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

Inhibition of reactive oxygen species production accompanying alternatively activated microglia by risperidone in a mouse ketamine model of schizophrenia

Recent studies have highlighted the potential involvement of reactive oxygen species (ROS) and microglia, a major source of ROS, in the pathophysiology of schizophrenia. In our study, we explored how the second-generation antipsychotic risperidone (RIS) affects ROS regulation and microglial activation in the hippocampus using a mouse ketamine (KET) model of schizophrenia. KET administration resulted in schizophrenia-like behaviors in male C57BL/6J mice, such as impaired prepulse inhibition (PPI) of the acoustic startle response and hyper-locomotion. These behaviors were mitigated by RIS. We found that the gene expression level of an enzyme responsible for ROS production (Nox2), which is primarily associated with activated microglia, was lower in KET/RIS-treated mice than in KET-treated mice. Conversely, the levels of antioxidant enzymes (Ho-1 and Gclc) were higher in KET/RIS-treated mice. The microglial density in the hippocampus was increased in KET-treated mice, which was counteracted by RIS. Hierarchical cluster analysis revealed three morphological subtypes of microglia. In control mice, most microglia were resting-ramified (type I, 89.7%). KET administration shifted the microglial composition to moderately ramified (type II, 44.4%) and hyper-ramified (type III, 25.0%). In KET/RIS-treated mice, type II decreased to 32.0%, while type III increased to 34.0%. An in vitro ROS assay showed that KET increased ROS production in dissociated hippocampal microglia, and this effect was mitigated by RIS. Furthermore, we discovered that a NOX2 inhibitor could counteract KET-induced behavioral deficits. These findings suggest that pharmacological inhibition of ROS production by RIS may play a crucial role in ameliorating schizophrenia-related symptoms. Moreover, modulating microglial activation to regulate ROS production has emerged as a novel avenue for developing innovative treatments for schizophrenia.

Positive Effects of Uric Acid on White Matter Microstructures and Treatment Response in Patients With Schizophrenia

BACKGROUND AND HYPOTHESIS

Schizophrenia involves microstructural changes in white matter (WM) tracts. Oxidative stress is a key factor causing WM damage by hindering oligodendrocyte development and myelin maturation. Uric acid (UA), an endogenous antioxidant, may protect against oxidative stress. We investigated the effect of UA on WM connectivity in antipsychotic-naive or -free patients with early- or chronic-stage schizophrenia.

STUDY DESIGN

A total of 192 patients with schizophrenia (122 recent-onset [ROS] and 70 chronic [CS]) and 107 healthy controls (HCs) participated in this study. Diffusion tensor imaging data and serum UA levels at baseline were obtained.

STUDY RESULTS

Fractional anisotropy was lower in the widespread WM regions across the whole brain, and diffusivity measures were higher in both schizophrenia groups than in HCs. The CS group showed lower diffusivity in some WM tracts than the ROS or HC groups. The linear relationship of serum UA levels with axial and mean diffusivity in the right frontal region was significantly different between schizophrenia stages, which was driven by a negative association in the CS group. WM diffusivity associated with serum UA levels correlated with 8-week treatment responses only in patients with CS, suggesting UA to be protective against long-term schizophrenia.

CONCLUSIONS

UA may protect against the WM damage associated with the progression of schizophrenia by reducing oxidative stress and supporting WM repair against oxidative damage. These results provide insights into the positive role of UA and may facilitate the development of novel disease-modifying therapies.

Smoking, Symptoms Improvement, and Total Antioxidant Capacity in Patients with Drug-naive First-episode Schizophrenia: A Prospective Cohort Study

BACKGROUND

It has been hypothesized that smoking is associated with the severity of negative symptoms. Until now, no studies have investigated whether the impact of smoking on negative symptoms is dependent on antioxidants. This study was designed to evaluate the effect of smoking on therapeutic response and total antioxidants capacity (TAOC) in antipsychotic-naïve first-episode (ANFE) patients.

METHODS

The severity of the patient's symptoms was assessed using the Positive and Negative Syndrome Scale (PANSS). A total of 237 ANFE patients were recruited and treated with risperidone (oral tablets, 4-6 mg/day twice a day) for 12 weeks. PANSS was assessed at baseline and a 12-week follow-up. Plasma TAOC levels were also assayed at baseline and week 12.

RESULTS

Relative to nonsmokers with ANFE SZ, smokers had higher PANSS negative subscores. There was no significant difference in TAOC changes after 12 weeks of treatment with risperidone between smokers and non-smokers. However, we found greater improvement in negative symptoms in smokers compared to non-smokers. Further analysis in smokers with SZ demonstrated that improvements in negative symptoms were not associated with changes in TAOC.

CONCLUSION

Our study suggested that smoking affected the severity of baseline negative symptoms and further contributed to their reduction after risperidone treatment. However, improvement in negative symptoms was not dependent on the changes in TAOC.

Obesity, antioxidants and negative symptom improvement in first-episode schizophrenia patients treated with risperidone

Negative symptoms remain a main therapeutic challenge in patients with schizophrenia (SZ). Obesity is associated with more severe negative symptoms after the first episode of psychosis. Oxidative stress caused by an impaired antioxidant defense system is involved in the pathophysiology of SZ. Yet, it is unclear regarding the role of obesity and antioxidants in negative symptom improvements in SZ. Therefore, this longitudinal study was designed to assess the impact of obesity on antioxidant defenses and negative symptom improvements in first-episode SZ patients. A total of 241 medication-naive and first-episode patients with SZ were treated with risperidone for 3 months. Outcome measures including symptoms, body weight, and total antioxidant status (TAS) levels were measured at baseline and the end of the third month. We found that after 12 weeks of treatment with risperidone, the body weight increased and clinical symptoms significantly improved. Baseline body mass index (BMI) was negatively correlated with negative symptom improvement after treatment and an increase in TAS was negatively associated with an increase in BMI only in the high BMI group. More importantly, the TAS × BMI interaction at baseline was an independent predictor of negative symptom improvement. Our longitudinal study indicates that the improvement in negative symptoms by risperidone was associated with baseline BMI and TAS levels in patients with SZ. Baseline BMI and TAS may be a predictor for negative improvement in SZ patients after risperidone treatment.

Comparative Analysis of the Pre- and Post-Medication Effects of Antipsychotic Agents on the Blood-Based Oxidative Stress Biomarkers in Patients with Schizophrenia: A Meta-Analysis

OBJECTIVE

Studies have shown that oxidative stress (OS) is related to the pathophysiology of schizophrenia (SCZ), but whether antipsychotics can induce OS has not been investigated well. Moreover, antipsychotics have differential effects on the OS level modulation, i.e., different types of antipsychotics have different effects on the cellular antioxidants or pro-oxidants.

METHODS

We followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines and investigated the OS indicators including both enzymatic and nonenzymatic markers, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), malondialdehyde (MDA), glutathione (GSH), vitamin C, etc., of SCZ patients at baseline and follow-up of mono-medication.

RESULTS

Twenty studies met the inclusion criteria, with a total of 1162 patients enrolled at baseline, and 1105 patients completed the follow-up. OS markers were changed after a period of antipsychotic treatment in SCZ patients. The GPx activity and MDA level decreased in the whole blood (P<0.05), also the serum MDA level decreased (P<0.05). For the first-episode SCZ patients, the activity of GPx and the level of MDA decreased, while the level of vitamin C increased (all P<0.05). The levels of MDA in patients receiving atypical antipsychotics decreased (P<0.05), while the level of GSH in patients with typical antipsychotics decreased (P=0.05).

CONCLUSION

Antipsychotic medication may cause changes in the levels of OS markers in different blood samples of SCZ patients. However, the available studies might not be sufficient to reveal the underlying facts accurately due to the poor quality of experimental designs in the published literature.

Smoking Affects the Predictive Roles of Antioxidant Enzymes in the Clinical Response to Risperidone in Schizophrenia: A Large-scale Cohort Study

OBJECTIVES

There is overwhelming evidence of the relationship between smoking and schizophrenia (SZ). Tobacco smoke is considered to ameliorate the symptoms and reduce the side effects of antipsychotics in SZ patients. However, the underlying biological mechanism by which tobacco smoke improves symptoms in SZ remains unclear. This study was designed to examine the effects of tobacco smoke on antioxidant enzyme activities and psychiatric symptoms after receiving 12-week risperidone monotherapy.

METHODS

Two hundred and fifteen antipsychotic-naïve first-episode (ANFE) patients were recruited and treated with risperidone for 3 months. The severity of the patient's symptoms was assessed by the Positive and Negative Syndrome Scale (PANSS) at baseline and at post-treatment. Plasma SOD, GSH-Px, and CAT activities were determined at baseline and follow-up.

RESULTS

Relative to nonsmoking patients with ANFE SZ, patients who smoked had higher baseline CAT activity. In addition, among non-smokers with SZ, baseline GSH-Px was associated with clinical symptom improvement, while baseline CAT was associated with positive symptom improvement in smokers with SZ.

CONCLUSION

Our findings demonstrate that smoking affects the predictive role of baseline SOD, GSHPx, and CAT activities on clinical symptom improvement in patients with SZ.

Smoke, GPx activity and symptoms improvement in patients with drug-naive first-episode schizophrenia: A large-scale 12-week follow-up study

The relationship between tobacco smoke and schizophrenia (SZ) is well established. Smoking is hypothesized to alleviate symptoms and reduce the adverse effects of antipsychotic medications in patients with SZ. However, the underlying biological mechanisms by which smoke improves symptoms in SZ remain unclear. The aim of this study was to investigate the effect of smoking on clinical symptoms and antioxidant enzyme activity after risperidone treatment in a 12-week prospective cohort study of drug-naïve first-episode (DNFE) SZ patients. Two hundred and fifteen DNFE patients were recruited and received 12 weeks of risperidone monotherapy. The Positive and Negative Syndrome Scale (PANSS) was used to assess the severity of patient's symptoms at baseline and post-treatment. Plasma GPx activity was also measured at baseline and at the end of 12 weeks. Smokers showed greater improvement in negative symptoms relative to nonsmokers with DNFE SZ. In addition, repeated ANCOVA analysis showed no significant interaction of time and group on GPx activity. Improvement in negative symptoms was not associated with changes in GPx activity. However, in nonsmokers, increased GPx activity was correlated with improvement in positive symptoms.

Influence of glutathione-related genetic variants in oxidative stress profile of Mexican patients with psychotic disorders

OBJECTIVE

Patients with psychotic disorders (PD) exhibit divergent outcomes in their clinical trajectories, which in part may result from glutathione (GSH)-related high-risk genotypes affecting their clinical course. We aimed to determine clozapine pharmacokinetic parameters, GSH levels, GSH peroxidase (GPx) activity, variants of genes involved in the synthesis and metabolism of GSH and its association with PD in Mexican patients on clozapine treatment and controls.

METHODS

75 PD patients on clozapine therapy and 40 paired healthy controls were included. Plasma clozapine/N-desmethylclozapine, GSH concentrations and GPx activity were determined, along with genotyping of GCLC and GSTP1 variants and copy number variations of GSTP1, GSTT1 and GSTM1. Clinical, molecular and biochemical data were analyzed by a logistic regression model.

RESULTS

GSH levels were significantly reduced and, conversely, GPx activity was higher in PD patients compared to controls. GCLC_GAG-7/9 genotype (OR=4.3, CI95=1.40-14.31, p=0.019) and hetero-/homozygous genotypes of GCLC_rs761142 (OR=6.09, CI95=1.93-22.59, p=0.003) were found as risk factors for psychosis. The genetic variants were not related to clozapine/N-desmethylclozapine levels or to metabolic ratio.

CONCLUSIONS

GCLC variants were associated with the oxidative stress profile of PD patients raising opportunities for intervention to improve their antioxidant defenses. Further studies with larger samples should explore this proposal.

Decreased Activity of Erythrocyte Catalase and Glutathione Peroxidase in Patients with Schizophrenia

Background and Objectives: Catalase and glutathione peroxidase (GPx) are important antioxidant enzymes that break down hydrogen peroxide (H2O2) in order to control its intracellular concentration, thus enabling its physiological role and preventing toxic effects. A lack or disruption of their function leads to the accumulation of hydrogen peroxide and the occurrence of oxidative stress. Accumulating studies have shown that the activities of key antioxidant enzymes are impaired in patients with schizophrenia. Since the published results are contradictory, and our previous studies found significantly higher erythrocyte superoxide dismutase (SOD) activity in patients with schizophrenia, the aim of this study was to determine the activity of enzymes that degrade hydrogen peroxide in the same group of patients, as well as to examine their dependence on clinical symptoms, therapy, and parameters associated with this disease. Materials and Methods: Catalase and GPx activities were determined in the erythrocytes of 68 inpatients with schizophrenia and 59 age- and gender-matched healthy controls. The clinical assessment of patients was performed by using the Positive and Negative Syndrome Scale (PANSS). The catalase activity was measured by the kinetic spectrophotometric method, while the GPx activity was determined by the commercially available Ransel test. Results: Erythrocyte catalase and GPx activities were significantly lower (p < 0.001 and p < 0.01, respectively) in subjects with schizophrenia than they were in healthy individuals. Lower catalase activity does not depend on heredity, disease onset, the number of episodes, or disease duration, while GPx activity showed significant changes in patients who had more than one episode and in those who had been suffering from the disease for over a year. Significantly lower catalase activity was noted in the PANSS(+/−) group in comparison with the PANSS(+) and PANSS(−) groups. The lowest catalase activity was found in subjects who were simultaneously treated with first- and second-generation antipsychotics; this was significantly lower than it was in those who received only one class of antipsychotics. Conclusion: These results indicate the presence of oxidative stress in the first years of clinically manifested schizophrenia and its dependence on the number of psychotic episodes, illness duration, predominant symptomatology, and antipsychotic medication.

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.

Sex-Specific Association between Antioxidant Defense System and Therapeutic Response to Risperidone in Schizophrenia: A Prospective Longitudinal Study

BACKGROUND

There are various differences in response to different antipsychotics and antioxidant defense systems (ADS) by sex. Previous studies have shown that several ADS enzymes are closely related to the treatment response of patients with antipsychotics-naïve first-episode (ANFE) schizophrenia.

OBJECTIVE

Therefore, the main goal of this study was to assess the sex difference in the relationship between changes in ADS enzyme activities and risperidone response.

METHODS

The plasma activities of glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), and total antioxidant status (TAS) were measured in 218 patients and 125 healthy controls. Patients were treated with risperidone for 3 months, and we measured PANSS for psychopathological symptoms and ADS biomarkers at baseline and at the end of 3 months of treatment. We compared sex-specific group differences between 50 non-responders and 168 responders at baseline and at the end of the three months of treatment.

RESULTS

We found that female patients responded better to risperidone treatment than male patients. At baseline and 3-month follow-up, there were no significant sex differences in TAS levels and three ADS enzyme activities. Interestingly, only in female patients, after 12 weeks of risperidone treatment, the GPx activity of responders was higher than that of non-responders.

CONCLUSION

These results indicate that after treatment with risperidone, changes in GPx activity were associated with treatment response, suggesting that changes in GPx may be a predictor of response to risperidone treatment in female patients with ANFE schizophrenia.

Plasma linoelaidyl carnitine levels positively correlated with symptom improvement in olanzapine-treated first-episode drug-naïve schizophrenia

INTRODUCTION

Olanzapine (OLA) is one of the most commonly used second-generation antipsychotics for the treatment of schizophrenia. However, the heterogeneity of therapeutic response to OLA among schizophrenia patients deserves further exploration. The role of carnitine in the clinical response to OLA monotherapy remains unclear.

OBJECTIVES

The current study was designed to investigate whether carnitine and its derivatives are linked to the response to OLA treatment. Drug-naïve first-episode patients with schizophrenia were recruited and treated with OLA for 4 weeks. Psychiatric symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS) in pre and post treatment.

RESULTS

After treatment, we found a significant decrease in 2-Octenoylcarnitine levels and a significant increase in linoelaidyl carnitine, 11Z-Octadecenylcarnitine and 9-Decenoylcarnitine levels. Furthermore, baseline linoelaidyl carnitine levels were correlated with the reduction of PANSS positive symptom subscore. Linear regression and logistic regression analyses found that the baseline linoelaidyl carnitine level was a predictive marker for the therapeutic response to OLA monotherapy for 4 weeks.

CONCLUSION

Our pilot study suggests that linoelaidyl carnitine levels at baseline may have a predictive role for the improvement of positive symptoms after OLA monotherapy in the patients with schizophrenia.

Association between Changes in Total Antioxidant Levels and Clinical Symptom Improvement in Patients with Antipsychotic-Naïve First-Episode Schizophrenia after 3 Months of Risperidone Monotherapy

Schizophrenia (SCZ) is associated with aberrant redox regulation in the early stages of brain development. There is growing evidence that the antioxidant defense system is closely associated with the therapeutic response to antipsychotics in SCZ patients. The aim of this study was to examine the effect of risperidone monotherapy on total antioxidant status (TAS) and the relationship between symptom improvement and changes in TAS in patients with antipsychotic-naïve first-episode (ANFE) SCZ. Clinical symptoms were evaluated using the Positive and Negative Syndrome Scale (PANSS). Two hundred and forty-six ANFE patients were treated with risperidone for 3 months. PANSS and TAS levels were assessed at baseline and at a 3-month follow-up. Relative to healthy controls, ANFE patients had higher TAS levels, which increased even further during the treatment. Moreover, baseline TAS levels were a predictor of symptom reduction after risperidone treatment. In addition, there was a significant association between increased TAS levels and the decreased cognitive factor. Our findings suggest that antioxidant protection is possibly associated with clinical improvement in ANFE patients after risperidone treatment.

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.

Pro/Antioxidant State as a Potential Biomarker of Schizophrenia

To allow better diagnosis and management of psychiatric illnesses, the use of easily accessible biomarkers are proposed. Therefore, recognition of some diseases by a set of related pathogenesis biomarkers is a promising approach. The study aims to assess the usefulness of examining oxidative stress (OS) in schizophrenia as a potential biomarker of illness using the commonly used data mining decision tree method. The study group was comprised of 147 participants: 98 patients with schizophrenia (SZ group), and the control group (n = 49; HC). The patients with schizophrenia were divided into two groups: first-episode schizophrenia (n = 49; FS) and chronic schizophrenia (n = 49; CS). The assessment included the following biomarkers in sera of patients: catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase-1 (SOD-1), glutathione reductase (GR), reduced glutathione (GSH), total antioxidant capacity (TAC), ferric reducing ability of plasma (FRAP), advanced glycation end products (AGEs), advanced oxidation protein products (AOPP), dityrosine (DITYR), kynurenine (KYN), N-formylkynurenine (NFK), tryptophan (TRY), total oxidant status (TOS), nitric oxide (NO) and total protein. Maximum accuracy (89.36%) for distinguishing SZ from HC was attained with TOS and GPx (cut-off points: 392.70 and 15.33). For differentiating between FS and CS, the most promising were KYN, AOPP, TAC and NO (100%; cut-off points: 721.20, 0.55, 64.76 and 2.59). To distinguish FS from HC, maximum accuracy was found for GSH and TOS (100%; cut-off points: 859.96 and 0.31), and in order to distinguish CS from HC, the most promising were GSH and TOS (100%; cut-off points: 0.26 and 343.28). Using redox biomarkers would be the most promising approach for discriminating patients with schizophrenia from healthy individuals and, in the future, could be used as an add-on marker to diagnose and/or respond to treatment.

Factor analysis of the relationship between PANSS score and family burden of patients with schizophrenia

This study aims to investigate the burden of family caregivers of patients with schizophrenia, and its influencing factors METHODS: A total of 105 patients with schizophrenia and their caregivers were investigated using the positive and negative symptom scale (PANSS) and family burden scale of disease (FBS) RESULTS: There was a strong correlation between the patient's recovery and family burden, especially between positive and negative symptoms and family financial burden, family daily activities, family recreational activities, and family relationship CONCLUSION: There is a strong correlation between the patient's recovery and family burden, and this is especially correlated to family economic burden, family daily activities, family recreational activities, and family relationship. Medical staff should pay attention to the psychological characteristics of patients and fully understand and avoid the adverse effects of family burden on the rehabilitation of patients.