A prospective, longitudinal study of platelet serotonin and plasma brain-derived neurotrophic factor concentrations in major depression: effects of vortioxetine treatment

Platelet Serotonin (5-HT) Concentration, Platelet Monoamine Oxidase B (MAO-B) Activity and HTR2A, HTR2C, and MAOB Gene Polymorphisms in Asthma

The complex role of the serotonin system in respiratory function and inflammatory diseases such as asthma is unclear. Our study investigated platelet serotonin (5-HT) levels and platelet monoamine oxidase B (MAO-B) activity, as well as associations with HTR2A (rs6314; rs6313), HTR2C (rs3813929; rs518147), and MAOB (rs1799836; rs6651806) gene polymorphisms in 120 healthy individuals and 120 asthma patients of different severity and phenotypes. Platelet 5-HT concentration was significantly lower, while platelet MAO-B activity was considerably higher in asthma patients; however, they did not differ between patients with different asthma severity or phenotypes. Only the healthy subjects, but not the asthma patients, carrying the MAOB rs1799836 TT genotype had significantly lower platelet MAO-B activity than the C allele carriers. No significant differences in the frequency of the genotypes, alleles, or haplotypes for any of the investigated HTR2A, HTR2C and MAOB gene polymorphisms have been observed between asthma patients and healthy subjects or between patients with various asthma phenotypes. However, the carriers of the HTR2C rs518147 CC genotype or C allele were significantly less frequent in severe asthma patients than in the G allele carriers. Further studies are necessary to elucidate the involvement of the serotonergic system in asthma pathophysiology.

The association of brain-derived neurotrophic factor with the diagnosis and treatment response in depression

INTRODUCTION

Recent evidence from the studies evaluating the association between brain derived neurotrophic factor (BDNF) concentration/levels, BDNF Val66Met (rs6265) polymorphism and major depressive disorders, referred as depression, and the association between BDNF levels and/or BDNF Val66Met with the treatment response in depression, is presented.

AREAS COVERED

This mini review focuses on the changes in the peripheral BDNF levels in blood (serum, plasma, platelets) in patients with depression before or after treatment with antidepressant drugs or different therapeutic strategies. In addition, this review describes the recent data on the possible association between different antidepressants/therapeutic strategies and the particular BDNF Val66Met genotypes, evaluating the risk alleles associated with the response in patients with depression.

EXPERT OPINION

BDNF has an important role in the pathophysiology and treatment response in depression. Most data reveal that peripheral BDNF levels are lower before than after antidepressant treatment and might be used as potential biomarkers of therapeutic response. Novel therapeutic strategies should target restoring/increasing BDNF levels.

Association between inflammatory cytokines and symptoms of major depressive disorder in adults

Objective

This study investigated the association between inflammatory cytokines and major depressive disorder.

Methods

Plasma biomarkers were measured by enzyme-linked immunosorbent assay (ELISA). Statistical analysis of baseline biomarkers in the major depression disorder (MDD) group and healthy controls (HC) group, and differences in biomarkers before and after treatment. Spearman analysis was performed to correlate baseline and after treatment MDD biomarkers with the 17-item Hamilton Depression Rating Scale (HAMD-17) total scores. Receiver operator characteristic (ROC) curves were analyzed for the effect of biomarkers on MDD and HC classification and diagnosis.

Results

Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels were significantly higher in the MDD group than in the HC group, while high mobility group protein 1 (HMGB1) levels were significantly lower in the MDD group. The AUCs for HMGB1, TNF-α, and IL-6 were 0.375, 0.733, and 0.783, respectively, according to the ROC curves. MDD patients with brain-derived neurotrophic factor precursor (proBDNF) levels were positively correlated with total HAMD-17 scores. The levels of proBDNF levels were positively correlated with the total HAMD-17 score in male MDD patients, and brain-derived neurotrophic factor (BDNF) and interleukin 18 (IL-18) levels were negatively correlated with the total HAMD-17 score in female MDD patients.

Conclusion

Inflammatory cytokines are associated with the severity of MDD, and TNF-α and IL-6 have the potential as objective biomarkers to aid in the diagnosis of MDD.

Reduced plasma BDNF concentration and cognitive decline in veterans with PTSD

Post-traumatic stress disorder (PTSD) is a trauma and stress related disorder frequently associated with cognitive decline. War veterans with PTSD have a higher risk of developing dementia than healthy subjects. Brain derived neurotrophic factor (BDNF) is an important protein that modulates plasticity, memory consolidation and cognitive processes. Lower circulating BDNF levels were related to memory impairment and cognitive deterioration. The aim of this study was to evaluate cognitive deterioration and plasma BDNF concentration in 120 veterans with combat related PTSD, 120 healthy controls, 47 subjects with mild cognitive impairment (MCI) and 76 patients with Alzheimer's disease (AD), and to assess if plasma BDNF concentration might be used as biomarker of cognitive deterioration. Veterans with PTSD had significantly decreased plasma BDNF concentration and worse cognitive performances (assessed using the Mini Mental State Examination, Clock Drawing test and Montreal Cognitive Assessment scores/categories) than healthy subjects, and similarly reduced plasma BDNF and cognitive decline as MCI subjects. Reduced plasma BDNF was found in cognitively impaired subjects. These results suggest that veterans with PTSD should be closely monitored in order to early detect and predict cognitive worsening and promote interventions that might help restore blood BDNF levels and cognitive functions.

Various BDNF administrations attenuate SPS-induced anxiety-like behaviors

Post-traumatic stress disorder (PTSD) has become epidemic following severely stressful incidents. Previous studies have shown that brain-derived neurotrophic factor (BDNF) has anxiolytic effects on various anxiety or depression disorders including PTSD. However, the detailed mechanisms of BDNF for treating PTSD were rarely investigated. In the current study, single-prolonged stress (SPS) was used as an animal model recapitulating specific aspects for a PTSD-like phenotype. The effects of BDNF on SPS-induced anxiety-like behaviors were investigated. We showed that the levels of BDNF in the cerebro-spinal fluid (CSF) were significantly reduced after the rats experienced SPS. The SPS-induced reductions of percentages of time spent in the central area to total time in the open field test, were dose-dependently mitigated after BDNF intracerebroventricular (i.c.v.) injections. BDNF i.c.v. administration also dose-dependently increased the preference of the light box in the light-dark box test. Both expressions of tyrosine kinase receptor B (TrkB) protein and mRNA in the prefrontal cortex (PFC) and amygdala were significantly increased after SPS challenges. BDNF i.c.v. administration attenuated these compensatory increases of TrkB. At last, the anxiolytic effects of BDNF on SPS model were also observed by using other two injection methods. These results inspired us to study that different administrations of BDNF were used in patients with PTSD in the future, in-depthly.

Serum brain-derived neurotrophic factor and glial cell-derived neurotrophic factor in patients with first-episode depression at different ages

OBJECTIVES

We investigated the differences in serum brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) levels and clinical symptoms with first-episode depression at different ages.

METHODS

Ninety patients (15-60 years old) diagnosed with first-episode depression were enrolled as the study group, and they were divided into early-onset, adult and late-onset groups. The age-matched control groups were healthy volunteers. Serum BDNF and GDNF concentrations were determined by enzyme-linked immunosorbent assay (ELISA). GraphPad Prism 9 was used for t tests, one-way ANOVAs, chi-square tests, and correlation analyses. p < 0.05 indicated significant differences.

RESULTS

Serum BDNF and GDNF levels were lower in the whole study group and the three subgroups than in the healthy groups. Illness severity, anxiety and education were higher in the early-onset than late-onset patients. Serum BDNF levels were lower in the adult than late-onset patients. Serum BDNF levels were negatively correlated with patient CGI-SI scores. After the LSD test for multiple comparisons, the results were also significant.

CONCLUSIONS

Low serum BDNF and GDNF levels may be involved in the pathophysiology of first-episode depression, and there were differences in serum BDNF levels at different ages, verifying that serum BDNF and GDNF could serve as potential biomarkers of depression. KEY POINTSDepression is often conceptualised as a systemic illness with different biological mechanisms, but satisfactory explanations have not been provided thus far.The aim of our study was to investigate differences in serum BDNF and GDNF levels and their relationships with clinical symptoms in patients with first-episode depression at different ages.The potential of the neurotrophic factor hypothesis to advance the diagnosis and treatment of depression will be a very exciting new strategy for future research.

Tailoring the therapeutic interventions for behavioral and psychological symptoms of dementia

INTRODUCTION

Behavioral and psychological symptoms of dementia (BPSD) are symptoms of non-cognitive nature, which frequently develop during the course and different stages of dementia. The diagnosis of BPSD is complex due to symptom variety, and relies on detailed clinical evaluation and medical history. Accurate assessment of BPSD is crucial in order to tailor therapeutic intervention (non-pharmacological and pharmacological) for each individual and monitor patient response to therapy.

AREAS COVERED

This review encompasses the epidemiology, classification, assessment and etiology of BPSD, as well as their impact on caregiver distress, and gives an overview of current and emerging non-pharmacological and pharmacological therapeutic options, as well as potential BPSD biomarkers, in order to provide a framework for improving BPSD diagnosis and developing novel, targeted and specific therapeutic strategies for BPSD.

EXPERT OPINION

Due to the large heterogeneity of BPSD and of the fact that drugs available only alleviate symptoms, finding an adequate treatment is very challenging and often involves a polytherapeutic approach. Non-pharmacologic interventions have shown promising results in improving BPSD, however further research is needed to confirm their beneficial effects. Thus, the modification of pre-existancing as well as the development of novel pharmacologic and non-pharmacologic solutions should be considered for BPSD therapy.

Brain-Derived Neurotrophic Factor and Extracellular Vesicle-Derived miRNAs in an Italian Cohort of Individuals With Obesity: A Key to Explain the Link Between Depression and Atherothrombosis

Background

Obesity and depression are intertwined diseases often associated with an increased risk of cardiovascular (CV) complications. Brain-Derived Neurotrophic Factor (BDNF), altered in the brain both of subjects with depression and obesity, provides a potential link between depression and thrombosis. Since the relationship among peripheral BDNF, depression and obesity is not well-defined, the aim of the present report has been to address this issue taking advantage of the contribution played by extracellular vesicle (EV)-derived miRNAs.

Research Process

Associations among circulating BDNF, depression and EV-derived miRNAs related to atherothrombosis have been evaluated in a large Italian cohort of obese individuals (n = 743), characterized by the Beck Depression Inventory (BDI-II) score.

Results

BDI-II was negatively associated with BDNF levels without a significant impact of the rs6265 BDNF polymorphism; this association was modified by raised levels of IFN-γ. BDNF levels were linked to an increase of 80 EV-derived miRNAs and a decrease of 59 miRNAs related to atherosclerosis and thrombosis. Network analysis identified at least 18 genes targeted by these miRNAs, 7 of which involved in depression and CV risk. The observation of a possible link among BDNF, depression, and miRNAs related to atherothrombosis and depression in obesity is novel and may lead to a wider use of BDNF as a CV risk biomarker in this specific subject group.

Pharmacological, Neurochemical, and Behavioral Mechanisms Underlying the Anxiolytic- and Antidepressant-like Effects of Flavonoid Chrysin

Chrysin (5,7-dihydroxyflavone) is a flavonoid isolated from plants, such as Passiflora coerulea, Passiflora incarnata, and Matricaria chamomilla. This natural molecule exerts diverse pharmacological effects, which includes antioxidant, anti-inflammatory, anti-cancer, neuroprotective, and anti-apoptotic effects. Additionally, in brain structures, such as the hippocampus, prefrontal cortex, raphe nucleus, and striatum, involved in the physiopathology of anxiety and depression disorders, several neuropharmacological activities, including the activation of neurotransmitter systems (GABAergic, serotonergic, dopaminergic, and noradrenergic), neurotrophic factors, such as brain-derived neurotrophic factor and the nerve growth factor, and some signaling pathways are affected. The results showed that the anxiolytic and antidepressant-like effects of chrysin occurs through its interaction with specific neurotransmitter systems, principally the GABAergic and the serotonergic, and activation of other neurotrophic factors. However, it is not possible to discard the antioxidant and anti-inflammatory activities of chrysin while producing its anxiolytic- and antidepressant-like effects. Although these results have been obtained principally from pre-clinical research, they consistently demonstrate the potential therapeutic use of flavonoid chrysin as an anxiolytic and antidepressant agent. Therefore, this flavonoid could be considered as a promising novel therapy for anxiety and depression disorders.

Effects of Antidepressant Treatment on Neurotrophic Factors (BDNF and IGF-1) in Patients with Major Depressive Disorder (MDD)

Major depressive disorder (MDD) remains the subject of ongoing research as a multifactorial disease and a serious public health problem. There is a growing body of literature focusing on the role of neurotrophic factors in pathophysiology of MDD. A neurotrophic hypothesis of depression proposes that abnormalities of neurotrophins serum levels lead to neuronal atrophy and decreased neurogenesis, resulting in mood disorders. Consequently, in accordance with recent findings, antidepressant treatment modifies the serum levels of neurotrophins and thus leads to a clinical improvement of MDD. The purpose of this review is to summarize the available data on the effects of various antidepressants on serum levels of neurotrophins such as brain-derived neurotrophic factor (BDNF) and insulin-like growth factor (IGF-1). In addition, the authors discuss their role as prognostic factors for treatment response in MDD. A literature search was performed using the PubMed database. Following the inclusion and exclusion criteria, nine original articles and three meta-analyses were selected. The vast majority of studies have confirmed the effect of antidepressants on BDNF levels. Research on IGF-1 is limited and insufficient to describe the correlation between different antidepressant drugs and factor serum levels; however, four studies indicated a decrease in IGF-1 after treatment. Preliminary data suggest BDNF as a promising predictor of treatment response in MDD patients. The role of IGF-1 needs further investigation.

Distinct association of plasma BDNF concentration and cognitive function in depressed patients treated with vortioxetine or escitalopram

RATIONALE

Cognitive dysfunction is frequent in major depressive disorder (MDD), and brain-derived neurotrophic factor (BDNF) is involved both in regulation of cognition and in therapeutic response in MDD.

OBJECTIVES

The aim of this study was to determine if baseline plasma BDNF might predict change in cognitive function in MDD patients treated with vortioxetine or escitalopram, and whether the alterations in BDNF levels correlate with changes in cognitive performance during treatment.

METHODS

Drug-naive or drug-free patients with MDD (N=121) were sampled and evaluated at baseline and 4 weeks after treatment initiation with vortioxetine or escitalopram. Cognitive function was evaluated using the F-A-S test, Digit Span test, and Digit Symbol Coding test. Plasma BDNF was determined using ELISA.

RESULTS

The results of the study indicate that both vortioxetine (V) and escitalopram (E) improved cognitive functions evaluated with F-A-S test (V: p<0.001; r=-0.427, E: p<0.001; r=-0.370), Digit Symbol Coding test (V: p<0.001; r=-0.706, E: p<0.001; r=-0.435), and Digit Span test-backward span (V: p=0.001; r=-0.311, E: p=0.042; r=-0.185), while only vortioxetine (p<0.001; r=-0.325) improved cognition evaluated with the Digit Span test-forward span. A moderate positive correlation between pretreatment plasma BDNF levels and improvement in cognitive performance was only detected in patients treated with vortioxetine (delta F-A-S test: p=0.011; r=0.325, delta Digit Span test-forward span: p=0.010, r=0.326).

CONCLUSIONS

These results suggest that higher baseline plasma BDNF levels might be associated with improvements in verbal fluency and working memory in vortioxetine, but not escitalopram treated patients. Vortioxetine treatment was superior in simple attention efficiency.

Can Molecular Biology Propose Reliable Biomarkers for Diagnosing Major Depression?

BACKGROUND

Modern medicine has provided considerable knowledge of the pathophysiology of mental disorders at the body, systemic, organ and neurochemical levels of the biological organization of the body. Modern clinical diagnostics of depression have some problems, that is why psychiatric society makes use of diagnostics and taxonomy of different types of depression by implemention of modern molecular biomarkers in diagnostic procedures. But up to now, there are no reliable biomarkers of major depressive disorder (MDD) and other types of depression.

OBJECTIVE

The purpose of this review is to find fundamentals in pathological mechanisms of depression, which could be a basis for development of molecular and genetic biomarkers, being the most feasible for clinical use.

METHOD

This review summarizes the published data using PubMed, Science Direct, Google Scholar and Scopus.

RESULTS

In this review, we summarized and discussed findings in molecular biology, genetics, neuroplasticity, neurotransmitters, and neuroimaging that could increase our understanding of the biological foundations of depression and show new directions for the development of reliable biomarkers. We did not find any molecular and genetic biomarker approved for the clinic. But the Genome-Wide Association Study method promises some progress in the development of biomarkers based on SNP in the future. Epigenetic factors also are a promising target for biomarkers. We have found some differences in the etiology of different types of atypical and melancholic depression. This knowledge could be the basis for development of biomarkers for clinical practice in diagnosis, prognosis and selection of treatment.

CONCLUSION

Depression is not a monoetiological disease. Many pathological mechanisms are involved in depression, thus up to now, there is no approved and reliable biomarker for diagnosis, prognosis and correction of treatment of depression. The structural and functional complexity of the brain, the lack of invasive technology, poor correlations between genetic and clinical manifestation of depression, imperfect psychiatric classification and taxonomy of subtypes of disease are the main causes of this situation. One of the possible ways to come over this situation can be to pay attention to the trigger mechanism of disease and its subtypes. Researchers and clinicians should focus their efforts on searching the trigger mechanism of depression and different types of it . HPA axis can be a candidate for such trigger in depression caused by stress, because it influences the main branches of disease: neuroinflammation, activity of biogenic amines, oxidative and nitrosative stress, epigenetic factors, metabolomics, etc. But before we shall find any trigger mechanism, we need to create complex biomarkers reflecting genetic, epigenetic, metabolomics and other pathological changes in different types of depression. Recently the most encouraging results have been obtained from genetics and neuroimaging. Continuing research in these areas should be forced by using computational, statistical and systems biology approaches, which can allow to obtain more knowledge about the neurobiology of depression. In order to obtain clinically useful tests, search for biomarkers should use appropriate research methodologies with increasing samples and identifying more homogeneous groups of depressed patients.

Plasma BDNF concentrations and the antidepressant effects of six ketamine infusions in unipolar and bipolar depression

Objectives

Accumulating evidence has implicated that brain derived neurotrophic factor (BDNF) is thought to be involved in the pathophysiology of depression, but its correlation with ketamine's antidepressant efficacy focusing on Chinese individuals with depression is not known. This study was aim to determine the correlation of plasma BDNF (pBDNF) concentrations and ketamine's antidepressant efficacy.

Methods

Ninety-four individuals with depression received six intravenous infusions ketamine (0.5 mg/kg). Remission and response were defined as Montgomery-Asberg Depression Rating Scale (MADRS) scores less than 10 and a reduction of 50% or more in MADRS scores, respectively. Plasma was collected at baseline and at 24 h and 2 weeks after completing six ketamine infusions (baseline, 13 d and 26 d).

Results

A significant improvement in MADRS scores and pBDNF concentrations was found after completing six ketamine infusions compared to baseline (all ps < 0.05). Higher baseline pBDNF concentrations were found in ketamine responders/remitters (11.0 ± 6.2/10.1 ± 5.8 ng/ml) than nonresponders/nonremitters (8.0 ± 5.5/9.2 ± 6.4 ng/ml) (all ps < 0.05). Baseline pBDNF concentrations were correlated with MADRS scores at 13 d (t =  - 2.011, p = 0.047) or 26 d (t =  - 2.398, p = 0.019) in depressed patients (all ps < 0.05). Subgroup analyses found similar results in individuals suffering from treatment refractory depression.

Conclusion

This preliminary study suggests that baseline pBDNF concentrations appeared to be correlated with ketamine's antidepressant efficacy in Chinese patients with depression.

Effect of vortioxetine vs. escitalopram on plasma BDNF and platelet serotonin in depressed patients

Escitalopram and vortioxetine are efficacious antidepressants. They directly target serotonin (5-HT) system, but vortioxetine mechanism of action is distinct from the one of selective serotonin reuptake inhibitors (SSRIs). Treatment with SSRIs decrease platelet 5-HT concentration and increase peripheral brain-derived neurotrophic factor (BDNF) levels. Since vortioxetine has a multimodal mechanism of action, it is expected to have a greater effect on circulatory BDNF concentration, compared to conventional antidepressants. This longitudinal study aimed to explore and compare the effects of 4-weeks of treatment with vortioxetine and escitalopram on plasma BDNF and platelet 5-HT concentration in patients with major depressive disorder (MDD). The results revealed that vortioxetine significantly increased plasma BDNF concentration (p = .018) and significantly decreased platelet 5-HT concentration (p < .001). Treatment with escitalopram significantly decreased platelet 5-HT concentration (p < .001), but it did not affect plasma BDNF concentration (p = .379). Response to vortioxetine was not predicted by baseline plasma BDNF or platelet 5-HT concentration, but response to escitalopram was predicted by baseline platelet 5-HT concentration. These effects might be due to vortioxetine unique mechanism of action, but the clinical implications are unclear. It remains to be determined whether this finding extends during long-term vortioxetine treatment, and which, if any, clinical effects emerge from BDNF increase.

Depression: Biological markers and treatment

Nowadays depression is considered as a systemic illness with different biological mechanisms involved in its etiology, including inflammatory response, hypothalamic-pituitary-adrenal (HPA) axis dysregulation and neurotransmitter and neurotrophic systems imbalance. Novel "omics" approaches, such as metabolomics and glycomics provide information about altered metabolic pathways and metabolites, as well as disturbances in glycosylation processes affected by or causing the development of depression. The clinical diagnosis of depression continues to be established based on the presence of the specific symptoms, but due to its heterogeneous underlying biological background, that differs according to the disease stage, there is an unmet need for treatment response biomarkers which would facilitate the process of appropriate treatment selection. This paper provides an overview of the role of major stress response system, the HPA axis, and its dysregulation in depression, possible involvement of neurotrophins, especially brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor and insulin-like growth factor-1, in the development of depression. Article discusses how activated inflammation processes and increased cytokine levels, as well as disturbed neurotransmitter systems can contribute to different stages of depression and could specific metabolomic and glycomic species be considered as potential biomarkers of depression. The second part of the paper includes the most recent findings about available medical treatment of depression. The described biological factors impose an optimistic conclusion that they could represent easy obtainable biomarkers potentially predicting more personalized treatment and diagnostic options.

Associations Between the Kynurenine Pathway, Proinflammatory Cytokines, and Brain-Derived Neurotrophic Factor in Hospitalized Patients With Chronic Schizophrenia: A Preliminary Study

Purpose: The kynurenine (Kyn) pathway may play a role in the pathophysiology of schizophrenia. This pathway shows crosstalk with proinflammatory cytokines, including interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α), and/or brain-derived neurotrophic factor (BDNF). Moreover, Kyn metabolites affect neurotransmission and cause neurotoxicity. To date, the influence of the Kyn pathway on proinflammatory cytokines and BDNF remains to be fully elucidated. The aim of this study was to investigate the relationships of the Kyn pathway with proinflammatory cytokines, BDNF, and psychiatric symptoms in patients with schizophrenia. Methods: Thirty patients with schizophrenia and ten healthy control participants were recruited for this study. All patients were diagnosed with schizophrenia using the Diagnostic and Statistical Manual for Mental Disorders, Fifth Edition (DSM-5). The healthy controls were those who did not fulfill any of the diagnostic criteria in the DSM-5. The serum levels of Kyn and its metabolites, proinflammatory cytokines, and BDNF were measured in patients with schizophrenia and healthy controls. Patients with schizophrenia were also assessed for psychiatric symptoms using the Positive and Negative Syndrome Scale (PANSS). Results: Patients with schizophrenia and healthy controls showed no significant differences in the levels of Kyn and its metabolites, proinflammatory cytokines, and BDNF. A significant positive correlation was found between the serum levels of TNF-α and Kyn (r = 0.53, p = 0.0026) and the Kyn/tryptophan (Trp) value (r = 0.67, p = 0.000046) in the schizophrenia group, but not in the healthy control group. Conclusion: TNF-α affects the Kyn pathway in patients with chronic schizophrenia, but not in the healthy individuals, although serum TNF-α levels showed no difference between the two groups. Associations between the Kyn pathway and the levels of proinflammatory cytokines and BDNF or psychotic symptoms might be complicated in hospitalized patients with chronic schizophrenia.

A Load to Find Clinically Useful Biomarkers for Depression

Depression is heterogeneous and complex disease with diverse symptoms. Its neurobiological underpinning is still not completely understood. For now, there are still no validated, easy obtainable, clinically useful noninvasive biomarker(s) or biomarker panel that will be able to confirm a diagnosis of depression, its subtypes and improve diagnostic procedures. Future multimodal preclinical and clinical research that involves (epi)genetic, molecular, cellular, imaging, and other studies is necessary to advance our understanding of the role of monoamines, GABA, HPA axis, neurotrophins, metabolome, and glycome in the pathogenesis of depression and their potential as diagnostic, prognostic, and treatment response biomarkers. These studies should be focused to include the first-episode depression and antidepressant drug-naïve patients with large sample sizes to reduce variability in different biological and clinical parameters. At present, metabolomics study revealed with high precision that a neurometabolite panel consisting of plasma metabolite biomarkers (GABA, dopamine, tyramine, kynurenine) might represent clinically useful biomarkers of MDD.

Antidepressants Promote and Prevent Cancers

The review states that antidepressants (ADs) increase brain-derived neurotrophic factor (BDNF) transmission concomitantly in the brain and the blood: ADs increasing BDNF synthesis in specific areas of the central nervous system (CNS) could presumably affect megakaryocyte's production of platelets. ADs increase BDNF levels in the CNS and improve mood. In the blood, ADs increase BDNF release from platelets. The hypothesis presented here is that the release of BDNF from platelets contributes to the ADs effects on neurogenesis and on tumor growth in the cancer disease. Oncological studies indicate that chemicals ADs exert an aggravating effect on the cancer disease, possibly by promoting proplatelets formation and enhancing BDNF release from platelets in the tumor.

Effects of Vortioxetine on depression model rats and expression of BDNF and Trk B in hippocampus

Effects of Vortioxetine on the expression of brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (Trk B) in hippocampus of depressive rats were investigated. Forty-five SD rats were randomly divided into three groups: model control, Vortioxetine and normal control group, with 15 rats in each group. The changes of body mass were recorded within 5 weeks, and the open field test, sugar water preference test and Morris water maze test were performed to evaluate the behavior and mental status of the rats. The expression of BDNF and Trk B in rat hippocampus was detected by enzyme-linked immuno sorbent assay. Compared with the model control group, the body mass, horizontal and vertical movement, sugar and water preference rate of the vortioxetine group in the 5th week were significantly higher than those of the model control group (P<0.05), and significantly lower than those of the normal control group (P<0.05). The escape latency of the Vortioxetine group within 4 days was significantly lower than that of model control group (P<0.05), but higher than that of normal control group (P<0.05). The target quadrant residence time of the Vortioxetine group was significantly lower than that of the model control group (P<0.05), but higher than that of the normal control group (P<0.05). Expression of BDNF and Trk B in the Vortioxetine group was significantly higher than that in the model control group (P<0.05), but lower than that of the normal control group (P<0.05). Collectively, Vortioxetine can effectively alleviate the symptoms of autonomous and exploratory behavior, and reduce the decrease of learning and memory in depressive rats. Vortioxetine can increase the expression of BDNF and Trk B in depressive rats and alleviate their depressive behavior.

Platelet Serotonin Concentration Is Associated with Illness Duration in Schizophrenia and Chronological Age in Depression

OBJECTIVE

Impaired serotonergic neurotransmission has been implicated in the pathogenesis of depression and schizophrenia. Blood platelets have been used for years as a peripheral model of neuronal serotonin dynamics. The objective was to investigate platelet count and serotonin concentration in patients with depression and schizophrenia, in an attempt to ascertain their clinical usefulness.

METHODS

953 participants were included in the study, 329 patients with depression, 339 patients with schizophrenia and 285 healthy controls. ELISA was used to assess platelet serotonin concentrations.

RESULTS

There were no statistically significant differences among groups regarding age, total platelet count and serotonin concentration. Linear regression analyses revealed inverse correlations between platelet serotonin concentration and age of patients with depression and healthy individuals, as well as between platelet serotonin concentration and illness duration in patients with schizophrenia. In other words, longer illness duration in patients with schizophrenia, and higher age in patients with depression and healthy individuals was associated with lower platelet serotonin concentrations.

CONCLUSION

Platelet count and serotonin concentration did not prove to be of diagnostic value in differentiating patients and healthy individuals. However, illness duration in patients with schizophrenia may be associated with reduced concentrations of platelet serotonin.

The Diagnostic Value of the Combination of Serum Brain-Derived Neurotrophic Factor and Insulin-Like Growth Factor-1 for Major Depressive Disorder Diagnosis and Treatment Efficacy

BACKGROUND

Last decades of psychiatric investigations have been marked by a search for biological markers that can clarify etiology and pathogenesis, confirm the diagnosis, screen individuals at risk, define the severity, and predict the course of mental disorders. In our study, we aimed to evaluate if BDNF and IGF-1 serum concentrations separately and in combination might be used as biomarkers for major depressive disorder (MDD) diagnosis and treatment efficacy and to evaluate the relationships among those proteins and clinical parameters of MDD.

METHODS

Forty-one MDD patients (according to DSM-5) and 32 healthy controls (HC) were included in this study. BDNF and IGF-1 serum concentrations, psychopathological (MADRS, CGI) and neuropsychological parameters (PDQ-5, RAVLT, TMT-B, DSST), functioning according to Sheehan Disability Scale were analyzed in all subjects at admission and 30 MDD patients after 8 weeks of vortioxetine treatment. Correlational analyses were performed to explore relationships between BDNF and IGF-1 and clinical characteristics. AUC-ROCs were calculated to determine if the value of serum BDNF and IGF-1 levels could serve for MDD diagnosis.

RESULTS

MDD patients had significantly lower serum BDNF (727.6 ± 87.9 pg/ml vs. 853.0 ± 93.9 pg/ml) and higher serum IGF-1 levels (289.15 ± 125.3 ng/ml vs. 170.2 ± 58.2 ng/ml) compared to HC. Significant correlations were obtained between BDNF levels and MDD status, depressive episode (DE) severity, precipitating factors, executive functions disruption (TMT-B, RAVLT immediate recall scores) and all subdomains of functioning. As for IGF-1, correlations were found between IGF-1 level and MDD status, DE severity, number and duration of DE, parameters of subjective and objective cognitive functioning (PDQ-5, RAVLT, TMT-B, DSST scores), and all subdomains of functioning. The associations between IGF-1 concentrations and cognitive tests' performance were stronger than those of BDNF. Separately both BDNF and IGF-1 demonstrated good discriminating ability for MDD diagnosis with AUC of 0.840 and 0.824, respectively. However, the combination of those neurotrophins had excellent diagnostic power to discriminate MDD patients from HC, providing an AUC of 0.916. Vortioxetine treatment significantly increased BDNF and attenuated IGF-1 serum concentrations, improved all psychopathological and neuropsychological parameters and functioning.

CONCLUSIONS

The combination of IGF-1 and BDNF might be considered as a diagnostic combination for MDD.

Changes in neuroplasticity following early-life social adversities: the possible role of brain-derived neurotrophic factor

Social adversities experienced in childhood can have a profound impact on the developing brain, leading to the emergence of psychopathologies in adulthood. Despite the burden this places on both the individual and society, the neurobiological aspects mediating this transition remain unclear. Recent advances in preclinical and clinical research have begun examining neuroplasticity-the nervous system's ability to form adaptive changes in response to new experience-in the context of early-life vulnerability to social adversities and plasticity-related alterations following such traumatic events. A key mediator of plasticity-related molecular processes is the brain-derived neurotrophic factor (BDNF), which has also been implicated in various psychiatric disorders related to childhood social adversities. Preclinical and clinical data suggest early-life social adversities (ELSA) might be associated with accelerated maturation of social network circuitry, a possible ontogenic adaptation to the adverse environment. Neural plasticity decreases by adulthood, lessening the efficacy of treatment in ELSA-related psychiatric disorders. However, literature data suggest that by increasing BDNF/TrkB signalling through antidepressant treatment a juvenile-like plasticity state can be induced, which allows for reorganization of the social circuitry when guided by psychotherapy and surrounded by a safe and positive environment.

Low molecular mass chondroitin sulfate suppresses chronic unpredictable mild stress-induced depression-like behavior in mice

The present study is aimed at testing the antidepressant--like effects and probable mechanisms of action of low molecular mass chondroitin sulfate (LMMCS) on depression induced by chronic unpredictable mild stress (CUMS) in mice. Four weeks of CUMS exposure resulted in depressive-like behavior, expressed by a significant decrease in the locomotor activity and sucrose consumption and increased immobility time in the forced swim test. Further, there was a significant reduction of 5-HT level in the hippocampus region of depressed mice. Treatment of mice for four weeks with LMMCS ameliorated significantly both the behavioral and biochemical changes induced by CUMS. These novel results suggest that LMMCS produces an antidepressant-like effect in mice subjected to CUMS, which might be related, at least in part, to the increase of 5-HT concentration in the hippocampus.

Effects of vortioxetine and fluoxetine on the level of Brain Derived Neurotrophic Factors (BDNF) in the hippocampus of chronic unpredictable mild stress-induced depressive rats

Vortioxetine is a novel antidepressant capable of improving depressive and cognitive symptoms associated with major depressive disorder (MDD). This study established whether treatment with vortioxetine, fluoxetine or vehicle alters the modulation of brain-derived neurotrophic factor (BDNF) under the 21-day chronic unpredictable mild stress (CUMS) condition in 54 Sprague-Dawley rats. Vortioxetine mitigated the reduction in rearing behavior by CUMS in the OFT on day 7 and 21, as well as sucrose preference on day 21. Histological examination by H&E staining showed that most hippocampal neurons in the CUMS + FLU and CUMS + VOR groups were intact, although some of them demonstrated karyopyknosis. The mean optical density value of hippocampal BDNF was significantly higher in the CUMS + VOR group than the CUMS and CUMS + FLU groups. There was a trend towards a higher number of hippocampal BDNF-positive cells in the CUMS + VOR group, although it did not reach statistical significance. In conclusion, vortioxetine, but not fluoxetine, increased hippocampal BDNF levels in rats subject to CUMS.

Monoaminergic and Histaminergic Strategies and Treatments in Brain Diseases

The monoaminergic systems are the target of several drugs for the treatment of mood, motor and cognitive disorders as well as neurological conditions. In most cases, advances have occurred through serendipity, except for Parkinson's disease where the pathophysiology led almost immediately to the introduction of dopamine restoring agents. Extensive neuropharmacological studies first showed that the primary target of antipsychotics, antidepressants, and anxiolytic drugs were specific components of the monoaminergic systems. Later, some dramatic side effects associated with older medicines were shown to disappear with new chemical compounds targeting the origin of the therapeutic benefit more specifically. The increased knowledge regarding the function and interaction of the monoaminergic systems in the brain resulting from in vivo neurochemical and neurophysiological studies indicated new monoaminergic targets that could achieve the efficacy of the older medicines with fewer side-effects. Yet, this accumulated knowledge regarding monoamines did not produce valuable strategies for diseases where no monoaminergic drug has been shown to be effective. Here, we emphasize the new therapeutic and monoaminergic-based strategies for the treatment of psychiatric diseases. We will consider three main groups of diseases, based on the evidence of monoamines involvement (schizophrenia, depression, obesity), the identification of monoamines in the diseases processes (Parkinson's disease, addiction) and the prospect of the involvement of monoaminergic mechanisms (epilepsy, Alzheimer's disease, stroke). In most cases, the clinically available monoaminergic drugs induce widespread modifications of amine tone or excitability through neurobiological networks and exemplify the overlap between therapeutic approaches to psychiatric and neurological conditions. More recent developments that have resulted in improved drug specificity and responses will be discussed in this review.

No association between the serotonin transporter linked polymorphic region polymorphism and severity of posttraumatic stress disorder symptoms in combat veterans with or without comorbid depression

Since both posttraumatic stress disorder (PTSD) and depression are associated with disturbances in the serotoninergic system, the aim of the study was to determine the association between severity of PTSD symptoms, serotonin transporter polymorphism (5-HTTLPR) and platelet serotonin (5-HT) concentration, in male combat veterans with PTSD (n = 325), who were subdivided according to presence of comorbid depression. The methodological approach included the psychiatric diagnostic interviews and rating scales (SCID for DSM-IV, HDRS, CAPS), polymerase chain reaction for 5-HTTLPR genotyping and spectrophotofluorometric method for measuring the platelet 5-HT concentration. PTSD veterans without depression had more severe PTSD symptoms, and less severe depressive symptoms, than PTSD veterans with depression. 5-HTTLPR genotype frequencies did not differ between veterans with mild, moderate and severe PTSD symptoms, and between depressed and non-depressed PTSD veterans. No significant association was found between the severity of PTSD symptoms and 5-HTTLPR genotype. Platelet 5-HT concentration was similar in PTSD veterans, with or without comorbid depression, and between two groups subdivided according to the severity of PTSD symptoms or 5-HTTLPR genotype. The study confirmed, on ethnically homogenous groups of veterans with matched combat experience, a lack of association between the PTSD symptoms severity and 5-HTTLPR or platelet 5-HT concentration.