Assessment of malondialdehyde levels in schizophrenia: a meta-analysis and some methodological considerations

Biomarkers for Psychosis: Are We There Yet? Umbrella Review of 1478 Biomarkers

Background and Hypothesis

This umbrella review aims to comprehensively synthesize the evidence of association between peripheral, electrophysiological, neuroimaging, neuropathological, and other biomarkers and diagnosis of psychotic disorders.

Study Design

We selected systematic reviews and meta-analyses of observational studies on diagnostic biomarkers for psychotic disorders, published until February 1, 2018. Data extraction was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Evidence of association between biomarkers and psychotic disorders was classified as convincing, highly suggestive, suggestive, weak, or non-significant, using a standardized classification. Quality analyses used the Assessment of Multiple Systematic Reviews (AMSTAR) tool.

Study Results

The umbrella review included 110 meta-analyses or systematic reviews corresponding to 3892 individual studies, 1478 biomarkers, and 392 210 participants. No factor showed a convincing level of evidence. Highly suggestive evidence was observed for transglutaminase autoantibodies levels (odds ratio [OR] = 7.32; 95% CI: 3.36, 15.94), mismatch negativity in auditory event-related potentials (standardized mean difference [SMD] = 0.73; 95% CI: 0.5, 0.96), P300 component latency (SMD = -0.6; 95% CI: -0.83, -0.38), ventricle-brain ratio (SMD = 0.61; 95% CI: 0.5, 0.71), and minor physical anomalies (SMD = 0.99; 95% CI: 0.64, 1.34). Suggestive evidence was observed for folate, malondialdehyde, brain-derived neurotrophic factor, homocysteine, P50 sensory gating (P50 S2/S1 ratio), frontal N-acetyl-aspartate, and high-frequency heart rate variability. Among the remaining biomarkers, weak evidence was found for 626 and a non-significant association for 833 factors.

Conclusions

While several biomarkers present highly suggestive or suggestive evidence of association with psychotic disorders, methodological biases, and underpowered studies call for future higher-quality research.

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.

Elevated activity of superoxide dismutase in male late-life schizophrenia and its correlation with clinical symptoms and cognitive deficits

BACKGROUND

Despite inconsistent findings, accumulative evidence has shown abnormalities of the key antioxidant enzyme, superoxide dismutase (SOD), in patients with schizophrenia. However, few studies explored SOD in late-life schizophrenia (LLS). Our work aimed to investigate changes in SOD activity and the relationship between SOD activity and psychotic symptoms or cognitive deficits in LLS.

METHODS

32 geriatric male patients with schizophrenia (age ≥ 60) and 28 age-matched male normal controls were recruited in the study. We assessed cognitive functions with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), evaluated the severity of clinical symptoms with the Positive and Negative Syndrome Scale (PANSS), and measured the plasma levels of SOD.

RESULTS

Patients with LLS presented with higher total levels of SOD compared to the controls (81.70 vs. 65.26 U/ml, p < .001). Except for the visuospatial index, the cognitive performance was significantly worse on RBANS total and other domain scores in the schizophrenia group than the control group. In the schizophrenia group, SOD levels were positively correlated with subscores of general psychopathology and negative symptoms and total scores of the PANSS (all p < .05), and inversely associated with performance in immediate memory, language, and RBANS total scores (all p < .05).

CONCLUSIONS

Our findings suggest that patients with LLS display disturbances in the antioxidant system, which may underlie the pathological process of cognitive impairments and negative symptoms in the late stage of schizophrenia. Supplementing with antioxidants could be a potential treatment.

Efficacof Cinnamon Extract (Cinnamomum burmannii) as Supplementation in Lir-psychotic-induced Rats through Oxidative Stress Regulation in Neuronal Cells

BACKGROUND: Cinnamon is a plant that is often found in Indonesia and is rich in secondary metabolites such as flavonoids, phenols, tannins, and alkaloids. Flavonoids and phenols are very potential as natural antioxidants to suppress various oxidant activities, including oxidant activity that occurs in the hippocampus, which is the underlying psychotic disorder. AIM: This study was aimed to explore the potential of cinnamon extract (CE) on psychotic symptoms. METHODS: Cinnamon simplicia was obtained from the Research and Testing Center for Traditional Medicine, Tawangmangu, Central Java, Indonesia. The extraction of cinnamon was carried out using the maceration method. The animals were subjected to lir-psychotic induction by intraperitoneal injection with ketamine (30 mg/kg BW) for 5 days. The rats were grouped into six groups; each group contained five animals; normal control group, a lir-psychotic group without treatment, lir-psychotic group with haloperidol, lir-psychotic with CE (25 mg/kg BW, 50 mg/kg BW, and 100 mg/kg BW). Oxidative stress in experimental animals was measured by evaluating malondialdehyde (MDA) expression in the brain tissue using immunohistochemical tests. RESULTS: There were differences in clinical symptoms of psychotic disorder in the animal model between before intervention with CE supplementation and after the intervention. The higher the CE dose administered, the better the improvement in psychotic symptoms seen in the psychotic-induced rats. CE supplementation could reduce MDA expression in the hippocampus. This suggests that there was an optimal significance of cinnamon supplementation in reducing oxidative stress from the hippocampus. CONCLUSION: CE was effective in improving psychotic symptoms in lir-psychotic rats through regulation of oxidative stress in neuronal cells.

Glutathione peroxidase-1 and neuromodulation: Novel potentials of an old enzyme

Glutathione peroxidase (GPx) acts in co-ordination with other signaling molecules to exert its own antioxidant role. We have demonstrated the protective effects of GPx,/GPx-1, a selenium-dependent enzyme, on various neurodegenerative disorders (i.e., Parkinson's disease, Alzheimer's disease, cerebral ischemia, and convulsive disorders). In addition, we summarized the recent findings indicating that GPx-1 might play a role as a neuromodulator in neuropsychiatric conditions, such as, stress, bipolar disorder, schizophrenia, and drug intoxication. In this review, we attempted to highlight the mechanistic scenarios mediated by the GPx/GPx-1 gene in impacting these neurodegenerative and neuropsychiatric disorders, and hope to provide new insights on the therapeutic interventions against these disorders.

Oxidative Stress-Related Mechanisms in Schizophrenia Pathogenesis and New Treatment Perspectives

Schizophrenia is recognized to be a highly heterogeneous disease at various levels, from genetics to clinical manifestations and treatment sensitivity. This heterogeneity is also reflected in the variety of oxidative stress-related mechanisms contributing to the phenotypic realization and manifestation of schizophrenia. At the molecular level, these mechanisms are supposed to include genetic causes that increase the susceptibility of individuals to oxidative stress and lead to gene expression dysregulation caused by abnormal regulation of redox-sensitive transcriptional factors, noncoding RNAs, and epigenetic mechanisms favored by environmental insults. These changes form the basis of the prooxidant state and lead to altered redox signaling related to glutathione deficiency and impaired expression and function of redox-sensitive transcriptional factors (Nrf2, NF-κB, FoxO, etc.). At the cellular level, these changes lead to mitochondrial dysfunction and metabolic abnormalities that contribute to aberrant neuronal development, abnormal myelination, neurotransmitter anomalies, and dysfunction of parvalbumin-positive interneurons. Immune dysfunction also contributes to redox imbalance. At the whole-organism level, all these mechanisms ultimately contribute to the manifestation and development of schizophrenia. In this review, we consider oxidative stress-related mechanisms and new treatment perspectives associated with the correction of redox imbalance in schizophrenia. We suggest that not only antioxidants but also redox-regulated transcription factor-targeting drugs (including Nrf2 and FoxO activators or NF-κB inhibitors) have great promise in schizophrenia. But it is necessary to develop the stratification criteria of schizophrenia patients based on oxidative stress-related markers for the administration of redox-correcting treatment.

Inflammation and JNK's Role in Niacin-GPR109A Diminished Flushed Effect in Microglial and Neuronal Cells With Relevance to Schizophrenia

Schizophrenia is a neuropsychiatric illness with no single definitive aetiology, making its treatment difficult. Antipsychotics are not fully effective because they treat psychosis rather than the cognitive or negative symptoms. Antipsychotics fail to alleviate symptoms when patients enter the chronic stage of illness. Topical application of niacin showed diminished skin flush in the majority of patients with schizophrenia compared to the general population who showed flushing. The niacin skin flush test is useful for identifying patients with schizophrenia at their ultra-high-risk stage, and understanding this pathology may introduce an effective treatment. This review aims to understand the pathology behind the diminished skin flush response, while linking it back to neurons and microglia. First, it suggests that there are altered proteins in the GPR109A-COX-prostaglandin pathway, inflammatory imbalance, and kinase signalling pathway, c-Jun N-terminal kinase (JNK), which are associated with diminished flush. Second, genes from the GPR109A-COX-prostaglandin pathway were matched against the 128-loci genome wide association study (GWAS) for schizophrenia using GeneCards, suggesting that G-coupled receptor-109A (GPR109A) may have a genetic mutation, resulting in diminished flush. This review also suggests that there may be increased pro-inflammatory mediators in the GPR109A-COX-prostaglandin pathway, which contributes to the diminished flush pathology. Increased levels of pro-inflammatory markers may induce microglial-activated neuronal death. Lastly, this review explores the role of JNK on pro-inflammatory mediators, proteins in the GPR109A-COX-prostaglandin pathway, microglial activation, and neuronal death. Inhibiting JNK may reverse the changes observed in the diminished flush response, which might make it a good therapeutic target.

Histogenous Hypoxia and Acid Retention in Schizophrenia: Changes in Venous Blood Gas Analysis and SOD in Acute and Stable Schizophrenia Patients

Background: Oxidative stress may play an important role in the pathogenesis of schizophrenia (SCH), and there is considerable indirect evidence that hypoxia is closely related to SCH, but direct evidence of hypoxia in SCH has never been found. Methods:In this study, superoxide dismutase (SOD), venous blood gas, and Positive and Negative Syndrome Scale (PANSS) were examined in 40 SCH patients and compared with those of 40 healthy controls. The patients were treated with combination of atypical antipsychotics and Ditan Huayu Lishen decoction (a Chinese medicine decoction) and examined in the acute and stable period, respectively. Comparisons of indicators between two groups were performed using an independent-samples t-test, comparison of indicators between the acute and stable periods in the SCH group was performed using paired-samples t-test. Pearson correlation and multiple linear regression analyses were performed to investigate the relationships between the effect indicators. Results: Higher venous pH, PvO₂, and fasting blood glucose levels and lower SOD, lactic acid, and PvCO₂ levels were found in SCH patients compared with the control group; SOD was negatively correlated with the general psychopathology subscale score (PANSS-G), and PvO₂ levels were closely related to venous pH in SCH and related to PvCO₂ in the control group. It was also found that SOD activity showed no significant difference in acute and stable period, whereas PvO₂ showed a downward trend, and venous pH was decreased significantly after treatment. Both the venous pH and PvO₂ were higher in patients with SCH than that in healthy controls. Conclusion: It suggests that histogenous hypoxia and acid retention exist in relation to SCH, and there is an improvement of acid retention and a downward trend in histogenous hypoxia after combination treatment. Venous pH, PvO₂, and PvCO₂ are trait variables, but not state variables of SCH. The theory of histogenous hypoxia and acid retention can well explain the decrease in pH value and the increase in lactic acid in brain tissue of patients with SCH. Histogenous hypoxia and acid retention closely related to glucose metabolism. So they may play an important role in pathophysiology for SCH.

Comparative Study of the Effects of Atypical Antipsychotic Drugs on Plasma and Urine Biomarkers of Oxidative Stress in Schizophrenic Patients

PURPOSE

Evidence that antipsychotic drugs (ADs) can affect oxidative stress estimated with various biomarkers in schizophrenic patients is controversial and limited. Therefore, in the present study, we assessed the ability of six atypical ADs (clozapine, olanzapine, quetiapine, risperidone, aripiprazole, and ziprasidone) used in schizophrenia treatment to modulate oxidative damage to different biomolecules such as lipids and proteins.

PATIENTS AND METHODS

We measured the levels of oxidative stress markers in plasma and urine: total antioxidant capacity by FRAP (according to a modified method of Benzie & Strain), thiobarbituric acid reactive species - TBARS (spectrophotometric method), 4-hydroxy-2-nonenal (4-HNE) (OxiSelect™ HNE Adduct Competitive ELISA Kit), 3-nitrotyrosine (3-NT) (OxiSelect™ Nitrotyrosine ELISA Kit) in plasma, and F2-isoprostanes (BIOXYTECH^® Urinary 8-epi-Prostaglandin F2α) in the urine of 60 schizophrenic patients (before and after treatment) and in 30 healthy subjects.

RESULTS

Our results showed that in schizophrenic patients levels of lipid peroxidation markers (TBARS, F2-isoprostanes) were higher than in healthy subjects but FRAP in schizophrenic patients was lower than in healthy controls and increased after 4-week treatment with tested ADs. A 4-week treatment with ADs caused the improvement of psychopathology symptoms estimated by Positive and Negative Syndrome Scale (PANSS) that was accompanied by decreased lipid peroxidation (F2-isoprostanes, TBARS; p=2.9x10^-6, p=7.6x10^-5, respectively) and an increase in total antioxidative capacity (FRAP) (p=5.16x10^-16).

CONCLUSION

Atypical antipsychotics especially clozapine, olanzapine and quetiapine demonstrate the effective outcome of antipsychotic treatment, beneficial antioxidative action by reducing lipid peroxidation and increased total plasma antioxidant activity.

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.

DNA damage and repair in neuropsychiatric disorders. What do we know and what are the future perspectives?

Over the past two decades, extensive research has been done to elucidate the molecular etiology and pathophysiology of neuropsychiatric disorders. In majority of them, including Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), bipolar disorder (BD), schizophrenia and major depressive disorder, increased oxidative and nitrosative stress was found. This stress is known to induce oxidative damage to biomolecules, including DNA. Accordingly, increased mitochondrial and nuclear DNA, as well as RNA damage, were observed in patients suffering from these diseases. However, recent findings indicate that the patients are characterised by impaired DNA repair pathways, which may suggest that these DNA lesions could be also a result of their insufficient repair. In the current systematic, critical review, we aim to sum up, using available literature, the knowledge about the involvement of nuclear and mitochondrial DNA damage and repair, as well as about damage to RNA in pathoetiology of neuropsychiatric disorders, i.e., AD, PD, ALS, BD, schizophrenia and major depressive disorder, as well as the usefulness of the discussed factors as being diagnostic markers and targets for new therapies. Moreover, we also underline the new directions to which future studies should head to elucidate these phenomena.

Serum Oxidative Stress Marker Levels in Unmedicated and Medicated Patients with Schizophrenia

Oxidative stress has been suggested to be involved in schizophrenia, but studies have demonstrated inconsistent results on oxidative stress marker level/activity in patients with schizophrenia. In order to clarify the circulating oxidative stress marker level/activity in patients with schizophrenia, this study recruited 80 schizophrenia patients (40 first-episode, drug-free and 40 chronically medicated patients) and 80 controls to analyze serum activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC), and levels of lipid peroxidation marker malondialdehyde (MDA) in schizophrenia patients, and whether they associate with the severity of the disease. We showed that only serum GSH-Px activity was significantly reduced in unmedicated patients with schizophrenia when compared with control subjects, whereas the other three analyzed oxidative stress markers did not show significant differences between cases and controls. Moreover, our results demonstrated that chronic medication increased GSH-Px activity and MDA levels in patients with schizophrenia, but reduced SOD activity in the patients. We also found that short-term antipsychotic treatments on the patients with schizophrenia reduced the SOD activity. Correlation analyses indicated that the oxidative stress marker activity/level is not significantly associated with the severity of schizophrenia, except that SOD level correlated with PANSS positive score significantly. Taken together, the data from the present study suggested that the dysfunctions of oxidative stress markers in patients with schizophrenia were mainly caused by antipsychotics, emphasizing increased oxidative stress as a potential side effect of antipsychotics on the patients.

Thiol/disulphide homeostasis in bipolar disorder

Bipolar disorder (BD) patients have increased oxidative stress, which can disturb thiol/disulphide homeostasis, causing disulphide formation. The aim of the study is to investigate dynamic thiol/disulphide (SH/SS) homeostasis in BD patients, which is a novel evaluation method of oxidative status. Ninety-four BD patients (50 in the manic episode and 44 in remission) and 44 healthy controls were included in the study. Blood serum native thiol (SH) and total thiol (ToSH) concentrations were measured in a paired test. The half value of the difference between native thiol and total thiol concentrations was calculated as the disulphide (SS) bond amount. Serum native thiol levels of the mania group were found to be lower than the remission and the control groups. There was a significant difference between the remission group and the control group in terms of native thiol. Serum total thiol level was lower in mania group than the control group. Detection of oxidative molecules for BD could be helpful, especially in treatment, follow-up periods and reducing morbidity. The results of our study besides the data available in the literature support that thiol and disulphide levels are useful markers for BD and promising therapeutic targets in terms of future pharmacological modulation.

The Diagnostic Value of Malondialdehyde, Superoxide Dismutase and Catalase Activity in Drug Naïve, First Episode, Non-Smoker Generalized Anxiety Disorder Patients

Objective

Generalized anxiety disorder (GAD) is a common anxiety disorder. Although lots of research done to reveal neurobiological basis of GAD, it is still unclear. Diagnosis of GAD depends on subjective complaints of patients, thus the need for a biological marker is constantly emerging. In this study, we aimed to investigate diagnostic value of malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) in GAD.

Methods

We evaluated MDA, SOD, and CAT levels in peripheral blood of 46 patients and 45 controls. MDA was measured with Ohkawa’s methods, SOD was measured with Fridovich method, and CAT was measured with Beutler’s method.

Results

MDA was significantly increased in patients than controls, medians 4.05 nmol/mg and 1.71 nmol/mg respectively, p<0.001; SOD and CAT activity was significantly decreased in patients than controls, medians of SOD were 159.07 U/mg and 301.87 U/mg, p<0.001 respectively, medians for CAT were 138.47 U/mg and 160.60 U/mg respectively. We found high correlation between Hamilton Anxiety Rating Scale and SOD, MDA r values were 0.723 and 0.715 respectively, p<0.001 for both. Receiver operator characteristic (ROC) curve analysis showed high diagnostic performance for MDA and SOD, low diagnostic performance for CAT, areas under curve were 1.0, 1.0, and 0.648 respectively.

Conclusion

Our results reveal possible diagnostic value of MDA, less likely of SOD but not CAT. Future studies should investigate diagnostic value of oxidants and antioxidantn enzymes in larger samples and include diagnostic value of these parameters.

The interplay between inflammation, oxidative stress, DNA damage, DNA repair and mitochondrial dysfunction in depression

A growing body of evidence suggests that inflammation, mitochondrial dysfunction and oxidant-antioxidant imbalance may play a significant role in the development and progression of depression. Elevated levels of reactive oxygen and nitrogen species - a result of oxidant-antioxidant imbalance - may lead to increased damage of biomolecules, including DNA. This was confirmed in depressed patients in a research study conducted by our team and other scientists. 8-oxoguanine - a marker of oxidative DNA damage - was found in the patients' lymphocytes, urine and serum. These results were confirmed using a comet assay on lymphocytes. Furthermore, it was shown that the patients' cells repaired peroxide-induced DNA damage less efficiently than controls' cells and that some single nucleotide polymorphisms (SNP) of the genes involved in oxidative DNA damage repair may modulate the risk of depression. Lastly, less efficient DNA damage repair observed in the patients can be, at least partly, attributed to the presence of specific SNP variants, as it was revealed through a genotype-phenotype analysis. In conclusion, the available literature shows that both oxidative stress and less efficient DNA damage repair may lead to increased DNA damage in depressed patients. A similar mechanism may result in mitochondrial dysfunction, which is observed in depression.

Redox dysregulation, immuno-inflammatory alterations and genetic variants of BDNF and MMP-9 in schizophrenia: Pathophysiological and phenotypic implications

BACKGROUND

Although a clear mechanism underlying the pathophysiology of schizophrenia (SZ) remains elusive, oxidative stress, inflammatory syndrome and immune activation have become an attractive hypothesis for explaining the pathophysiology of SZ. Data from prior studies on the role of matrix metalloproteinase 9 (MMP-9) and brain-derived neurotrophic factor (BDNF) single nucleotide polymorphisms (SNPs) in SZ are contradictory. We aimed to investigate whether oxidative stress, inflammatory and immune activation markers as well as MMP-9 levels may be implicated in SZ pathogenesis. The association of MMP-9 and BDNF SNPs with the clinical expression of SZ was examined.

SUBJECTS AND METHODS

Ninety-four subjects were recruited, including 44 SZ patients and 50 healthy controls. Serum levels of thiobarbituric acid reactive substances (TBARS), protein carbonyl content (PCC), nitrite, C-reactive protein (CRP), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), Beta-2 microglobulin (Β2M), complement component 3 (C3), C4 and MMP-9 were measured. The MMP-9 -1562C>T and BDNF196G>A SNPs were genotyped using polymerase chain reaction-restriction fragment length polymorphism assay. Psychopathology was assessed using the positive and negative syndrome scale (PANSS).

RESULTS

SZ patients showed significantly higher TBARS, PCC, nitrite, CRP, IL-6, TNF-α, Β2M, C3 and MMP-9 levels than controls. In distinguishing SZ patients from healthy controls, CRP and MMP-9 yielded similar discriminatory performance, and both perform better than IL-6, Β2M, C3, nitrite, TBARS, PCC, TNF-α and C4. The MMP-9 -1562C>T SNP genotypes distribution didn't differ significantly between controls and SZ patients. As compared to controls, SZ patients harbor a significantly higher frequency of the BDNF196GG genotype and a lower frequency of the BDNF196GA/AA genotype. Patients carrying the MMP-9 -1562CC or BDNF196GG genotype revealed a significantly higher PANSS than those carrying MMP-9 -1562CT/TT or BDNF196GA/AA genotype. Male gender and the MMP-9 -1562CC genotype were identified as independent predictive factors for higher PANSS.

CONCLUSIONS

Redox dysregulation and alterations in the immuno-inflammatory pathways are major culprits in the pathogenesis of SZ. MMP-9 and BDNF SNPs are associated with the clinical phenotype of SZ and, thus, may be a useful marker predicting the phenotypic expression and prognosis of SZ patients.

Evaluation of Paraoxonase, Arylesterase and Malondialdehyde Levels in Schizophrenia Patients Taking Typical, Atypical and Combined Antipsychotic Treatment

Objective

Human serum paraoxonase (PON1) prevents lipids from peroxidation and functions as an antioxidant mechanism. Malonyldialdehyde (MDA) is the final product of lipid peroxidation and can be used as an indicator of oxidative stress. The aim of this study was to investigate PON1, MDA, and arylesterase (ARY) levels in schizophrenic patients who are taking typical, atypical, or combined (typical and atypical) antipsychotic drug treatment, with respect to those of healthy controls.

Methods

We evaluated 41 patients (11 taking typical antipsychotics, 19 taking atypical antipsychotics, 11 taking combined anti-psychotics) and 43 healthy controls.

Results

MDA levels were higher in schizophrenic patients taking typical antipsychotics compared with healthy controls (p=0.001). ARY levels were higher in patients taking atypical antipsychotics compared with healthy controls (p=0.005). PON1 activity was similar in all groups.

Conclusion

Our results indicate that treatment with typical antipsychotic drugs could be related to increased MDA levels; and antipsychotic medication may increase PON1 levels in schizophrenic patients.

Impaired fornix-hippocampus integrity is linked to peripheral glutathione peroxidase in early psychosis

Several lines of evidence implicate the fornix-hippocampus circuit in schizophrenia. In early-phase psychosis, this circuit has not been extensively investigated and the underlying mechanisms affecting the circuit are unknown. The hippocampus and fornix are vulnerable to oxidative stress at peripuberty in a glutathione (GSH)-deficient animal model. The purposes of the current study were to assess the integrity of the fornix-hippocampus circuit in early-psychosis patients (EP), and to study its relationship with peripheral redox markers. Diffusion spectrum imaging and T1-weighted magnetic resonance imaging (MRI) were used to assess the fornix and hippocampus in 42 EP patients compared with 42 gender- and age-matched healthy controls. Generalized fractional anisotropy (gFA) and volumetric properties were used to measure fornix and hippocampal integrity, respectively. Correlation analysis was used to quantify the relationship of gFA in the fornix and hippocampal volume, with blood GSH levels and glutathione peroxidase (GPx) activity. Patients compared with controls exhibited lower gFA in the fornix as well as smaller volume in the hippocampus. In EP, but not in controls, smaller hippocampal volume was associated with high GPx activity. Disruption of the fornix-hippocampus circuit is already present in the early stages of psychosis. Higher blood GPx activity is associated with smaller hippocampal volume, which may support a role of oxidative stress in disease mechanisms.

Relationship between neutrophil/lymphocyte ratio with oxidative stress and psychopathology in patients with schizophrenia

INTRODUCTION

The aim of our study was to evaluate the relationship between neutrophil/lymphocyte ratio (NLR) and total antioxidant status (TAS), total oxidative status (TOS), oxidative stress index (OSI), paraoxonase, and total thiol (T.thl) in schizophrenic patients compared to healthy control group and investigate the relationship between these parameters and psychopathological symptoms.

METHODS

The study population consisted of 61 healthy control subjects and 64 volunteer patients monitored in the outpatient clinics of psychiatry of Antalya Education and Research Hospital. Hemograms were determined by using a fully automated hematology analyzer (Beckman Coulter LH780). Serum TOS, TAS, paraoxonase, and T.thl were measured using a novel automated colorimetric measurement method developed by Erel. Sociodemographic data forms were completed by the participants. The Positive and Negative Syndrome Scale (PANSS) was used to assess the patients.

RESULTS

Neutrophils, NLR, TAS, and TOS significantly increased, whereas lymphocytes, T.thl, and T.thl/OSI ratio were significantly lower in the schizophrenia patient group compared to the control group. A statistically significant positive relationship was found between PANSS positive subscale with leukocytes and significantly negative relationships were found between PANSS positive subscale with lymphocytes and T.thl/OSI ratio. Significant positive relationships were found between PANSS total subscale with leukocytes and NLR. Statistically significant negative relationships were found between PANSS total subscale with lymphocytes and T.thl/OSI ratio. In the group of patients with schizophrenia, a significant negative correlation was found between NLR with T.thl/OSI. In the group of patients with schizophrenia, a significant positive correlation was found between NLR with TOS and OSI.

CONCLUSION

By measuring NLR, which is simple, inexpensive, and suitable for routine use, we can obtain information about oxidative stress and psychopathological symptoms in patients with schizophrenia. Inflammation and oxidative stress are important in the pathogenesis of schizophrenia and are closely related with the patients' clinical symptoms.

Agomelatine Protection in an LPS-Induced Psychosis-Relevant Behavior Model

BACKGROUND The aim of this study was to investigate the effect of agomelatine in a psychosis-relevant behavior model. MATERIAL AND METHODS We used 18 adult male Wistar rats in this study. Twelve rats given LPS for endotoxemia were randomly divided into 2 groups (n=6). Group I was treated with 1 mL/kg 0.9% NaCl i.p. and Group II was treated with 40 mg/kg agomelatine. Six normal rats served as the control group and were not given LPS for endotoxemia. Cylindrical steel cages containing vertical and horizontal metal bars with top cover were used. Rats were put in these cages for the purpose of orientation for 10 min. Apomorphine was given to rats removed from cages, and then they were immediately put back in the cages for the purpose of observing stereotyped conduct. Brain HVA levels and plasma TNF-a levels were evaluated in tissue homogenates using ELISA. The proportion of malondialdehyde (MDA) was measured in samples taken from plasma for detection of lipid peroxidation similar to thiobarbituric acid reactive substances. RESULTS LPS induced-plasma TNF-α, brain TNF-α, and plasma MDA levels were significantly lower in the LPS+agomelatine group compared to the LPS+saline group (p<0.05). HVA levels and stereotype scores were significantly lower in the LPS+agomelatine group compared to the LPS+saline group (p <0.001). CONCLUSIONS Agomelatine reduced TNF-α, HVA, MDA levels, and the stereotype score in relevant models of psychosis. Our results suggest that the anti-inflammatory effect of agomelatine involved oxidant cleansing properties and that its effects on the metabolism of dopamine can play an important role in the model of psychosis.

The Antipsychotic Effects of Omega-3 Fatty Acids in Rats

BACKGROUND

In humans, omega-3 fatty acids are necessary for cell membranes, brain function and nerve transmission continuation. When animals are exposed to a new environment-or as a result of an apomorphine application that creates an agonistic effect on D1 and D2 receptors-they display behavioral reactions like rearing and stereotypy. This study aims to reveal the possible antipsychotic and oxidative effects of omega-3 fatty acids by comparing with chlorpromazine, a conventional antipsychotic drug, through evaluating the novelty-induced rearing and apomorphine-induced stereotypic behaviors, as well as malondialdehyde and glutathione levels in rats.

METHODS

Twenty-eight, adult, male, Wistar rats were used in the study. Briefly, 4 groups of rats (n = 7) were administered docosahexaenoic acid (DHA) + eicosapentaenoic acid (EPA) (300 mg/kg; DHA: 120 mg/kg + EPA: 180 mg/kg intraperitoneally [IP]), DHA + EPA (150 mg/kg; DHA: 60 mg/kg + EPA: 90 mg/kg IP), chlorpromazine (1 mg/kg, IP) and isotonic saline (1 mL/kg, IP). One hour later, apomorphine (2 mg/kg, subcutaneously) was administered to each rat. After the apomorphine administration, rats were observed for stereotypic behavior.

RESULTS

This study shows that omega-3 fatty acids, "similar to antipsychotics," reversed the psychotic like effects, increase of oxidants and decrease of antioxidants that are composed experimentally in rats.

CONCLUSIONS

The application of omega-3 fatty acids has antipsychotic effects and causes an oxidative imbalance. This study adds new evidence to the current literature regarding the possible antipsychotic effects of omega-3 fatty acids.

Increased oxidative stress and oxidative DNA damage in non-remission schizophrenia patients

Increasing evidence shows that oxidative stress plays a role in the pathophysiology of schizophrenia. But there is not any study which examines the effects of oxidative stress on DNA in schizophrenia patients. Therefore we aimed to assess the oxidative stress levels and oxidative DNA damage in schizophrenia patients with and without symptomatic remission. A total of 64 schizophrenia patients (38 with symptomatic remission and 26 without symptomatic remission) and 80 healthy volunteers were included in the study. 8-hydroxydeoxyguanosine (8-OHdG), total oxidant status (TOS) and total antioxidant status (TAS) were measured in plasma. TOS, oxidative stress index (OSI) and 8-OHdG levels were significantly higher in non-remission schizophrenic (Non-R-Sch) patients than in the controls. TOS and OSI levels were significantly higher in remission schizophrenic (R-Sch) patients than in the controls. TAS level were significantly lower and TOS and OSI levels were significantly higher in R-Sch patients than in Non-R-Sch patients. Despite the ongoing oxidative stress in patients with both R-Sch and Non-R-Sch, oxidative DNA damage was higher in only Non-R-Sch patients compared to controls. It is suggested that oxidative stress can cause the disease via DNA damage, and oxidative stress plays a role in schizophrenia through oxidative DNA damage.

Psychiatric Disorders and Polyphenols: Can They Be Helpful in Therapy?

The prevalence of psychiatric disorders permanently increases. Polyphenolic compounds can be involved in modulation of mental health including brain plasticity, behaviour, mood, depression, and cognition. In addition to their antioxidant ability other biomodulating properties have been observed. In the pathogenesis of depression disturbance in neurotransmitters, increased inflammatory processes, defects in neurogenesis and synaptic plasticity, mitochondrial dysfunction, and redox imbalance are observed. Ginkgo biloba, green tea, and Quercus robur extracts and curcumin can affect neuronal system in depressive patients. ADHD patients treated with antipsychotic drugs, especially stimulants, report significant adverse effects; therefore, an alternative treatment is searched for. An extract from Ginkgo biloba and from Pinus pinaster bark, Pycnogenol, could become promising complementary supplements in ADHD treatment. Schizophrenia is a devastating mental disorder, with oxidative stress involved in its pathophysiology. The direct interference of polyphenols with schizophrenia pathophysiology has not been reported yet. However, increased oxidative stress caused by haloperidol was inhibited ex vivo by different polyphenols. Curcumin, extract from green tea and from Ginkgo biloba, may have benefits on serious side effects associated with administration of neuroleptics to patients suffering from schizophrenia. Polyphenols in the diet have the potential to become medicaments in the field of mental health after a thorough study of their mechanism of action.

Impaired metabolic reactivity to oxidative stress in early psychosis patients

Because increasing evidence point to the convergence of environmental and genetic risk factors to drive redox dysregulation in schizophrenia, we aim to clarify whether the metabolic anomalies associated with early psychosis reflect an adaptation to oxidative stress. Metabolomic profiling was performed to characterize the response to oxidative stress in fibroblasts from control individuals (n = 20) and early psychosis patients (n = 30), and in all, 282 metabolites were identified. In addition to the expected redox/antioxidant response, oxidative stress induced a decrease of lysolipid levels in fibroblasts from healthy controls that were largely muted in fibroblasts from patients. Most notably, fibroblasts from patients showed disrupted extracellular matrix- and arginine-related metabolism after oxidative stress, indicating impairments beyond the redox system. Plasma membrane and extracellular matrix, 2 regulators of neuronal activity and plasticity, appeared as particularly susceptible to oxidative stress and thus provide novel mechanistic insights for pathophysiological understanding of early stages of psychosis. Statistically, antipsychotic medication at the time of biopsy was not accounting for these anomalies in the metabolism of patients' fibroblasts, indicating that they might be intrinsic to the disease. Although these results are preliminary and should be confirmed in a larger group of patients, they nevertheless indicate that the metabolic signature of reactivity to oxidative stress may provide reliable early markers of psychosis. Developing protective measures aimed at normalizing the disrupted pathways should prevent the pathological consequences of environmental stressors.

Associations of oxidative stress status parameters with traditional cardiovascular disease risk factors in patients with schizophrenia

BACKGROUND

The purpose of this study was to assess oxidative stress status parameters and their possible associations with traditional cardiovascular risk factors in patients with schizophrenia, as well as their potential for patient-control discrimination.

METHODS

Fasting glucose, lipid profile and oxidative stress status parameters were assessed in 30 schizophrenic patients with atypical antipsychotic therapy and 60 control subjects.

RESULTS

Malondialdehyde (MDA), pro-oxidant/antioxidant balance (PAB) and total anti-oxidant status (TAS) were significantly higher whereas total sulfhydryl (SH) groups were significantly lower in schizophrenic patients vs. control group. Higher serum PAB values showed an independent association with schizophrenia. The addition of PAB to conventional risk factors improved discrimination between healthy control subjects and patients.

CONCLUSION

Increased oxidative stress and changed lipid profile parameters are associated in schizophrenic patients and may indicate risk for atherosclerosis. The serum PAB level may reflect the levels of oxidative stress in schizophrenia and improve discrimination of patients from controls.

Polyphenols from Berries of Aronia melanocarpa Reduce the Plasma Lipid Peroxidation Induced by Ziprasidone

Background. Oxidative stress in schizophrenia may be caused partially by the treatment of patients with antipsychotics. The aim of the study was to establish the effects of polyphenol compounds derived from berries of Aronia melanocarpa (Aronox) on the plasma lipid peroxidation induced by ziprasidone in vitro. Methods. Lipid peroxidation was measured by the level of thiobarbituric acid reactive species (TBARS). The samples of plasma from healthy subjects were incubated with ziprasidone (40 ng/ml; 139 ng/ml; and 250 ng/ml) alone and with Aronox (5 ug/ml; 50 ug/ml). Results. We observed a statistically significant increase of TBARS level after incubation of plasma with ziprasidone (40 ng/ml; 139 ng/ml; and 250 ng/ml) (after 24 h incubation: P = 7.0 × 10(-4), P = 1.6 × 10(-3), and P = 2.7 × 10(-3), resp.) and Aronox lipid peroxidation caused by ziprasidone was significantly reduced. After 24-hour incubation of plasma with ziprasidone (40 ng/ml; 139 ng/ml; and 250 ng/ml) in the presence of 50 ug/ml Aronox, the level of TBARS was significantly decreased: P = 6.5 × 10(-8), P = 7.0 × 10(-6), and P = 3.0 × 10(-5), respectively. Conclusion. Aronox causes a distinct reduction of lipid peroxidation induced by ziprasidone.

Changes in oxidative stress markers in patients with schizophrenia: the effect of antipsychotic drugs

The aim of this study was to investigate the serum levels or activities of oxidative stress markers in patients with schizophrenia in acute phase and evaluate the changes in superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH) and thiobarbituric acid-reactive substances (TBARS) after treatment. We consecutively enrolled 41 patients with schizophrenia in acute phase, and 27 patients were followed up with a 4-week antipsychotic treatment. Serum oxidative stress markers were measured with assay kits. We found that Positive and Negative Syndrome Scale (PANSS) total scores were significantly negatively correlated with serum GPx activity and GSH levels and positively correlated with serum SOD activity in patients with schizophrenia in acute phase. In addition, serum GPx activity had a positive correlation with GSH levels and negative correlation with SOD activity. We also found that serum SOD activity was significantly negatively correlated with TBARS levels in patients in acute phase. Furthermore, we found significantly increased changes only in GPx activity in female patients receiving the 4-week treatment (P=0.006). In conclusion, our results suggest that SOD, GPX and GSH might be indicators of schizophrenia severity in acute phase. Furthermore, antipsychotic drugs might affect serum GPx activity in female patients receiving the 4-week treatment.

Meta-analysis of oxidative stress in schizophrenia

BACKGROUND

Schizophrenia is associated with impaired antioxidant defense, including abnormal serum, plasma, and red blood cell (RBC) oxidative stress parameters. We performed a meta-analysis of these associations, considering the effect of clinical status and antipsychotic treatment after an acute exacerbation of psychosis.

METHODS

We identified articles by searching PubMed, PsychInfo, and Institute for Scientific Information, and the reference lists of identified studies.

RESULTS

Forty-four studies met the inclusion criteria. Total antioxidant status seemed to be a state marker, because levels were significantly decreased in cross-sectional studies of serum and plasma in first-episode psychosis (FEP) and significantly increased in longitudinal studies of antipsychotic treatment for acute exacerbations of psychosis (p < .01 for each). The RBC catalase and plasma nitrite seemed to be state-related markers, because levels in cross-sectional studies were significantly decreased in FEP (p < .01) and significantly increased in stable outpatients (p = .01). In contrast, RBC superoxide dismutase seemed to be a trait marker for schizophrenia, because levels in cross-sectional studies were significantly decreased in acutely relapsed inpatients, FEP, and stable outpatients (p < .01 for each).

CONCLUSIONS

Oxidative stress abnormalities in FEP suggest an effect that might be independent of antipsychotic medications. Although some parameters (total antioxidant status, RBC catalase, and plasma nitrite) might be state markers for acute exacerbations of psychosis, others (RBC superoxide dismutase) might be trait markers; however, more longitudinal studies are needed. Our findings suggest that oxidative stress might serve as a potential biomarker in the etiopathophysiology and clinical course of schizophrenia.

Reduced antioxidant defense systems in schizophrenia and bipolar I disorder

Numerous evidence and proofs suggest that the oxidative stress contributes to the pathogenesis of schizophrenia (SZ) and bipolar disorder (BD). The aim of this study is to determine the glutathione levels and the antioxidant enzyme activities in blood samples of patients suffering from SZ and patients with bipolar disorder in comparison with the healthy controlled subjects. It was a case-controlled study carried on upon three groups: forty-six SZ patients (41 men and 5 women, mean age=33.2±7years), thirty BD patients (25 men and 5 women, mean age=31.3±8years) and forty healthy controls (33 men and 7 women, mean age=32.3±7years). The glutathione levels are the total glutathione (GSHt), the reduced glutathione (GSHr), and the oxidized glutathione (GSSG) and the antioxidant enzyme activities that are the superoxide dismutase (SOD), the glutathione peroxidase (GPx), and the catalase (CAT) are determined by the spectrophotometer. We noticed that the GSHt and the GSHr levels significantly decreased in both SZ and BD patients in comparison with the healthy control subjects. As for SOD and CAT activities they remained lower for the patients with SZ when compared both with the controls or the BD patients. We noticed as well that the CAT activity was significantly lower in the BD group than that in the control group, whereas, GPx activity showed no significant change in each group. Hence, this report of the decreased plasma levels of GSHt and GSHr, and the impaired antioxidant enzyme activities in SZ and BD patients aims at highlighting the GSH deficit that seems to be contributing to these disorders, and showing that it may be an important indirect biomarker of the oxidative stress for the SZ and BD.

Similarities in serum oxidative stress markers and inflammatory cytokines in patients with overt schizophrenia at early and late stages of chronicity

Schizophrenia (SZ) is a debilitating neurodevelopmental disorder that strikes at a critical period of a young person's life. Its pathophysiology could be the result of deregulation of synaptic plasticity, with downstream alterations of inflammatory immune processes regulate by cytokines, impaired antioxidant defense and increased lipid peroxidation. The aim of this study was to examine serum oxidative stress markers and inflammatory cytokines in early and late phases of chronic SZ. Twenty-two patients at early stage (within first 10 years of a psychotic episode), 39 at late stage (minimum 10 years after diagnosis of SZ) and their respective matched controls were included. Each subject had 5 ml blood samples collected by venipuncture to examined thiobarbituric acid-reactive substances (TBARS), total reactive antioxidant potential (TRAP), protein carbonyl content (PCC), Interleukins 6 and 10 (IL-6, IL-10) and tumor necrosis factor alpha (TNF-alpha). TBARS, IL-6 and PCC levels were significantly higher in patients with SZ at early and late stages than in controls. There were no differences for TRAP and TNF-alpha levels in patients with SZ at early and late stages than in controls. IL-10 levels were decreased in patients at late stage and a decrease trend in early stage was found. Results provided evidence consistent with comparable biological markers across chronic SZ. The concept of biochemical staging proposed by others for bipolar disorder is not seen in this cohort of patients with SZ, at least for cytokines and oxidative stress markers. Our findings reinforce the need of assessment of individuals in ultra high risk to develop psychosis and first-episode population.

Bimodal distribution of polyunsaturated fatty acids in schizophrenia suggests two endophenotypes of the disorder

BACKGROUND

There is conflicting evidence of whether polyunsaturated fatty acids (PUFA) in red blood cells are bimodally distributed in schizophrenia. The purpose of this study was to examine the distribution of PUFA, as well as its links to plausible causal factors.

METHODS

A 16-week cohort study and a case-control study as part of a randomized controlled trial. Ninety-nine patients with DSM-IV schizophrenia, schizoaffective disorder, or schizophreniform disorder, aged 18 to 39, were consecutively included at admission to psychiatric departments of nine Norwegian hospitals. Fatty acids were measured in 97 of these patients and in 20 healthy control subjects. The primary outcome measure was the bimodality test statistic T, assessed by a χ(2) test of the likelihood of one or two normal distributions of PUFA.

RESULTS

At baseline, levels of polyunsaturated fatty acids were highly significantly bimodally distributed among patients. One third of patients constituted a group (low PUFA) who had PUFA levels at one fifth (p < .001) of those in high PUFA patients and healthy control subjects, which did not differ. Bimodality was mainly accounted for by docosahexaenoic acid and arachidonic acid. Bimodality was confirmed after 16 weeks. α-tocopherol was a robust predictor of PUFA at both occasions. Desaturase and elongase indexes differed between PUFA groups. Smoking, gender, antipsychotic medication, and dietary factors did not explain the bimodal distribution.

CONCLUSIONS

Red blood cell PUFA were bimodally distributed among acutely ill patients with schizophrenia and schizoaffective disorder. Endogenous deficiencies of redox regulation or synthesis of long-chain PUFA in the low PUFA group may explain our findings.

Increased annexin-V and decreased TNF-α serum levels in chronic-medicated patients with schizophrenia

Schizophrenia (SZ) is a chronic severe mental disorder. Increased inflammatory processes have been shown in acute and chronic SZ. Apoptotic processes may alter the neuronal network and are involved in the pathogenesis of several neurodegenerative diseases, such as SZ. Annexin-V seems to have a role on inhibition of pro-inflammatory activities during apoptosis. Tumor necrosis factor (TNF-alpha) is a cytokine involved in systemic inflammation and is a member of a group of cytokines which stimulate acute phase reactions. A chronic immune activation in SZ has been shown. The aim of this study was to compare annexin-V and TNF-alpha serum levels in chronic medicated patients with SZ and healthy controls. Thirty-eight outpatients from the HCPA Schizophrenia Program and 38 healthy controls were enrolled to this study protocol. Annexin-V and TNF-alpha serum levels were measured with ELISA. Serum annexin-V levels were significantly higher in patients with SZ than in controls (p<0.001) and TNF-alpha significantly lower (p<0.001). The present result of increased annexin-V and decreased serum levels of TNF-alpha compared to controls may be a result of the stabilization phase of psychosis and a reduction in metabolic brain aggression. In this complex picture, increased levels of annexin-V and decreased levels of TNF-alpha in our sample would be explained by illness stability and chronic treatment. Our findings support the hypothesis of a state dependant process of inflammation in SZ. Further prospective studies to clarify the findings described in this paper are needed.

Oxidative stress in schizophrenia

Increasing evidence indicates that oxidative damage exists in schizophrenia. Available literature about possible mechanisms of oxidative stress induction was reviewed. Furthermore, possibilities of measuring biomarkers of schizophrenia outside the central nervous system compartment, their specificity for different types of schizophrenia and potential therapeutic strategies to prevent oxidative injuries in schizophrenia were discussed. Data were extracted from published literature found in Medline, Embase, Biosis, Cochrane and Web of Science, together with hand search of references. Search terms were: schizophrenia, oxidative stress, antipsychotics, antioxidants and fatty acids. Finding a sensitive, specific and non invasive biomarker of schizophrenia, which could be measured in peripheral tissue, still stays an important task. Antioxidant enzymes, markers of lipid peroxidation, oxidatively modified proteins and DNA are most commonly used. As it considers the supplemental therapy, according to our meta-analysis vitamin E could potentially improve tardive dyskinesia, while for the effect of therapy with polyunsaturated fatty acids there is no clear evidence. Oxidative stress is a part of the pathology in schizophrenia and appears as a promising field to develop new therapeutic strategies. There is a need for well designed, placebo controlled trials with supplementation therapy in schizophrenia.

Serum thiobarbituric acid-reactive substances and free thiol levels in schizophrenia patients: effects of antipsychotic drugs

This study investigated the levels of serum thiobarbituric acid-reactive substances (TBARS) and free thiols in schizophrenia patients and healthy control subjects, and evaluated the effects of antipsychotic drugs. During a 2-year period, 77 schizophrenia patients and 110 healthy control subjects were recruited. Psychiatric diagnoses of schizophrenia were made according to DSM-IV criteria. Serum TBARS and free thiol levels were measured using the standard procedure in the laboratory room. Using analysis of covariance with body mass index adjustment, we found that schizophrenia patients had significantly lower serum levels of free thiols than the controls. Fifty-five patients were followed up and their serum TBARS and free thiol levels were measured at the end of the 4-week treatment with antipsychotic drugs. We found that there were significantly decreased changes in free thiol levels, but not in TBARS levels. Furthermore, patients taking risperidone had significantly decreased changes in free thiol levels. Additionally, the responders showed significantly decreased changes in free thiol levels, but not in TBARS levels. In conclusion, these analytical results suggested that serum free thiols might play an important role in the psychopathology of schizophrenia and could be used as markers for determining the treatment response in schizophrenia.

Winter/summer seasonal changes in malondialdehyde formation as a source of variance in oxidative stress schizophrenia research

BACKGROUND

Malondialdehyde (MDA), an oxidative stress biological marker, is one of the most frequently used markers of lipid peroxidation in schizophrenia research. Data regarding MDA levels in schizophrenia are controversial. Our aim is to study the existence of winter/summer seasonal changes in serum MDA levels in schizophrenic patients.

METHODS

Twenty-three clinically stable treated chronic paranoid schizophrenic outpatients were studied in summer and winter. Blood was sampled between 08:30 and 09:00 h. Serum MDA was determined by the thiobarbituric acid reactive substances technique. The clinical state was assessed by means of the Clinical Global Impression (CGI) scale.

RESULTS

Mean serum MDA levels were significantly higher in summer than winter (2.49+/-0.25 vs. 1.86+/-0.11 nmol/ml, P<0.03). Summer MDA was increased by a 33.9% compared to winter MDA. Age, gender, smoking status, body mass index, psychopharmacological treatment, illness duration, age of illness onset and CGI did not affect significantly MDA levels.

CONCLUSION

Our results show that serum MDA presents a winter/summer rhythm of formation, with higher levels in summer than winter. It is strongly advisable to take into account the summer/winter variation in MDA levels when researching into this field.

Effects of N-acetylcysteine on substance use in bipolar disorder: A randomised placebo-controlled clinical trial

OBJECTIVE

To evaluate the effect of N-acetylcysteine (NAC) on substance use in a double-blind, placebo-controlled trial of NAC in bipolar disorder. It is hypothesised that NAC will be superior to placebo for reducing scores on the Clinical Global Impressions scale for Substance Use (CGI-SU).

METHODS

Participants were randomised to a 6-months of treatment with 2 g/day NAC (n = 38) or placebo (n = 37). Substance use was assessed at baseline using a Habits instrument. Change in substance use was assessed at regular study visits using the CGI-SU.

RESULTS

Among the 75 participants 78.7% drank alcohol (any frequency), 45.3% smoked tobacco and 92% consumed caffeine. Other substances were used by fewer than six participants. Caffeine use was significantly lower for NAC-treated participants compared to placebo at week 2 of treatment but not at other study visits.

CONCLUSIONS

NAC appeared to have little effect on the participants who were using substances. A larger study on a substance-using population will be necessary to determine if NAC may be a useful treatment for substance use.

Effects of N-acetylcysteine on substance use in bipolar disorder: a randomised placebo-controlled clinical trial

OBJECTIVE

To evaluate the effect of N-acetylcysteine (NAC) on substance use in a double-blind, placebo-controlled trial of NAC in bipolar disorder. It is hypothesised that NAC will be superior to placebo for reducing scores on the Clinical Global Impressions scale for Substance Use (CGI-SU).

METHODS

Participants were randomised to 6-months of treatment with 2 g/day NAC (n = 38) or placebo (n = 37). Substance use was assessed at baseline using the Habits instrument. Change in substance use was assessed at regular study visits using the CGI-SU.

RESULTS

Amongst the 75 participants 78.7% drank alcohol (any frequency), 45.3% smoked tobacco and 92% consumer caffeine. Other substances were used by fewer than six participants. Caffeine use was significantly lower for NAC-treated participants compared with placebo at week 2 of treatment but not at other study visits.

CONCLUSION

NAC appeared to have little effect on substance use in this population. A larger study on a substance using population will be necessary to determine if NAC may be a useful treatment for substance use.

Serum levels of brain-derived neurotrophic factor and thiobarbituric acid reactive substances in chronically medicated schizophrenic patients: a positive correlation

OBJECTIVE

The neurotrophins, antioxidant enzymes and oxidative markers have reciprocal interactions. This report verified in chronically stable medicated schizophrenic patients whether there are correlations between the serum levels of superoxide dismutase, a key enzyme in the antioxidant defense, thiobarbituric acid reactive substances, a direct index of lipid peroxidation, and brain-derived neurotrophic factor, the most widely distributed neurotrophin.

METHOD

Sixty DSM-IV schizophrenic patients were included (43 males, 17 females). Mean age was 34.7 +/- 10.8 years, mean age at first episode was 19.8 +/- 7.9 years, and mean illness duration was 14.9 +/- 8.5 years. Each subject had a blood sample collected for the determination of serum levels of brain-derived neurotrophic factor, thiobarbituric acid reactive substances and superoxide dismutase.

RESULTS

Brain-derived neurotrophic factor levels showed a positive correlation with thiobarbituric acid reactive substances levels (r = 0.333, p = 0.009). Brain-derived neurotrophic factor levels were not correlated with superoxide dismutase levels (r = - 0.181, p = 0.166), and superoxide dismutase levels were not correlated with thiobarbituric acid reactive substances levels (r = 0.141, p = 0.284).

CONCLUSIONS

The positive correlation between brain-derived neurotrophic factor and thiobarbituric acid reactive substances suggests the need of further investigation on intracellular interactions of neurotrophins, antioxidant enzymes and oxidative markers. In addition, this opens a venue for investigation on treatments for the prevention of neurotoxicity along the course of schizophrenia.

Elevated serum superoxide dismutase and thiobarbituric acid reactive substances in different phases of bipolar disorder and in schizophrenia

There is an increasing body of evidence suggesting that oxidative stress may play a role in the pathophysiology of both schizophrenia (SZ) and bipolar disorder (BD).

METHODS

We compared the antioxidant enzyme, serum superoxide dismutase (SOD) and the lipid peroxidation product, thiobarbituric acid reactive substances (TBARS) as assessed in depressed (N=21), manic (N=32) and euthymic (N=31) bipolar patients, and in chronically medicated patients with schizophrenia (N=97), all fulfilling DSM-IV diagnostic criteria, and a group of healthy controls (N=32).

RESULTS

Serum SOD (U/mg protein) activity was significantly increased (p<0.001) in manic (7.44+/-3.88) and depressed (6.12+/-4.64) BD patients and SZ (9.48+/-4.51) when compared to either controls (1.81+/-0.63) or euthymic (2.75+/-1.09) BD patients. TBARS (mol/L) levels were significantly higher in the SZ group (4.95+/-1.56, p=0.016), bipolar euthymic (6.36+/-1.46, p<0.001), bipolar manic (7.54+/-1.74, p<0.001), and bipolar depressed patients (5.28+/-1.54, p=0.028) compared to controls (3.96+/-1.51).

DISCUSSION

Our findings show increased SOD activity in SZ, as well as in depressed and manic bipolar patients, but not in euthymic BD subjects. This suggests a dysregulation in oxidative defenses in both disorders. It is likely that such changes reflect state changes in bipolar disorder. It is possible that this is a compensatory response to the oxidative stress that occurs in the acute phase of bipolar episodes. TBARS results show increases in lipid peroxidation in mania. TBARS levels in SZ and in euthymic as well as depressed individuals with BD were higher than in controls. This suggests persistent increases in SZ, which may reflect ongoing symptomatology or treatment, and a state dependent gradient in BD, with greatest oxidative stress in mania. These data support oxidative biology as both a key component of the pathophysiology of both BD and SZ, and the use of agents that modulate oxidative biology as a promising avenue for intervention in both disorders.

Altered antioxidant defense system in clinically stable patients with schizophrenia and their unaffected siblings

OBJECTIVE

To determine Red Blood Cell (RBC) antioxidant enzyme activities and plasma Thiobarbituric Acid Reactive Substances (TBARS) in clinically stable patients with schizophrenia and their unaffected siblings.

METHODS

A case-control study carried out on three groups: 60 schizophrenic patients treated with neuroleptics, 33 of their unaffected siblings and 30 healthy controls with no family psychiatric history. Biological markers were measured on fasting patients after a period of tobacco abstinence: RBC antioxidant enzyme activities - superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) - by spectrophotometry and plasma levels of TBARS by spectrofluorimetry.

RESULTS

RBC SOD and CAT activities were significantly lower in schizophrenic patients and their unaffected siblings compared to the control group (P<0.001). Schizophrenic patients also had significantly lower RBC GSH-Px activity than controls (P=0.03), whereas their unaffected siblings had significantly higher RBC GSH-Px activity than controls (P=0.04). Plasma TBARS were higher in schizophrenic patients than their unaffected siblings: 2.1+/-0.8 micromol/l vs. 1.7+/-0.6 micromol/l (P=0.06).

CONCLUSIONS

Our results showed a decrease in antioxidant enzyme activities and an increase in lipid peroxidation confirming the existence of oxidative stress in schizophrenic patients treated with neuroleptics. Additionally, this suggests that the increase in GSH-Px activity in unaffected siblings would be a protective mechanism against oxidative stress and damage. Other studies are necessary to confirm these findings.