Novel Pathways in the Treatment of Major Depression: Focus on the Glutamatergic System

Courtes A, Jones G, Soares JC, Machado-Vieira R. Pharmacotherapies Targeting GABA-Glutamate Neurotransmission for Treatment-Resistant Depression

Treatment-resistant depression (TRD) is a term used to describe a particular type of major depressive disorder (MDD). There is no consensus about what defines TRD, with various studies describing between 1 and 4 failures of antidepressant therapies, with or without electroconvulsive therapy (ECT). That is why TRD is such a growing concern among clinicians and researchers, and it explains the necessity for investigating novel therapeutic targets beyond conventional monoamine pathways. An imbalance between two primary central nervous system (CNS) neurotransmitters, L-glutamate and γ-aminobutyric acid (GABA), has emerged as having a key role in the pathophysiology of TRD. In this review, we provide an evaluation and comprehensive review of investigational antidepressants targeting these two systems, accessing their levels of available evidence, mechanisms of action, and safety profiles. N-methyl-D-aspartate (NMDA) receptor antagonism has shown the most promise amongst the glutamatergic targets, with ketamine and esketamine (Spravato) robustly generating responses across trials. Two specific NMDA-glycine site modulators, D-cycloserine (DCS) and apimostinel, have also generated promising initial safety and efficacy profiles, warranting further investigation. Combination dextromethorphan-bupropion (AXS-05/Auvelity) displays a unique mechanism of action and demonstrated positive results in particular applicability in subpopulations with cognitive dysfunction. Currently, the most promising GABA modulators appear to be synthetic neurosteroid analogs with positive GABAA receptor modulation (such as brexanolone). Overall, advances in the last decade provide exciting perspectives for those who do not improve with conventional therapies. Of the compounds reviewed here, three are approved by the Food and Drug Administration (FDA): esketamine (Spravato) for TRD, Auvelity (dextromethorphan-bupropion) for major depressive disorder (MDD), and brexanolone (Zulresso) for post-partum depression (PPD). Notably, some concerns have arisen with esketamine and brexanolone, which will be detailed in this study.

Which clinical factors and biochemical parameters are associated with late-life major depression?

INTRODUCTION

Late-life major depression (MD) is a frequent and high-cost psychiatric disorder. Our purpose was to detect clinical and biological factors possibly associated with this condition to better prevent and treat it.

METHODS

We recruited 343 patients, consecutively admitted for a Major Depressive Episode to the inpatient clinic of Policlinico of Milan and ASST Monza, Italy. A large set of clinical and biochemical variables was collected from clinical charts. Univariate analyses were performed both dividing the sample into two groups (age < or ≥65) and considering age as a continuous quantitative variable. Regression analyses were then performed considering as independent variables only those statistically significant at univariate analyses.

RESULTS

Patients aged ≥ 65 resulted in having longer duration of illness, shorter duration of last antidepressant therapy, higher number of antidepressants assumed in the past, higher frequency of treatment-resistant depression, higher frequency of overweight/obesity and diabetes. As for biochemical parameters, patients ≥ 65 showed lower total plasmatic proteins and albumin, higher uric acid and creatinine.

CONCLUSIONS

These preliminary results suggest less effectiveness of antidepressants, more susceptibility to metabolic disorders and poor nutritional status in patients with late-life depression; such aspects may consequently be taken into consideration for a proper therapeutic approach. KEY POINTSDepression in late life seems to be associated with poorer response to antidepressants;Clinicians should prefer compounds with minimal pharmacokinetic interactions and less risk of side effects including metabolic ones;The poor nutritional status and the higher risk of metabolic disorders in older patients points out the importance of proper diet and healthy lifestyle in this group of subjects;Further studies are needed to confirm the results of this research.

Roles of microglia in adult hippocampal neurogenesis in depression and their therapeutics

Adult hippocampal neurogenesis generates functional neurons from neural progenitor cells in the hippocampal dentate gyrus (DG) to complement and repair neurons and neural circuits, thus benefiting the treatment of depression. Increasing evidence has shown that aberrant microglial activity can disrupt the appropriate formation and development of functional properties of neurogenesis, which will play a crucial role in the occurrence and development of depression. However, the mechanisms of the crosstalk between microglia and adult hippocampal neurogenesis in depression are not yet fully understood. Therefore, in this review, we first introduce recent discoveries regarding the roles of microglia and adult hippocampal neurogenesis in the etiology of depression. Then, we systematically discuss the possible mechanisms of how microglia regulate adult hippocampal neurogenesis in depression according to recent studies, which involve toll-like receptors, microglial polarization, fractalkine-C-X3-C motif chemokine receptor 1, hypothalamic-pituitary-adrenal axis, cytokines, brain-derived neurotrophic factor, and the microbiota-gut-brain axis, etc. In addition, we summarize the promising drugs that could improve the adult hippocampal neurogenesis by regulating the microglia. These findings will help us understand the complicated pathological mechanisms of depression and shed light on the development of new treatment strategies for this disease.

Prevalence and clinical correlates of abnormal lipid metabolism in first-episode and drug-naïve patients with major depressive disorder with abnormal glucose metabolism

Comorbid glucose metabolism abnormalities are very common in patients with major depressive disorder (MDD), and glucose metabolism and lipid metabolism are closely related. However, there are few researches on the incidence and related factors of lipid metabolism abnormalities among MDD patients with comorbid glucose metabolism abnormalities. A cross-sectional study involving 1718 first-episode and drug-naïve (FEDN) MDD patients was conducted. The 17-item Hamilton Depression Scale (HAMD-17), Hamilton Anxiety Rating Scale (HAMA) and Positive and Negative Syndrome Scale (PANSS) positive subscale were utilized to evaluate depressive, anxiety and psychotic symptom, respectively. Serum thyroid function-related parameters, glucose- and lipid-metabolism parameters were measured. The prevalence of abnormal lipid metabolism was significantly higher in FEDN MDD patients with abnormal glucose metabolism than in those without abnormal glucose metabolism (P < 0.001). In MDD patients with abnormal glucose metabolism, TSH, FT3 and body mass index (BMI) levels were significantly higher in the abnormal lipid metabolism subgroup than in the non-abnormal lipid metabolism subgroup. Binary logistic regression analysis showed that TSH, FT3 and BMI were the influencing factors of abnormal lipid metabolism in MDD patients with abnormal glucose metabolism (all P < 0.05). MDD patients with abnormal glucose metabolism have a high prevalence of abnormal lipid metabolism. Moreover, abnormal glucose metabolism was an independent risk factor for abnormal lipid metabolism in patients with MDD. In addition, thyroid hormone function and BMI may contribute to the co-occurrence of abnormal lipid metabolism in MDD patients with abnormal glucose metabolism.

A comprehensive review and meta-analysis of neurological side effects related to second-generation antidepressants in individuals with major depressive disorder

Second-generation antidepressants (SGADs) often cause neurological side effects (SEs). This meta-analysis seeks to quantify the short-term rates of neurological SEs related to routinely used second-generation antidepressants used to treat major depressive disorder (MDD). A search of the PubMed, EMBASE,Cochrane Library databases and Web of Science was done to uncover double-blind, randomized, placebo-controlled studies evaluating the effectiveness of frequently used SGADs medicines in people with MDD. Qualifying studies were required to concentrate on the use of SGADs routinely used in MDD and to uncover data on treatment-emergent neurological SEs occurring within 12 weeks of therapy. Overall, 143 RCT studies containing 188 treatment arms were included in the meta-analyses. Most SGADs increased the risk of neurological SEs compared to placebo. The least tolerated antidepressants on the neurological tract were desvenlafaxine (OR=1.98; CI 0.85-4.65; p-value=0.12) and venlafaxine (OR=1.15; CI 0.96-1.38; p-value=0.13). Agomelatine, bupropion and vortioxetine exhibited reduced neurological SEs, showing diminished risk in insomnia (OR=0.56; CI 0.36-0.88; p-value=0.01), somnolence (OR=0.46; CI 0.27-0.79; p-value=0.01), vision blurred (OR=0.43; CI 0.19-0.96; p-value=0.04), respectively. Most SGADs did not or just marginally increased the risk of headache compared to placebo. In conclusion, frequently used SGADs demonstrated distinct patterns of neurological SEs, which physicians should consider when prescribing antidepressants to promote treatment adherence and favorable outcomes in patients with MDD.

Ketamine Evolving Clinical Roles and Potential Effects with Cognitive, Motor and Driving Ability

While driving under the influence of drugs, drivers are more likely to be involved in and cause more accidents than drivers who do not drive under the influence. Ketamine is derived from phencyclidine and acts as a noncompetitive antagonist and allosteric modulator of N-methyl-D-aspartate receptors. Ketamine has been used to treat a variety of psychiatric disorders, with the most notable being treatment-resistant depression. With the rise of at-home ketamine treatment companies, the safety of unsupervised administration remains under evaluation. A study with ketamine and a ketamine-like medication, rapasitnel, showed that those who were given ketamine experienced more sleepiness and had decreased self-reported motivation and confidence in their driving abilities. Moreover, there seem to be significant differences in the acute versus persistent effects of ketamine, as well as the anesthetic versus subanesthetic doses, both in terms of effects and outcomes. These divergent effects complicate the clinical uses of ketamine, specifically involving driving, drowsiness, and cognitive abilities. This review aims to describe not only the various clinical uses of ketamine but also the potentially detrimental effects of driving under the influence, which should be understood to help with counseling the patients who use these substances, both for their well-being and to protect public safety.

Omega-3 Fatty Acids Supplementation in the Treatment of Depression: An Observational Study

Depression is a common mood disorder characterized by persistent sadness and loss of interest. Research suggests an association between the inclusion of omega-3 fatty acids in the diet and a reduced risk for depression. The present study evaluated the effectiveness of omega-3 fatty acid supplements in alleviating depressive symptoms in patients with mild to moderate depression. A total of 165 patients suffering from mild to moderated depression were randomized to receive omega-3 fatty acid supplementation, an antidepressant (single agent), or a combination of an antidepressant and omega-3 fatty acid supplementation. The clinical features of depression were assessed using the Hamilton Depression Rating Scale (HDRS) during the follow-up period. A statistically significant improvement in depressive symptoms was observed from baseline to first, second and third follow-ups within each treatment arm as measured by HRDS scores (p = 0.00001). Further, the HDRS scores at the third follow-up were significantly lower in patients on combination therapy of omega-3 fatty acid supplement and antidepressants (arm-3) than the patients on the omega-3 fatty acid supplement alone (arm-1) [Q = 5.89; p = 0.0001] or the patients taking an antidepressant alone (arm 2) [Q = 4.36; p = 0.0068]. The combination of an omega-3 fatty acid supplement and an antidepressant elicited significantly higher improvement in depressive symptoms than the supplement or the antidepressant alone.

Esketamine for treatment‑resistant depression: A review of clinical evidence (Review)

Treatment-resistant depression (TRD) is a challenge for psychiatrists, even after more than seven decades since the first antidepressants were used in clinical practice. Non-monoaminergic-based drugs with antidepressant properties have been developed, but to date, only esketamine and brexanolone have been approved for TRD and postpartum depression, respectively. A narrative review on the efficacy and safety of esketamine in the main categories of depressive disorders has been conducted through four electronic databases (Pubmed, Cochrane, EMBASE and Clarivate/Web of Science) The primary objective of the present review was to find evidence that may support the usefulness of esketamine for patients diagnosed with TRD as well as data about its potential adverse effects in the short and long term. A total of 14 papers were reviewed, and their results support the recommendation of esketamine for treatment of TRD as an add-on to antidepressants, but more data is needed in order to assess its long-term efficacy and safety. It must also be mentioned that there have been a few trials which did not report a significant effect on the severity of depressive symptoms with esketamine in TRD, therefore, caution is indicated for patients initiated on this adjuvant agent. There has been insufficient data to formulate specific guidelines about esketamine administration because evidence about favorable or negative prognostic factors of this treatment has been lacking, and the duration of its administration has not been unanimously accepted. Novel directions for research have been identified, especially in the case of patients with TRD and substance use disorders, geriatric or bipolar depression or in major depression with psychotic features.

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.

How does IL-6 change after combined treatment in MDD patients? A systematic review

A growing amount of research suggests that inflammatory responses have a crucial role in the complex pathophysiology of Major Depressive Disorder (MDD), a disabling medical condition. The present review has two primary goals. Firstly, to highlight and summarize results from studies that investigated the changes of IL-6 in MDD patients before and after combined treatment. The second aim is to enlighten the need for further research on the difference in the concentration of the pro-inflammatory cytokines between MDD and Treatment-Resistant MDD. The protocol of this study was written using PRISMA, and it is registered at PROSPERO (identification: CRD42021289233). We searched the following bibliographic databases to identify potentially eligible articles without any time limit until September 2021: Pubmed, Web of Science, Scopus, PsycINFO. As they met the eligibility criteria, 14 articles were included in this systematic review. The selected studies assessed twelve different elements as an adjunction to the standard pharmacotherapy (ECT, Ketamine, CBT, NCT, Ketoprofene, Lithium, Celecoxib, Metformin tDCS, Pentoxifylline, ethyl-EPA, Zinc). Significant results were found in the studies that analyzed the impact of combined treatment with the adjunction of the following elements: ECT, Ketamine, CBT, NCT, Celecoxib, Metformin, and Pentoxifylline. Overall, this systematic review identifies several potentially beneficial combined treatments for MDD patients. Further evidence is needed to confirm the efficacy of reducing IL-6 levels in patients with Treatment-Resistant MDD.

[Comparative Harm/Benefit Analysis of Various Psychotropic Substances from the Perspective of German Drug Users and Addiction Medicine Experts - A Contribution to Psychoeducation of Substance-Addicted Individuals and Restriction/Legalization Debates]

BACKGROUND

To date, we cannot find any current international comparative study on the assessment of a benefit/harm profile of various licit and illicit psychoactive substances conducted by adult drug users and addiction experts as well. Particularly, there is no study from the German-speaking area of Western Europe.

METHODS

In addition to the data already published by 101 German addiction medicine experts (published in this journal, [1]), we carried out interviews using a structured questionnaire with 100 German substance dependent users, residing in acute and rehabilitation clinical setting, to evaluate 34 psychoactive substances regarding their health and social harm potential for users and others as well as their potential benefit.

RESULTS

Both, users and experts estimated traditional illicit drugs, such as heroin, crack/cocaine and methamphetamine, to be particularly harmful. Synthetic cannabinoids, alcohol and benzodiazepines were in the upper midfield, cannabis and psychotropic mushrooms in the lower midfield, and gabapentinoids at the bottom of the harm rankings of both, users and experts. In comparison with the experts, the users estimated methadone and benzodiazepines to be significantly more harmful. In the benefit analysis, users rated traditional illicit drugs including cannabis and psychotropic mushrooms as well as nicotine as significantly more useful than the experts. In contrast to the experts (traditional illicit drugs), the users did not assess any substance as very harmful and very useless at the same time. Only a few users reported to have experiences with opioid analgesics which, however, did not differ between the users´ and experts´ harm/benefit-assessments. Neither users nor experts predicted cannabis-legalization to change the overall risk potential of cannabis. Specific cognitive valuation biases seemed to be prominent in both groups.

CONCLUSION

This study presents first harm/benefit assessments of psychotropic substances from the perspective of German addiction medicine experts and drug users. The results can be valuable to the psychoeducation of substance-addicted individuals and to current restriction or legalization debates.

Are mGluR2/3 Inhibitors Potential Compounds for Novel Antidepressants?

Depression is the most common mental illness characterized by anhedonia, avolition and loss of appetite and motivation. The majority of conventional antidepressants are monoaminergic system selective inhibitors, yet the efficacies are not sufficient. Up to 30% of depressed patients are resistant to treatment with available antidepressants, underscoring the urgent need for development of novel therapeutics to meet clinical needs. Recent years, compounds acting on the glutamate system have attracted wide attention because of their strong, rapid and sustained antidepressant effects. Among them, selective inhibitors of metabotropic glutamate receptors 2 and 3 (mGluR2/3) have shown robust antidepressant benefits with fewer side-effects in both preclinical and clinical studies. Thus, we here attempt to summarize the antidepressant effects and underlying mechanisms of these inhibitors revealed in recent years as well as analyze the potential value of mGluR2/3 selective inhibitors in the treatment of depression.

Where do we go next in antidepressant drug discovery? A new generation of antidepressants: a pivotal role of AMPA receptor potentiation and mGlu2/3 receptor antagonism

INTRODUCTION

Major depressive disorder remains a prevalent world-wide health problem. Currently available antidepressant medications take weeks of dosing, do not produce antidepressant response in all patients, and have undesirable ancillary effects.

AREAS COVERED

The present opinion piece focuses on the major inroads to the creation of new antidepressants. These include N-methyl-D-aspartate (NMDA) receptor antagonists and related compounds like ketamine, psychedelic drugs like psilocybin, and muscarinic receptor antagonists like scopolamine. The preclinical and clinical pharmacological profile of these new-age antidepressant drugs is discussed.

EXPERT OPINION

Preclinical and clinical data have accumulated to predict a next generation of antidepressant medicines. In contrast to the current standard of care antidepressant drugs, these compounds differ in that they demonstrate rapid activity, often after a single dose, and effects that outlive their presence in brain. These compounds also can provide efficacy for treatment-resistant depressed patients. The mechanism of action of these compounds suggests a strong glutamatergic component that involves the facilitation of AMPA receptor function. Antagonism of mGlu2/3 receptors is also relevant to the antidepressant pharmacology of this new class of drugs. Based upon the ongoing efforts to develop these new-age antidepressants, new drug approvals are predicted in the near future.

The molecular pathophysiology of depression and the new therapeutics

Major depressive disorder (MDD) is a highly prevalent and disabling disorder. Despite the many hypotheses proposed to understand the molecular pathophysiology of depression, it is still unclear. Current treatments for depression are inadequate for many individuals, because of limited effectiveness, delayed efficacy (usually two weeks), and side effects. Consequently, novel drugs with increased speed of action and effectiveness are required. Ketamine has shown to have rapid, reliable, and long-lasting antidepressant effects in treatment-resistant MDD patients and represent a breakthrough therapy for patients with MDD; however, concerns regarding its efficacy, potential misuse, and side effects remain. In this review, we aimed to summarize molecular mechanisms and pharmacological treatments for depression. We focused on the fast antidepressant treatment and clarified the safety, tolerability, and efficacy of ketamine and its metabolites for the MDD treatment, along with a review of the potential pharmacological mechanisms, research challenges, and future clinical prospects.

The efficacy and tolerability of memantine for depressive symptoms in major mental diseases: A systematic review and updated meta-analysis of double-blind randomized controlled trials

OBJECTIVE

To date, there is limited evidence on the antidepressant effects of memantine in patients with major mental diseases. We conducted a systematic review and meta-analysis to assess the efficacy of memantine in such populations.

METHODS

A literature search was performed for randomized controlled trials (RCTs) from the date of their inception until September 28, 2021, using PubMed, Medline, Embase, and the Cochrane Library. Changes in depression scores were the primary outcome. The response rate and remission rate to the treatment were secondary outcomes. We also assessed the dropout rate for tolerance.

RESULTS

Eleven double-blind RCTs were included with 899 participants. Memantine significantly reduced depressive symptom scores compared with the control group (k = 11, n = 899, Hedges' g = -0.17, 95% confidence interval [CI] = -0.30 to -0.04, p = 0.009) with a small effect size. For secondary outcomes, memantine did not show a significant effect on response rate nor remission rate. In the subgroup analysis, memantine significantly reduced depressive symptom scores in patients with mood disorders (k = 8, n = 673, Hedges' g = -0.17, 95% CI = -0.32 to -0.01, p = 0.035) with a small effect size, but not in patients with schizophrenia.

CONCLUSION

The present meta-analysis indicates that memantine effectively alleviates depressive symptoms in patients with mood disorders with a small effect size. Furthermore, memantine is well-tolerated and acceptable.

The Role of Caspase Family in Acute Brain Injury: The Potential Therapeutic Targets in the Future

The caspase family is commonly involved in the pathophysiology of acute brain injury (ABI) through complex apoptotic, pyroptotic, and inflammatory pathways. Current translational strategies for caspase modulation in ABI primarily focus on caspase inhibitors. Because there are no caspase-inhibiting drugs approved for clinical use on the market, the development of caspase inhibitors remains an attractive challenge for researchers and clinicians. Therefore, we conducted the present review with the aim of providing a comprehensive introduction of caspases in ABI. In this review, we summarized the available evidence and potential mechanisms regarding the biological function of caspases. We also reviewed the therapeutic effects of caspase inhibitors on ABI and its subsequent complications. However, various important issues remain unclear, prompting further verification of the efficacy and safety regarding clinical application of caspase inhibitors. We believe that our work will be helpful to further understand the critical role of the caspase family and will provide novel therapeutic potential for ABI treatment.

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

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

Analysis of the superior temporal gyrus as a possible biomarker in schizophrenia using voxel-based morphometry of the brain magnetic resonance imaging: a comprehensive review

The lack of predictive biomarkers for therapeutic responses to schizophrenia leads clinical procedures to be decided without taking into account the subjects' neuroanatomical features, a consideration, which could help in identifying specific pharmacological treatments for the remission of symptoms. Magnetic resonance imaging (MRI) is a technique widely used for radiological diagnosis and produces 3-dimensional images in excellent anatomical detail, and with a great capacity to differentiate soft tissue. Various MRI techniques of the human brain have emerged as a result of research, enabling structural tests that may help to in consolidate previous findings and lead to the discovery of new patterns of abnormality in schizophrenia. A literature review was undertaken to assess the superior temporal gyrus (STG) as a possible biomarker in schizophrenia with the use of voxel-based morphometry of the brain using MRI. Many findings in studies of schizophrenia using MRI have been inconclusive and, in some cases, conflicting, although interesting results have been obtained when attempting to correlate neuroimaging changes with aspects of clinical features and prognosis of the disease. The individuals affected by this mental illness appear to have smaller STG volumes when compared to healthy controls and also to subjects with a diagnosis of first-episode affective psychosis or groups of individuals at high risk of psychosis. However, the wide variety of definitions surrounding the STG found in a number of studies is a contributing factor to the lack of correlation between brain abnormalities and clinical symptoms. For instance, disagreements have arisen due to studies using regions of interest to analyze the STG whereas other studies prioritize the analysis of only STG subregions or specific supratemporal plane regions. It is necessary to standardize the nomenclature of the areas to be studied in the future, as this will enable more consistent results, allowing higher clinical and morphological correlations.

[Weighing the benefits and harms of psychotropic and analgesic substances - A perspective of German addiction medicine experts]

BACKGROUND

In Europe, there have been several addiction-expert rankings of harms related to the use of psychotropic substances in the last 15 years. Among them, only one expert ranking took into account the potential benefits of these drugs. Non-Opioidergic Analgesics (NOAs), such as gabapentinoids and NSAIDs, which have been increasingly the subject of abuse / misuse reports, have not been considered in such expert rankings. Likewise, there is currently no multi-substance comparison as to whether the valuation rank of the harmfulness of an illegal drug may change along with an imagined change in legal status in Germany.

OBJECTIVES AND METHODS

Using a questionnaire, 101 experienced addiction physicians (first cohort) evaluated 33 psychoactive substances including analgesics with regard to their health and social harms as well as potential usefulness for the consumer and their environment / society ('others'). In addition, this cohort investigated whether the harmfulness assessment of an illegal substance changes if it would be legalized. In order to obtain the average overall harmfulness (overall risk) of a substance, the percentage contribution of each dimension to the overall harmfulness was determined in a second survey (second cohort, 36 experienced addiction medicine experts). Finally, the average benefit and overall risk ratings of each substance were related to each other.

RESULTS

Prescription psychoactive substances such as analgesics, NOAs (including gabapentinoids) and opioidergic maintenance medications to treat opiate dependence were judged to have a favorable benefit-harm profile. Cannabis and ketamine were placed in the midfield of both, the harm and benefit rankings. Together with most illicit narcotic drugs, alcohol and nicotine, have been ranked among the most harmful and least useful substances, whereby alcohol was judged on average to be more harmful but also more useful than nicotine. In the event of potential legalization, the overall harm of the traditional illegal drugs methamphetamine, heroin, cocaine and cannabis was estimated to be reduced. This was mainly due to a more favorable valuation of the harm to others under these virtual conditions.

CONCLUSION

Prescription substances including opioidergic and non-opioidergic analgesics as well as opioid maintenance therapy medications (methadone and buprenorphine) were assigned a favorable benefit-harm profile. Alcohol, nicotine and traditional illicit drugs (with the exception of cannabis and ketamine) were determined to have an unfavorable profile. The overall harm of traditional illicit drugs was assessed to decrease along with legalization, mainly by decreasing the harm to others in this virtual event.

New approaches to symptomatic treatments for Alzheimer's disease

BACKGROUND

Successful development of agents that improve cognition and behavior in Alzheimer's disease (AD) is critical to improving the lives of patients manifesting the symptoms of this progressive disorder.

DISCUSSION

There have been no recent approvals of cognitive enhancing agents for AD. There are currently 6 cognitive enhancers in Phase 2 trials and 4 in phase 3. They represent a variety of novel mechanisms. There has been progress in developing new treatments for neuropsychiatric symptoms in AD with advances in treatment of insomnia, psychosis, apathy, and agitation in AD. There are currently 4 AD-related psychotropic agents in Phase 2 trials and 7 in Phase 3 trials. Many novel mechanisms are being explored for the treatment of cognitive and behavioral targets. Progress in trial designs, outcomes measures, and population definitions are improving trial conduct for symptomatic treatment of AD.

CONCLUSIONS

Advances in developing new agents for cognitive and behavioral symptoms of AD combined with enhanced trial methods promise to address the unmet needs of patients with AD for improved cognition and amelioration of neuropsychiatric symptoms.

An Update on Glutamatergic System in Suicidal Depression and on the Role of Esketamine

BACKGROUND

A research on mood disorder pathophysiology has hypothesized abnormalities in glutamatergic neurotransmission, by suggesting further investigation on glutamatergic N-methyl-Daspartate (NMDA) receptor modulators in treating Major Depressive Disorder (MDD). Esketamine (ESK), an NMDA receptor antagonist able to modulate glutamatergic neurotransmission has been recently developed as an intranasal formulation for treatment-resistant depression (TRD) and for rapid reduction of depressive symptomatology, including suicidal ideation in MDD patients at imminent risk for suicide.

OBJECTIVE

The present study aims at investigating recent clinical findings on research on the role of the glutamatergic system and ESK in treating suicidal depression in MDD and TRD.

METHODS

A systematic review was here carried out on PubMed/Medline, Scopus and the database on U.S. N.I.H. Clinical Trials (https://clinicaltrials.gov) and the European Medical Agency (EMA) (https://clinicaltrialsregister.eu) from inception until October 2019.

RESULTS

Intravenous infusion of ESK is reported to elicit rapid-acting and sustained antidepressant activity in refractory patients with MDD and TRD. In phase II studies, intranasal ESK demonstrated a rapid onset and a persistent efficacy in patients with TRD as well as in MDD patients at imminent risk for suicide. However, some data discrepancies have emerged in phase III studies.

CONCLUSION

The U.S. Food and Drug Administration (FDA) granted fast track and Breakthrough Therapy Designation to Janssen Pharmaceuticals®, Inc. for intranasal ESK in 2013 for treatment-resistant depression (TRD) and in 2016 for the treatment of MDD with an imminent risk of suicide. However, further studies should be implemented to investigate the long-term efficacy and safety of intranasal ESK.

The effect of intravenous, intranasal, and oral ketamine in mood disorders: A meta-analysis

BACKGROUND

Ketamine is established as a rapid and effective treatment in adults with treatment-resistant depression (TRD). The availability of different formulations and routes of delivery invites the need for evaluating relative effect sizes.

METHODS

Effect size with respect to depression symptom reduction for each formulation and route of delivery was compared at discrete time-points (i.e., 24 h, 2-6 days, 7-20 days, 21-28 days) in adults with TRD. A random-effects meta-analysis was conducted to evaluate the effect size across intravenous, intranasal and oral routes of administration. Analysis was also conducted evaluating the effect size of racemic ketamine to esketamine.

RESULTS

The pooled effect size for intranasal ketamine/esketamine at 24 h was g = 1.247 (n = 5, 95% CI: 0.591-1.903, p < 0.01). At 2-6 days, the pooled effect size for intravenous ketamine/esketamine was g = 0.949 (n = 14, 95% CI: -0.308-2.206, p = 0.139). At 7-20 days, intranasal ketamine had a pooled effect size of g = 1.018 (n = 4, 95% CI: 0.499-1.538, p < 0.01). At 21-28 days, oral ketamine had a pooled effect size of g = 0.633 (n = 2, 95% CI: 0.368-0.898, p < 0.01).

LIMITATIONS

Additional comparative studies are needed with regards to the efficacy of different formulations and routes of delivery.

CONCLUSIONS

The short-term efficacy of intravenous and intranasal ketamine/esketamine for adults with TRD was established. Interpreting the efficacy of oral ketamine was limited by the need for studies with larger samples across independent sites. No conclusions regarding comparative efficacy of the disparate formulations and routes of delivery can be derived from this analysis. Direct comparative studies are needed to further inform treatment options for TRD.

Prediction of Antidepressant Treatment Outcome Using Event-Related Potential in Patients with Major Depressive Disorder

(1) Background: Prediction of treatment outcome has been one of the core objectives in clinical research of patients with major depressive disorder (MDD). This study explored the possibility of event-related potential (ERP) markers to predict antidepressant treatment outcomes among MDD patients; (2) Methods: Fifty-two patients with MDD were recruited and evaluated through Hamilton depression (HAM-D), Hamilton anxiety rating scale (HAM-A), and CORE. Patients underwent a battery of ERP measures including frontal alpha symmetry (FAA) in the low alpha band (8–10 Hz), mismatch negativity (MMN), and loudness-dependent auditory evoked potentials (LDAEP); (3) Results: During the eight weeks of study, 61% of patients achieved remission, and 77% showed successful treatment responsiveness. Patients with low FAA in F5/F6 demonstrated a significantly higher remission/response ratio and better treatment responsiveness (F (2.560, 117.755) = 3.84, p = 0.016) compared to patients with high FAA. In addition, greater FAA in F7/F8 EEG channels was significantly associated with greater melancholia scores (r = 0.34, p = 0.018). Other ERP markers lacked any significant effect; (4) Conclusions: Our results suggested low FAA (i.e., greater left frontal activity) could reflect a good treatment response in MDD patients. These findings support that FAA could be a promising index in understanding both MDD and melancholic subtype.

Adjunctive vortioxetine for SSRI-resistant major depressive disorder: a "real-world" chart review study

Objective:

Selective serotonin reuptake inhibitors (SSRIs) are the cornerstone of treatment of major depressive disorder (MDD). However, non-response is common, often necessitating combination strategies. The present study assessed the efficacy of vortioxetine as an add-on therapy in patients with SSRI-resistant MDD.

Methods:

The charts of 36 adult outpatients with DSM-IV-TR MDD who had not achieved a response after at least 8 weeks of treatment with an SSRI were reviewed retrospectively. Subjects were treated with vortioxetine (5-20 mg/day) for 8 weeks added to the current SSRI. The main outcome measures were change from baseline in total Hamilton Scale for Depression (HAM-D) score and the rate of response (a 50% or greater reduction in HAM-D score and a Clinical Global Impression ‐ Improvement module [CGI-I] score of 1 or 2 at endpoint). HAM-D scores ≤ 7 were considered as remission. Additional outcome measures included the Snaith-Hamilton Pleasure Scale (SHAPS) and the Scale for Suicide Ideation (SSI).

Results:

32 patients completed the 8 weeks of treatment. At 8 weeks, a significant reduction in HAM-D score was observed (p ≤ 0.001), with response obtained by 41.7% and remission by 33.3% of patients. Significant reductions in SHAPS and SSI were also observed (p ≤ 0.001 for both scales).

Conclusions:

Adjunctive vortioxetine may be useful and well-tolerated in stage I treatment-resistant depression. However, the limitations of this study (such as small sample size, absence of randomization and control group, retrospective design, etc.) must be considered.

Ketamine in Major Depressive Disorder: Mechanisms and Future Perspectives

Major depressive disorder (MDD) is a serious psychiatric illness that causes functional impairment in many people. While monoaminergic antidepressants have been used to effectively treat MDD, these antidepressants have limitations in that they have delayed onset of action and many patients remain treatment-resistant. Therefore, there is a need to develop antidepressants with a novel target, and researchers have directed their attention to the glutamatergic system. Ketamine, although developed as an anesthetic, has been found to produce an antidepressant effect at sub-anesthetic doses via N-Methyl-D-aspartic acid (NMDA) receptor blockade as well as NMDA receptor- independent pathways. A single infusion of ketamine produced rapid improvement in clinical symptoms to a considerable level and led to the resolution of serious depressive symptoms, including imminent suicidal ideation, in patients with MDD. A series of recent randomized controlled trials have provided a high level of evidence for the therapeutic efficacy of ketamine treatment in MDD and presented new insights on the dose, usage, and route of administration of ketamine as an antidepressant. With this knowledge, it is expected that ketamine treatment protocols for MDD will be established as a treatment option available in clinical practice. However, long-term safety must be taken into consideration as ketamine has abuse potential and it is associated with psychological side effects such as dissociative or psychotomimetic effects.

Neural and Behavioral Correlates of Clinical Improvement to Ketamine in Adolescents With Treatment Resistant Depression

Treatment-resistant depression (TRD) is a serious problem in adolescents. Development and optimization of novel interventions for these youth will require a deeper knowledge of the neurobiology of depression. A well-established phenomenon of depression is an attention bias toward negativity and away from positivity that is evidenced behaviorally and neurally, but it is unclear how symptom reduction is related to changes to this bias. Neurobiological research using a treatment probe has promise to help discover the neural changes that accompany symptom improvement. Ketamine has utility for such research because of its known rapid and strong antidepressant effects in the context of TRD. Our previous study of six open-label ketamine infusions in 11 adolescents with TRD showed variable response, ranging from full remission, partial response, non-response, or clinical worsening. In this study, we examined the performance of these participants on Word Face Stroop (WFS) fMRI task where they indicated the valence of affective words superimposed onto either congruent or incongruent emotional faces before and after the ketamine infusions. Participants also completed a clinical assessment (including measurement of depression symptomology and anhedonia/pleasure) before and after the ketamine infusions. Following ketamine treatment, better WFS performance correlated with self-reported decreased depressive symptoms and increased pleasure. Analyses of corticolimbic, corticostriatal and default mode (DMN) networks showed that across networks, decreased activation during all conditions (congruent negative, congruent positive, incongruent negative, and incongruent positive) correlated with decreases in depressive symptoms and with increases in pleasure. These findings suggest that in adolescents with TRD, clinical improvement may require an attenuation of the negativity bias and re-tuning of these three critical neural networks to attenuate DMN and limbic regions activation and allow more efficient recruitment of the reward network. Lower activation across conditions may facilitate shifting across different salient emotional stimuli rather than getting trapped in downward negative spirals.

Potential Benefits of Nobiletin, A Citrus Flavonoid, against Alzheimer's Disease and Parkinson's Disease

Alzheimer’s disease (AD), which is characterized by the presence of amyloid-β (Aβ) plaques and neurofibrillary tangles, accompanied by neurodegeneration, is the most common form of age-related neurodegenerative disease. Parkinson’s disease (PD) is the second most common neurodegenerative disease after AD, and is characterized by early prominent loss of dopaminergic neurons in the substantia nigra pars compacta. As currently available treatments are not able to significantly alter the progression of these diseases, successful therapeutic and preventive interventions are strongly needed. In the course of our survey of substances from natural resources having anti-dementia and neuroprotective activity, we found nobiletin, a polymethoxylated flavone from the peel of Citrus depressa. Nobiletin improved cognitive deficits and the pathological features of AD, such as Aβ pathology, hyperphosphorylation of tau, and oxidative stress, in animal models of AD. In addition, nobiletin improved motor and cognitive deficits in PD animal models. These observations suggest that nobiletin has the potential to become a novel drug for the treatment and prevention of neurodegenerative diseases such as AD and PD.