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

Antioxidant and neurodevelopmental gene polymorphisms in prematurely born individuals influence hypoxia-related oxidative stress

Preterm born (PTB) infants are at risk for injuries related to oxidative stress. We investigated the association between antioxidant and neurodevelopmental gene polymorphisms and oxidative stress parameters in PTB male young adults and their term-born counterparts at rest and during exercise. Healthy young PTB (N = 22) and full-term (N = 15) males underwent graded exercise tests in normobaric normoxic (FiO2 = 0.21) and hypoxic (FiO2 = 0.13) conditions. CAT rs1001179 was associated with decrease in nitrites in the whole group and in PTB individuals (P = 0.017 and P = 0.043, respectively). GPX1 rs1050450 was associated with decrease in ferric reducing antioxidant power in the whole group and in full-term individuals (P = 0.017 and P = 0.021, respectively). HIF1A rs11549465 was associated with decrease in nitrotyrosine and increase in malondialdehyde (P = 0.022 and P = 0.018, respectively). NOTCH4 rs367398 was associated with increase in advanced oxidation protein products and nitrites (P = 0.002 and P = 0.004, respectively) in hypoxia. In normoxia, NOTCH4 rs367398 was associated with increase in malondialdehyde in the whole group (P = 0.043). BDNF rs6265 was associated with decreased nitrites/nitrates in the whole group and in PTB individuals (P = 0.009 and P = 0.043, respectively). Polymorphisms in investigated genes and PTB might influence oxidative stress response after exercise in normoxic or hypoxic conditions far beyond the neonatal period in young male adults.

The Implications of Brain-Derived Neurotrophic Factor in the Biological Activities of Platelet-Rich Plasma

Platelet-rich plasma (PRP) is a biological blood-derived therapeutic obtained from whole blood that contains higher levels of platelets. PRP has been primarily used to mitigate joint degeneration and chronic pain in osteoarthritis (OA). This clinical applicability is based mechanistically on the release of several proteins by platelets that can restore joint homeostasis. Platelets are the primary source of brain-derived neurotrophic factor (BDNF) outside the central nervous system. Interestingly, BDNF and PRP share key biological activities with clinical applicability for OA management, such as anti-inflammatory, anti-apoptotic, and antioxidant. However, the role of BDNF in PRP therapeutic activities is still unknown. Thus, this work aimed to investigate the implications of BDNF in therapeutic outcomes provided by PRP therapy in vitro and in-vivo, using the MIA-OA animal model in male Wistar rats. Initially, the PRP was characterized, obtaining a leukocyte-poor-platelet-rich plasma (LP-PRP). Our assays indicated that platelets activated by Calcium release BDNF, and suppression of M1 macrophage polarization induced by LP-PRP depends on BDNF full-length receptor, Tropomyosin Kinase-B (TrkB). OA animals were given LP-PRP intra-articular and showed functional recovery in gait, joint pain, inflammation, and tissue damage caused by MIA. Immunohistochemistry for activating transcriptional factor-3 (ATF-3) on L4/L5 dorsal root ganglia showed the LP-PRP decreased the nerve injury induced by MIA. All these LP-PRP therapeutic activities were reversed in the presence of TrkB receptor antagonist. Our results suggest that the therapeutic effects of LP-PRP in alleviating OA symptoms in rats depend on BDNF/TrkB activity.

The importance of oxidative biomarkers in diagnosis, treatment, and monitoring schizophrenia patients

INTRODUCTION

The etiology of schizophrenia (SCZ), an incredibly complex disorder, remains multifaceted. Literature suggests the involvement of oxidative stress (OS) in the pathophysiology of SCZ.

OBJECTIVES

Determination of selected OS markers and brain-derived neurotrophic factor (BDNF) in patients with chronic SCZ and those in states predisposing to SCZ-first episode psychosis (FP) and ultra-high risk (UHR).

MATERIALS AND METHODS

Determination of OS markers and BDNF levels by spectrophotometric methods and ELISA in 150 individuals (116 patients diagnosed with SCZ or in a predisposed state, divided into four subgroups according to the type of disorder: deficit schizophrenia, non-deficit schizophrenia, FP, UHR). The control group included 34 healthy volunteers.

RESULTS

Lower activities of analyzed antioxidant enzymes and GSH and TAC concentrations were found in all individuals in the study group compared to controls (p < 0.001). BDNF concentration was also lower in all groups compared to controls except in the UHR subgroup (p = 0.01). Correlations were observed between BDNF, R-GSSG, GST, GPx activity, and disease duration (p < 0.02). A small effect of smoking on selected OS markers was also noted (rho<0.06, p < 0.03).

CONCLUSIONS

OS may play an important role in the pathophysiology of SCZ before developing the complete clinical pattern of the disorder. The redox imbalance manifests itself with such severity in individuals with SCZ and in a state predisposing to the development of this psychiatric disease that natural antioxidant systems become insufficient to compensate against it completely. The discussed OS biomarkers may support the SCZ diagnosis and predict its progression.

IL-8 (CXCL8) Correlations with Psychoneuroimmunological Processes and Neuropsychiatric Conditions

Interleukin-8 (IL-8/CXCL8), an essential CXC chemokine, significantly influences psychoneuroimmunological processes and affects neurological and psychiatric health. It exerts a profound effect on immune cell activation and brain function, suggesting potential roles in both neuroprotection and neuroinflammation. IL-8 production is stimulated by several factors, including reactive oxygen species (ROS) known to promote inflammation and disease progression. Additionally, CXCL8 gene polymorphisms can alter IL-8 production, leading to potential differences in disease susceptibility, progression, and severity across populations. IL-8 levels vary among neuropsychiatric conditions, demonstrating sensitivity to psychosocial stressors and disease severity. IL-8 can be detected in blood circulation, cerebrospinal fluid (CSF), and urine, making it a promising candidate for a broad-spectrum biomarker. This review highlights the need for further research on the diverse effects of IL-8 and the associated implications for personalized medicine. A thorough understanding of its complex role could lead to the development of more effective and personalized treatment strategies for neuropsychiatric conditions.

The relationship between the gut microbiota and oxidative stress in the cognitive function of schizophrenia: A pilot study in China

Cognitive impairment is a core symptom of schizophrenia. The gut microbiota (GM) and oxidative stress may play important roles in the pathophysiological mechanisms of cognitive impairment. This study aimed to explore the relationship between GM and oxidative stress in the cognitive function of schizophrenia. GM obtained by 16S RNA sequencing and serum superoxide dismutase (SOD) levels from schizophrenia patients (N = 68) and healthy controls (HCs, N = 72) were analyzed. All psychiatric symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). Cognitive function was assessed using the MATRICS Consensus Cognitive Battery (MCCB). Correlation analysis was used to explore the relationship between GM, SOD, and cognitive function. Machine learning models were used to identify potential biomarkers. Compared to HCs, the relative abundances of Collinsella, undefined Ruminococcus, Lactobacillus, Eubacterium, Mogibacterium, Desulfovibrio, Bulleidia, Succinivibrio, Corynebacterium, and Atopobium were higher in patients with schizophrenia, but Faecalibacterium, Anaerostipes, Turicibacter, and Ruminococcus were lower. In patients with schizophrenia, the positive factor, general factor, and total score of MCCB positively correlated with Lactobacillus, Collinsella, and Lactobacillus, respectively; SOD negatively correlated with Eubacterium, Collinsella, Lactobacillus, Corynebacterium, Bulleidia, Mogibacterium, and Succinivibrio, but positively correlated with Faecalibacterium, Ruminococcus, and MCCB verbal learning index scores; Faecalibacterium and Turicibacter were positively correlated with MCCB visual learning index scores and speed of processing index scores, respectively. Our findings revealed a correlation between SOD and GM and confirmed that cognitive dysfunction in patients with schizophrenia involves abnormal SOD levels and GM changes.

Unlocking the Therapeutic Potential of Exosomes Derived From Nasal Olfactory Mucosal Mesenchymal Stem Cells: Restoring Synaptic Plasticity, Neurogenesis, and Neuroinflammation in Schizophrenia

BACKGROUND AND HYPOTHESIS

Schizophrenia (SCZ) is a multifaceted mental disorder marked by a spectrum of symptoms, including hallucinations, delusions, cognitive deficits, and negative symptoms. Its etiology involves intricate interactions between genetic and environmental factors, posing significant challenges for effective treatment. We hypothesized that intranasal administration of exosomes derived from nasal olfactory mucosal mesenchymal stem cells (OM-MSCs-exos) could alleviate SCZ-like behaviors in a murine model induced by methylazoxymethanol (MAM).

STUDY DESIGN

We conducted a comprehensive investigation to assess the impact of intranasally delivered OM-MSC-exos on SCZ-like behaviors in MAM-induced mice. This study encompassed behavioral assessments, neuroinflammatory markers, glial activation, synaptic protein expression, and neurogenesis within the hippocampus.

STUDY RESULTS

Our findings demonstrated that intranasal administration of OM-MSC-exos effectively ameliorated SCZ-like behaviors, specifically addressing social withdrawal and sensory gating deficits in the MAM-induced murine model. Furthermore, OM-MSC-exos intervention yielded a reduction in neuroinflammatory markers and a suppression of microglial activation within the hippocampus. Simultaneously, we observed an upregulation of key synaptic protein expression, including PSD95 and TH, the rate-limiting enzyme for dopamine biosynthesis.

CONCLUSIONS

Our study underscores the therapeutic potential of OM-MSC-exos in mitigating SCZ-like behavior. The OM-MSC-exos have the capacity to modulate glial cell activation, diminish neuroinflammation, and promote BDNF-associated synaptic plasticity and neurogenesis, thus ameliorating SCZ-like behaviors. In summary, intranasal administration of OM-MSC-exos offers a multifaceted approach to address SCZ mechanisms, promising innovative treatments for this intricate disorder.

Serum brain-derived neurotrophic factor levels in type 2 diabetes mellitus patients and its association with cognitive impairment: A meta-analysis

OBJECTIVE

To compare the serum levels of brain-derived neurotrophic factor (BDNF) in type 2 diabetes mellitus (T2DM) patients with healthy controls (HC) and evaluate the BDNF levels in T2DM patients with/without cognitive impairment.

METHODS

PubMed, EMBASE, and the Cochrane Library databases were searched for the published English literature on BDNF in T2DM patients from inception to December 2022. The BDNF data in the T2DM and HC groups were extracted, and the study quality was evaluated using the Agency for Healthcare Research and Quality. A meta-analysis of the pooled data was conducted using Review Manager 5.3 and Stata 12.0 software.

RESULTS

A total of 18 English articles fulfilled with inclusion criteria. The standard mean difference of the serum BDNF level was significantly lower in T2DM than that in the HC group (SMD: -2.04, z = 11.19, P <0.001). Besides, T2DM cognitive impairment group had a slightly lower serum BDNF level compared to the non-cognitive impairment group (SMD: -2.59, z = 1.87, P = 0.06).

CONCLUSION

BDNF might be involved in the neuropathophysiology of cerebral damage in T2DM, especially cognitive impairment in T2DM.

Finding biomarkers of experience in animals

At a time when there is a growing public interest in animal welfare, it is critical to have objective means to assess the way that an animal experiences a situation. Objectivity is critical to ensure appropriate animal welfare outcomes. Existing behavioural, physiological, and neurobiological indicators that are used to assess animal welfare can verify the absence of extremely negative outcomes. But welfare is more than an absence of negative outcomes and an appropriate indicator should reflect the full spectrum of experience of an animal, from negative to positive. In this review, we draw from the knowledge of human biomedical science to propose a list of candidate biological markers (biomarkers) that should reflect the experiential state of non-human animals. The proposed biomarkers can be classified on their main function as endocrine, oxidative stress, non-coding molecular, and thermobiological markers. We also discuss practical challenges that must be addressed before any of these biomarkers can become useful to assess the experience of an animal in real-life.

Variations of plasma oxidative stress levels in male patients with chronic schizophrenia. Correlations with psychopathology and matrix metalloproteinase-9: a case-control study

BACKGROUND

Accumulating evidence has indicated that oxidative stress (OS) and matrix metalloproteinase-9 (MMP-9) may contribute to the mechanism of schizophrenia. In the present study, we aimed to evaluate the associations of OS parameters and MMP-9 levels with psychopathological symptoms in male chronic schizophrenia patients.

METHODS

This study was an observational, cross-sectional, retrospective case-control study. Plasma hydrogen peroxide (H2O2), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), serum matrix metalloproteinase-9 (MMP-9), and tissue inhibitors of metalloproteinases-1 (TIMP-1) levels were assayed in 80 male patients with chronic schizophrenia and 80 matched healthy controls. Schizophrenia symptoms were assessed by the Positive and Negative Syndrome Scale (PANSS). Multivariate regression was used to analyze relationships between OS parameters and MMP-9, and clinical symptoms.

RESULTS

Our results demonstrated that levels of antioxidant enzymes, SOD, GSH-Px, H2O2, and MDA were significantly decreased, whereas CAT and MMP-9 levels were increased in patients with schizophrenia, when compared with healthy controls (all P < 0.05). In schizophrenia patients, correlation analyses showed that H2O2 levels were significantly and positively correlated with PANSS positive scores, CAT and MDA levels were significant negatively correlated with PANSS negative scores and PANSS total scores, and MDA levels were significantly positively correlated with MMP-9 levels (all P < 0.05). However, we did not find that MMP-9 played an interaction role between OS parameters and PANSS total scores and subscales scores (all P > 0.05).

CONCLUSIONS

Our results showed that alterations of plasma OS parameters in male patients with chronic schizophrenia were associated with psychopathology and MMP-9, suggesting that OS and neuroinflammation may play important role in the mechanism of schizophrenia.

BDNF-loaded PDADMAC-heparin multilayers: a novel approach for neuroblastoma cell study

Biomaterial science has contributed tremendously to developing nanoscale materials for delivering biologically active compounds, enhancing protein stability, and enabling its therapeutic use. This paper presents a process of formation of polyelectrolyte multilayer (PEM) prepared by sequential adsorption of positively charged polydiallyldimethylammonium chloride (PDADMAC) and negatively charged heparin sodium salt (HP), from low polyelectrolyte concentration, on a solid substrate. PEM was further applied as a platform for the adsorption of a brain-derived growth factor (BDNF), which is a protein capable of regulating neuronal cell development. The multilayers containing BDNF were thoroughly characterized by electrokinetic (streaming potential measurements, SPM) and optical (optical waveguide lightmode spectroscopy, OWLS) techniques. It was found that BDNF was significantly adsorbed onto polyelectrolyte multilayers terminated by HP under physiological conditions. We further explore the effect of established PEMs in vitro on the neuroblastoma SH-SY5Y cell line. An enzyme-linked immunosorbent assay (ELISA) confirmed that BDNF was released from multilayers, and the use of the PEMs intensified its cellular uptake. Compared to the control, PEMs with adsorbed BDNF significantly reduced cell viability and mitochondrial membrane polarization to as low as 72% and 58%, respectively. HPLC analysis showed that both PDADMAC-terminated and HP-terminated multilayers have antioxidative properties as they almost by half decreased lipid peroxidation in SH-SY5Y cells. Finally, enhanced formation of spheroid-like, 3D structures was observed by light microscopy. We offer a well-characterized PEM with antioxidant properties acting as a BDNF carrier, stabilizing BDNF and making it more accessible to cells in an inhomogeneous, dynamic, and transient in vitro environment. Described multilayers can be utilized in future biomedical applications, such as boosting the effect of treatment by selective anticancer as adjuvant therapy, and in biomedical research for future development of more precise neurodegenerative disease models, as they enhance cellular 3D structure formation.

The usefulness of a complete blood count in the prediction of the first episode of schizophrenia diagnosis and its relationship with oxidative stress

A complete blood count (CBC) is a routinely performed blood examination. Only a few studies assess the relationship between CBC and oxidative stress (OS) in schizophrenia (SZ). The aim of the study was to assess the utility of CBC in the prediction of SZ diagnosis, and the relationship between CBC and OS. The study included: 47 individuals with the first episode of psychosis (26 drug-naive: FEP-nt; 21 patients under antipsychotic treatment: FEP-t) and 30 healthy persons (control group, HC). CBC and oxidative stress-related parameters were assessed in blood samples. The FEP group had higher levels of WBC, MCHC, NEU, MONO, EOZ, BASO, and %EOZ compared to HC (p<0.05). Various relationships between OS and CBC were found, and this connection was significantly different between healthy individuals and patients. The most promising C&RT model for discriminating FEP from HC was combining monocytes, eosinophils, and neutrophils (accuracy: 77%, 95%CI = 0.67-0.87). The analysis singled out WBC and HT (accuracy: 74%, 95%CI = 0.64-0.90) as the most promising to distinguish FEP-nt from HC; WBC and %Neu to allocate to FEP-t or HC group (accuracy: 87%, 95%CI = 0.64-0.90); RDW-SD and LYMPH (accuracy: 86%, 95% CI = 0.75-97) for distinguishing FEP-nt from FEP-t. CBC could be a promising, cheap tool to determine abnormalities related to schizophrenia. However, more studies with larger sample sizes are required.

Temperature- and chemical-induced neurotoxicity in zebrafish

Throughout their lives, humans encounter a plethora of substances capable of inducing neurotoxic effects, including drugs, heavy metals and pesticides. Neurotoxicity manifests when exposure to these chemicals disrupts the normal functioning of the nervous system, and some neurotoxic agents have been linked to neurodegenerative pathologies such as Parkinson's and Alzheimer's disease. The growing concern surrounding the neurotoxic impacts of both naturally occurring and man-made toxic substances necessitates the identification of animal models for rapid testing across a wide spectrum of substances and concentrations, and the utilization of tools capable of detecting nervous system alterations spanning from the molecular level up to the behavioural one. Zebrafish (Danio rerio) is gaining prominence in the field of neuroscience due to its versatility. The possibility of analysing all developmental stages (embryo, larva and adult), applying the most common "omics" approaches (transcriptomics, proteomics, lipidomics, etc.) and conducting a wide range of behavioural tests makes zebrafish an excellent model for neurotoxicity studies. This review delves into the main experimental approaches adopted and the main markers analysed in neurotoxicity studies in zebrafish, showing that neurotoxic phenomena can be triggered not only by exposure to chemical substances but also by fluctuations in temperature. The findings presented here serve as a valuable resource for the study of neurotoxicity in zebrafish and define new scenarios in ecotoxicology suggesting that alterations in temperature can synergistically compound the neurotoxic effects of chemical substances, intensifying their detrimental impact on fish populations.

The Influence of Electroconvulsive Therapy (ECT) on Brain-Derived Neurotrophic Factor (BDNF) Plasma Level in Patients with Schizophrenia-A Systematic Review and Meta-Analysis

The main aim of this systematic review and meta-analysis is to establish whether there is a correlation between the brain-derived neurotrophic factor (BDNF) level and electroconvulsive therapy (ECT) treatment and the reduction in psychotic symptoms in patients diagnosed with schizophrenia. A systematic search of PubMed/Medline, Cochrane Library, Web of Science, Scopus and Embase was conducted up to March 2023. Inclusion criteria: studies in which adult patients with schizophrenia treated with antipsychotic medication received ECT therapy and had the BDNF level measured before and after ECT treatment. Exclusion criteria: animal and in vitro studies or studies not involving complete information about the treatment and concentration of BDNF in plasma. The risk of bias was assessed using Egger's regression-based test for meta-analysis with continuous outcomes. Six studies comprising 248 individuals with schizophrenia were included. A statistically significant increase in BDNF levels after ECT treatment was observed only in two studies (p < 0.001 and p < 0.027, respectively), whereas in four other studies, an upward trend without statistical significance was noticed. The estimated overall size effect revealed that ECT therapy caused a slight change in the BDNF level but without statistical significance (ES = -0.328). Different numbers of ECT procedures (4-10), final measurement of the BDNF level made at a different time point, using bilateral or unilateral electrode positioning during ECT and treatment with different combinations of typical or atypical antipsychotic medications may be potential reasons for the lack of statistical significance in the changes in BDNF levels after treatment. Data regarding the measurement of BDNF levels pre and post ECT therapy in patients with schizophrenia are very limited without an extended follow-up period and evaluation of mental health change. Our meta-analysis showed that treatment with ECT therapy and antipsychotic medication increases serum BDNF levels in patients with drug-resistant schizophrenia compared to patients treated with medication only; however, this effect is not statistically significant.

Oxidative Stress Biomarkers among Schizophrenia Inpatients

Background. Finding the associations between schizophrenia symptoms and the biomarkers of inflammation, oxidative stress and the kynurenine pathway may lead to the individualization of treatment and increase its effectiveness. Methods. The study group included 82 schizophrenia inpatients. The Positive and Negative Symptoms Scale (PANSS), the Brief Assessment of Cognition in Schizophrenia (BACS) and the Calgary Depression in Schizophrenia Scale were used for symptom evaluation. Biochemical analyses included oxidative stress parameters and brain-derived neurotrophic factor (BDNF). Results. Linear models revealed the following: (1) malondiadehyde (MDA), N-formylkynurenine (N-formKYN), advanced oxidation protein products (AOPP), advanced glycation end-products of proteins (AGE) and total oxidative status (TOS) levels are related to the PANSS-total score; (2) MDA, reduced glutathione (GSH) and BDNF levels are related to the PANSS-negative score; (3) TOS and kynurenine (KYN) levels are related to the PANSS-positive score; (4) levels of total antioxidant status (TAS) and AOPP along with the CDSS score are related to the BACS-total score; (5) TAS and N-formKYN levels are related to the BACS-working memory score. Conclusions. Oxidative stress biomarkers may be associated with the severity of schizophrenia symptoms in positive, negative and cognitive dimensions. The identification of biochemical markers associated with the specific symptom clusters may increase the understanding of biochemical profiles in schizophrenia patients.

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.

The Effect of Clozapine and Novel Glutamate Modulator JNJ-46356479 on Nitrosative Stress in a Postnatal Murine Ketamine Model of Schizophrenia

Schizophrenia (SZ) is a heterogeneous mental disorder, affecting ~1% of the worldwide population. One of the main pathophysiological theories of SZ is the imbalance of excitatory glutamatergic pyramidal neurons and inhibitory GABAergic interneurons, involving N-methyl-D-aspartate receptors (NMDAr). This may lead to local glutamate storms coupled with excessive dendritic pruning and subsequent cellular stress, including nitrosative stress, during a critical period of neurodevelopment, such as adolescence. Nitrosative stress is mediated by nitric oxide (NO), which is released by NO synthases (NOS) and has emerged as a key signaling molecule implicated in SZ. Regarding glutamatergic models of SZ, the administration of NMDAr antagonists has been found to increase NOS levels in the prefrontal cortex (PFC) and ventral hippocampus (HPC). We hypothesized that suboptimal NOS function in adolescence could be a target for early treatments, including clozapine (CLZ) and the novel metabotropic glutamate receptor modulator JNJ-46356479 (JNJ). We analyzed the protein levels of NOS isoforms in adult PFC and HPC of a postnatal ketamine induced murine model of SZ receiving CLZ or JNJ during adolescence by western blot. Endothelial NOS and neuronal NOS increased under ketamine administration in PFC and decreased in CLZ or JNJ treatments. The same trends were found in the HPC in neuronal NOS. In contrast, inducible NOS was increased under JNJ treatment with respect to ketamine induction in the HPC, and the same trends were found in the PFC. Taken together, our findings suggest a misbalance of the NOS system following NMDAr antagonist administration, which was then modulated under early CLZ and JNJ treatments.

Negative relationship between brain-derived neurotrophic factor (BDNF) and attention: A possible elevation in BDNF level among high-altitude migrants

Objective

Brain-derived neurotrophic factor (BDNF), a member of the neurotrophic family that plays a vital role in regulating neuronal activity and synaptic plasticity in the brain, affects attention. However, studies investigating the association between BDNF and attention in long-term high-altitude (HA) migrants are limited in the literature. As HA affects both BDNF and attention, the relationship between these factors becomes more complex. Therefore, this study aimed to evaluate the relationship between peripheral blood concentrations of BDNF and the three attentional networks in both behavioral and electrical aspects of the brain in long-term HA migrants.

Materials and methods

Ninety-eight Han adults (mean age: 34.74 ± 3.48 years, 51 females and 47 males, all have lived at Lhasa for 11.30 ± 3.82 years) were recruited in this study. For all participants, the serum BDNF levels were assessed using enzyme-linked immunosorbent assay; event-related potentials (N1, P1, and P3) were recorded during the Attentional Networks Test, which was used as the measure of three attentional networks.

Results

Executive control scores were negatively correlated with P3 amplitude (r = -0.20, p = 0.044), and serum BDNF levels were positively correlated with executive control scores (r = 0.24, p = 0.019) and negatively correlated with P3 amplitude (r = -0.22, p = 0.027). Through grouping of BDNF levels and three attentional networks, executive control was found to be significantly higher in the high BDNF group than in the low BDNF group (p = 0.010). Different BDNF levels were associated with both orienting scores (χ² = 6.99, p = 0.030) and executive control scores (χ² = 9.03, p = 0.011). The higher the BDNF level, the worse was the executive function and the lower was the average P3 amplitude and vice versa. Females were found to have higher alerting scores than males (p = 0.023).

Conclusion

This study presented the relationship between BDNF and attention under HA. The higher the BDNF level, the worse was the executive control, suggesting that after long-term exposure to HA, hypoxia injury of the brain may occur in individuals with relatively higher BDNF levels, and this higher BDNF level may be the result of self-rehabilitation tackling the adverse effects brought by the HA environment.

Dexmedetomidine Attenuates Methotrexate-Induced Neurotoxicity and Memory Deficits in Rats through Improving Hippocampal Neurogenesis: The Role of miR-15a/ROCK-1/ERK1/2/CREB/BDNF Pathway Modulation

Methotrexate (MTX) is a widely used neurotoxic drug with broad antineoplastic and immunosuppressant spectra. However, the exact molecular mechanisms by which MTX inhibits hippocampal neurogenesis are yet unclear. Dexmedetomidine (Dex), an α2-adrenergic receptor agonist, has recently shown neuroprotective effects; however, its full mechanism is unexplored. This study investigated the potential of Dex to mitigate MTX-induced neurotoxicity and memory impairment in rats and the possible role of the miR-15a/ROCK-1/ERK1/2/CREB/BDNF pathway. Notably, no former studies have linked this pathway to MTX-induced neurotoxicity. Male Sprague Dawley rats were placed into four groups. Group 1 received saline i.p. daily and i.v. on days 8 and 15. Group 2 received Dex at 10 μg/kg/day i.p. for 30 days. Group 3 received MTX at 75 mg/kg i.v. on days 8 and 15, followed by four i.p. doses of leucovorin at 6 mg/kg after 18 h and 3 mg/kg after 26, 42, and 50 h. Group 4 received MTX and leucovorin as in group 3 and Dex daily dosages as in group 2. Bioinformatic analysis identified the association of miR-15a with ROCK-1/ERK1/2/CREB/BDNF and neurogenesis. MTX lowered hippocampal doublecortin and Ki-67, two markers of neurogenesis. This was associated with the downregulation of miR-15a, upregulation of its target ROCK-1, and reduction in the downstream ERK1/2/CREB/BDNF pathway, along with disturbed hippocampal redox state. Novel object recognition and Morris water maze tests demonstrated the MTX-induced memory deficiencies. Dex co-treatment reversed the MTX-induced behavioral, biochemical, and histological alterations in the rats. These neuroprotective actions could be partly mediated through modulating the miR-15a/ROCK-1/ERK1/2/CREB/BDNF pathway, which enhances hippocampal neurogenesis.

Role of uric acid as a biomarker of cognitive function in schizophrenia during maintenance period

Background

Previous studies involving uric acid (UA) in some specialized disease populations have found that high UA is associated with enhanced patient function. The mechanism to explain this association may be that UA, an important antioxidant, exerts neuroprotective effects. Patients with schizophrenia (SCZ) have severe oxidative stress abnormalities, and cognitive impairment is a major obstacle to their rehabilitation. Only few studies have been conducted on UA and cognitive impairment in SCZ. This study aims to clarify the relationship between UA and cognitive impairment and explore whether UA could be used as a potential biological marker of cognition in SCZ during maintenance period.

Methods

A total of 752 cases of SCZ during maintenance period from Baiyun Jingkang Hospital were included. Cognition was measured using the Mini-Mental State Examination scale. UA was measured using the Plus method. The participants were grouped on the basis of UA to evaluate the association of cognition with low-normal (3.50-5.07 mg/dL for men, 2.50-4.19 mg/dL for women), middle-normal (5.07-6.39 mg/dL for men, 4.19-5.18 mg/dL for women), high-normal (6.39-7.00 mg/dL for men, 5.18-6.00 mg/dL for women), and high (>7.00 mg/dL for men, >6.00 mg/dL for women) levels of UA. Multiple logistic regression and linear regression models and restricted cubic spline (RCS) were utilized to evaluate the relationship.

Results

Uric acid was positively associated with cognitive function. Subgroup analyses showed that high UA was associated with enhanced cognition in participants with low anticholinergic cognitive burden (ACB).

Conclusion

Uric acid may be used as a simple objective biological indicator to assess cognition in SCZ during maintenance period.

Carob Seed Peels Effect on Cognitive Impairment and Oxidative Stress Status in Methionine-Induced Mice Models of Schizophrenia

Background:Ceratonia siliqua L. (Carob tree) is a Mediterranean evergreen, well known for its medicinal properties. The different parts of Carob were proven to exert antidiabetic, antibacterial, antifungal, and antiproliferative effects. Hence, the present paper aims to validate the positive correlation between the high antioxidant activity of carob seed peels and the improvement of negative symptoms of schizophrenia. Materials & Methods: The antioxidant activity was carried out using the β-carotene test. Methionine and carob seed peels (CSP) extracts (50 and 100 mg/kg) were orally administrated to mice for a week. After administration, behavioral tests were assessed using the Y-maze, elevated plus maze, and forced swimming tests, as well as the novel object recognition task. Furthermore, the oxidative stress status was evaluated by analyzing the levels of the antioxidant enzymes: Superoxide dismutase (SOD), glutathione peroxidase (GPx), and malondialdehyde levels (MDA). Results: Both extracts exhibited remarkable antioxidant activity and showed antibacterial effect against Gram-positive bacteria tested (Bacillus subtilis and Staphylococcus aureus) and against Pseudomonas aeruginosa (Gram-negative). Therefore, Escherichia coli was very resistant. The behavioral tests proved the efficacy of CSP in enhancing the cognitive impairment of animal models of schizophrenia. Hence, the stated correlation between oxidative stress and schizophrenia was confirmed by the increased SOD and GPx activities and the decreased MDA level. Conclusions: The present study gave further confirmation of the potential correlation between oxidative stress and the development of psychiatric disorders and highlighted the use of natural antioxidants, especially Ceratonia siliqua L. in the improvement of cognitive impairment in the dementia of schizophrenia.

Aflatoxin G1 exposure altered the expression of BDNF and GFAP, histopathological of brain tissue, and oxidative stress factors in male rats

Background and purpose

Aflatoxins are highly toxic compounds that can cause acute and chronic toxicity in humans and animals. This study aimed to evaluate the expression of BDNF and GFAP, histopathological changes, and oxidative stress factors in brain tissue exposed to aflatoxin G1 (AFG1) in male rats.

Experimental approach

Twenty-eight male Wistar rats were used. Animals were randomly divided into 4 groups of 7 each. The control group received 0.2 mL of corn oil and the treatment groups were exposed to AFG1 (2 mg/kg) intra-peritoneally for 15, 28, and 45 days. The tissue was used for histopathological studies, and the level of TAC, SOD, and MDA, and the expression of BDNF and GFAP genes were evaluated.

Findings/Results

Real-time PCR results showed that AFG1 increased GFAP expression and decreased BDNF expression in AFG1-treated groups compared to the control group. The tissue level of TAC and SOD over time in the groups receiving AFG1 significantly decreased and the tissue level of MDA increased compared to the control group. Histopathological results showed that AFG1 can cause cell necrosis, a reduction of the normal cells number in the hippocampal region of CA1, cerebral edema, shrinkage of nerve cells, formation of space around neuroglia, and diffusion of gliosis in the cerebral cortex after 45 days.

Conclusion and implication

AFG1, by causing pathological complications in cortical tissue, was able to affect the exacerbation of nerve tissue damage and thus pave the way for future neurological diseases.

Oxidative Stress and Emergence of Psychosis

Treatment and prevention strategies for schizophrenia require knowledge about the mechanisms involved in the psychotic transition. Increasing evidence suggests a redox imbalance in schizophrenia patients. This narrative review presents an overview of the scientific literature regarding blood oxidative stress markers’ evolution in the early stages of psychosis and chronic patients. Studies investigating peripheral levels of oxidative stress in schizophrenia patients, first episode of psychosis or UHR individuals were considered. A total of 76 peer-reviewed articles published from 1991 to 2022 on PubMed and EMBASE were included. Schizophrenia patients present with increased levels of oxidative damage to lipids in the blood, and decreased levels of non-enzymatic antioxidants. Genetic studies provide evidence for altered antioxidant functions in patients. Antioxidant blood levels are decreased before psychosis onset and blood levels of oxidative stress correlate with symptoms severity in patients. Finally, adjunct treatment of antipsychotics with the antioxidant N-acetyl cysteine appears to be effective in schizophrenia patients. Further studies are required to assess its efficacy as a prevention strategy. Redox imbalance might contribute to the pathophysiology of emerging psychosis and could serve as a therapeutic target for preventive or adjunctive therapies, as well as biomarkers of disease progression.

The relationship between cognitive impairment and superoxide dismutase activity in untreated first-episode patients with schizophrenia

Objectives: Cognitive decline is an essential characteristic of schizophrenia and may be due to the disturbance between reactive oxygen species generation and antioxidant capacity. The study aimed to explore the association between cognitive deficits and antioxidant defence parameters in untreated first-episode patients with schizophrenia.Methods: We determined important antioxidant enzymes, total superoxide dismutase (SOD) and manganese SOD (MnSOD), and their relationship with cognitive impairment in 168 untreated patients with first-episode schizophrenia and 168 age- and sex-matched healthy controls. The evaluation of psychopathological symptoms of all patients was based on the Positive and Negative Syndrome Scale (PANSS). We measured cognitive function by the Repeated Battery for the Assessment of Neuropsychological Status (RBANS) and activities of total SOD and MnSOD in all participants.Results: The results showed that untreated patients with first-episode schizophrenia had deficient cognitive functioning in four RBANS indices and total scores, except for the visuospatial/constructional index, as well as higher plasma total SOD activity compared with the control subjects. In addition, significant negative correlations were identified between MnSOD activity and attention index or RBANS total score in patients.Conclusions: Our results suggest that oxidative stress may be partly responsible for cognitive dysfunction in the early course of schizophrenia.

Low VGF is associated with executive dysfunction in patients with major depressive disorder

OBJECTIVES

Executive dysfunction is considered to be one of the cognitive impairment dimensions that are easily observed in depression, but its underlying molecular mechanism is still unclear. Study have shown that the neuropeptide VGF (non-acronymic) plays an important role in the regulation of hippocampal neurogenesis and neuroplasticity. Previous studies have shown that VGF may be related to the psychopathology of depression and cognitive impairment. However, the correlation between VGF and executive dysfunction in MDD has not been investigated.

METHODS

A total of 35 MDD patients and 31 healthy control patients were enrolled in this study. The 17-item Hamilton Depression Rating Scale (HDRS) was used to measure the severity of depression, and the Wisconsin Card Sorting Test (WCST) was used to assess executive dysfunction. Double antibody sandwich enzyme-linked immunosorbent assay (ELISA) was used to determine serum VGF in peripheral blood.

RESULTS

The level of serum VGF in MDD patients was significantly lower compared to that in the healthy control group (p < 0.001). Moreover, Response Administered (RA) scores, Response preservative errors (RPE), and Non-response preservative errors (NRPE) were all higher in the MDD group (all p < 0.05). In contrast, Categories Completed (CC) and Response Correct (RC) scores were lower (all p < 0.05). Further results showed a significant correlation between serum VGF with RA (r = -0.372, p = 0.028) and RPE scores (r = 0.507, p = 0.002) in patients with depression, while serum VGF showed no correlation with the severity of depression in either group.

CONCLUSIONS

VGF may play an important role in executive function dysfunction in MDD patients, and VGF levels may become a new marker for predicting executive function dysfunction in depression.

Effects of antipsychotics on antioxidant defence system in patients with schizophrenia: A meta-analysis

Theory of oxidative stress is suggested in the pathophysiology of schizophrenia. To determine the cause of impaired antioxidant defense system in schizophrenia, a meta-analysis was performed by selecting studies published from 1964 to 2021 from Pubmed and Scopus databases. Data were analysed using Comprehensive Meta-Analysis version 2 and calculated effect sizes were compared between unmedicated and medicated patients with schizophrenia and healthy controls. Heterogeneity, publication bias assessments and subgroup analyses of drug-free and drug-naïve patients, and patients treated with atypical and typical antipsychotics were conducted. Subgroup analysis of confounding factors including age, gender, illness duration and patient status was also conducted. We found that glutathione peroxidase (GPx) was significantly decreased in all patients. Significantly lower catalase (CAT), glutathione (GSH) and albumin (ALB) were found in unmedicated patients only. Both groups showed significantly weakened non-enzymatic antioxidant capacity. Subgroup analyses indicated that weakened non-enzymatic antioxidant capacity may be associated with schizophrenia. Antioxidant status was more impaired in drug-free patients compared with other subgroups. This indicated that antipsychotics may improve antioxidant defense system. Although effect sizes were smaller, future studies may focus on the effect of antipsychotic discontinuation. In overall, schizophrenia was associated with impaired antioxidant defense system especially the non-enzymatic antioxidant system.

Polymorphism of Transferrin Gene Impacts the Mediating Effects of Psychotic Symptoms on the Relationship between Oxidative Stress and Cognition in Patients with Chronic Schizophrenia

A series of studies indicated that iron distribution that partly derives from transferrin-bound iron in the peripheral nervous system in the brain may act in processes such as myelination and brain development. However, the relationship between schizophrenia, its psychotic symptoms, and the transferrin (TF) gene has not been systematically explored. Our study aimed to investigate how a particular polymorphism of the transferrin gene, rs3811655, affects the superoxide dismutase (SOD), malondialdehyde (MDA), psychotic symptoms, cognition, or the mediation model between antioxidant enzymes and cognition via symptoms. A total of 564 patients with chronic schizophrenia and 468 healthy control subjects were recruited. The psychotic symptoms and cognition were assessed by the Positive and Negative Syndrome Scale (PANSS) and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), respectively. Furthermore, the serum SOD, MDA activity, and transferrin gene polymorphism were measured in patients. Our results demonstrated that patients with the G allele possessed more severe negative symptoms, worse cognitive performance with respect to attention, and higher serum Mn-SOD activity. Additionally, the rs3811655 polymorphism may act as a moderator in the association between Cu/Zn-SOD activity and cognition, as well as psychotic symptoms in patients suffering from schizophrenia. According to this study, the single nucleotide polymorphism (SNP) rs3811655 polymorphism may fail to contribute to the susceptibility of schizophrenia in an individual but is involved in the iron-induced oxidative stress disturbance and cognitive impairment in schizophrenia. This deepens our understanding of the critical role of iron-induced oxidative stress that might underlie the pathophysiology of schizophrenia.

Cognitive Impairment and Psychopathology Are Related to Plasma Oxidative Stress in Long Term Hospitalized Patients With Chronic Schizophrenia

BACKGROUND

The present study aimed to examine whether plasma oxidative stress is associated with cognitive impairment in long term hospitalized patients with chronic schizophrenia.

METHOD

Ninety-six chronic schizophrenia patients and 94 healthy unaffected subjects were enrolled. Plasma markers of oxidative stress, including malondialdehyde (MDA), manganese superoxide dismutase (MnSOD), catalase (CAT), and glutathione peroxidase (GSH-Px), were measured. Psychiatric symptoms and cognitive function were assessed with the Positive and Negative Syndrome Scale (PANSS) and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), respectively.

RESULTS

Plasma MDA levels and MnSOD and GSH-Px activities were significantly lower in schizophrenia patients than in healthy controls (P < 0.001), while plasma CAT activity was higher than in healthy controls (P < 0.005). Cognitive scores on the RBANS and all of its five subscales (all P < 0.001) were significantly lower in schizophrenia patients than in healthy unaffected subjects. CAT and GSH-Px activities were positively correlated with the cognitive function scores corresponding to Visuospatial/Constructional abilities in the patient group (r = 0.298, 0.213, respectively, P < 0.05). Also, the multiple regression analysis revealed that CAT and GSH-Px activities were independent and separate contributors to the Visuospatial/Constructional index of the RBANS. Meanwhile, CAT activity was negatively correlated with general pathological symptoms (r = -0.307, Bonferroni corrected P = 0.008) and the total score of the PANSS domains (r = -0.299, Bonferroni corrected P = 0.012).

CONCLUSION

Our results that the reduced of MDA level and the increased CAT activity in plasma in male patients with chronic schizophrenia suggest that redox imbalance may be associated with the pathophysiology of schizophrenia, and it can induce impaired cognition and psychiatric symptoms.

Brain Derived Neurotrophic Factor and Cognitive Dysfunction in the Schizophrenia-Bipolar Spectrum: A Systematic Review and Meta-Analysis

BACKGROUND

Cognitive impairment is a core feature of disorders on the schizophrenia-bipolar spectrum, i.e., schizophrenia, bipolar disorder, and schizoaffective disorder. Brain-derived neurotrophic factor (BDNF) has been proposed to be a biomarker of cognitive impairment in these disorders as it plays a critical role in neuroplasticity and proposed to mediate some of the psychotropic effects of medication. However, despite numerous studies investigating the association between circulating BDNF and these disorders, no solid conclusions have been drawn regarding its involvement in cognitive impairment.

OBJECTIVES

The current systematic review and meta-analysis aims to examine blood BDNF levels and cognitive dysfunction in patients on the schizophrenia-bipolar spectrum as well as to evaluate whether circulating BDNF measurements can act as a biomarker for cognitive dysfunction.

METHODS

Studies were identified by searching Embase and Medline databases for English language articles published in peer-reviewed journals between 2000 January and 2021 June according to the PRISMA guidelines. A total of 815 articles were identified of which 32 met the inclusion criteria for the systematic review - reporting on comparisons between blood BDNF levels and cognitive functions of schizophrenia or bipolar disorder patients versus healthy controls (no studies involving schizoaffective patients were specifically obtained for the time being). Twenty-four of these studies (19 with schizophrenia and 5 with bipolar disorder patients) were eligible to be included in the meta-analysis.

RESULTS

Our findings indicated that circulating BDNF levels were significantly reduced in patients experiencing an acute episode of schizophrenia or bipolar disorder compared to healthy controls. Cognitive function was also found to be significantly worse in patients, however, correlations between BDNF levels and cognitive impairment were not always detected. Interventions, especially pharmacotherapy seemed to improve certain aspects of cognition and increase circulating BDNF levels.

CONCLUSION

Circulating BDNF alone does not seem to be a valid biomarker of cognitive dysfunction in patients with disorders on the schizophrenia-bipolar spectrum, owing to several confounding factors. Changes of the circulating levels of BDNF should be evaluated in a wider context of other stress-, immune-, and inflammatory-related factors.

Blood-based oxidation markers in medicated and unmedicated schizophrenia patients: A meta-analysis

Increased reactive species due to the effect of antipsychotics on oxidative stress may be involved in the development of schizophrenia. However, antipsychotics may have different direct antioxidant effects due to their chemical structures. The present meta-analysis aimed to investigate whether the cause increased oxidant status in schizophrenia patients is due to the illness or induction by antipsychotics. Studies published from 1964 to 2021 were selected from Pubmed and Scopus databases. Data were analysed using Comprehensive Meta-Analysis version 2. Effect sizes were calculated and compared between unmedicated and medicated patients and healthy controls. Heterogeneity and publication bias were assessed. Subgroup analyses were conducted on drug-free and drug-naïve patients, and patients treated with atypical and typical antipsychotics. We found that medicated patients had significantly higher malondialdehyde (MDA), thiobarbituric acid reactive substances (TBARS) and total oxidant status (TOS). Meanwhile, significantly increased plasma/serum MDA and nitric oxide (NO) were observed in unmedicated patients only. Higher lipid peroxidation in the drug-naïve group may be associated schizophrenia. However, both atypical and typical antipsychotics may worsen lipid peroxidation. Antipsychotic discontinuation in the drug-free group led to significantly increased plasma/serum NO, with larger effect size than the atypical antipsychotic group. In conclusion, medicated schizophrenia patients were more suffered from increased oxidative stress. Therefore, future study may focus on the mechanism of action of specific antipsychotic on oxidative stress.

Lipophilic vs. hydrophilic statins and psychiatric hospitalizations and emergency room visits in US Veterans with schizophrenia and bipolar disorder

Objective –

Psychiatric hospitalizations and emergency department (ED) visits are costly, stigmatizing, and often ineffective. Given the immune and kynurenine activation in bipolar disorder (BD) and schizophrenia, as well as the immune-modulatory effects of statins, we aimed to compare the relative risk (RRs) of psychiatric hospitalizations and ED visits between individuals prescribed lipophilic vs. hydrophilic statins vs. no statins. We hypothesized (a) reduced rates of hospitalization and ER utilization with statins versus no statins and (b) differences in outcomes between statins, as lipophilia increases the capability to penetrate the blood–brain barrier with potentially beneficial neuroimmune, antioxidant, neuroprotective, neurotrophic, and endothelial stabilizing effects, and, in contrast, potentially detrimental decreases in brain cholesterol concentrations leading to serotoninergic dysfunction, changes in membrane lipid composition, thus affecting ion channels and receptors.

Methods –

We used VA service utilization data from October 1, 2010 to September 30, 2015. The RRs for psychiatric hospitalization and ED visits, were estimated using robust Poisson regression analyses. The number of individuals analyzed was 683,129.

Results –

Individuals with schizophrenia and BD who received prescriptions for either lipophilic or hydrophilic statins had a lower RR of psychiatric hospitalization or ED visits relative to nonstatin controls. Hydrophilic statins were significantly associated with lower RRs of psychiatric hospitalization but not of ED visits, compared to lipophilic statins.

Conclusion –

The reduction in psychiatric hospitalizations in statin users (vs. nonusers) should be interpreted cautiously, as it carries a high risk of confounding by indication. While the lower RR of psychiatric hospitalizations in hydrophilic statins relative to the lipophilic statins is relatively bias free, the finding bears replication in a specifically designed study. If replicated, important clinical implications for personalizing statin treatment in patients with mental illness, investigating add-on statins for improved therapeutic control, and mechanistic exploration for identifying new treatment targets are natural next steps.

Developments in Biological Mechanisms and Treatments for Negative Symptoms and Cognitive Dysfunction of Schizophrenia

The causal mechanisms and treatment for the negative symptoms and cognitive dysfunction in schizophrenia are the main issues attracting the attention of psychiatrists over the last decade. The first part of this review summarizes the pathogenesis of schizophrenia, especially the negative symptoms and cognitive dysfunction from the perspectives of genetics and epigenetics. The second part describes the novel medications and several advanced physical therapies (e.g., transcranial magnetic stimulation and transcranial direct current stimulation) for the negative symptoms and cognitive dysfunction that will optimize the therapeutic strategy for patients with schizophrenia in future.

Caffeine consumption and schizophrenia: A highlight on adenosine receptor-independent mechanisms

Schizophrenia is a common psychiatric disorder which affects approximately 1% of the population worldwide. However, the complexity of etiology, treatment resistance and side effects induced by current antipsychotics, relapse prevention, and psychosocial rehabilitation are still to be uncovered. Caffeine, as the world's most widely consumed psychoactive drug, plays a crucial role in daily life. Plenty of preclinical and clinical evidence has illustrated that caffeine consumption could have a beneficial effect on schizophrenia. In this review, we firstly summarize the factors associated with the caffeine-induced beneficial effect. Then, a variety of mechanism of actions independent of adenosine receptor signaling will be discussed with an emphasis on the potential contribution of the microbiome-gut-brain axis to provide more possibilities for future therapeutic, prognosis, and social rehabilitation strategy.

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.

Vitamin D3 administration prevents memory deficit and alteration of biochemical parameters induced by unpredictable chronic mild stress in rats

The present study aimed to investigate the effects of vitamin D3 (Vit D) administration on memory function, hippocampal level of amyloid-beta (Aβ), brain-derived neurotrophic factor (BDNF) and oxidative stress status in a rat model of unpredictable chronic mild stress (UCMS). Vit D was intraperitoneally administered at doses of 100, 1000, and 10,000 IU/kg. Animals were subjected to UCMS for a total period of 4 weeks. Memory function was assessed using morris water maze (MWM) and passive avoidance (PA) tests. Biochemical markers were measured to reveal the status of oxidative stress and antioxidant defense system. In addition, the levels of Aβ and BDNF were measured in hippocampal region. In the UCMS group, latency to find the platform was greater and the time spent in target quadrant (MWM test) as well as the latency to enter the dark compartment (PA test), were less than the vehicle group. Hippocampal malondialdehyde (MDA) and Aβ concentrations in the UCMS group were higher than the vehicle group. Hippocampal level of thiol and BDNF plus the activities of catalase and superoxide dismutase (SOD) were reduced in UCMS group compared to the control subjects (i.e. vehicle group). Interestingly, Vit D treatment supplementation reversed the mentioned effects of UCMS. Our findings indicated that Vit D administration improves UCMS-induced impairment of learning and memory through prevention of adverse effects on Aβ, BDNF and oxidative stress parameters.

Cell and molecular toxicity of lanthanum nanoparticles: are there possible risks to humans?

Lanthanum nanoparticles are widely used in industry, agriculture, and biomedicine. Over 900 kg of lanthanum is annually released into the environment only in Europe, 50 times higher than the metals, mercury, and cadmium's environmental spread. Human health risk associated with long-term exposure to the abundant lanthanum nanoparticles is a concerning environmental issue. Due to lanthanum's ability to disrupt the main biological barriers and interrupt various cells' hemostasis, they seem to cause severe disruptions to various tissues. This review opens a new perspective regarding the cellular and molecular interaction of nanosized and ionic lanthanum with the possible toxicity on the nervous system and other tissues that would show lanthanum nanoparticles' potential danger to follow in toxicological science.

Altered Antioxidant Defenses in Drug-Naive First Episode Patients with Schizophrenia Are Associated with Poor Treatment Response to Risperidone: 12-Week Results from a Prospective Longitudinal Study

Abnormal redox regulation is thought to contribute to schizophrenia (SCZ). Accumulating studies have shown that the plasma antioxidant enzyme activity is closely associated with the course and outcome in antipsychotics-naïve first-episode (ANFE) patients with SCZ. The main purpose of this study was to investigate the effect of risperidone on oxidative stress markers in ANFE patients and the relationship between risperidone response and changes in oxidative stress markers. Plasma activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) enzyme, total antioxidant status (TAS), and malondialdehyde (MDA) levels were measured in 354 ANFE patients and 152 healthy controls. The clinical symptoms were evaluated by the Positive and Negative Syndrome Scale (PANSS). Patients received risperidone monotherapy for 12 weeks and oxidative stress markers and PANSS were measured at baseline and at follow-up. Compared with healthy controls, the patients exhibited higher activities of SOD, CAT, and TAS levels, but lower MDA levels and GPx activity. A comparison between 168 responders and 50 non-responders at baseline and 12-week follow-up showed that GPx activity decreased in both groups after treatment. Moreover, GPx activity decreased less in responders and was higher in responders than in non-responders at follow-up. These results demonstrate that the redox regulatory system and antioxidant defense enzymes may have predictive value for the response of ANFE patients to risperidone treatment.

Left lateral parietal rTMS improves cognition and modulates resting brain connectivity in patients with Alzheimer's disease: Possible role of BDNF and oxidative stress

Repetitive Transcranial Magnetic Stimulation (rTMS) is a non-invasive neuromodulation technique which is increasingly used for cognitive impairment in Alzheimer's Disease (AD). Although rTMS has been shown to modify Brain-Derived Neurotrophic Factor (BDNF) and oxidative stress levels in many neurological and psychiatric diseases, there is still no study evaluating the relationship between memory performance, BDNF, oxidative stress, and resting brain connectivity following rTMS in Alzheimer's patients. Furthermore, there are increasing clinical data showing that the stimulation of strategic brain regions may lead to more robust improvements in memory functions compared to conventional rTMS. In this study, we aimed to evaluate the possible disease-modifying effects of rTMS on the lateral parietal cortex in AD patients who have the highest connectivity with the hippocampus. To fill the mentioned research gaps, we have evaluated the relationships between resting-state Functional Magnetic Resonance Imaging (fMRI), cognitive scores, blood BDNF levels, and total oxidative/antioxidant status to explain the therapeutic and potential disease-modifying effects of rTMS which has been applied at 20 Hz frequencies for two weeks. Our results showed significantly increased visual recognition memory functions and clock drawing test scores which were associated with elevated peripheral BDNF levels, and decreased oxidant status after two weeks of left lateral parietal TMS stimulation. Clinically our findings suggest that the left parietal region targeted rTMS application leads to significant improvement in familiarity-based cognition associated with the network connections between the left parietal region and the hippocampus.

BDNF as a Biomarker of Cognition in Schizophrenia/Psychosis: An Updated Review

Brain Derived Neurotrophic Factor (BDNF) has been linked to cognitive symptoms of schizophrenia, which has been documented in previous reviews by several authors. However, a trend has recently emerged in this field moving from studying schizophrenia as a disease to studying psychosis as a group. This review article focuses on recent BDNF studies in relation to cognition in human subjects during different stages of the psychotic process, including subjects at high risk of developing psychosis, patients at their first episode of psychosis, and patients with chronic schizophrenia. We aim to provide an update of BDNF as a biomarker of cognitive function on human subjects with schizophrenia or earlier stages of psychosis, covering new trends, controversies, current research gaps, and suggest potential future developments in the field. We found that most of current research regarding BDNF and cognitive symptoms in psychosis is done around schizophrenia as a disease. Therefore, it is necessary to expand the study of the relationship between BDNF and cognitive symptoms to psychotic illnesses of different stages and origins.

Association of Peroxiredoxin 1 and brain-derived neurotrophic factor serum levels with depression and anxiety symptoms in patients with irritable bowel syndrome

BACKGROUND

Oxidative stress is considered a possible mechanism of irritable bowel syndrome (IBS) and depression. This study determined the possible association of serum peroxiredoxin 1 (PRDX1; a key antioxidant enzyme) and brain-derived neurotrophic factor (BDNF) with anxiety and depression symptoms in IBS patients.

METHODS

According to the Rome IV diagnostic criteria, 177 IBS patients from February 2019 to July 2019 were included. Serum levels of PRDX1, BDNF, and TNFα were detected by enzyme-linked immunosorbent assay. Levels of anxiety and depression were assessed with the Self-rating Anxiety Scale (SAS) and Self-rating Depression Scale (SDS).

RESULTS

Compared with normal IBS patients, patients with anxiety and depression symptoms had significantly higher serum PRDX1 (p<0.001; p=0.002) and TNFα (p<0.001; p = 0.002) and significantly lower BDNF (p < 0.001; p = 0.002). Serum PRDX1 (r = 0.659, p < 0.001; r = 0.466, p < 0.001) and TNFα (r = 0.531, p < 0.001; r = 0.449, p < 0.001) were positively correlated with SAS and SDS, respectively, whereas BDNF was negatively correlated with SAS (r = 0.594, p < 0.001) and SDS (r = 0.534, p < 0.001). Multivariable regression analysis revealed that IBS severity, BDNF, and PRDX1 were significant predictors of anxiety. BDNF was also a significant predictor of depression.

CONCLUSION

Elevated PRDX1 and decreased BDNF in serum may be closely related to psychological symptoms in IBS. Results of this study suggested that PRDX1 may be an important target for IBS treatment in fighting against intestinal and psychological symptoms.

Interaction of Serum Copper and Neurometabolites on Executive Dysfunction in Unmedicated Patients With Major Depressive Disorder

Objective: The mechanism of executive function (EF) impairment in major depressive disorder (MDD) remains unclear. Previous studies have demonstrated that altered serum copper levels and neurometabolic alterations may be associated with the psychopathology and cognitive impairment of MDD. While, their inter-relationships in MDD remain uncertain. The present study aims to assess whether the interaction between serum copper levels and neurometabolic alterations is involved in the deficit of executive function (EF) in patients with unmedicated MDD. Methods: Serum copper levels and EFs were measured in 41 MDD patients and 50 control subjects. EFs were evaluated by Trail Making Test, Part-B (TMT-B), Digit Symbol Substitution Test (DSST), Wisconsin Card Sorting Task (WCST), and Semantic Verbal Fluency testing (SVFT). Additionally, 41 patients and 41 healthy controls underwent proton magnetic resonance spectroscopy (¹H-MRS) to obtain ratios of N-acetyl aspartate to creatine (NAA/Cr) and choline-containing compounds to creatine (Cho/Cr) in the lenticular nucleus (LN) of basal ganglia (BG). Finally, association and interaction analysis were conducted to investigate their inter-relationships. Results: The results showed that patients performed worse in the DSST, WCST, TMT-B time and SVFT. Moreover, patients had higher serum copper levels, but lower NAA/Cr ratios in left LN of BG than healthy controls. In patients, serum copper levels were found to significantly negative associated with Categories Completed (CC) number of WCST (r = -0.408, p = 0.008), and positive associated with the Total Errors (TE) and Nonperseverative Errors (PE) number of WCST (r = 0.356, p = 0.023; r = -0.356, p = 0.022). In addition, the NAA/Cr ratios of left LN were found to significantly negative associated with VFS (r = -0.401, p = 0.009), as well as negative associated with serum copper levels (r = -0.365, p = 0.019). Finally, the interaction between copper and NAA may as influencing factors for SVFT and CC number of WCST in patients. Conclusion: Our results indicated that the interaction of abnormal copper levels and NAA/Cr neurometabolic disruption of the LN may impact executive dysfunction, and this may relevant to the pathophysiology of executive impairment in MDD patients.

Associations of C-Reactive Protein, Free Triiodothyronine, Thyroid Stimulating Hormone and Creatinine Levels with Agitation in Patients with Schizophrenia: A Comparative Cross-Sectional Study

PURPOSE

Agitation is prevalent among inpatients with schizophrenia. The aim of this study was to investigate whether biochemical parameters are associated with agitation in schizophrenia.

PATIENTS AND METHODS

Agitation was evaluated by the Positive and Negative Syndrome Scale-Excited Component questionnaire (PANSS-EC). Fasting serum levels of C-reactive protein (CRP), free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), uric acid (UA), creatinine, glucose and lipids were measured.

RESULTS

The analysis included 154 inpatients with schizophrenia (71 with agitation, 83 without agitation) and 75 healthy control subjects. Patients with schizophrenia and agitation had higher serum levels of CRP, FT3, FT4 and UA as well as lower levels of serum TSH and creatinine than patients without agitation (all P < 0.05). Multivariate logistic regression analysis indicated that serum CRP (odds ratio [OR] = 1.470, P = 0.001), FT3 (OR = 13.026, P < 0.001), TSH (OR = 0.758, P = 0.033) and creatinine (OR = 0.965, P = 0.004) were significantly associated with agitation in schizophrenia. CRP, FT3, TSH and creatinine achieved an area under the ROC curve of 0.626, 0.728, 0.620 and 0.663 respectively in discriminating schizophrenia with or without agitation.

CONCLUSION

Increased serum CRP and FT3 levels and decreased serum TSH and creatinine levels are independent risk factors for agitation in hospitalized patients with schizophrenia. Inflammation, thyroid hormones and renal function may be involved in the pathogenesis of agitation in schizophrenia.

BDNF serum levels and cognitive improvement in drug-naive first episode patients with schizophrenia: A prospective 12-week longitudinal study

Abnormal brain-derived neurotrophic factor (BDNF) levels are involved in cognitive decline in patients with schizophrenia. The role of atypical antipsychotic risperidone in improving cognitive function remains unclear. The study aimed to investigate the effect of risperidone monotherapy on cognitive impairment in drug-naïve first-episode (DNFE) patients with schizophrenia and whether BDNF levels were correlated to the improvement of cognition. 354 DNFE patients and 152 healthy controls were recruited, and we compared their serum BDNF levels and cognition shown on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). High and low BDNF subgroups were defined by median split. Then, 211 patients were treated with risperidone monotherapy for 12 weeks, and their serum BDNF levels and cognition were measured again after treatment. DNFE patients had poorer cognitive functions and lower BDNF levels compared to controls. Lower BDNF levels were correlated with delayed memory in DNFE patients with high baseline BDNF levels. After 12 weeks of treatment, risperidone significantly improved immediate memory, delayed memory and RBANS total scores and BDNF levels were slightly increased. In patients with low-BDNF, BDNF levels were significantly increased after risperidone treatment, while in patients with high-BDNF, BDNF levels were significantly decreased. In addition, baseline BDNF levels were associated with improvement of delayed memory and were a prognostic factor for the improvement of the delayed memory and RBANS total score in patients with high-BDNF. Our result suggests risperidone treatment can partially improve certain domains of the cognitive impairment and baseline BDNF levels are related to cognitive response to risperidone in DNFE patients with schizophrenia.

Cognitive Enhancing Effect of High-Frequency Neuronavigated rTMS in Chronic Schizophrenia Patients With Predominant Negative Symptoms: A Double-Blind Controlled 32-Week Follow-up Study

Accumulating studies have shown that high-frequency (HF) repetitive transcranial magnetic stimulation (rTMS) may improve cognitive dysfunction of the patients with schizophrenia (SCZ), but with inconsistent results. The present study aims to assess the efficacy of different frequencies of neuronavigated rTMS in ameliorating cognitive impairments and alleviating the psychotic symptoms. A total of 120 patients were randomly assigned to 3 groups: 20 Hz rTMS (n = 40), 10 Hz rTMS (n = 40), or sham stimulation (n = 40) for 8 weeks, and then followed up at week 32. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was performed to assess the cognitive functions of the patients at baseline, at the end of week 8, and week 32 follow-up. Psychotic symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS) at baseline and at the end of week 2, week 4, week 6, week 8, and week 32 follow-up. Our results demonstrated that 20 Hz rTMS treatment produced an effective therapeutic benefit on immediate memory of patients with chronic SCZ at week 8, but not in the 10 Hz group. Interestingly, both 10 Hz and 20 Hz rTMS treatments produced delayed effects on cognitive functions at the 6-month follow-up. Moreover, in both 10 Hz rTMS and 20 Hz rTMS, the improvements in RBANS total score were positively correlated with the reduction of PANSS positive subscore at the 6-month follow-up. Stepwise regression analysis identified that the visuospatial/constructional index, immediate memory index, and prolactin at baseline were predictors for the improvement of cognitive impairments in the patients. Our results suggest that add-on HF rTMS could be an effective treatment for cognitive impairments in patients with chronic SCZ, with a delayed effect. Trial registration: clinicaltrials.gov identifier-NCT03774927.

Lowered Antioxidant Defenses and Increased Oxidative Toxicity Are Hallmarks of Deficit Schizophrenia: a Nomothetic Network Psychiatry Approach

There is now evidence that schizophrenia and deficit schizophrenia are neuro-immune conditions and that oxidative stress toxicity (OSTOX) may play a pathophysiological role. Aims of the study: to compare OSTOX biomarkers and antioxidant (ANTIOX) defenses in deficit versus non-deficit schizophrenia. We examined lipid hydroperoxides (LOOH), malondialdehyde (MDA), advanced oxidation protein products (AOPP), sulfhydryl (-SH) groups, paraoxonase 1 (PON1) activity and PON1 Q192R genotypes, and total radical-trapping antioxidant parameter (TRAP) as well as immune biomarkers in patients with deficit (n = 40) and non-deficit (n = 40) schizophrenia and healthy controls (n = 40). Deficit schizophrenia is characterized by significantly increased levels of AOPP and lowered -SH, and PON1 activity, while no changes in the OSTOX/ANTIOX biomarkers were found in non-deficit schizophrenia. An increased OSTOX/ANTIOX ratio was significantly associated with deficit versus non-deficit schizophrenia (odds ratio = 3.15, p < 0.001). Partial least squares analysis showed that 47.6% of the variance in a latent vector extracted from psychosis, excitation, hostility, mannerism, negative symptoms, psychomotor retardation, formal thought disorders, and neurocognitive test scores was explained by LOOH+AOPP, PON1 genotype + activity, CCL11, tumor necrosis factor (TNF)-α, and IgA responses to neurotoxic tryptophan catabolites (TRYCATs), whereas -SH groups and IgM responses to MDA showed indirect effects mediated by OSTOX and neuro-immune biomarkers. When overall severity of schizophrenia increases, multiple immune and oxidative (especially protein oxidation indicating chlorinative stress) neurotoxicities and impairments in immune-protective resilience become more prominent and shape a distinct nosological entity, namely deficit schizophrenia. The nomothetic network psychiatry approach allows building causal-pathway-phenotype models using machine learning techniques.

Interrelationships Between BDNF, Superoxide Dismutase, and Cognitive Impairment in Drug-Naive First-Episode Patients With Schizophrenia

The pathogenesis and etiology of schizophrenia (SCZ) remains unclear. Accumulating studies showed that complex interrelationships between brain-derived neurotrophic factor (BDNF) and an imbalanced redox system has a crucial role in the psychopathology of SCZ. However, the influence of the interrelationships of BDNF and superoxide dismutase (SOD) on cognitive impairment and clinical symptomatology in drug-naive first-episode (DNFE) SCZ patients has not been studied thoroughly. Serum BDNF levels, plasma total SOD, manganese-SOD (Mn-SOD), copper/zinc-containing SOD (CuZn-SOD) activities, and malondialdehyde (MDA) levels were measured in 327 DNFE patients with SCZ and 391 healthy controls. Cognitive functions were measured using the Repeatable Battery for the Assessment of Neuropsychological status (RBANS) and clinical symptoms were evaluated by the Positive and Negative Syndrome Scale (PANSS). Compared with the controls, the DNFE patients had increased activities of total SOD and CuZn-SOD, and reduced levels of BDNF and MDA. BDNF levels were positively correlated with CuZn-SOD activity in patients. In addition, we found that elevated Mn-SOD and CuZn-SOD activities were related to PANSS depression factor. Moreover, an interactive effect of BDNF levels and Mn-SOD activity was associated with attentional index score in the patients. Therefore, our findings suggested that interrelationships between BDNF and antioxidant mechanisms might underlie the pathological mechanisms of cognitive impairments and symptomatology in the DNFE patients with SCZ.

Oxidative-Antioxidant Imbalance and Impaired Glucose Metabolism in Schizophrenia

Schizophrenia is a neurodevelopmental disorder featuring chronic, complex neuropsychiatric features. The etiology and pathogenesis of schizophrenia are not fully understood. Oxidative-antioxidant imbalance is a potential determinant of schizophrenia. Oxidative, nitrosative, or sulfuric damage to enzymes of glycolysis and tricarboxylic acid cycle, as well as calcium transport and ATP biosynthesis might cause impaired bioenergetics function in the brain. This could explain the initial symptoms, such as the first psychotic episode and mild cognitive impairment. Another concept of the etiopathogenesis of schizophrenia is associated with impaired glucose metabolism and insulin resistance with the activation of the mTOR mitochondrial pathway, which may contribute to impaired neuronal development. Consequently, cognitive processes requiring ATP are compromised and dysfunctions in synaptic transmission lead to neuronal death, preceding changes in key brain areas. This review summarizes the role and mutual interactions of oxidative damage and impaired glucose metabolism as key factors affecting metabolic complications in schizophrenia. These observations may be a premise for novel potential therapeutic targets that will delay not only the onset of first symptoms but also the progression of schizophrenia and its complications.

Astroglial Mechanisms Underlying Chronic Insomnia Disorder: A Clinical Study

PURPOSE

The objective of this study was to investigate whether the serum biomarkers S100 calcium binding protein B (S100B), glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF), and glial cell line-derived neurotrophic factor (GDNF) change in patients with chronic insomnia disorder (CID), and if this is the case, whether the altered levels of these serum biomarkers are associated with poor sleep quality and cognitive decline in CID.

PATIENTS AND METHODS

Fifty-seven CID outpatients constituted the CID group; thirty healthy controls (HC) were also enrolled. Questionnaires, polysomnography, Chinese-Beijing Version of Montreal Cognitive Assessment (MoCA-C) and Nine Box Maze Test (NBMT) were used to assess their sleep and neuropsychological function. Serum S100B, GFAP, BDNF, and GDNF were evaluated using enzyme-linked immunosorbent assay.

RESULTS

The CID group had higher levels of S100B and GFAP and lower levels of BDNF and GDNF than the HC group. Spearman correlation analysis revealed that poor sleep quality, assessed by subjective and objective measures, was positively correlated with S100B level and negatively correlated with BDNF level. GFAP level correlated positively with poor subjective sleep quality. Moreover, S100B and GFAP levels correlated negatively with general cognitive function assessed using MoCA-C. GFAP level correlated positively with poor spatial working memory (SWM) in the NBMT; BDNF level was linked to poor SWM and object recognition memory (ORcM) in the NBMT. However, principal component analysis revealed that serum S100B level was positively linked to the errors in object working memories, BDNF and GDNF concentrations were negatively linked with errors in ORcM, and GFAP concentration was positively correlated with the errors in the SWM and spatial reference memories.

CONCLUSION

Serum S100B, GFAP, BDNF, and GDNF levels were altered in patients with CID, indicating astrocyte damage, and were associated with insomnia severity or/and cognitive dysfunction.