic origin are known as exosomes. These vesicles are released by cells and are found in biofluids, such as saliva, urine, and plasma. These vesicles are made up of small RNA, DNA, proteins, and play a vital role in many physiological processes. In the central nervous system (CNS), they participate in various physiological processes such as stress of nerve cells, communication between the cells, synaptic plasticity, and neurogenesis. The role of exosomes in depression needs to be explored further. It is known that exosomes can cross the blood brain barrier (BBB), which is made up of glial cells astrocytes. One of the advantages of these vesicles is that they are able to transfer macromolecules like DNA, protein, mRNAs, and miRNAs to recipient cells. This review focuses on the potential role of exosomes in depression and their utilization as a treatment option or diagnostic tool of depression.

Default mode network activity in depression subtypes

Depression continues to carry a major disease burden worldwide, with limitations on the success of traditional pharmacological or psychological treatments. Recent approaches have therefore focused upon the neurobiological underpinnings of depression, and on the "individualization" of depression symptom profiles. One such model of depression has divided the standard diagnostic criteria into four "depression subtypes", with neurological and behavioral pathways. At the same time, attention has been focused upon the region of the brain known as the "default mode network" (DMN) and its role in attention and problem-solving. However, to date, no review has been published of the links between the DMN and the four subtypes of depression. By searching the literature studies from the last 20 years, 62 relevant papers were identified, and their findings are described for the association they demonstrate between aspects of the DMN and the four depression subtypes. It is apparent from this review that there are potential positive clinical and therapeutic outcomes from focusing upon DMN activation and connectivity, via psychological therapies, transcranial magnetic stimulation, and some emerging pharmacological models.

Meaningful Change in Depression Symptoms Assessed with the Patient Health Questionnaire (PHQ-9) and Montgomery-Åsberg Depression Rating Scale (MADRS) Among Patients with Treatment Resistant Depression in Two, Randomized, Double-blind, Active-controlled Trials of Esketamine Nasal Spray Combined With a New Oral Antidepressant

BACKGROUND

Patients with major depressive disorder who do not respond to ≥2 different pharmacological treatments within the current depressive episode are considered to have treatment resistant depression (TRD). This analysis determined meaningful change thresholds (MCT) of the Patient Health Questionnaire (PHQ-9) and Montgomery-Åsberg Depression Rating Scale (MADRS) using anchor-based methods and compared proportions of meaningful changes in patients with TRD across treatment groups from two Phase 3 trials for esketamine nasal spray (SPRAVATO^TM).

METHODS

Data from two Phase 3 trials in patients with TRD, TRANSFORM-1 and -2, were used in this analysis. The MCTs for the PHQ-9 and MADRS were derived using a clinician global impression of severity anchor. Blinded probability density functions displayed score distributions between anchor categories. Proportions of meaningful response were compared between treatment groups using chi-square tests supported by unblinded cumulative distribution functions of change scores.

RESULTS

Baseline scores were similar for the PHQ-9 and MADRS between the esketamine/antidepressant (AD) and AD/placebo groups. The most appropriate MCT on the PHQ-9 was -6 points. By Day 28, 86.5% of patients reached or exceeded the PHQ-9 MCT in the esketamine/AD group compared to 70% in the placebo/AD group. The most appropriate MCT for the MADRS was -10 points. By Day 28, 78.2% of patients reached or exceeded the MADRS MCT in the esketamine/AD group compared to 65.0% in the placebo/AD group.

CONCLUSIONS

Individual-level meaningful change for the PHQ-9 and MADRS was effectively quantified using a clinical anchor to interpret efficacy from patients with TRD and their treating clinicians.

Preventing Suicide Through Better Firearm Safety Policy in the United States

The U.S. suicide rate continues to increase, despite federal investment in developing preventive behavioral health care interventions. Important determinants of suicide-social, economic, and circumstantial-have little or no connection to psychopathology. Firearm injuries account for over half of suicides, and firearm access is perhaps the most important modifiable determinant. Thus gun safety policy deserves special attention as a pathway to suicide prevention. This article summarizes arguments for several recommended statutory modifications to firearm restrictions at the state level. The policy challenge is to develop and implement evidence-based strategies to keep guns out of the hands of people at highest risk of suicide, without unduly infringing the rights of a large number of gun owners who are unlikely to harm anyone. Recommendations for states include expansion and refinement of legal criteria prohibiting firearm purchase, possession, or access to better align with suicide risk, including prohibition for persons with brief involuntary psychiatric holds or repeated alcohol-impaired driving convictions; enactment of extreme risk protection order laws, which allow temporary removal of firearms from persons who are behaving dangerously, and entering purchase prohibition data for these persons in the FBI's background-check database; and adoption of an innovative policy known as precommitment against suicide as well as voluntary self-enrollment in the FBI's background-check database.