Effects of ketamine on metabolic parameters in depressive disorders: A systematic review.

BACKGROUND: Persons with Major Depressive Disorder (MDD), notably treatment-resistant depression (TRD), are differentially affected by type 2 diabetes mellitus and associated morbidity. Ketamine is highly efficacious in the treatment of adults living with MDD, notably TRD. Herein, we sought to determine the effect of ketamine on metabolic parameters in animal stress paradigms and human studies. METHODS: We performed a comprehensive search on PubMed, OVID, and Scopus databases for primary research articles from inception to May 5, 2024. Study screening and data extraction were performed by two reviewers (S.W. and G.H.L.). Both preclinical and clinical studies were included in this review. RESULTS: Results from the preclinical studies indicate that in experimental diabetic conditions, ketamine does not disrupt glucose-insulin homeostasis. Within adults with MDD, ketamine is associated with GLUT3 transporter upregulation and differentially affects metabolomic signatures. In adults with TRD, ketamine induces increased brain glucose uptake in the prefrontal cortex. Available evidence suggests that ketamine does not adversely affect metabolic parameters. LIMITATIONS: There are a paucity of clinical studies evaluating the effects of ketamine on glucose-insulin homeostasis in adults with MDD. CONCLUSIONS: Our results indicate that ketamine is not associated with significant and/or persistent disruptions in metabolic parameters. Available evidence indicates that ketamine does not adversely affect glucose-insulin homeostasis. These results underscore ketamine's efficacy and safety as an antidepressant treatment that is not associated with metabolic disturbances commonly reported with current augmentation therapies.

Stable construction and analysis of MDD modular networks based on multi-center EEG data.

BACKGROUND: The modular structure can reflect the activity pattern of the brain, and exploring it may help us understand the pathogenesis of major depressive disorder (MDD). However, little is known about how to build a stable modular structure in MDD patients and how modules are separated and integrated. METHOD: We used four independent resting state Electroencephalography (EEG) datasets. Different coupling methods, window lengths, and optimized community detection algorithms were used to find a reliable and robust modular structure, and the module differences of MDD were analyzed from the perspectives of global module attributes and local topology in multiple frequency bands. RESULTS: The combination of the Phase Lag Index (PLI) and the Louvain algorithm can achieve better results and can achieve stability at smaller window lengths. Compared with Healthy Controls (HC), MDD had higher Modularity (Q) values and the number of modules in low-frequency bands. In addition, MDD showed significant structural changes in the frontal and parietal-occipital lobes, which were confirmed by further correlation analysis. CONCLUSION: Our results provided a reliable validation of the modular structure construction method in MDD patients and contributed strong evidence for the changes in emotional cognition and visual system function in MDD patients from a new perspective. These results would afford valuable insights for further exploration of the pathogenesis of MDD.

Graph-based Analysis to Predict Repetitive Transcranial Magnetic Stimulation Treatment Response in Patients With Major Depressive Disorder Using EEG Signals.

Introduction: Repetitive transcranial magnetic stimulation (rTMS) is a non-pharmacological treatment for drug-resistant major depressive disorder (MDD) patients. Since the success rate of rTMS treatment is about 50%-55%, it is essential to predict the treatment outcome before starting based on electroencephalogram (EEG) signals, leading to identifying effective biomarkers and reducing the burden of health care centers. Methods: To this end, pretreatment EEG data with 19 channels in the resting state from 34 drug-resistant MDD patients were recorded. Then, all patients received 20 sessions of rTMS treatment, and a reduction of at least 50% in the total beck depression inventory (BDI-II) score before and after the rTMS treatment was defined as a reference. In the current study, effective brain connectivity features were determined by the direct directed transfer function (dDTF) method from patients' pretreatment EEG data in all frequency bands separately. Then, the brain functional connectivity patterns were modeled as graphs by the dDTF method and examined with the local graph theory indices, including degree, out-degree, in-degree, strength, out-strength, in-strength, and betweenness centrality. Results: The results indicated that the betweenness centrality index in the Fp2 node and the δ frequency band are the best biomarkers, with the highest area under the receiver operating characteristic curve value of 0.85 for predicting the rTMS treatment outcome in drug-resistant MDD patients. Conclusion: The proposed method investigated the significant biomarkers that can be used to predict the rTMS treatment outcome in drug-resistant MDD patients and help clinical decisions.

Evaluation of male-specific psychoeducation for major depressive disorder compared to cognitive behavioral therapy psychoeducation: A randomized controlled investigation in mentally distressed men.

Background: Research suggests that male-specific psychotherapy approaches for major depressive disorder (MDD) that consider traditional masculinity ideologies (TMI) may achieve improved treatment efficacy and reduced therapy dropout. However, studies examining male-specific psychotherapy for MDD or specific therapy aspects remain lacking. Methods: An anonymous online study on men's mental health examined 152 self-reporting mentally distressed cisgender men (Mage = 25.5 ± 9.1) from German-speaking countries of Europe. After completing baseline assessments (T1) of state self-esteem, state shame, positive/negative affect, depressive symptoms, and TMI, men were randomly assigned to read either a male-specific (MSP) or a cognitive behavioral therapy-oriented (CBT) psychoeducation text for MDD. Immediately afterwards, participants rated its usefulness and completed follow-up assessments (T2). Results: Men in the MSP condition showed a stronger decrease in shame and negative affect as compared to men in the CBT-psychoeducation condition. Furthermore, in the MSP condition, prototypical depression symptoms tended to increase as compared to the CBT-psychoeducation, whereas male-typical externalizing depression symptoms tended to decrease. Conclusion: MSP for MDD may help depressed men feel less ashamed about their MDD and experience less negative affect about their condition than CBT-psychoeducation. Furthermore, MSP for MDD may elicit a shift from male-typical externalizing depression symptoms to prototypical depression symptoms.

Enhancing neuroplasticity in major depression: A novel 10 Hz-rTMS protocol is more effective than iTBS.

BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) is an effective treatment in major depressive disorder (MDD). However, intermittent theta-burst stimulation (iTBS) and rTMS protocols using 10 Hz stimulation frequency might differ in their effect on neuroplasticity and on clinical symptoms. This study compares the effect of iTBS and a novel 10 Hz-rTMS with shortened single session duration, on motor excitability and neuroplasticity and on clinical symptoms in MDD. METHODS: 30 patients with MDD received either iTBS or the novel 10 Hz-rTMS daily over three weeks to the left dorsolateral prefrontal cortex. Before and after the interventions, motor excitability, short-latency intracortical inhibition and long-term-potentiation-like plasticity in the motor cortex and clinical symptoms were measured by use of transcranial magnetic stimulation. RESULTS: After the intervention, the level of neuroplasticity increased and clinical symptoms of depression were reduced in both groups, though both effects were significantly stronger after the novel 10 Hz-rTMS. Importantly, the changes in neuroplasticity and clinical symptoms were correlated: the stronger neuroplasticity increased, the stronger was the improvement of clinical symptoms. LIMITATIONS: Short intervention period of 3 weeks. Clinical symptoms were measured by self-assessment only and are therefore preliminary. CONCLUSIONS: The novel 10 Hz-rTMS is more effective in increasing neuroplasticity in MDD and potentially also in reducing clinical symptoms than iTBS. This might be due to a differential mode of action on neuroplasticity and to the stimulation frequency of 10 Hz (within the alpha range) being more suitable to reset the brain's activity and to support neuroplastic changes.

Evaluating cognitive assessment tools for patients with major depressive disorder receiving electroconvulsive therapy: A systematic review and meta-analysis.

BACKGROUND: Major Depressive Disorder (MDD) affects 350 million people worldwide. Electroconvulsive therapy (ECT) is effective, yet research on cognitive assessments post-treatment is lacking. This study systematically reviews and meta-analyzes the effectiveness of cognitive assessment tools post-ECT to optimize MDD treatment. METHODS: Following PRISMA guidelines, this review was pre-registered on PROSPERO (CRD42023470318). Searches were conducted across nine databases up to November 12, 2023. Quality assessment for Randomized Controlled Trials (RCTs) and quasi-experimental studies was performed using the Cochrane risk of bias tool, JBI critical appraisal tools, and the Jadad scale. Meta-analyses for short-term and long-term cognitive function involved 24 and 18 tools, respectively. FINDINGS: Thirty studies (20 RCTs and 10 quasi-experimental) involving 2462 MDD patients were evaluated. Results indicated no significant differences in overall short-term and long-term cognitive functions post-ECT. Short-term analysis showed impairments in memory, learning, and verbal abilities but improvements in attention and processing speed. Long-term analysis revealed enhancements in memory, learning, verbal, and visuospatial abilities compared to baseline. Based on GRADE classification, we recommend 11 tools for assessing acute cognitive function and 10 tools for chronic cognitive impairment. These tools demonstrated high reliability and validity, supporting their clinical use. INTERPRETATION: These findings provide critical evidence for future ECT clinical guidelines in managing MDD. The recommended tools can aid clinicians in adjusting ECT regimens, identifying early cognitive changes, and improving therapeutic outcomes in MDD treatment.

Smoking as a mediator in the association between major depressive disorder and schizophrenia on lung cancer risk: a bidirectional/multivariable and mediation Mendelian randomization study.

Background & Aims: Major depressive disorder and schizophrenia have been hypothesized to be closely associated with cancer. However, the associations between these psychiatric conditions and the development of lung cancer remain uncertain. This study aimed to explore the causal relationship among major depressive disorder, schizophrenia, and the risk of lung cancer. Methods: Two-sample bidirectional/multivariable and mediation Mendelian randomization (MR) analyses were conducted. Genome-wide summary data on major depressive disorder (N=500,199) and schizophrenia (N=127,906) were utilized. Data on the risk of lung cancer (overall, adenocarcinoma, and squamous cell) were collected from a cohort of individuals of European ancestry (N=27,209). Three smoking-related behaviors (smoking initiation, pack years of smoking, and cigarettes smoked per day) were included in the multivariable and mediation MR analyses. Results: Patients with schizophrenia had a significantly greater risk of developing lung cancer (odds ratio (OR) = 1.144, 95% confidence interval (95% CI): 1.048-1.248, P = 0.003). The number of cigarettes smoked per day partially mediated the relationship between schizophrenia and the overall risk of lung cancer (OR = 1.185, 95% CI: 1.112-1.264, P = 0.021, proportion of mediation effect: 61.033%). However, there is no reliable evidence indicating an association between major depressive disorder and the risk of lung cancer (overall, adenocarcinoma, and squamous cell cancer). Conclusions: The findings indicated an association between schizophrenia and an increased risk of lung cancer, with smoking served as a partial mediator. When smoking was included in the regression analysis, the explanatory power of schizophrenia diagnosis was reduced, suggesting that smoking may be an important causal contributor to lung cancer in this population. Given the high prevalence of smoking among individuals with schizophrenia, these results underscore the need for further research to explore the underlying mechanisms of smoking's impact. Consequently, greater emphasis should be placed on monitoring the respiratory health of individuals with schizophrenia and implementing early interventions to address smoking-related behaviors.

Nutritional Strategies in Major Depression Disorder: From Ketogenic Diet to Modulation of the Microbiota-Gut-Brain Axis.

Major depressive disorder (MDD) is a leading cause of disability worldwide. While traditional pharmacological treatments are effective for many cases, a significant proportion of patients do not achieve full remission or experience side effects. Nutritional interventions hold promise as an alternative or adjunctive approach, especially for treatment-resistant depression. This review examines the potential role of nutrition in managing MDD through addressing biological deficits and modulating pathways relevant to its pathophysiology. Specifically, it explores the ketogenic diet and gut microbiome modulation through various methods, including probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplantation. Numerous studies link dietary inadequacies to increased MDD risk and deficiencies in nutrients like omega-3 s, vitamins D and B, magnesium, and zinc. These deficiencies impact neurotransmitters, inflammation, and other biological factors in MDD. The gut-brain axis also regulates mood, stress response, and immunity, and disruptions are implicated in MDD. While medications aid acute symptoms, nutritional strategies may improve long-term outcomes by preventing relapse and promoting sustained remission. This comprehensive review aims to provide insights into nutrition's multifaceted relationship with MDD and its potential for developing more effective integrated treatment approaches.

Challenges in Diagnosing and Managing Severe Hypernatremia in Patients With Major Depressive Disorder: A Case Report.

Hypernatremia, characterized by a plasma sodium concentration above 145 mmol/L, is frequently observed in critically ill patients, often due to factors such as gastrointestinal losses, dehydration, and diabetes insipidus. Psychiatric patients, particularly those with major depressive disorder, are also at risk of developing hypernatremia due to abnormalities in thirst sensation, mineralocorticoid excess, or medication side effects. Severe hypernatremia in psychiatric patients is associated with a high mortality rate, presenting challenges in diagnosis and management. The treatment of chronic hypernatremia (>48 hours) typically involves administering isotonic saline to hypovolemic patients until normalization of vital signs, followed by dextrose 5% in water (D5W) based on water deficit and losses. The goal is to decrease plasma sodium by 8-10 mmol/day. Acute hypernatremia (<48 hours) is corrected with a plasma sodium reduction of 1 mmol/L/hour in the first six to eight hours. While there are no clear guidelines for sodium correction in severe hypernatremia, the literature suggests a safe correction rate of 8-10 mmol/day for chronic hypernatremia and 1 mmol/L/hour for acute cases. In a specific case, a 51-year-old female with severe depression and reduced oral intake was admitted. She exhibited signs of dehydration and was found to have severe hypernatremia (191 mmol/L) with acute kidney injury. Treatment involved D5W, followed by D5W/half-normal saline at 150 mL/hr. Within 24 hours, her plasma sodium decreased to 178 mmol/L and gradually normalized to 143 mmol/L without neurological complications. This case highlights the challenges and underscores the importance of early recognition and management of severe hypernatremia in psychiatric patients. The primary treatment approach addresses water deficits and losses and administers D5W. Recent findings suggest that rapid correction of the condition is acceptable.

Combination of Transcranial Magnetic Stimulation and Ketamine in Treatment-Resistant Depression: A Systematic Review.

Treatment-resistant depression (TRD) is a significant challenge in psychiatric practice, affecting a substantial proportion of patients with major depressive disorder (MDD). Traditional treatment modalities often fall short, necessitating the exploration of alternative therapies. This literature review examines the combined use of Transcranial Magnetic Stimulation (TMS) and ketamine in treating TRD. The objective of this study is to evaluate the efficacy, safety, and potential synergies of combining TMS and ketamine in the treatment of TRD. A comprehensive literature search was conducted using PubMed and Google Scholar databases from 2014 to 2024. The search terms included combinations of "Transcranial Magnetic Stimulation," "Ketamine," "Depression," "Major Depressive Disorder," "Treatment-Resistant Depression," and "Combination." After screening for relevance and applying inclusion and exclusion criteria, six studies were selected for review, including three case reports, a retrospective study, a pilot study, and a review study. The selected studies demonstrated that the combination of TMS and ketamine resulted in substantial and sustained improvement in depressive symptoms for patients with TRD. Case reports and retrospective studies highlighted significant reductions in depression severity and improvements in psychosocial functioning. The combination therapy showed a higher efficacy compared to monotherapies of either TMS or ketamine alone. Notably, adverse effects were generally mild and transient, with no severe adverse events reported in most studies. In conclusion, the combination of TMS and ketamine presents a promising treatment modality for patients with TRD, offering significant improvements in depressive symptoms and better outcomes compared to traditional monotherapies. However, the heterogeneity in study designs and small sample sizes underline the need for larger, randomized controlled trials to establish standardized protocols and further validate these findings.

Applying neural ordinary differential equations for analysis of hormone dynamics in Trier Social Stress Tests.

Introduction: This study explores using Neural Ordinary Differential Equations (NODEs) to analyze hormone dynamics in the hypothalamicpituitary-adrenal (HPA) axis during Trier Social Stress Tests (TSST) to classify patients with Major Depressive Disorder (MDD). Methods: Data from TSST were used, measuring plasma ACTH and cortisol concentrations. NODE models replicated hormone changes without prior knowledge of the stressor. The derived vector fields from NODEs were input into a Convolutional Neural Network (CNN) for patient classification, validated through cross-validation (CV) procedures. Results: NODE models effectively captured system dynamics, embedding stress effects in the vector fields. The classification procedure yielded promising results, with the 1x1 CV achieving an AUROC score that correctly identified 83% of Atypical MDD patients and 53% of healthy controls. The 2x2 CV produced similar outcomes, supporting model robustness. Discussion: Our results demonstrate the potential of combining NODEs and CNNs to classify patients based on disease state, providing a preliminary step towards further research using the HPA axis stress response as an objective biomarker for MDD.

DNA Methylation of PXDN Is Associated with Early-Life Adversity in Adult Mental Disorders.

Early-life adversity (ELA) is characterized by exposure to traumatic events during early periods of life, particularly involving emotional, sexual and/or physical adversities during childhood. Mental disorders are strongly influenced by environmental and lifestyle-related risk factors including ELA. However, the molecular link between ELA and the risk of an adult mental disorder is still not fully understood. Evidence is emerging that long-lasting changes in the epigenetic processes regulating gene expression, such as DNA methylation, play an important role in the biological mechanisms linking ELA and mental disorders. Based on a recent study, we analyzed the DNA methylation of a specific CpG site within the gene PXDN-cg10888111-in blood in the context of ELA across a set of psychiatric disorders, namely Borderline Personality Disorder (BPD), Major Depressive Disorder (MDD) and Social Anxiety Disorder (SAD), and its potential contribution to their pathogenesis. We found significant hypermethylation in mentally ill patients with high levels of ELA compared to patients with low levels of ELA, whereas cg10888111 methylation in healthy control individuals was not affected by ELA. Further investigations revealed that this effect was driven by the MDD cohort. Providing a direct comparison of cg10888111 DNA methylation in blood in the context of ELA across three mental disorders, our results indicate the role of PXDN regulation in the response to ELA in the pathogenesis of mental disorders, especially MDD. Further studies will be needed to validate these results and decipher the corresponding biological network that is involved in the transmission of ELA to an adult mental disorder in general.

The mediating role of family functioning between childhood trauma and depression severity in major depressive disorder and bipolar disorder.

BACKGROUND: Childhood trauma (CT) and family functioning exert significant influences on the course and long-term outcome of major depressive disorder (MDD) and bipolar disorder (BD) patients. Hence, we examined the intricate relationship between CT, family function, and the severity of depressive episodes in MDD and BD patients. METHODS: 562 patients with depressive episodes (336 MDD and 226 BD) and 204 healthy controls (HCs) were included in this retrospective study. The 17-item Hamilton Depression Rating Scale (HAMD-17), Childhood Trauma Questionnaire (CTQ), and Family Adaptability and Cohesion Evaluation Scale (FACES II-CV) were assessed. Pearson correlation analysis and mediation analysis were performed. RESULTS: CT had both a direct and indirect impact on depression severity in MDD and BD groups. In MDD, family adaptability mediated the impact of all CT subtypes on depression severity (Effect = 0.113, [0.030, 0.208]). In BD, family cohesion played a mediating role between emotional neglect (EN) and HAMD-17 scores (Effect = 0.169, [0.008, 0.344]). Notable differences were observed in onset age, illness duration, episode frequency, family history, and CT subtypes between MDD and BD (P < 0.05). LIMITATIONS: This study has several limitations including recall bias, lack of objective family functioning measures, small sample size, and cross-sectional design. CONCLUSIONS: Family functioning mediated the impact of CT on depressive symptoms severity in MDD and BD patients. MDD patients with a history of CT exhibited reduced family adaptability, while BD patients with a history of EN had weaker familial emotional bonds. Our findings highlighted the importance of family-focused preventive interventions in mitigating the long-term effects of CT.

Bioinformatics and systems biology approach to identify the pathogenetic link of neurological pain and major depressive disorder.

Neurological pain (NP) is always accompanied by symptoms of depression, which seriously affects physical and mental health. In this study, we identified the common hub genes (Co-hub genes) and related immune cells of NP and major depressive disorder (MDD) to determine whether they have common pathological and molecular mechanisms. NP and MDD expression data was downloaded from the Gene Expression Omnibus (GEO) database. Common differentially expressed genes (Co-DEGs) for NP and MDD were extracted and the hub genes and hub nodes were mined. Co-DEGs, hub genes, and hub nodes were analyzed for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. Finally, the hub nodes, and genes were analyzed to obtain Co-hub genes. We plotted Receiver operating characteristic (ROC) curves to evaluate the diagnostic impact of the Co-hub genes on MDD and NP. We also identified the immune-infiltrating cell component by ssGSEA and analyzed the relationship. For the GO and KEGG enrichment analyses, 93 Co-DEGs were associated with biological processes (BP), such as fibrinolysis, cell composition (CC), such as tertiary granules, and pathways, such as complement, and coagulation cascades. A differential gene expression analysis revealed significant differences between the Co-hub genes ANGPT2, MMP9, PLAU, and TIMP2. There was some accuracy in the diagnosis of NP based on the expression of ANGPT2 and MMP9. Analysis of differences in the immune cell components indicated an abundance of activated dendritic cells, effector memory CD8+ T cells, memory B cells, and regulatory T cells in both groups, which were statistically significant. In summary, we identified 6 Co-hub genes and 4 immune cell types related to NP and MDD. Further studies are needed to determine the role of these genes and immune cells as potential diagnostic markers or therapeutic targets in NP and MDD.

Microglial circ-UBE2K exacerbates depression by regulating parental gene UBE2K via targeting HNRNPU.

Background: Knowledge about the pathogenesis of depression and treatments for this disease are lacking. Epigenetics-related circRNAs are likely involved in the mechanism of depression and have great potential as treatment targets, but their mechanism of action is still unclear. Methods: Circular RNA UBE2K (circ-UBE2K) was screened from peripheral blood of patients with major depressive disorder (MDD) and brain of depression model mice through high-throughput sequencing. Microinjection of circ-UBE2K overexpression lentivirus and adeno-associated virus for interfering with microglial circ-UBE2K into the mouse hippocampus was used to observe the role of circ-UBE2K in MDD. Sucrose preference, forced swim, tail suspension and open filed tests were performed to evaluate the depressive-like behaviors of mice. Immunofluorescence and Western blotting analysis of the effects of circ-UBE2K on microglial activation and immune inflammation. Pull-down-mass spectrometry assay, RNA immunoprecipitation (RIP) test and fluorescence in situ hybridization (FISH) were used to identify downstream targets of circ-UBE2K/ HNRNPU (heterogeneous nuclear ribonucleoprotein U) axis. Results: In this study, through high-throughput sequencing and large-scale screening, we found that circ-UBE2K levels were significantly elevated both in the peripheral blood of patients with MDD and in the brains of depression model mice. Functionally, circ-UBE2K-overexpressing mice exhibited worsened depression-like symptoms, elevated brain inflammatory factor levels, and abnormal microglial activation. Knocking down circ-UBE2K mitigated these changes. Mechanistically, we found that circ-UBE2K binds to heterogeneous nuclear ribonucleoprotein U (HNRNPU) to form a complex that upregulates the expression of the parental gene ubiquitin conjugating enzyme E2 K (UBE2K), leading to abnormal microglial activation and neuroinflammation and promoting the occurrence and development of depression. Conclusions: The findings of the present study revealed that the expression of circUBE2K, which combines with HNRNPU to form the circUBE2K/HNRNPU complex, is increased in microglia after external stress, thus regulating the expression of the parental gene UBE2K and mediating the abnormal activation of microglia to induce neuroinflammation, promoting the development of MDD. These results indicate that circ-UBE2K plays a newly discovered role in the pathogenesis of depression.

Neural substrates of predicting anhedonia symptoms in major depressive disorder via connectome-based modeling.

MAIN PROBLEM: Anhedonia is a critical diagnostic symptom of major depressive disorder (MDD), being associated with poor prognosis. Understanding the neural mechanisms underlying anhedonia is of great significance for individuals with MDD, and it encourages the search for objective indicators that can reliably identify anhedonia. METHODS: A predictive model used connectome-based predictive modeling (CPM) for anhedonia symptoms was developed by utilizing pre-treatment functional connectivity (FC) data from 59 patients with MDD. Node-based FC analysis was employed to compare differences in FC patterns between melancholic and non-melancholic MDD patients. The support vector machines (SVM) method was then applied for classifying these two subtypes of MDD patients. RESULTS: CPM could successfully predict anhedonia symptoms in MDD patients (positive network: r = 0.4719, p < 0.0020, mean squared error = 23.5125, 5000 iterations). Compared to non-melancholic MDD patients, melancholic MDD patients showed decreased FC between the left cingulate gyrus and the right parahippocampus gyrus (p_bonferroni = 0.0303). This distinct FC pattern effectively discriminated between melancholic and non-melancholic MDD patients, achieving a sensitivity of 93.54%, specificity of 67.86%, and an overall accuracy of 81.36% using the SVM method. CONCLUSIONS: This study successfully established a network model for predicting anhedonia symptoms in MDD based on FC, as well as a classification model to differentiate between melancholic and non-melancholic MDD patients. These findings provide guidance for clinical treatment.

Profiling the combination of bupropion and dextromethorphan as a treatment option for major depressive disorder.

INTRODUCTION: Major Depressive Disorder (MDD) is a common mental health disorder marked by sadness, hopelessness, and anhedonia. Various therapies exist, but their effectiveness is limited. Dextromethorphan hydrobromide combined with bupropion hydrochloride (Auvelity®) is a recently approved alternative for treating this condition in adults. AREAS COVERED: This review summarizes the neurobiology of major depression and delves into the pharmacology, efficacy, safety, and tolerability of dextromethorphan plus bupropion in adult patients. It is based on observational studies, clinical trials, and other secondary studies obtained through systematic literature searches. EXPERT OPINION: The combination of bupropion and dextromethorphan as a new pharmacotherapy for mental health is an interesting addition to the treatment options that can be used for MDD. The combination can be used in a range of scenarios, including as a first line therapy, as a second option when a patient has failed to achieve remission with a serotonin targeting agent, and for treatment resistant depression. Further research for other indications, including addiction disorders, may provide exciting results. Although a new combination, clinicians will be very familiar with both agents, increasing their acceptability. This pharmacotherapy also may bring increased impetus for discovering other combinations that may have beneficial synergistic effects.

Insulin resistance, clinical presentation and resistance to selective serotonin and noradrenaline reuptake inhibitors in major depressive disorder.

BACKGROUND: The understanding of mechanisms underlying non-response to antidepressants is limited. The latest data highlights the role of insulin resistance (IR) in major depressive disorder (MDD) pathophysiology, presentation, and treatment efficacy. This work aimed to assess IR in MDD and explore the relationships between IR, MDD presentation and non-response to selective serotonin and noradrenaline reuptake inhibitors (SNRI). METHODS: 67 MDD individuals: 36 responsive (MDD T[+]), 31 non-responsive (MDD T[-]) to SNRI and 30 healthy controls were recruited. The treatment response criteria were: Clinical Global Impression Scale-Improvement score of 1 or 2 after ≥ 8 weeks of treatment. Participants were assessed by physician and self-report tools measuring depression, anhedonia, anxiety, bipolarity, sleep quality. Blood samples were collected to assess fasting glucose and insulin levels and calculate HOMA-IR (homeostasis model assessment of insulin resistance). RESULTS: MDD T[-] vs. MDD T[+] had significantly higher body mass index, insulin levels, and HOMA-IR. MDD T[-] presented higher levels of depressed mood, appetite/weight changes, loss of interest, energy, overall depressive symptoms, and sleep impairment; some evaluations suggested higher anhedonia and anxiety in MDD T[-] vs. MDD T[+]. Insulin and IR were weakly but significantly correlated with the severity of psychomotor symptoms, energy level, thoughts of death/suicide, self-criticism, appetite/weight, depressed mood symptoms, sleep problems. IR was weakly but significantly correlated with anhedonia. CONCLUSION: IR appears to be linked to depressive symptoms characteristic of the "metabolic" MDD subtype, such as psychomotor changes, energy level, anhedonia, sleep problems, appetite/weight changes, state and trait anxiety, sleep quality, and non-response to SNRI.

Assessing the associations of 1,400 blood metabolites with major depressive disorder: a Mendelian randomization study.

Background and objectives: Major Depressive Disorder (MDD) is one of the most prevalent and debilitating health conditions worldwide. Previous studies have reported a link between metabolic dysregulation and MDD. However, evidence for a causal relationship between blood metabolites and MDD is lacking. Methods: Using a two-sample bidirectional Mendelian randomization analysis (MR), we assessed the causal relationship between 1,400 serum metabolites and Major Depressive Disorder (MDD). The Inverse Variance Weighted method (IVW) was employed to estimate the causal association between exposures and outcomes. Additionally, MR-Egger regression, weighted median, simple mode, and weighted mode methods were used as supplementary approaches for a comprehensive appraisal of the causality between blood metabolites and MDD. Pleiotropy and heterogeneity tests were also conducted. Lastly, the relevant metabolites were subjected to metabolite function analysis, and a reverse MR was implemented to explore the potential influence of MDD on these metabolites. Results: After rigorous screening, we identified 34 known metabolites, 13 unknown metabolites, and 18 metabolite ratios associated with Major Depressive Disorder (MDD). Among all metabolites, 33 were found to have positive associations, and 32 had negative associations. The top five metabolites that increased the risk of MDD were the Arachidonate (20:4n6) to linoleate (18:2n6) ratio, LysoPE(18:0/0:0), N-acetyl-beta-alanine levels, Arachidonate (20:4n6) to oleate to vaccenate (18:1) ratio, Glutaminylglutamine, and Threonine to pyruvate ratio. Conversely, the top five metabolites that decreased the risk of MDD were N6-Acetyl-L-lysine, Oleoyl-linoleoyl-glycerol (18:1 to 18:2) [2] to linoleoyl-arachidonoyl-glycerol (18:2 to 20:4) [2] ratio, Methionine to phosphate ratio, Pregnanediol 3-O-glucuronide, and 6-Oxopiperidine-2-carboxylic acid. Metabolite function enrichment was primarily concentrated in pathways such as Bile Acid Biosynthesis (FDR=0.177), Glutathione Metabolism (FDR=0.177), Threonine, and 2-Oxobutanoate Degradation (FDR=0.177). In addition, enrichment was noted in pathways like Valine, Leucine, and Isoleucine Biosynthesis (p=0.04), as well as Ascorbate and Aldarate Metabolism (p=0.04). Discussion: Within a pool of 1,400 blood metabolites, we identified 34 known metabolites and 13 unknown metabolites, as well as 18 metabolite ratios associated with Major Depressive Disorder (MDD). Additionally, three functionally enriched groups and two metabolic pathways were selected. The integration of genomics and metabolomics has provided significant insights for the screening and prevention of MDD.

Exploring the potential of drug repurposing for treating depression.

Researchers are interested in drug repurposing or drug repositioning of existing pharmaceuticals because of rising costs and slower rates of new medication development. Other investigations that authorized these treatments used data from experimental research and off-label drug use. More research into the causes of depression could lead to more effective pharmaceutical repurposing efforts. In addition to the loss of neurotransmitters like serotonin and adrenaline, inflammation, inadequate blood flow, and neurotoxins are now thought to be plausible mechanisms. Because of these other mechanisms, repurposing drugs has resulted for treatment-resistant depression. This chapter focuses on therapeutic alternatives and their effectiveness in drug repositioning. Atypical antipsychotics, central nervous system stimulants, and neurotransmitter antagonists have investigated for possible repurposing. Nonetheless, extensive research is required to ensure their formulation, effectiveness, and regulatory compliance.