A meta-analysis of peripheral blood nerve growth factor levels in patients with schizophrenia

MicroRNAs as potential biomarkers for diagnosis of schizophrenia and influence of antipsychotic treatment

ABSTRACT

Characterized by positive symptoms (such as changes in behavior or thoughts, including delusions and hallucinations), negative symptoms (such as apathy, anhedonia, and social withdrawal), and cognitive impairments, schizophrenia is a chronic, severe, and disabling mental disorder with late adolescence or early adulthood onset. Antipsychotics are the most commonly used drugs to treat schizophrenia, but those currently in use do not fully reverse all three types of symptoms characterizing this condition. Schizophrenia is frequently misdiagnosed, resulting in a delay of or inappropriate treatment. Abnormal expression of microRNAs is connected to brain development and disease and could provide novel biomarkers for the diagnosis and prognosis of schizophrenia. The recent studies reviewed included microRNA profiling in blood- and urine-based materials and nervous tissue materials. From the studies that had validated the preliminary findings, potential candidate biomarkers for schizophrenia in adults could be miR-22-3p, -30e-5p, -92a-3p, -148b-5p, -181a-3p, -181a-5p, -181b-5p, -199b-5p, -137 in whole blood, and miR-130b, -193a-3p in blood plasma. Antipsychotic treatment of schizophrenia patients was found to modulate the expression of certain microRNAs including miR-130b, -193a-3p, -132, -195, -30e, -432 in blood plasma. Further studies are warranted with adolescents and young adults having schizophrenia and consideration should be given to using animal models of the disorder to investigate the effect of suppressing or overexpressing specific microRNAs.

Plasmodium knowlesi infection is associated with elevated circulating biomarkers of brain injury and endothelial activation

Introduction

Malaria remains a major public health concern with substantial morbidity and mortality worldwide. In Malaysia, the emergence of Plasmodium knowlesi has led to a surge in zoonotic malaria cases and deaths in recent years. Signs of cerebral involvement have been observed in a non-comatose, fatal case of severe knowlesi infection, but the potential impact of this malaria species on the brain remains underexplored. To address this gap, we investigated circulating levels of brain injury, inflammation, and vascular biomarkers in a cohort of knowlesi-infected patients and controls.

Methods

Archived plasma samples from 19 patients with confirmed symptomatic knowlesi infection and 19 healthy, age-matched controls from Peninsular Malaysia were analysed. A total of 52 plasma biomarkers of brain injury, inflammation, and vascular activation were measured using Luminex and SIMOA assays. Wilcoxon tests were used to examine group differences, and biomarker profiles were explored through hierarchical clustering heatmap analysis.

Results

Bonferroni-corrected analyses revealed significantly elevated brain injury biomarker levels in knowlesi-infected patients, including S100B (p<0.0001), Tau (p=0.0007), UCH-L1 (p<0.0001), αSyn (p<0.0001), Park7 (p=0.0006), NRGN (p=0.0022), and TDP-43 (p=0.005). Compared to controls, levels were lower in the infected group for BDNF (p<0.0001), CaBD (p<0.0001), CNTN1 (p<0.0001), NCAM-1 (p<0.0001), GFAP (p=0.0013), and KLK6 (p=0.0126). Hierarchical clustering revealed distinct group profiles for circulating levels of brain injury and vascular activation biomarkers.

Conclusions

Our findings highlight for the first time the impact of Plasmodium knowlesi infection on the brain, with distinct alterations in cerebral injury and endothelial activation biomarker profiles compared to healthy controls. Further studies are warranted to investigate the pathophysiology and clinical significance of these altered surrogate markers, through both neuroimaging and long-term neurocognitive assessments.

Plasma levels of neurotrophin 4/5, NGF and pro-BDNF influence transition to mental disorders in a sample of individuals at ultra-high risk for psychosis

BACKGROUND

Neurotrophins (NTs) and their precursors (pro-NTs) are polypeptides with important roles in neuronal development, differentiation, growth, survival and plasticity, as well as apoptosis and neuronal death. Imbalance in NT levels were observed in schizophrenia spectrum disorders, but evidence in ultra-high risk for psychosis (UHR) samples is scarce.

METHODS

A naturalistic sample of 87 non-help-seeking UHR subjects and 55 healthy controls was drawn from the general population. Blood samples were collected and NT-3, NT-4/5, BDNF, pro-BDNF, NGF, pro-NGF were analyzed through enzyme linked immunosorbent assay (ELISA). Information on cannabis and tobacco use was also collected. Logistic regression models and path analysis were used to control for confounders (tobacco, age, cannabis use).

RESULTS

NT-4/5 was significantly decreased, and pro-BDNF was significantly increased in UHR individuals compared to controls. Cannabis use and higher NGF levels were significantly related to transition to psychiatric disorders among UHR subjects. Increased pro-BDNF and decreased NT-4/5 influenced transition by the mediation of perceptual abnormalities.

CONCLUSIONS

Our study shows for the first time that NTs are altered in UHR compared to healthy control individuals, and that they can be a predictor of transition to psychiatric illnesses in this population. Future studies should employ larger naturalistic samples to confirm the findings.

Vascular-related biomarkers in psychosis: a systematic review and meta-analysis

Background

While the molecular underpinnings of vascular dysfunction in psychosis are under active investigation, their implications remain unclear due to inconsistent and sometimes sparse observations. We conducted a comprehensive meta-analysis to critically assess the alterations of vascular-related molecules in the cerebrospinal fluid (CSF) and blood of patients with psychotic disorders compared with healthy individuals.

Methods

Databases were searched from inception to February 23, 2023. Meta-analyses were performed using a random-effects model. Meta-regression and subgroup analyses were conducted to assess the effects of clinical correlates.

Results

We identified 93 eligible studies with 30 biomarkers investigated in the CSF and/or blood. Among the biomarkers examined, psychotic disorders were associated with elevated CSF-to-serum albumin ratio (standardized mean difference [SMD], 0.69; 95% confidence interval [CI], 0.35-1.02); blood S100B (SMD, 0.88; 95% CI, 0.59-1.17), matrix metalloproteinase-9 (MMP-9; SMD, 0.66; 95% CI, 0.46-0.86), and zonulin (SMD, 1.17; 95% CI, 0.04-2.30). The blood levels of S100B, MMP-9, nerve growth factor (NGF), vascular endothelial growth factor (VEGF), intercellular adhesion molecule 1 (ICAM-1), and vascular adhesion molecule 1 (VCAM-1) were altered in patient subgroups differing in demographic and clinical characteristics. Blood S100B level was positively correlated with age and duration of illness. Substantial between-study heterogeneity was observed in most molecules.

Conclusion

The alterations in certain vascular-related fluid markers in psychotic disorders suggest disturbances in normal vascular structures and functions. However, not all molecules examined displayed clear evidence of changes. While potential impacts of clinical factors, including the administered treatment, were identified, the exploration remained limited. Further studies are needed to investigate the diverse patterns of expression, and understand how these abnormalities reflect the pathophysiology of psychosis and the impact of clinical factors.

MicroRNA schizophrenia: Etiology, biomarkers and therapeutic targets

The three sets of symptoms associated with schizophrenia-positive, negative, and cognitive-are burdensome and have serious effects on public health, which affects up to 1% of the population. It is now commonly believed that in addition to the traditional dopaminergic mesolimbic pathway, the etiology of schizophrenia also includes neuronal networks, such as glutamate, GABA, serotonin, BDNF, oxidative stress, inflammation and the immune system. Small noncoding RNA molecules called microRNAs (miRNAs) have come to light as possible participants in the pathophysiology of schizophrenia in recent years by having an impact on these systems. These small RNAs regulate the stability and translation of hundreds of target transcripts, which has an impact on the entire gene network. There may be improved approaches to treat and diagnose schizophrenia if it is understood how these changes in miRNAs alter the critical related signaling pathways that drive the development and progression of the illness.

Prospects for Neurotrophic Factor-Based Early Intervention in Schizophrenia: Lessons Learned from the Effects of Antipsychotic Drugs on Cognition, Neurogenesis, and Neurotrophic Factors

Although reducing psychotic symptoms in schizophrenia has been a major focus of therapeutic interventions for decades, improving cognition is considered a better predictor of functional outcomes. However, the most commonly prescribed antipsychotic drugs (APDs) show only marginal beneficial effects on cognition in patients with schizophrenia. The neural mechanisms underlying cognitive disturbances in schizophrenia remain unknown that making drug development efforts very challenging. Since neurotrophic factors are the primary architects of neurogenesis, synaptic plasticity, learning, and memory, the findings from preclinical and clinical studies that assess changes in neurogenesis and neurotrophic factors and their relationship to cognitive performance in schizophrenia, and how these mechanisms might be impacted by APD treatment, may provide valuable clues in developing therapies to combat cognitive deficit in schizophrenia. Numerous evidence produced over the years suggests a deficit in a wide spectrum of neurotrophic factors in schizophrenia. Since schizophrenia is considered a neurodevelopmental disorder, early intervention with neurotrophic factors may be more effective in ameliorating the cognitive deficits and psychopathological symptoms associated with this pathology. In this context, results from initial clinical trials with neurotrophic factors and their future potential to improve cognition and psychosocial functioning in schizophrenia are discussed.

Cognitive impairment in psychiatric diseases: Biomarkers of diagnosis, treatment, and prevention

Psychiatric diseases, such as schizophrenia, bipolar disorder, autism spectrum disorder, and major depressive disorder, place a huge health burden on society. Cognitive impairment is one of the core characteristics of psychiatric disorders and a vital determinant of social function and disease recurrence in patients. This review thus aims to explore the underlying molecular mechanisms of cognitive impairment in major psychiatric disorders and identify valuable biomarkers for diagnosis, treatment and prevention of patients.

The emerging role of furin in neurodegenerative and neuropsychiatric diseases

Furin is an important mammalian proprotein convertase that catalyzes the proteolytic maturation of a variety of prohormones and proproteins in the secretory pathway. In the brain, the substrates of furin include the proproteins of growth factors, receptors and enzymes. Emerging evidence, such as reduced FURIN mRNA expression in the brains of Alzheimer's disease patients or schizophrenia patients, has implicated a crucial role of furin in the pathophysiology of neurodegenerative and neuropsychiatric diseases. Currently, compared to cancer and infectious diseases, the aberrant expression of furin and its pharmaceutical potentials in neurological diseases remain poorly understood. In this article, we provide an overview on the physiological roles of furin and its substrates in the brain, summarize the deregulation of furin expression and its effects in neurodegenerative and neuropsychiatric disorders, and discuss the implications and current approaches that target furin for therapeutic interventions. This review may expedite future studies to clarify the molecular mechanisms of furin deregulation and involvement in the pathogenesis of neurodegenerative and neuropsychiatric diseases, and to develop new diagnosis and treatment strategies for these diseases.

The role of BDNF and NGF plasma levels in first-episode schizophrenia: A longitudinal study

Neurotrophins have been proposed to be involved in biological mechanisms which might underlie different clinical outcomes in schizophrenia. The aims of the present study were to examine the BDNF/NGF plasma levels in a cohort of first-episode schizophrenia (FES) patients in remission as potential biological predictors of relapse; to study the associations between these neurotrophins and the symptomatology severity through different stages after a FES in two independent cohorts. 2EPs-Cohort: 69 first-episode in clinical remission were included. BDNF/NGF plasma levels and symptom severity were measured at enrollment and at 3-year or at the time of the second episode/relapse. FLAMM-PEPs-Cohort: 65 first-episodes were also included. BDNF/NGF and symptom severity were obtained at enrollment and 2-year follow-up. Symptomatology was assessed with the Marder-PANSS-Factor scores. Plasma neurotrophins did not differ significantly over time and neither BDNF/NGF were predictors of relapse. Besides, in remission stages, baseline BDNF levels showed significant correlations with both positive and negative symptoms (p<0.05); NGF, with negative symptomatology (p<0.01). Similarly, in the FLAMM-PEPs-Cohort, baseline BDNF/NGF levels showed significant correlations with negative symptoms (and not positive symptomatology) at follow-up (p<0.05). In both cohorts, lower levels correlated with higher symptom severity. Findings did not support a role for BDNF/NGF plasma levels as biomarkers of relapse in FES patients. Nevertheless, baseline BDNF/NGF may lead to be considered potentially useful biomarkers of long-term severity in schizophrenia and of the underlying illness traits, specially of negative symptomatology severity. More longitudinal studies in FES samples and adding a control group are warranted to replicate these findings.

Consensus on potential biomarkers developed for use in clinical tests for schizophrenia

Background

Schizophrenia is a serious mental illness affecting approximately 20 million individuals globally. Both genetic and environmental factors contribute to the illness. If left undiagnosed and untreated, schizophrenia results in impaired social function, repeated hospital admissions, reduced quality of life and decreased life expectancy. Clinical diagnosis largely relies on subjective evidence, including self-reported experiences, and reported behavioural abnormalities followed by psychiatric evaluation. In addition, psychoses may occur along with other conditions, and the symptoms are often episodic and transient, posing a significant challenge to the precision of diagnosis. Therefore, objective, specific tests using biomarkers are urgently needed for differential diagnosis of schizophrenia in clinical practice.

Aims

We aimed to provide evidence-based and consensus-based recommendations, with a summary of laboratory measurements that could potentially be used as biomarkers for schizophrenia, and to discuss directions for future research.

Methods

We searched publications within the last 10 years with the following keywords: ‘schizophrenia’, ‘gene’, ‘inflammation’, ‘neurotransmitter’, ‘protein marker’, ‘gut microbiota’, ‘pharmacogenomics’ and ‘biomarker’. A draft of the consensus was discussed and agreed on by all authors at a round table session.

Results

We summarised the characteristics of candidate diagnostic markers for schizophrenia, including genetic, inflammatory, neurotransmitter, peripheral protein, pharmacogenomic and gut microbiota markers. We also proposed a novel laboratory process for diagnosing schizophrenia in clinical practice based on the evidence summarised in this paper.

Conclusions

Further efforts are needed to identify schizophrenia-specific genetic and epigenetic markers for precise diagnosis, differential diagnosis and ethnicity-specific markers for the Chinese population. The development of novel laboratory techniques is making it possible to use these biomarkers clinically to diagnose disease.

Fibroblast Growth Factor 9 as a Potential Biomarker for Schizophrenia

Preclinical and clinical studies have suggested that fibroblast growth factor (FGF) system contributed to the onset and development of schizophrenia (SCZ). However, there was no strong clinical evidence to link an individual FGF with SCZ. In this study, we aim to measure blood FGF9 levels in the patients with SCZ with and/or without medication, and test whether FGF9 has a potential to be a biomarker for SCZ. We recruited 130 patients with SCZ and 111 healthy individuals, and the ELISA and qRT-PCR assays were used to measure serum FGF9 levels in the participants. ELISA assay demonstrated that serum FGF9 protein levels were dramatically reduced in first-episode, drug-free patients, but not in chronically medicated patients when compared to healthy control subjects. Further analysis showed that treatment of the first-episode, drug-free SCZ patients with antipsychotics for 8 weeks significantly increased the serum FGF9 levels. In addition, we found that blood FGF9 mRNA levels were significantly lower in first-onset SCZ patients than controls. Under the receiver operating characteristic curve, the optimal cutoff values for FGF9 protein level as an indicator for diagnosis of drug-free SCZ patients was projected to be 166.4 pg/ml, which yielded a sensitivity of 0.955 and specificity of 0.86, and the area under the curve was 0.973 (95% CI, 0.954-0.993). Furthermore, FGF9 had good performance to discriminate between drug-free SCZ patients and chronically medicated patients, the optimal cutoff value for FGF9 concentration was projected to be 165.035 pg/ml with a sensitivity of 0.86 and specificity of 0.919, and the AUC was 0.968 (95% CI, 0.944, 0.991). Taken together, our results for the first time demonstrated the dysregulation of FGF9 in SCZ, and FGF9 has the potential to be served as a biomarker for SCZ.

Altered Peripheral Immune Profiles in First-Episode, Drug-Free Patients With Schizophrenia: Response to Antipsychotic Medications

Previous research has demonstrated aberrations in the levels of inflammatory cytokines in patients with schizophrenia (SCZ), but most of the respective studies have tested a narrow set of inflammatory cytokines. Here, we aimed to analyze broad immune profiles in the peripheral blood of the first-episode drug-free (FEDF) patients with SCZ at baseline and after an 8-week treatment with atypical antipsychotics. Serum samples from 24 FEDF patients with SCZ and 25 healthy control (HC) subjects were tested using Luminex multiplex analysis for 30 cytokines, chemokines, and growth factors. Multiple comparison tests demonstrated that interleukin-2 (IL-2), IL-4, interferon-gamma (IFN-γ), monokine induced by IFN-γ, and granulocyte colony-stimulating factor (G-CSF) levels were significantly increased, whereas those of the epidermal growth factor were significantly decreased in the FEDF patients with SCZ. Moreover, the levels of the 6 dysregulated cytokines as well as those of 12 additional soluble factors in FEDF patients with SCZ were significantly decreased after 8 weeks of antipsychotic treatment. Furthermore, the transcription of G-CSF and IFN-γ was significantly increased in FEDF patients with SCZ when compared with controls, and G-CSF and IFN-γ mRNA levels were highly correlated with their respective protein concentrations. Receiver operating characteristic curves showed that G-CSF and IFN-γ had good performance in differentiating between FEDF patients with SCZ and HC subjects. Taken together, our data revealed that FEDF patients with SCZ were accompanied by a unique pattern of immune profile, and antipsychotic medications seemed to suppress the immune function in these patients, which could be used to develop novel targets for the diagnosis and treatment of SCZ.

Superoxide Dismutase, BDNF, and Cognitive Improvement in Drug-Naive First-Episode Patients With Schizophrenia: A 12-Week Longitudinal Study

OBJECTIVE

Cognitive improvement after antipsychotic agents in patients with schizophrenia (SCZ) appears to involve redox regulation through neurotrophins such as brain derived neurotropic factor (BDNF). This study examined whether cognitive improvement was associated with the increase in superoxide dismutase (SOD) and whether higher levels of BDNF could have a permissive role in allowing SOD to improve cognition.

METHODS

We examined this hypothesis in 183 drug-naïve first-episode SCZ patients taking risperidone monotherapy for 12 weeks. We measured total copper-zinc SOD (CuZn-SOD), manganese SOD (Mn-SOD), and SOD activities and BDNF levels in these patients and compared their levels with 152 healthy controls. We assessed cognitive functioning and clinical symptoms at baseline and 12-week follow-up.

RESULTS

After treatment with risperidone, CuZn-SOD activity was significantly increased, and BDNF levels were slightly increased. Increased CuZn-SOD activity was associated with the cognitive effectiveness of risperidone monotherapy. The BDNF levels and SOD activities were correlated at baseline but not after 12-week treatment. Furthermore, baseline CuZn-SOD activity positively correlated with improvement on the delayed memory subscale of the Repeatable Battery for the Assessment of Neuropsychological Status only in the high BDNF subgroup.

CONCLUSIONS

Our longitudinal study suggests that risperidone can enhance SOD activity and that, in combination with higher baseline BDNF levels acting in a permissive role, can improve cognitive impairments in SCZ. Greater baseline CuZn-SOD activity also may have predictive value for cognitive improvement of delayed memory in SCZ patients receiving risperidone treatment.

Exosome Transplantation From Patients With Schizophrenia Causes Schizophrenia-Relevant Behaviors in Mice: An Integrative Multi-omics Data Analysis

Exosomes are involved in the pathophysiology of neuropsychiatric diseases, but the role of exosomes in schizophrenia (SCZ) is unclear. Here, we demonstrate that transplantation of serum exosomes from SCZ patients into mice caused behavioral abnormalities such as deficits in prepulse inhibition and sociability, hyperactivity, and anxiogenesis. A comparative bioinformatics analysis suggested shared and distinct differentially expressed genes (DEGs) and enriched molecular pathways in the brains of SCZ exosome-recipient mice, methylazoxymethanol acetate-treated rats, and SCZ patients, which correlates evidence of altered prefrontal-hippocampal functional coherence in SCZ. A large proportion of SCZ-relevant DEGs in the exosome-recipient mice were targets of DE exosomal miRNAs in SCZ patients. Furthermore, we identified 20 hub genes for SCZ risk genes, including BDNF and NRG1, which were DE miRNA targets in SCZ. Collectively, our study suggests that SCZ exosome transplantation caused SCZ-relevant behaviors in mice, and epigenetic regulation may contribute to the phenotypes in the SCZ exosome-recipient mice. Our results may provide a potential animal model and novel therapeutic targets for SCZ.

Neurotrophic Factor Levels in Preterm Infants: A Systematic Review and Meta-Analysis

Objectives: Through a systematic review and meta-analysis of the literature we aimed to compare the levels of BDNF, NGF, NT-3, NT-4, and GDNF between human term and preterm infants, and investigate factors implicated in the variability of effect size estimates. Methods: The analysis was performed in three online databases, MEDLINE Complete, PsycINFO, and CINAHL. A random effects model was used to calculate the standardized mean difference (SMD) of neurotrophic factor levels in preterm infants vs. term within a 95% confidence interval (CI). To explore sources of heterogeneity meta-regression models were implemented. Results: Sixteen studies were included in this meta-analysis. A combined sample of 1,379 preterm and 1,286 term newborns were evaluated. We identified significant lower BDNF (SMD = -0.32; 95% CI: -0.59, -0.06; p = 0.014) and NT-3 (SMD = -0.31; 95% CI: -0.52, -0.09; p = 0.004) levels in preterm compared to term infants. No significant difference was observed in NGF and NT-4 levels between groups. Given that only two effect sizes were generated for GDNF levels, no meta-analytical model was performed. Meta-regression models revealed sample type (placental tissue, cerebrospinal fluid, peripheral blood, and umbilical cord blood) as a significant moderator of heterogeneity for BDNF meta-analysis. No significant associations were found for gestational week, birth weight, and clinical comorbidity of newborns with effect sizes. Conclusions: Our findings indicated that lower BDNF and NT-3 levels may be associated with preterm birth. Future studies with larger samples sizes should investigate neurodevelopmental manifestations resulting from neurotrophic factor dysregulation among preterm infants.

Incidence of psychological illness after coronavirus outbreak: a meta-analysis study

Background

The COVID-19 has had an enormous impact worldwide and is still spreading. Globally confirmed infections have surpassed 41.1 million, of which more than 1 million resulted in deaths. Considering the relationship between public health disasters and emotional disorders, it is essential to examine psychological well-being related to this pandemic.

Method

We performed a systematic search on psychological problems from PubMed to 10 October 2020, and conducted a meta-analysis using Comprehensive Meta-Analysis V.3 software.

Results

The results showed a 19.4% and 26.8% pooled incidence for depression and post-traumatic stress disorder (PTSD), respectively, during the SARS and Middle East Respiratory Syndrome (MERS)-related coronavirus outbreaks. However, overall prevalence of depression was somewhat higher at 27.0% during the COVID-19 period. The pooled incidence of PTSD during COVID-19 compared with SARS and MERS outbreaks, was lower, at 16.4%.

Conclusion

The results suggest that there are shared and distinct psychological responses following SARS, MERS and COVID-19, and show pessimistic estimates of a wide range of potentially upcoming psychological problems.

The interaction of ASAH1 and NGF gene involving in neurotrophin signaling pathway contributes to schizophrenia susceptibility and psychopathology

The neurodevelopmental hypothesis of schizophrenia has been widely accepted. In light of our previous microarray data, two neurodevelopment-related genes were focused on inclduing the N-acylsphingosine amidohydrolase 1 gene (ASAH1) and the nerve growth factor gene (NGF). The evidence that ASAH1 and NGF are associated with schizophrenia is far from conclusive. Furthermore, their interactions in schizophrenia have not been investigated. Total 413 patients and 578 controls were included. Eleven single-nucleotide polymorphisms (SNPs) in ASAH1 and NGF were selected. A multifactor dimensionality reduction (MDR) was applied to investigate gene-gene interactions in schizophrenia, and the traditional odds ratio methods was applied to validate it. The effects of ASAH1, NGF and their interaction on the severity of the disease were analyzed by 3 × 3 covariance analysis of (ANCOVA). The biological interaction between ASAH1 and NGF was examined. KEGG was used to identify the related signaling pathways. After correction by Bonferroni, there were no differences in the genotypic, allelic, or haplotypic frequencies of 11 SNPs between patients and controls. However, the interaction of certain SNPs had effect on susceptibility to schizophrenia, including two high-risk and one low-risk genotypic combinations (OR = 1.49 [1.11-2.00]; OR = 1.45 [1.09-1.92], and OR = 0.64 [0.41-0.98]). ASAH1-rs7830490 and its interaction with NGF-rs4332358 were associated with the general psychopathological subscale score (F _adjusted = 3.94, p _adjusted = 0.01; F _adjusted = 2.36, p _adjusted = 0.03). We also found that ASAH1 and NGF interacted with CaMK2B involving in the neurotrophin signaling pathway. Our results suggest that the interaction of ASAH1 and NGF with CaMK2B involved in neurotrophin signaling pathway may contribute to schizophrenia susceptibility and psychopathology.

Peripheral blood neurotrophic factor levels in children with autism spectrum disorder: a meta-analysis

Increasing evidence suggests that abnormal regulation of neurotrophic factors is involved in the etiology and pathogenesis of Autism Spectrum Disorder (ASD). However, clinical data on neurotrophic factor levels in children with ASD were inconsistent. Therefore, we performed a systematic review of peripheral blood neurotrophic factors levels in children with ASD, and quantitatively summarized the clinical data of peripheral blood neurotrophic factors in ASD children and healthy controls. A systematic search of PubMed and Web of Science identified 31 studies with 2627 ASD children and 4418 healthy controls to be included in the meta-analysis. The results of random effect meta-analysis showed that the peripheral blood levels of brain-derived neurotrophic factor (Hedges’ g = 0.302; 95% CI = 0.014 to 0.591; P = 0.040) , nerve growth factor (Hedges’ g = 0.395; 95% CI = 0.104 to 0.686; P = 0.008) and vascular endothelial growth factor (VEGF) (Hedges’ g = 0.097; 95% CI = 0.018 to 0.175; P = 0.016) in children with ASD were significantly higher than that of healthy controls, whereas blood neurotrophin-3 (Hedges’ g =  − 0.795; 95% CI =  − 1.723 to 0.134; P = 0.093) and neurotrophin-4 (Hedges’ g = 0.182; 95% CI =  − 0.285 to 0.650; P = 0.445) levels did not show significant differences between cases and controls. Taken together, these results clarified circulating neurotrophic factor profile in children with ASD, strengthening clinical evidence of neurotrophic factor aberrations in children with ASD.

Vitamin D and Neurotrophin Levels and Their Impact on the Symptoms of Schizophrenia

INTRODUCTION

Vitamin D is involved in brain development and functioning, as well as in regulation of neurotrophic factors. Changes in the expression of those factors are possibly responsible for morphologic abnormalities and symptoms in patients suffering from schizophrenia.

OBJECTIVE

The main goal of this research was to investigate the interrelationship between vitamin D, nerve growth factors (NGF, brain-derived neurotrophic factor [BDNF], and neuregulin-1 [NRG1]), and schizophrenia symptom domains.

METHODS

This research included 97 inpatients diagnosed with schizophrenia. Schizophrenia symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). Blood samples were taken in order to analyze concentrations of vitamin D, BDNF, NRG1, and NGF growth factors. The obtained results were used in a multiple regression analysis.

RESULTS

The vitamin D concentration positively affected the concentration of NRG1 (F = 8.583, p = 0.005) but not the concentration of other investigated growth factors (BDNF and NGF). The clinical characteristics and symptom domains of schizophrenia seemed to be unaffected by the concentrations of vitamin D, BDNF, and NGF, while the NRG1 concentration significantly affected positive symptom domains of schizophrenia (F = 4.927, p = 0.030).

CONCLUSION

The vitamin D concentration positively affected NRG1 levels but not schizophrenia symptomatology as measured by PANSS. The as-sociation between the two could be intermediated via NRG1.

Decreased Peripheral BDNF Levels and Cognitive Impairment in Late-Life Schizophrenia

Objectives: There are relatively few studies on mechanisms of cognitive deficits in late-life schizophrenia (LLS). Brain-derived neurotrophic factor (BDNF), as an important neuroplastic molecule, has been reported to be involved in neurocognitive impairment in schizophrenia. This study aimed to examine whether peripheral BDNF levels were associated with cognitive deficits in LLS, which has not been explored yet. Methods: Forty-eight LLS patients and 45 age-matched elderly controls were recruited. We measured all participants on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) for cognition and serum BDNF levels. Psychopathological symptoms in patients were assessed by the Positive and Negative Syndrome Scale (PANSS). Results: The levels of BDNF in LLS patients were significantly lower than those in healthy controls (8.80 ± 2.30 vs. 12.63 ± 5.08 ng/ml, p < 0.001). The cognitive performance of LLS patients was worse than that of the controls on RBANS total score and scores of immediate memory, attention, language, and delayed memory (all p ≤ 0.005). BDNF was positively associated with attention in LLS patients (r = 0.338, p = 0.019). Conclusion: Our findings suggest that older patients with schizophrenia exhibit lower BDNF levels and more cognitive deficits than older controls, supporting the accelerated aging hypothesis of schizophrenia. Moreover, decreased BDNF is related to attention deficits, indicating that BDNF might be a candidate biomarker of cognitive impairments in LLS patients.

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.

Biomarkers for suicidal behavior: miRNAs and their potential for diagnostics through liquid biopsy - a systematic review

Background: Given that approximately 70% of miRNAs in the body are neuronal, we critically assessed current studies on miRNAs and suicidal behavior. Materials & Methods: To further define the role of miRNAs in suicide, we searched for studies on extracellular vesicles (exosomes) because miRNAs are particularly enriched in exosomes. miRNAs also have important physiological roles, and they can cross the blood-brain barrier and participate in cell-to-cell communication with both nearby and distant cells. Results & Conclusion: This critical assessment suggests that several miRNAs can be closely related to neurophysiology, suicidal behavior, and psychiatric disorders. However, clear overlap is poor due to either different methodologies applied or to molecular differences between suicidal behaviors and studied psychiatric disorders.

Metabolomic Identification of Exosome-Derived Biomarkers for Schizophrenia: A Large Multicenter Study

Exosomes have been suggested as promising targets for the diagnosis and treatment of neurological diseases, including schizophrenia (SCZ), but the potential role of exosome-derived metabolites in these diseases was rarely studied. Using ultra-performance liquid chromatography-tandem mass spectrometry, we performed the first metabolomic study of serum-derived exosomes from patients with SCZ. Our sample comprised 385 patients and 332 healthy controls recruited from 3 clinical centers and 4 independent cohorts. We identified 25 perturbed metabolites in patients that can be used to classify samples from patients and control participants with 95.7% accuracy (95% CI: 92.6%-98.9%) in the training samples (78 patients and 66 controls). These metabolites also showed good to excellent performance in differentiating between patients and controls in the 3 test sets of participants, with accuracies 91.0% (95% CI: 85.7%-96.3%; 107 patients and 62 controls), 82.7% (95% CI: 77.6%-87.9%; 104 patients and 142 controls), and 99.0% (95% CI: 97.7%-100%; 96 patients and 62 controls), respectively. Bioinformatic analysis suggested that these metabolites were enriched in pathways implicated in SCZ, such as glycerophospholipid metabolism. Taken together, our findings support a role for exosomal metabolite dysregulation in the pathophysiology of SCZ and indicate a strong potential for exosome-derived metabolites to inform the diagnosis of SCZ.

Blood Oxidative Stress Marker Aberrations in Patients with Huntington's Disease: A Meta-Analysis Study

Huntington's disease (HD) is a hereditary autosomal dominant neurodegenerative disease. Although studies have shown that blood oxidative stress markers are dysregulated in HD patients, clinical data on the blood oxidative stress markers of HD patients is inconsistent. To better understand the pathogenesis of HD, we performed a systematic review and meta-analysis of blood oxidative stress markers in HD patients and healthy control (HC) subjects. A database search from PubMed and Web of Science identified 12 studies with 375 HD patients and 447 HC subjects in this meta-analysis. A random-effects meta-analysis showed that blood lipid peroxidation products (Hedges' g = 0.883, 95%CI = 0.637 to 1.130, p < 0.001), 8-hydroxyguanosine (Hedges' g = 1.727, 95%CI = 0.489 to 2.965, p = 0.006) levels, and the activity of glutathione peroxidase (Hedges' g = 2.026, 95%CI = 0.570 to 3.482, p = 0.006) were significantly increased in HD patients compared to controls. In contrast, reduced glutathione levels were lower in HD patients than in controls (Hedges' g = −0.611, 95%CI = −1.016 to − 0.207, p = 0.003). However, blood superoxide dismutase, cholesterol, high-density lipoproteins, low-density lipoproteins, and triglycerides did not show significant differences between cases and controls. Taken together, this study clarified the associations between blood oxidative stress markers and HD, supporting the clinical evidence that HD is accompanied by increased oxidative stress.

Blood homocysteine levels in children with autism spectrum disorder: An updated systematic review and meta-analysis

Results of studies on peripheral blood levels of homocysteine (Hcy) in children with autism spectrum disorder (ASD) are inconsistent, and conclusions from two previous meta-analyses on this subject published in 2012 are already outdated. Therefore, we conducted an updated systematic review and meta-analysis to quantitatively summarize the peripheral blood Hcy data in children with ASD compared with healthy controls (HC). We searched PubMed, EMBASE, PsycINFO, PsycARTICLES, Web of Science, and Cochrane Library databases from inception to September 2019 for eligible studies, with no language restriction. Using random-effects model, we computed summary statistics. Thirty-one studies (3304 participants including 1641 cases) were included. The pooled results showed that the peripheral blood Hcy levels were significantly elevated in children with ASD when compared to HC (Hedges's g = 0.56, 95% CI = 0.36 to 0.76, P < 0.001). By sensitivity analyses, we confirmed that our results were quite robust. Additionally, no publication bias was observed in this meta-analysis. In conclusion, our study support the association of increased circulating Hcy levels with ASD in children, and the involvement of Hcy in the occurrence of ASD. However, in view of the significant between-study heterogeneity, the conclusions should be interpreted cautiously and more investigation is required.

Different serum protein factor levels in first-episode drug-naive patients with schizophrenia characterized by positive and negative symptoms

AIM

The clinical features of schizophrenia can be mainly divided into two symptom domains: positive and negative. Patients in each symptom domain respond differently to treatments, and their prognoses vary accordingly. Serum protein factors, such as nerve growth factor (NGF), neurotrophin-3 (NT-3), interleukin-6 (IL-6), interleukin-1 beta (IL-1β), and the calcium-binding protein, S100β, have been reported to be involved in the pathogenesis of schizophrenia. However, their roles in the positive and negative symptom domains have not been determined. In this study, we investigated whether the serum levels of these five protein factors differed among first-episode drug-naive schizophrenia patients in each symptom domain and in healthy controls.

METHODS

Double-antibody sandwich ELISA were used to quantify the amounts of the five protein factors in serum.

RESULTS

Compared with the levels in the controls (n = 60), increased serum levels of IL-6, IL-1β, and S100β and decreased serum levels of NGF and NT-3 were observed in first-episode drug-naive schizophrenia patients. Additionally, the serum levels of IL-6 and IL-1β were significantly higher in schizophrenia patients characterized by negative symptoms (negative group, n = 37) than in those characterized by positive symptoms (positive group, n = 46). Based on multivariate regression analyses, serum levels of IL-1β were positively associated with the Negative Symptom subscore of the Positive and Negative Syndrome Scale in the negative group and in all patients with schizophrenia.

CONCLUSION

The two subtypes of schizophrenia may have different pathological mechanisms. Patients characterized by negative symptoms probably have more serious disturbances in neuroimmunology.

Oxidative Stress Marker Aberrations in Multiple Sclerosis: A Meta-Analysis Study

Oxidative stress has been suggested to play a key role in multiple sclerosis (MS), but clinical data on oxidative stress markers in MS patients were inconsistent. This study sought to quantitatively summarize the data of oxidative stress markers in the blood and cerebrospinal fluid (CSF) of patients with MS in the literature. We conducted a systematic search of PubMed and Web of Science and included studies if they provided data on the concentrations of oxidative stress markers in the peripheral blood and CSF of MS patients and healthy control (HC) subjects. The systematic search resulted in the inclusion of 31 studies with 2,001 MS patients and 2,212 HC subjects for meta-analysis. Random-effects meta-analysis demonstrated that patients with MS had significantly increased concentrations of blood oxidative stress markers compared with HC subjects for malondialdehyde (MDA; Hedges' g, 2.252; 95% CI, 1.080 to 3.424; p < 0.001) and lipid hydroperoxide by tert-butyl hydroperoxide-initiated chemiluminescence (CL-LOOH; Hedges' g, 0.383; 95% CI, 0.065 to 0.702; p = 0.018). In contrast, concentrations of albumin (Hedges' g, −1.036; CI, −1.679 to −0.394; p = 0.002) were significantly decreased in MS patients when compared with those in HC subjects. However, the other analyzed blood oxidative stress markers did not show significant differences between cases and controls. Furthermore, this meta-analysis showed significant association between CSF MDA and MS (Hedges' g, 3.275; 95% CI, 0.859 to 5.691; p = 0.008). Taken together, our results revealed increased blood and CSF MDA and decreased blood albumin levels in patients with MS, strengthening the clinical evidence of increased oxidative stress in MS.

NRG1, PIP4K2A, and HTR2C as Potential Candidate Biomarker Genes for Several Clinical Subphenotypes of Depression and Bipolar Disorder

GSK3B, BDNF, NGF, NRG1, HTR2C, and PIP4K2A play important roles in molecular mechanisms of psychiatric disorders. GSK3B occupies a central position in these molecular mechanisms and is also modulated by psychotropic drugs. BDNF regulates a number of key aspects in neurodevelopment and synaptic plasticity. NGF exerts a trophic action and is implicated in cerebral alterations associated with psychiatric disorders. NRG1 is active in neural development, synaptic plasticity, and neurotransmission. HTR2C is another important psychopharmacological target. PIP4K2A catalyzes the phosphorylation of PI5P to form PIP2, the latter being implicated in various aspects of neuronal signal transduction. In the present study, the six genes were sequenced in a cohort of 19 patients with bipolar affective disorder, 41 patients with recurrent depressive disorder, and 55 patients with depressive episode. The study revealed a number of genetic variants associated with antidepressant treatment response, time to recurrence of episodes, and depression severity. Namely, alleles of rs35641374 and rs10508649 (NRG1 and PIP4K2A) may be prognostic biomarkers of time to recurrence of depressive and manic/mixed episodes among patients with bipolar affective disorder. Alleles of NC_000008.11:g.32614509_32614510del, rs61731109, and rs10508649 (also NRG1 and PIP4K2A) seem to be predictive biomarkers of response to pharmacological antidepressant treatment on the 28th day assessed by the HDRS-17 or CGI-I scale. In particular, the allele G of rs10508649 (PIP4K2A) may increase resistance to antidepressant treatment and be at the same time protective against recurrent manic/mixed episodes. These results support previous data indicating a biological link between resistance to antidepressant treatment and mania. Bioinformatic functional annotation of associated variants revealed possible impact for transcriptional regulation of PIP4K2A. In addition, the allele A of rs2248440 (HTR2C) may be a prognostic biomarker of depression severity. This allele decreases expression of the neighboring immune system gene IL13RA2 in the putamen according to the GTEx portal. The variant rs2248440 is near rs6318 (previously associated with depression and effects of psychotropic drugs) that is an eQTL for the same gene and tissue. Finally, the study points to several protein interactions relevant in the pathogenesis of mood disorders. Functional studies using cellular or animal models are warranted to support these results.

A synergistic effect between family intervention and rTMS improves cognitive and negative symptoms in schizophrenia: A randomized controlled trial

OBJECTIVE

The present study explored an efficient new therapy that combined repetitive transcranial magnetic stimulation (rTMS) and family intervention in addition to risperidone to improve schizophrenia.

METHODS

A randomized controlled trial (January 2016-September 2017) involving 200 patients, of which 188 patients completed the 12-week study, and 50 controls were conducted in the research. The patients were randomly assigned to 12 weeks of treatment with risperidone alone (risperidone group), rTMS and risperidone (rTMS group), family intervention and risperidone (family intervention group), rTMS and risperidone plus family intervention (combined group). MATRICS Consensus Cognitive Battery (MCCB) and the Positive and Negative Symptoms Scale (PANSS) were used to evaluate treatment efficacy. Repeated measures analysis of variance (RMANOVA) were performed to evaluate different treatment efficacy between four groups after 12 weeks of treatment.

RESULTS

(1) There were no significant differences in sex, age, education, cognitive function, or PANSS scores between the four groups at baseline (p's > 0.05). (2) There was a significant decrease in the PANSS scores and an increase in the MCCB scores after 12 weeks of treatment in all groups (time effect p's < 0.001). (3) The improvements in positive symptoms and negative symptoms were more obvious in the combined group than in other groups (p's < 0.05). (4) The combined group showed the superior effect in cognition function after 12 weeks. (5) And, interestingly, a remarkable synergistic effect between rTMS and family intervention therapy was observed.

CONCLUSION

There was a synergistic effect between rTMS and the family intervention as an effective combined therapy in improving schizophrenia. This study is registered with Chictr.org, number ChiCTR1900024422 (http://www.chictr.org.cn/edit.aspx?pid=34285&htm=4).

Blood biomarker levels of methylation capacity in autism spectrum disorder: a systematic review and meta-analysis

OBJECTIVE

To compare the peripheral blood levels of methionine (Met), S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), and the SAM/SAH ratio (the most core and predictive indices of cellular methylation ability) between patients with autism spectrum disorder (ASD) and control subjects.

METHODS

PubMed, Embase, PsycINFO, Web of Science, and Cochrane Library were searched from inception to August 2, 2019, without language restriction. The random-effects model was used to summarize effect sizes.

RESULTS

We retrieved 1,493 records, of which 22 studies met inclusion criteria. Our overall analyses revealed that individuals with ASD had significantly decreased levels of Met (22 studies; Hedges' g = -0.62; 95% confidence interval [CI]: -0.89, -0.35), SAM (8 studies; Hedges' g = -0.60; 95% CI: -0.86, -0.34), and the SAM/SAH ratio (8 studies; Hedges' g = -0.98; 95% CI: -1.30, -0.66) and significantly increased levels of SAH (8 studies; Hedges' g = 0.69; 95% CI: 0.43, 0.94). The findings of the overall analyses were quite stable after being verified by sensitivity analyses and in agreement with the corresponding outcomes of subgroup analyses. Additionally, our results from meta-analytic techniques confirmed that the effect estimates of this meta-analysis did not originate from publication bias.

CONCLUSION

Individuals with ASD have substantially aberrant peripheral blood levels of Met, SAM, SAH, and the SAM/SAH ratio, which supports the association between impaired methylation capacity and ASD. Therefore, further investigations into these indices as potential biomarkers for diagnosis and therapeutic targets of ASD are warranted.

A systematic review and meta-analysis of serum cholesterol and triglyceride levels in patients with Parkinson's disease

Objectives

Numerous studies have reported that lipid metabolic abnormalities may play an important role in the development of Parkinson’s disease (PD), with mixed results. This meta-analysis aims to systematically assess the relationship between serum cholesterol or triglyceride and the PD risk and to further determine the role of dyslipidemia in potential predictive value.

Methods

This research systematically consulted and screened observational studies to evaluate the association of serum lipids with the risk of PD as of April 01, 2020 based on the inclusion and exclusion criteria. Two researchers screened and extracted the data independently. Then this article summarized the characteristics of all clinical studies and collected the corresponding data to perform pooled and sensitivity analyses. The meta-analysis was performed by using the RevMan 5.3 software after data extraction, quality assessment and analysis of publication bias.

Results

Twenty-one related studies (13 case-control and 8 cohort studies) were selected with a total of 980,180 subjects, including 11,188 PD patients. Meta-analysis showed that higher levels of serum triglyceride (S-TG) [standard mean different (SMD) = − 0.26 (95% confidence interval (CI): − 0.39 to − 0.13, p<0.00001), relative risk (RR) = 0.67 (95% CI: 0.60 to 0.75, p<0.00001)] could be considered as protective factors for the pathogenesis of PD. However, there was no significant association between serum high density lipoprotein cholesterol (S-HDL) and the risk of PD. Meanwhile, serum low density lipoprotein cholesterol (S-LDL) [SMD = -0.26 (95% CI: − 0.43 to − 0.07, p = 0.006), RR = 0.76 (95% CI: 0.59 to 0.97, p = 0.03)] and serum total cholesterol (S-TC) levels [SMD = -0.21 (95% CI: − 0.33 to − 0.10, p = 0.0002), RR = 0.86 (95% CI: 0.77 to 0.97, p = 0.01)] were negatively associated with PD risk.

Conclusions

This systematic review suggests that elevated serum levels of TG, LDL and TC may be protective factors for the pathogenesis of PD. Further longitudinal and well-designed prospective studies with a large sample size are needed to confirm the findings in this meta-analysis.

Evidence-based umbrella review of 162 peripheral biomarkers for major mental disorders

The literature on non-genetic peripheral biomarkers for major mental disorders is broad, with conflicting results. An umbrella review of meta-analyses of non-genetic peripheral biomarkers for Alzheimer's disease, autism spectrum disorder, bipolar disorder (BD), major depressive disorder, and schizophrenia, including first-episode psychosis. We included meta-analyses that compared alterations in peripheral biomarkers between participants with mental disorders to controls (i.e., between-group meta-analyses) and that assessed biomarkers after treatment (i.e., within-group meta-analyses). Evidence for association was hierarchically graded using a priori defined criteria against several biases. The Assessment of Multiple Systematic Reviews (AMSTAR) instrument was used to investigate study quality. 1161 references were screened. 110 met inclusion criteria, relating to 359 meta-analytic estimates and 733,316 measurements, on 162 different biomarkers. Only two estimates met a priori defined criteria for convincing evidence (elevated awakening cortisol levels in euthymic BD participants relative to controls and decreased pyridoxal levels in participants with schizophrenia relative to controls). Of 42 estimates which met criteria for highly suggestive evidence only five biomarker aberrations occurred in more than one disorder. Only 15 meta-analyses had a power >0.8 to detect a small effect size, and most (81.9%) meta-analyses had high heterogeneity. Although some associations met criteria for either convincing or highly suggestive evidence, overall the vast literature of peripheral biomarkers for major mental disorders is affected by bias and is underpowered. No convincing evidence supported the existence of a trans-diagnostic biomarker. Adequately powered and methodologically sound future large collaborative studies are warranted.

Vagus nerve stimulation and Neurotrophins: a biological psychiatric perspective

Since 2004, vagus nerve stimulation (VNS) has been used in treatment-resistant or treatment-intolerant depressive episodes. Today, VNS is suggested as possible therapy for a larger spectrum of psychiatric disorders, including schizophrenia, obsessive compulsive disorders, and panic disorders. Despite a large body of literature supports the application of VNS in patients' treatment, the exact mechanism of action of VNS remains not fully understood. In the present study, the major knowledges on the brain areas and neuronal pathways regulating neuroimmune and autonomic response subserving VNS effects are reviewed. Furthermore, the involvement of the neurotrophins (NTs) Nerve Growth Factor (NGF) and Brain Derived Neurotrophic Factor (BDNF) in vagus nerve (VN) physiology and stimulation is revised. The data on brain NGF/BDNF synthesis and in turn on the activity-dependent plasticity, connectivity rearrangement and neurogenesis, are presented and discussed as potential biomarkers for optimizing stimulatory parameters for VNS. A vagus nerve-neurotrophin interaction model in the brain is finally proposed as a working hypothesis for future studies addressed to understand pathophysiology of psychiatric disturbance.

A Network Analysis of Epigenetic and Transcriptional Regulation in a Neurodevelopmental Rat Model of Schizophrenia With Implications for Translational Research

Prenatal administration of mitotoxin methylazoxymethanol acetate (MAM) in rats produces behavioral, pharmacological, and anatomical abnormalities once offspring reach adulthood, thus establishing a widely used neurodevelopmental model of schizophrenia. However, the molecular aspects underlying this disease model are not well understood. Therefore, this study examines epigenetic and transcriptional dysregulation in the prefrontal cortex and hippocampus of MAM rats as these are brain regions closely associated with schizophrenia pathogenesis. Upon sequencing messenger and microRNA (mRNA and miRNA, respectively), differential expression was revealed in the prefrontal cortex and hippocampus between MAM- and saline-treated rats; sequencing data were validated by qualitative real-time polymerase chain reaction. Bioinformatic analyses demonstrated that the differentially expressed (DE) genes were strongly enriched in interactive pathways related to schizophrenia, including chemical synaptic transmission, cognition, and inflammatory responses; also, the potential target genes of the DE miRNAs were enriched in pathways related to synapses and inflammation. The blood of schizophrenia patients and healthy controls was further analyzed for several top DE mRNAs: DOPA decarboxylase, ret proto-oncogene, Fc receptor-like 2, interferon lambda receptor 1, and myxovirus (influenza virus) resistance 2. The results demonstrated that the expression of these genes was dysregulated in patients with schizophrenia; combining these mRNAs sufficiently differentiated schizophrenia patients from controls. Taken together, this study suggests that the MAM model has the potential to reproduce hippocampus and prefrontal cortex abnormalities, relevant to schizophrenia, at the epigenetic and transcriptional levels. These data also provide novel targets for schizophrenia diagnoses and treatments.

Interaction of oxidative stress and BDNF on executive dysfunction in patients with chronic schizophrenia

Executive dysfunction is increasingly recognized as one of the widely observed dimensions of cognitive impairments in the course of schizophrenia (SCZ). However, the potential molecular pathological mechanisms remain elusive. Previous studies have demonstrated that decreased brain-derived neurotrophic factor (BDNF) and oxidative damage may be associated with the psychopathology and cognitive impairment of SCZ. The present study aims to assess whether the interaction between BDNF and oxidative damage is involved in the disruption of executive function (EF) in patients with chronic SCZ. Serum BDNF and plasma oxidative stress markers were measured in 189 patients and 60 control subjects. EFs were evaluated by Wisconsin card sorting tests (WCST), Stroop word/color test (Stroop), and verbal fluency tests (VFT). The results showed that patients performed worse in the VFT, WCST and Stroop tests than healthy subjects. Moreover, patients had lower activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) and lower BDNF levels, but higher malondialdehyde (MDA) levels than healthy controls. In patients, BDNF was negatively correlated with SOD (p < 0.01). For patients, catalase (CAT) activity was negatively associated with WCST error score (p = 0.02) and BDNF was positively correlated to VFT score (p = 0.02). However, all these correlations between biomarkers and EF domains did not pass Bonferroni corrections. Finally, multiple regression analyses identified BDNF × SOD activity and BDNF × MDA as influencing factors for VFT score in patients (both p < 0.05). Our results highlight the complex interplay between OS parameters and BDNF in the pathophysiology of EF impairment in SCZ, consistent with its neurodevelopmental hypothesis.

Interaction of BDNF and cytokines in executive dysfunction in patients with chronic schizophrenia

Multiple lines of evidence indicate that patients with chronic schizophrenia (SCZ) display executive dysfunction across the illness course. However, the potential molecular pathophysiologic mechanisms remain poorly elucidated. Neurodevelopmental changes caused by alterations of inflammatory mediators and neurotrophins have been shown to occur in the earliest stages of SCZ, and be associated with executive dysfunction (ED) in SCZ. Therefore, the current study was to investigate whether the interplay between BDNF and inflammatory mediators was involved in the disruption of executive function of long-term hospitalized patients with chronic SCZ. Serum cytokines and BDNF levels were measured in 112 long-term hospitalized patients with chronic SCZ and 44 healthy normal controls. Executive functions were assessed by verbal fluency tests (VFT), the Stroop word-color test (Stroop), and the Wisconsin card sorting tests (WCST).The results showed that the patients had higher IL-2, IL-6, IL-8, but lower TNF-α and BDNF compared to control subjects. In the patient group, BDNF was positively associated with IL-2 and IL-8 levels, while lower BDNF levels were correlated with ED measured by VFT and WCST tests. Multiple stepwise regression analyses confirmed that BDNF × IL-8 and BDNF × TNF-α were factors influencing the total score of VFT, while BDNF × IL-8 and BDNF × TNF-α were recognized as influencing factors for WCST scores. Our results suggest complex interactions between BDNF and cytokines were involved in the pathophysiology of executive function impairments in patients with SCZ.

Genome-Wide, Integrative Analysis Implicates Exosome-Derived MicroRNA Dysregulation in Schizophrenia

Genetic variants conferring risk for schizophrenia (SCZ) have been extensively studied, but the role of posttranscriptional mechanisms in SCZ is not well studied. Here we performed the first genome-wide microRNA (miRNA) expression profiling in serum-derived exosome from 49 first-episode, drug-free SCZ patients and 46 controls and identified miRNAs and co-regulated modules that were perturbed in SCZ. Putative targets of these SCZ-affected miRNAs were enriched strongly for genes that have been implicated in protein glycosylation and were also related to neurotransmitter receptor and dendrite (spine) development. We validated several differentially expressed blood exosomal miRNAs in 100 SCZ patients as compared with 100 controls by quantitative reverse transcription-polymerase chain reaction. The potential regulatory relationships between several SCZ-affected miRNAs and their putative target genes were also validated. These include hsa-miR-206, which is the most upregulated miRNA in the blood exosomes of SCZ patients and that previously reported to regulate brain-derived neurotrophic factor expression, which we showed reduced mRNA and protein levels in the blood of SCZ patients. In addition, we found 11 miRNAs in blood exosomes from the miRNA sequence data that can be used to classify samples from SCZ patients and control subjects with close to 90% accuracy in the training samples, and approximately 75% accuracy in the testing samples. Our findings support a role for exosomal miRNA dysregulation in SCZ pathophysiology and provide a rich data set and framework for future analyses of miRNAs in the disease, and our data also suggest that blood exosomal miRNAs are promising biomarkers for SCZ.

Dysregulation of Fibroblast Growth Factor 10 in the Peripheral Blood of Patients with Schizophrenia

The fibroblast growth factor (FGF) system has been suggested to be involved in the development of schizophrenia (SCZ). However, the potential roles of all FGFs have not been well studied in the literature. Here, we investigated the concentration of peripheral blood fibroblast 10 (FGF10) in patients with SCZ to determine whether FGF10 could serve as a biomarker for SCZ. We recruited 130 SCZ patients (57 first-episode, drug-free patients and 73 chronically medicated patients) and 111 healthy controls. Our results showed that serum FGF10 levels were significantly decreased in SCZ patients when compared with controls. Sub-group analyses revealed that both first-episode, drug-free patients and chronically medicated patients had lower levels of FGF10 than controls. Moreover, both male and female SCZ patients had significantly decreased blood FGF10 levels relative to control subjects. Using a receiver operating characteristic curve, the optimal cutoff value of FGF10 level as an indicator for diagnosis of first-onset SCZ patients was projected to be 152.3 pg/ml, which yielded a sensitivity of 0.658 and specificity of 0.649, with an area under the curve of 0.665 (95% confidence interval, 0.577-0.754). Taken together, our results are the first to demonstrate an association between FGF10 and SCZ, providing further evidence for the neurotrophic factor hypothesis of SCZ.

Aberrations in Oxidative Stress Markers in Amyotrophic Lateral Sclerosis: A Systematic Review and Meta-Analysis

Oxidative stress has been reported to be involved in the onset and development of amyotrophic lateral sclerosis (ALS). Data from clinical studies have highlighted increased peripheral blood oxidative stress markers in patients with ALS, but results are inconsistent. Therefore, we quantitatively pooled data on levels of blood oxidative stress markers in ALS patients from the literature using a meta-analytic technique. A systematic search was performed on PubMed and Web of Science, and we included studies analyzing blood oxidative stress marker levels in patients with ALS and normal controls. We included 41 studies with 4,588 ALS patients and 6,344 control subjects, and 15 oxidative stress marker levels were subjected to random-effects meta-analysis. The results demonstrated that malondialdehyde (Hedges' g, 1.168; 95% CI, 0.812 to 1.523; P < 0.001), 8-hydroxyguanosine (Hedges' g, 2.194; 95% CI, 0.554 to 3.835; P = 0.009), and Advanced Oxidation Protein Product (Hedges' g, 0.555; 95% CI, 0.317 to 0.792; P < 0.001) levels were significantly increased in patients with ALS when compared with control subjects. Uric acid (Hedges' g, -0.798; 95% CI, -1.117 to -0.479; P < 0.001) and glutathione (Hedges' g, -1.636; 95% CI, -3.020 to -0.252; P = 0.02) levels were significantly reduced in ALS patients. In contrast, blood Cu, superoxide dismutase, glutathione peroxidase, ceruloplasmin, triglycerides, total cholesterol, low-density lipoprotein, high-density lipoprotein, coenzyme-Q10, and transferrin levels were not significantly different between cases and controls. Taken together, our results showed significantly increased blood levels of 8-hydroxyguanosine, malondialdehyde, and Advanced Oxidation Protein Product and decreased glutathione and uric acid levels in the peripheral blood of ALS patients. This meta-analysis helps to clarify the oxidative stress marker profile in ALS patients, supporting the hypothesis that oxidative stress is a central component underpinning ALS pathogenesis.

Association between hair lead levels and autism spectrum disorder in children: A systematic review and meta-analysis

A number of studies measured lead levels in hair from children with autism spectrum disorder (ASD) to detect the relationship between cumulated lead exposure and the development of ASD, but results are inconsistent. We aimed to conduct a systematic review and meta-analysis using the published studies to explore the actual association of hair lead levels with ASD in children. We searched PubMed, Embase, PsycINFO, and Cochrane Library databases (up to December 11, 2018). The random-effects model was applied to summarize effect sizes. Subgroup and meta-regression analyses were performed simultaneously. Twenty eligible studies involving 1787 participants (941 autistic children and 846 healthy subjects) were included. Our results of primary analysis showed that there were no statistically significant differences in the levels of hair lead between children with ASD and healthy individuals (Hedges's g = 0.251; 95% confidence interval: -0.121, 0.623; P = 0.187). We identified 2 sources of between-study heterogeneity: analytical technology and the sample size of patients. Additionally, no publication bias was observed in this meta-analysis. In conclusion, this study does not support the association of hair lead levels with ASD in children, and the involvement of cumulated lead exposure in the occurrence of ASD.

Effect of lurasidone vs olanzapine on neurotrophic biomarkers in unmedicated schizophrenia: A randomized controlled trial

Neurotrophic factors like Brain-Derived Neurotrophic Factor (BDNF), Neurotrophin 3 (NT3) and Nerve Growth Factor (NGF), play a role in neuroplasticity and neurogenesis contributing to the pathogenesis of schizophrenia. The objective of the present study was to investigate and compare the effect of olanzapine and lurasidone on the change in serum neurotrophins in patients with schizophrenia. The present study was a randomized, open-label, active-controlled, parallel design clinical trial. After randomization baseline evaluations of serum BDNF, NGF, NT3, Positive and Negative Syndrome Scale (PANSS) scoring, Social and Occupational Functioning Assessment Scale (SOFAS) scoring of 101 unmedicated schizophrenia patients were done. Patients were reassessed after 6 weeks of monotherapy with olanzapine or lurasidone. Serum BDNF increased after treatment with both the drug groups but rise with olanzapine was found to be significantly higher (916.22; 95 %CI: 866.07 to 966.37; p < 0.001) in comparison to lurasidone. Increase in levels NGF and NT3 was also observed but there was no significant difference between the groups (NGF: 2.32; CI: 3.54 to -3.53; p = 0.57 and NT3: 0.99; CI: 2.11 to 0.14; p = 0.086). The difference in improvement in PANSS and SOFASS with both the drugs was not statistically significant. Both the drugs alleviate the symptoms of schizophrenia but olanzapine was better tolerated. Our findings suggest that increase in serum BDNF with olanzapine monotherapy is significantly higher than that with lurasidone but there is no significant difference in change in serum NGF and NT3. TRIAL REGISTRATION: ClinicalTrials.gov identifier: (NCT03304457).

Endophenotypes in Schizophrenia: Digging Deeper to Identify Genetic Mechanisms

Schizophrenia (SZ) is a severe psychotic disorder that is highly heritable and common in the general population. The genetic heterogeneity of SZ is substantial, with contributions from common, rare, and de novo variants, in addition to environmental factors. Large genome-wide association studies have detected many variants that are associated with SZ, yet the pathways by which these variants influence risk remain largely unknown. SZ is also clinically heterogeneous, with patients exhibiting a broad range of deficits and symptom severity that vary over the course of illness and treatment, which has complicated efforts to identify risk variants. However, the underlying brain dysfunction forms a more stable trait marker that quantitative neurocognitive and neurophysiological endophenotypes may be able to objectively measure. These endophenotypes are less likely to be heterogeneous than the disorder and provide a neurobiological context to detect risk variants and underlying pathways among genes associated with SZ diagnosis. Furthermore, many endophenotypes are translational into animal model systems, allowing for direct evaluation of the neural circuit dysfunctions and neurobiological substrates. We review a selection of the most promising SZ endophenotypes, including prepulse inhibition, mismatch negativity, oculomotor antisaccade, letter-number sequencing, and continuous performance tests. We also highlight recent findings from large consortia that suggest the potential role of genes, particularly in the neuregulin and glutamate pathways, in several of these endophenotypes. Although endophenotypes require additional time and effort to assess, the insight into the underlying neurobiology that they provide may ultimately reveal the underlying genetic architecture for SZ and suggest novel treatment targets.

Sex difference in the association of body mass index and BDNF levels in Chinese patients with chronic schizophrenia

RATIONALE AND OBJECTIVE

Schizophrenia displays sex differences in many aspects. Decreased brain-derived neurotrophic factor (BDNF) levels have been reported to be associated with high body weight or obesity as well as other psychopathological aspects in schizophrenia patients. This study aimed to explore sex differences in the relationship between serum BDNF levels and obesity in patients with chronic schizophrenia.

METHODS

We recruited 132 Chinese patients with chronic schizophrenia (98 males and 34 females) and compared sex differences in the body mass index (BMI), obesity, serum BDNF levels, and their associations. Psychopathology symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). A regression model with various demographic and clinical variables was applied to predict the serum levels of BDNF.

RESULTS

Female patients had a higher rate of obesity and higher BMI, but lower BDNF levels than male schizophrenia patients. A significantly negative correlation was observed between BMI and BDNF levels only in female patients but not in male patients. The multiple regression model with demographic and clinical variables significantly predicted BDNF levels only in female patients, with a medium size effect. And only in female patients, BMI made a significant contribution to this prediction.

CONCLUSION

Our results indicate significant sex differences in the obesity, BMI, BDNF levels, and their association in chronic patients with schizophrenia, showing a significant inverse correlation between BMI and BDNF levels only in female patients. Thus, sex needs to be considered when assessing the relationship between BDNF and metabolic syndromes in schizophrenia.

Elevated serum vascular endothelial growth factor in treatment-resistant schizophrenia treated with electroconvulsive therapy: Positive association with therapeutic effects

OBJECTIVES

As the name implies, vascular endothelial growth factor (VEGF) enhances angiogenesis, promotes vascular permeability, and stimulates neurogenesis in the adult brain. Furthermore, animal model studies have shown that electroconvulsive therapy (ECT), which is primarily utilised in cases of treatment-resistant schizophrenia (TRS), regulates the expression of VEGF. The current study focuses largely on the effect of ECT on VEGF serum concentration, and the relationship between VEGF and therapeutic effects in patients diagnosed with TRS.

METHODS

Participants comprised 40 TRS patients and 43 healthy controls. Clinical severity was assessed (i.e. 1 day before commencement of ECT and 1 day following ECT) using the positive and negative syndrome scale (PANSS). Blood samples were also collected for VEGF measurements at corresponding time points.

RESULTS

Pre-treatment serum VEGF levels were significantly lower in TRS patients compared to healthy controls. VEGF concentrations increased significantly following ECT, whereas no difference was found in controls. Moreover, there was a positive correlation between the change in VEGF and therapeutic effects.

CONCLUSIONS

Elevated serum VEGF in TRS treated with ECT is positively associated with therapeutic effects, suggesting that alterations in VEGF levels may constitute an index by which to evaluate the improvement in clinical condition.

Correlation of metabolic parameters, neurotrophin-3, and neurotrophin-4 serum levels in women with schizophrenia and first-onset depression

BACKGROUND

Neurotrophin-3 (NTF3) and neurotrophin-4 (NTF4) play a crucial role in the neurodevelopment, differentiation, survival, and protection of neurons in different brain regions. Schizophrenia and depression are highly associated with metabolic abnormalities. Longitudinal and cross-sectional comparisons of NTF3 and NTF4 levels, as well as clinical and metabolic parameters, were studied in schizophrenia, first-episode depression, and control groups.

MATERIALS AND METHODS

Serum NTF3 and NTF4 levels, body mass index (BMI), fasting serum glucose and lipid profile: cholesterol, triglyceride, high-density lipoprotein (HDL-C) and low-density lipoprotein (LDL-C) were measured at baseline and week 8 in 133 women: 55 patients with schizophrenia (19 with first-episode and 36 chronic), 30 patients with a first-episode depression and 48 healthy controls. The severity of the symptoms was evaluated with the Positive and Negative Syndrome Scale, 17-item Hamilton Depression Rating Scale and the Beck Depression Inventory.

RESULTS

Longitudinal and cross-sectional comparisons did not detect any differences in the serum levels of NTF3 and NTF4 between studied groups. NTF3 and NTF4 levels were strongly correlated. Correlation of NTF3 and HDL-C levels at baseline was observed. Significant changes in cholesterol and fasting serum glucose levels in first-episode depression patients during 8 weeks of treatment were detected. Significant differences in BMI and LDL-C levels between schizophrenia and first-episode depression patients were discovered.

CONCLUSIONS

To our knowledge, this is the first research which correlates NTF3 and NTF4 with metabolic parameters. Our study does not support the theory that the peripheral levels of NTF3 and NTF4 are disturbed in schizophrenia or first-episode depression.

Nerve Growth Factor Serum Levels Are Associated With Regional Gray Matter Volume Differences in Schizophrenia Patients

Numerous neuroimaging studies have revealed structural brain abnormalities in schizophrenia patients. There is emerging evidence that dysfunctional nerve growth factor (NGF) signaling may contribute to structural brain alterations found in these patients. In this pilot study, we investigated whether there was a correlation between NGF serum levels and gray matter volume (GMV) in schizophrenia patients. Further, we investigated whether there was an overlap between the correlative findings and cross-sectional GMV differences between schizophrenia patients (n = 18) and healthy controls (n = 19). Serum NGF was significantly correlated to GMV in the left prefrontal lobe, the left midcingulate cortex, and the brainstem in schizophrenia patients. However, we did not find any correlations of NGF serum levels with GMV in healthy controls. Schizophrenia patients showed smaller GMV than healthy controls in brain regions located in the bilateral limbic system, bilateral parietal lobe, bilateral insula, bilateral primary auditory cortex, left frontal lobe, and bilateral occipital regions. In a conjunction analysis, GMV in the left midcingulate cortex (MCC) appears negatively correlated to NGF serum levels in the group of schizophrenia patients and also to be reduced compared to healthy controls. These results suggest an increased vulnerability of schizophrenia patients to changes in NGF levels compared to healthy controls and support a role for NGF signaling in the pathophysiology of schizophrenia. As our pilot study is exploratory in nature, further studies enrolling larger sample sizes will be needed to further corroborate our findings and to investigate the influence of additional covariates.

Cerebrospinal Fluid Inflammatory Cytokine Aberrations in Alzheimer's Disease, Parkinson's Disease and Amyotrophic Lateral Sclerosis: A Systematic Review and Meta-Analysis

It has been suggested that cytokine-mediated inflammation plays a key role for the onset and/or development of neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD) and Amyotrophic lateral sclerosis (ALS). However, clinical studies have yielded inconsistent results for the aberrant cytokine levels in circulation of patients with AD, PD, and ALS. Previous studies have used meta-analysis to address the inconsistent data for blood cytokine levels in the patients with AD, PD, and ALS. Here, we performed a systemic review of cerebrospinal fluid inflammatory cytokine data in patients with AD, PD and ALS, and sought to quantitatively summarize the CSF inflammatory cytokine data with a meta-analytical technique. The systematic search from Pubmed and Web of Science identified 71 articles with 2629 patients and 2049 controls for the meta-analysis. Random-effects meta-analysis demonstrated that CSF TGF-β, MCP-1, and YKL-40 levels were significantly elevated in AD patients when compared with controls. In addition, patients with PD had heightened levels of TGF-β1, IL-6, and IL-1β in CSF. Furthermore, G-CSF, IL-2, IL-15, IL-17, MCP-1, MIP-1α, TNF-α, and VEGF levels were significantly increased in patients with ALS as compared with controls. Taken together, these results not only strengthen the clinical evidence that neurodegenerative diseases are accompanied by the increased inflammatory response, but also reveal the unique inflammatory response profile in the central nervous system of patients with AD, PD and ALS. Given the robust associations between some cytokines and neurodegenerative diseases found in this meta-analysis, CSF inflammatory cytokines may be used as biomarkers for these diseases in the future.

Effects of haloperidol and clozapine on synapse-related gene expression in specific brain regions of male rats

We investigated the effects of clozapine and haloperidol, drugs that are widely used in the treatment of schizophrenia, on gene expression in six cortical and subcortical brain regions of adult rats. Drug treatments started at postnatal day 85 and continued over a 12-week period. Ten animals received haloperidol (1 mg/kg bodyweight) and ten received clozapine (20 mg/kg bodyweight) orally each day. Ten control rats received no drugs. The ten genes selected for this study did not belong to the dopaminergic or serotoninergic systems, which are typically targeted by the two substances, but coded for proteins of the cytoskeleton and proteins belonging to the synaptic transmitter release machinery. Quantitative real-time PCR was performed in the prelimbic cortex, cingulate gyrus (CG1) and caudate putamen and in the hippocampal cornu ammonis 1 (CA1), cornu ammonis 3 (CA3) and dentate gyrus. Results show distinct patterns of gene expression under the influence of the two drugs, but also distinct gene regulations dependent on the brain regions. Haloperidol-medicated animals showed statistically significant downregulation of SNAP-25 in CA3 (p = 0.0134) and upregulation of STX1A in CA1 (p = 0.0133) compared to controls. Clozapine-treated animals showed significant downregulation of SNAP-25 in CG1 (p = 0.0013). Our results clearly reveal that the drugs' effects are different between brain regions. These effects are possibly indirectly mediated through feedback mechanisms by proteins targeted by the drugs, but direct effects of haloperidol or clozapine on mechanisms of gene expression cannot be excluded.