Oxidative stress biomarkers and clinical dimensions in first 10 years of schizophrenia

The association of SOD and HsCRP with the efficacy of sulforaphane in schizophrenia patients with residual negative symptoms

OBJECTIVES

Emerging evidence indicates a connection between oxidative stress, immune-inflammatory processes, and the negative symptoms of schizophrenia. In addition to possessing potent antioxidant and anti-inflammatory properties, sulforaphane (SFN) has shown promise in enhancing cognitive function among individuals with schizophrenia. This study aims to investigate the efficacy of combined treatment with SFN in patients with schizophrenia who experience negative symptoms and its effect on the levels of superoxide dismutase (SOD) and the inflammatory marker, high-sensitivity C-reactive protein (HsCRP).

DESIGN

Forty-five patients with schizophrenia were recruited, who mainly experienced negative symptoms during a stable period. In addition to the original treatments, the patients received SFN tablets at a daily dose of 90 mg for 24 weeks. At baseline, 12 weeks, and 24 weeks, the participants were interviewed and evaluated. The reduction rate of the Positive and Negative Syndrome Scale (PANSS) was used to assess each participant. The side effects scale of Treatment Emergent Symptom Scale (TESS) was applied to assess the adverse reactions. Additionally, the levels of the SOD, HsCRP, and other indicators were examined.

RESULTS

The study findings revealed a significant decrease in PANSS negative subscale scores (P < 0.001). Furthermore, there was a significant increase in SOD activity and HsCRP levels (P < 0.001 and P < 0.05). Notably, the group of participants who exhibited a reduction in PANSS negative subscale scores demonstrated a significant improvement in HsCRP levels (P < 0.05).

CONCLUSIONS

Our study suggests that SFN may potentially serve as a safe adjunctive intervention to improve the negative symptoms of schizophrenia. The potential mechanism by which SFN improves negative symptoms in schizophrenia patients may involve its anti-inflammatory properties, specifically its ability to reduce HsCRP levels. Trial registration ClinicalTrial.gov (ID: NCT03451734).

The combination of oxytocin and mindfulness-based group therapy for empathy and negative symptoms in schizophrenia spectrum disorders - A double-blinded, randomized, placebo-controlled pilot study

Treatment options for social cognition and negative symptoms in schizophrenia spectrum disorders (SSD) remain limited. Oxytocin could be a promising augmentation approach, but the social context influences the effect in humans. This pilot study hypothesized that oxytocin in a positive social setting through mindfulness-based group therapy (MBGT) would positively affect empathy and negative symptoms as well as affect and stress in an exploratory approach in SSD. An experimental, randomized, double-blinded (participants, psychotherapists), placebo-controlled pilot study with 41 individuals with SSD was conducted at the Charité - Universitätsmedizin Berlin. Oxytocin or placebo (24 I.U.) was administered intranasally 45 min before two sessions of MBGT each. A 2 × 2 mixed model ANCOVA design was calculated to assess empathy by the Interpersonal Reactivity Index and the Multifaceted Empathy Test and negative symptoms by the Self-Evaluation of Negative Symptoms. No benefit of oxytocin compared to placebo on empathy was observed, but significant between-group differences favoring oxytocin were found regarding the negative symptoms Diminished emotional range and Avolition. Negative affect and stress were significantly reduced compared to baseline. Mindfulness increased in both groups. Results indicated protocol adherence and retention rate of 91.1%, a drop-out rate of 8.9 % and a completion of 96 % of all sessions by the participants. No severe adverse events or side effects were reported. Our findings indicate proof-of-concept and suggest a potential role of oxytocin on negative symptoms and related variables in SSD in combination with MBGT. Future research should examine the stability of these effects with larger sample sizes.

Pterin metabolism, inflammation and oxidative stress biochemical markers in schizophrenia: Factor analysis and assessment of clinical symptoms associations

Various aspects of folate and tetrahydrobiopterin (BH4) metabolism disturbances have been detected in patients with schizophrenia.Data were obtained that disturbances in the pterins (folates and BH4) metabolism can be associated with oxidative stress and inflammation, but has not yet been confirmed in clinical studies in schizophrenia. Within the framework of this study, a correlation and factor analysis of biochemical markersof pterin metabolism, inflammation and redox imbalance in patients with schizophrenia was performed in order to test the hypothesis of the single etiopathogenetic node, including the studied biochemical processes. Methods: 125 patients with schizophrenia and 95 healthy volunteers were randomly selected and evaluated with a biochemical examination of BH4, folate, B12, homocysteine, C-reactive protein, interleukin-6, reduced glutathione levels in the blood serum; activity of superoxide dismutase and catalase - in erythrocytes; malondialdehyde - in blood plasma. All patients underwent an examination using standardized psychopathology rating scales. Spearman rank coefficient (ρ) with Benjamini-Hochberg correction was used for the correlation analysis. The principal components analysis (PCA) was used as a factor analysis. Results: Significant correlations were found within groups of pterin metabolism, inflammatory markers and redox-imbalance, and also between separate inflammation, oxidative stress and markers of pterin metabolism. The performed factor analysis made it possible to distinguish two components: 1 - pterin metabolism, 2 - oxidativeinflammatory markers. Despite the weak statistical associations and, possibly, functional relationships between pterin metabolism and oxidative/inflammation markers, each of the components has its own clinical correlates and, probably, a separate contribution to the pathology of schizophrenia.

Catalase and interleukin-6 serum elevation in a prediction of treatment-resistance in male schizophrenia patients

BACKGROUND

Oxidative stress (OS) and neuroinflammatory pathways play an important role in the pathophysiology of schizophrenia. The present study investigated the relationship between OS, inflammatory cytokines, and clinical features in male patients with treatment-resistant schizophrenia (TRS).

METHOD

We measured plasma OS parameters, including manganese-superoxide dismutase (Mn-SOD), copper/zinc-containing SOD (CuZn-SOD), total-SOD (T-SOD), malondialdehyde (MDA), catalase (CAT), and glutathione peroxidase (GSH-Px); and serum inflammatory cytokines, including interleukin (IL)- 1α, IL-6, tumor necrosis factor-alpha (TNF-α), and interferon (IFN)-γ, from 80 male patients with chronic schizophrenia (31 had TRS and 49 had chronic stable schizophrenia (CSS)), and 42 healthy controls. The severity of psychotic symptoms was evaluated using the Positive and Negative Syndrome Scale (PANSS).

RESULTS

Compared with healthy controls, plasma Mn-SOD, CuZn-SOD, T-SOD, GSH-Px, and MDA levels were significantly lower, while CAT and serum IL-6 levels were higher in both TRS and CSS male patients (all P < 0.05). Significant differences in the activities of CAT (F = 6.068, P = 0.016) and IL-6 levels (F = 6.876, P = 0.011) were observed between TRS and CSS male patients after analysis of covariance. Moreover, a significant positive correlation was found between IL-6 levels and PANSS general psychopathology subscores (r = 0.485, P = 0.006) and between CAT activity and PANSS total scores (r = 0.409, P = 0.022) in TRS male patients. CAT and IL-6 levels were predictors for TRS. Additionally, in chronic schizophrenia patients, a significant positive correlation was observed between IL-6 and GSH-Px (r = 0.292, P = 0.012), and the interaction effect of IL-6 and GSH-Px was positively associated with PANSS general psychopathology scores (r = 0.287, P = 0.014).

CONCLUSION

This preliminary study indicated that variations in OS and inflammatory cytokines may be involved in psychopathology for patients with chronic schizophrenia, especially in male patients with TRS.

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.

Recent Reports on Redox Stress-Induced Mitochondrial DNA Variations, Neuroglial Interactions, and NMDA Receptor System in Pathophysiology of Schizophrenia

Schizophrenia (SZ) is a chronic psychiatric disorder affecting several people worldwide. Mitochondrial DNA (mtDNA) variations could invoke changes in the OXPHOS system, calcium buffering, and ROS production, which have significant implications for glial cell survival during SZ. Oxidative stress has been implicated in glial cells-mediated pathogenesis of SZ; the brain comparatively more prone to oxidative damage through NMDAR. A confluence of scientific evidence points to mtDNA alterations, Nrf2 signaling, dynamic alterations in dorsolateral prefrontal cortex (DLPFC), and provocation of oxidative stress that enhance pathophysiology of SZ. Furthermore, the alterations in excitatory signaling related to NMDAR signaling were particularly reported for SZ pathophysiology. Current review reported the recent evidence for the role of mtDNA variations and oxidative stress in relation to pathophysiology of SZ, NMDAR hypofunction, and glutathione deficiency. NMDAR system is influenced by redox dysregulation in oxidative stress, inflammation, and antioxidant mediators. Several studies have demonstrated the relationship of these variables on severity of pathophysiology in SZ. An extensive literature search was conducted using Medline, PubMed, PsycINFO, CINAHL PLUS, BIOSIS Preview, Google scholar, and Cochrane databases. We summarize consistent evidence pointing out a plausible model that may elucidate the crosstalk between mtDNA alterations in glial cells and redox dysregulation during oxidative stress and the perturbation of NMDA neurotransmitter system during current therapeutic modalities for the SZ treatment. This review can be beneficial for the development of promising novel diagnostics, and therapeutic modalities by ascertaining the mtDNA variations, redox state, and efficacy of pharmacological agents to mitigate redox dysregulation and augment NMDAR function to treat cognitive and behavioral symptoms in SZ.

Validation of a European Spanish adaptation of the Apathy Evaluation Scale-self-rated version (AES-S) in patients with schizophrenia

INTRODUCTION

Apathy is a negative symptom of schizophrenia and is associated with poor real world functioning. Therefore, it is important to have validated psychometric instruments to assess this symptom. This is the first study to validate the Spanish adaptation of the self-rated version of the Apathy Assessment Scale (AES-S) in patients with schizophrenia.

MATERIALS AND METHODS

Naturalistic, cross-sectional, validation study in 104 patients with schizophrenia evaluated using the following scales: Clinical Global Impression-Severity (CGI-S), Personal and Social Performance (PSP), Clinical Assessment Interview for Negative Symptoms (CAINS), Self-report of Negative Symptoms (SNS), Motivation and Pleasure Scale-Self-Report (MAP-SR), Calgary Depression Scale for Schizophrenia (CDSS), and Apathy Evaluation Scale-self-rated version (AES-S).

RESULTS

Reliability: Internal consistency (Cronbach's alpha) was 0.908. Convergent validity: The Pearson correlation coefficient between AES-S and CAINS-MAP total scores was -0.483 (p<0.001). For SNS, total and avolition subscale scores were -0.803 and -0.639 (p<0.001), respectively. With the MAP-SR, the correlation coefficient was -0.727 (p<0.001). Divergent validity: The Pearson correlation coefficient between AES-S and PSP total scores was 0.504 (p<0.001). Furthermore, with the CDSS, the correlation coefficient was -0.431 (p<0.001). Discriminant validity: The AES-S discriminated between different levels of illness severity according to CGI-S scores. Factor analysis: A three-component solution explained 57.32% of the variance. Pearson correlations between coefficients were 1-2=0.265, 1-3=0.464, and 2-3=0.060.

CONCLUSION

The Spanish AES-S is a reliable and valid instrument for assessing apathy in Spanish patients with schizophrenia. It seems to be appropriate for use in everyday clinical practice as a means of monitoring apathy in these patients.

Association of acute psychosocial stress with oxidative stress: Evidence from serum analysis

Growing evidence implicates an association between psychosocial stress and oxidative stress (OxSt) although there are not yet reliable biomarkers to study this association. We used a Trier Social Stress Test (TSST) and compared the response of a healthy control group (HC; N=10) against the response of a schizophrenia group (SCZ; N=10) that is expected to have higher levels of OxSt. Because our previous study showed inconsistent changes in conventional molecular markers for stress responses in the neuroendocrine and immune systems, we analyzed the same serum samples using a separate reducing capacity assay that provides a more global measurement of OxSt. This assay uses the moderately strong oxidizing agent iridium (Ir) to probe a sample's reducing capacity. Specifically, we characterized OxSt by this Ir-reducing capacity assay (Ir-RCA) using two measurement modalities (optical and electrochemical) and we tuned this assay by imposing an input voltage sequence that generates multiple output metrics for data-driven analysis. We defined five OxSt metrics (one optical and four electrochemical metrics) and showed: (i) internal consistency among each metric in the measurements of all 40 samples (baseline and post TSST for N=20); (ii) all five metrics were consistent with expectations of higher levels of OxSt for the SCZ group (three individual metrics showed statistically significant differences); and (iii) all five metrics showed higher levels of OxSt Post-TSST (one metric showed statistically significant difference). Using multivariant analysis, we showed that combinations of OxSt metrics could discern statistically significant increases in OxSt for both the SCZ and HC groups 90 min after the imposed acute psychosocial stress.

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Ir-reducing capacity assay (Ir-RCA) provides a robust global measure of oxidative stress in serum.

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The multiple oxidative stress (OxSt) output metrics of this Ir-RCA are useful for data-driven analysis.

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The combination of OxSt metrics can discern significant increases in OxStwithin 90 mins of an imposed psychosocial stress.

Association of antioxidant deficiency and the level of products of protein and lipid peroxidation in patients with the first episode of schizophrenia

Schizophrenia is considered a multifactorial disease, where one of the pathogenetic links is oxidative stress; however, the results of studies are often contradictory, largely due to significant heterogeneity among study methods. The present study was undertaken to compare the levels of oxidative stress markers in the peripheral blood of patients with a first episode of schizophrenia (FES) and in healthy volunteers (HV). The study included 50 patients with FES and 37 HV. Blood samples were collected for spectrophotometric assessment of reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), aldehyde-2,4-dinitrophenylhydrazone (ADNPH), and ketone-2,4-dinitrophenylhydrazone (KDNPH) in blood plasma. Results showed that in patients with FES compared with HV, a significant decrease in CAT activity and an increase in oxidative modification of proteins (OMP) were found. In both groups, a significant increase in the level of MDA with age was revealed. In patients, the GSH plasma level was inversely proportional to the ADNPH level, and SOD activity was directly proportional to the KDNPH level. In volunteers there was no such correlation; however, there was a direct correlation between CAT activity and the levels of OMP and MDA. In both groups, a moderate direct correlation between peroxidation products was observed. The results confirm that a redox imbalance (a deficiency of antioxidants, in particular CAT, and excess OMP) may be a pathogenetic link in schizophrenia, which is manifested already at an early stage of the disease.

Potential Novel Therapies for Neurodevelopmental Diseases Targeting Oxidative Stress

Neurodevelopmental disorders are a category of diseases that is not yet fully understood. Due to their common traits and pathways, often it is difficult to differentiate between them based on their symptoms only. A series of hypotheses are trying to define their etiology, such as neuroinflammation, neurodegeneration, and immunology, but none have managed to explain their multifactorial manifestation. One feature that may link all theories is that of oxidative stress, with a redox imbalance as well as several other markers of oxidative damage (on lipids, proteins, and nucleic acids) being observed in both postmortem samples of the brain of patients with schizophrenia and autism spectrum disorders. However, the implication of oxidative stress in pathology is still distrustfully looked upon. For this purpose, in the current paper, we were interested in reviewing the implications of oxidative stress in these disorders as well as the impact of N-acetylcysteine on the oxidative status with a focus on the glutathione level and N-methyl-D-aspartate receptor. We were also interested in finding papers targeting the use of antioxidant properties of different plant extracts.

[Antioxidant status of blood plasma of acutely psychotic patients and its correlation with Nrf2 activation]

OBJECTIVE

To study the correlation between the blood plasma antioxidant profile and the transcriptional activity of the Nrf2 gene in acute psychosis in patients with schizophrenia and alcoholism.

MATERIAL AND METHODS

The study included 40 patients with the first episode of the paranoid form of schizophrenia, 33 patients with schizophrenic psychosis who had previously received therapy, 22 patients with first-time acute alcohol psychosis, and 25 healthy volunteers. The level of Nrf2 in peripheral blood mononuclear cells was estimated by flow cytometry, and the antioxidant profile of blood plasma was estimated with chemiluminometry.

RESULTS

The total and «thiol» antioxidant capacity were reduced in patients with initially diagnosed schizophrenic psychosis and alcoholic psychosis. In patients after treatment, the total antioxidant capacity was higher compared to previously untreated patients. The level of Nrf2 protein in mononuclear cells in patients with the first psychotic episode was significantly lower than in patients with alcoholism and lower than in the control group. In patients with alcoholic psychosis, Nrf2 level was correlated with both the total antioxidant capacity due to uric acid and the «thiol» antioxidant capacity; in patients with psychosis in schizophrenia, Nrf2 level was correlated only with the «thiol» antioxidant capacity.

CONCLUSIONS

The correlation between the total and «thiol» antioxidant capacity and the level of Nrf2 in mononuclear cells of patients with alcohol delirium indicates the undamaged state of the regulation. The absence of a correlation between the total antioxidant capacity and the level of Nrf2 in patients with schizophrenia indicates a disturbance of the activation of the Nrf2 pathway due to, possibly, a part associated with the participation of uric acid.

Regulation of Reactive Oxygen Species-Mediated Damage in the Pathogenesis of Schizophrenia

The biochemical integrity of the brain is paramount to the function of the central nervous system, and oxidative stress is a key contributor to cerebral biochemical impairment. Oxidative stress, which occurs when an imbalance arises between the production of reactive oxygen species (ROS) and the efficacy of the antioxidant defense mechanism, is believed to play a role in the pathophysiology of various brain disorders. One such disorder, schizophrenia, not only causes lifelong disability but also induces severe emotional distress; however, because of its onset in early adolescence or adulthood and its progressive development, consuming natural antioxidant products may help regulate the pathogenesis of schizophrenia. Therefore, elucidating the functions of ROS and dietary antioxidants in the pathogenesis of schizophrenia could help formulate improved therapeutic strategies for its prevention and treatment. This review focuses specifically on the roles of ROS and oxidative damage in the pathophysiology of schizophrenia, as well as the effects of nutrition, antipsychotic use, cognitive therapies, and quality of life on patients with schizophrenia. By improving our understanding of the effects of various nutrients on schizophrenia, it may become possible to develop nutritional strategies and supplements to treat the disorder, alleviate its symptoms, and facilitate long-term recovery.

Validation of a European Spanish adaptation of the Apathy Evaluation Scale-self-rated version (AES-S) in patients with schizophrenia

INTRODUCTION

Apathy is a negative symptom of schizophrenia and is associated with poor real world functioning. Therefore, it is important to have validated psychometric instruments to assess this symptom. This is the first study to validate the Spanish adaptation of the self-rated version of the Apathy Assessment Scale (AES-S) in patients with schizophrenia.

MATERIALS AND METHODS

Naturalistic, cross-sectional, validation study in 104 patients with schizophrenia evaluated using the following scales: Clinical Global Impression-Severity (CGI-S), Personal and Social Performance (PSP), Clinical Assessment Interview for Negative Symptoms (CAINS), Self-report of Negative Symptoms (SNS), Motivation and Pleasure Scale-Self-Report (MAP-SR), Calgary Depression Scale for Schizophrenia (CDSS), and Apathy Evaluation Scale-self-rated version (AES-S).

RESULTS

Reliability: Internal consistency (Cronbach's alpha) was 0.908. Convergent validity: The Pearson correlation coefficient between AES-S and CAINS-MAP total scores was -0.483 (p<0.001). For SNS, total and avolition subscale scores were -0.803 and -0.639 (p<0.001), respectively. With the MAP-SR, the correlation coefficient was -0.727 (p<0.001). Divergent validity: The Pearson correlation coefficient between AES-S and PSP total scores was 0.504 (p<0.001). Furthermore, with the CDSS, the correlation coefficient was -0.431 (p<0.001). Discriminant validity: The AES-S discriminated between different levels of illness severity according to CGI-S scores. Factor analysis: A three-component solution explained 57.32% of the variance. Pearson correlations between coefficients were 1-2=0.265, 1-3=0.464, and 2-3=0.060.

CONCLUSION

The Spanish AES-S is a reliable and valid instrument for assessing apathy in Spanish patients with schizophrenia. It seems to be appropriate for use in everyday clinical practice as a means of monitoring apathy in these patients.