Plasma homocysteine levels in young male patients in the exacerbation and remission phase of schizophrenia

A Proactive Intervention Study in Metabolic Syndrome High-Risk Populations Using Phenome-Based Actionable P4 Medicine Strategy

The integration of predictive, preventive, personalized, and participatory (P4) healthcare advocates proactive intervention, including dietary supplements and lifestyle interventions for chronic disease. Personal profiles include deep phenotypic data and genetic information, which are associated with chronic diseases, can guide proactive intervention. However, little is known about how to design an appropriate intervention mode to precisely intervene with personalized phenome-based data. Here, we report the results of a 3-month study on 350 individuals with metabolic syndrome high-risk that we named the Pioneer 350 Wellness project (P350). We examined: (1) longitudinal (two times) phenotypes covering blood lipids, blood glucose, homocysteine (HCY), and vitamin D3 (VD3), and (2) polymorphism of genes related to folic acid metabolism. Based on personalized data and questionnaires including demographics, diet and exercise habits information, coaches identified 'actionable possibilities', which combined exercise, diet, and dietary supplements. After a 3-month proactive intervention, two-thirds of the phenotypic markers were significantly improved in the P350 cohort. Specifically, we found that dietary supplements and lifestyle interventions have different effects on phenotypic improvement. For example, dietary supplements can result in a rapid recovery of abnormal HCY and VD3 levels, while lifestyle interventions are more suitable for those with high body mass index (BMI), but almost do not help the recovery of HCY. Furthermore, although people who implemented only one of the exercise or diet interventions also benefited, the effect was not as good as the combined exercise and diet interventions. In a subgroup of 226 people, we examined the association between the polymorphism of genes related to folic acid metabolism and the benefits of folate supplementation to restore a normal HCY level. We found people with folic acid metabolism deficiency genes are more likely to benefit from folate supplementation to restore a normal HCY level. Overall, these results suggest: (1) phenome-based data can guide the formulation of more precise and comprehensive interventions, and (2) genetic polymorphism impacts clinical responses to interventions. Notably, we provide a proactive intervention example that is operable in daily life, allowing people with different phenome-based data to design the appropriate intervention protocol including dietary supplements and lifestyle interventions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-023-00115-z.

Association of homocysteine with white matter dysconnectivity in schizophrenia

Several studies have shown white matter (WM) dysconnectivity in people with schizophrenia (SZ). However, the underlying mechanism remains unclear. We investigated the relationship between plasma homocysteine (Hcy) levels and WM microstructure in people with SZ using diffusion tensor imaging (DTI). Fifty-three people with SZ and 83 healthy controls (HC) were included in this retrospective observational study. Tract-Based Spatial Statistics (TBSS) were used to evaluate group differences in WM microstructure. A significant negative correlation between plasma Hcy levels and WM microstructural disruption was noted in the SZ group (Spearman's ρ = -.330, P = 0.016) but not in the HC group (Spearman's ρ = .041, P = 0.712). These results suggest that increased Hcy may be associated with WM dysconnectivity in SZ, and the interaction between Hcy and WM dysconnectivity could be a potential mechanism of the pathophysiology of SZ. Further, longitudinal studies are required to investigate whether high Hcy levels subsequently cause WM microstructural disruption in people with SZ.

Sulfur-containing amino acids and risk of schizophrenia

BACKGROUND

Schizophrenia is a chronic and complex severe psychiatric disorder. Male and female are different in their risks for schizophrenia for the biologic and sociocultural reasons. Homocysteine (Hcy), Cysteine (Cys), and methionine (Met) play important roles in metabolism, and the three amino acids may also be involved in pathogenesis of schizophrenia.

OBJECTIVE

This study aimed to test the associations between sulfur-containing amino acid blood levels and risk of schizophrenia, evaluating the different risk in male and female.

METHODS

We organized a case-control study on 876 individuals with schizophrenia and 913 age- and sex-matched healthy subjects as control group. The concentrations of Hcy, Cys and Met were measured by liquid chromatography-tandem mass spectrometry technology. Subsequently, restricted cubic spline was applied to explore full-range associations of these amino acids with schizophrenia. Interactions between levels of the three amino acids and sex on additive scale were also tested.

RESULTS

Hcy levels at ≤29 μmol/L were associated with sharply increased risk of schizophrenia, inversely, Met was associated with sharply decreased risk of schizophrenia at levels ≤22 μmol/L. Increased Cys levels were associated with decreased risk of schizophrenia. Almost inverse associations were observed between Cys/Hcy and Met/Hcy ratios and schizophrenia. Significant synergistic interactions between levels of all the three amino acids and sex were discovered on an additive scale.

CONCLUSIONS

Our study suggests a close association between sulfur-containing amino acids and schizophrenia with different risk in male and female. Future studies are demanded to clarify the pathogenic role of Hcy, Cys and Met in schizophrenia.

Association of Prolactin, Oxytocin, and Homocysteine With the Clinical and Cognitive Features of a First Episode of Psychosis Over a 1-Year Follow-Up

BACKGROUND

The clinical debut of schizophrenia is frequently a first episode of psychosis (FEP). As such, there is considerable interest in identifying associations between biological markers and clinical or cognitive characteristics that help predict the progression and outcome of FEP patients. Previous studies showed that high prolactin, low oxytocin, and high homocysteine are factors associated with FEP 6 months after diagnosis, at which point plasma levels were correlated with some clinical and cognitive characteristics.

METHODS

We reexamined 75 patients at 12 months after diagnosis to measure the evolution of these molecules and assess their association with clinical features.

RESULTS

At follow-up, FEP patients had lower prolactin levels than at baseline, and patients treated with risperidone or paliperidone had higher prolactin levels than patients who received other antipsychotic agents. By contrast, no changes in oxytocin and homocysteine plasma levels were observed between the baseline and follow-up. In terms of clinical features, we found that plasma prolactin and homocysteine levels were correlated with the severity of the psychotic symptoms in male FEP patients, suggesting that they might be factors associated with psychotic symptomatology but only in men. Together with oxytocin, these molecules may also be related to sustained attention, verbal ability, and working memory cognitive domains in FEP patients.

CONCLUSION

This study suggests that focusing on prolactin, oxytocin, and homocysteine at a FEP may help select adequate pharmacological treatments and develop new tools to improve the outcome of these patients, where sex should also be borne in mind.

Abnormalities in one-carbon metabolism in young patients with psychosis

INTRODUCTION

Folates, the main actors in one-carbon (C1) metabolism, are involved in synthesising monoamines and maintaining genomic stability. Previous studies support the association between C1 metabolism and schizophrenia. The main purpose of this study was to assess the prevalence of plasma folate, and/or vitamin B12 deficiencies and hyperhomocysteinemia in young patients with psychotic disorders.

METHODS

We included young inpatients (15-30 years old) with psychosis between 2014 and 2017 from Sainte-Anne Hospital in Paris. Plasma folate, vitamin B12 deficiency and homocysteinemia dosages were done at admission. Clinical data were extracted retrospectively, and patients diagnosed with a first-episode psychosis (FEP), schizophrenia, schizoaffective disorder, or persistent delusional disorder were retained for the analysis.

RESULTS

Among the 334 inpatients, 188 (56%) had C1 dosages available (135 males; 53 females). From the 188 patients, 32% had a C1 abnormality. This abnormality reached 38% of FEP patients. The most frequent abnormality was folate deficiency: 21% of all patients and 27% of FEP. Lower levels of folates were found in males compared to females (p = 0.02) and were correlated with more severe disorder, as assessed by Clinical Global Impression - Severity (CGI-S; p = 0.009). Antipsychotic dosage was positively associated with B12 levels (p = 0.013) and negatively with homocysteinemia (p = 0.034).

CONCLUSION

One-carbon metabolism anomalies in young patients with psychotic disorders are highly prevalent, reaching almost half of the patients with FEP. Potential protective effects from females and antipsychotics have emerged. These results spotlight the need for new therapeutic prospects, such as folate supplementation, to achieve personalised medical approaches to the early stages of psychotic disorders.

Increased serum homocysteine in first episode and drug-naïve individuals with schizophrenia: sex differences and correlations with clinical symptoms

BACKGROUND

Accumulating evidence shows that homocysteine (Hcy) is implicated in the pathophysiology of schizophrenia, and plays an important role in clinical characteristics. This study evaluated the relationships between Hcy levels and clinical features in first-episode, Chinese Han, drug-naïve (FEDN) patients with schizophrenia.

METHODS

FEDN individuals (119 with schizophrenia and 81 healthy controls matched for age, sex, education, and body mass index (BMI)) were enrolled. The serum Hcy levels were determined by enzyme cycle assay experiments. Severities of clinical symptoms were rated on the Positive and Negative Syndrome Scale (PANSS).

RESULTS

FEDN individuals with schizophrenia had higher Hcy levels compared with healthy controls (F = 46.865, P < 0.001). Correlation analysis and multiple stepwise regression analyses showed that serum Hcy levels in FEDN schizophrenia individuals were positively correlated with PANSS general psychopathology subscale (r = 0.294, P = 0.001) and PANSS total score (r = 0.273, P = 0.003). No significant association was found between Hcy and age, BMI, PANSS positive subscale, and the PANSS negative subscale (all, P > 0.05). Male individuals had significantly higher serum Hcy levels than female individuals (F = 7.717, P = 0.006) after controlling for confounding factors (F = 0.759, P = 0.011).

CONCLUSIONS

Serum Hcy levels were increased in FEDN individuals with schizophrenia, and Hcy levels may be involved in pathophysiological mechanisms. Sex differences in Hcy levels were observed, with higher levels in male FEDN individuals compared to females.

Relationship of serum homocysteine and vitamin D with positive, negative, and extrapyramidal symptoms in schizophrenia: a case-control study in Iran

BACKGROUND

Schizophrenia is a devastating condition characterized by frequent recurrences, cognitive decline, and emotional and functional disabilities. This condition includes positive and negative symptoms and cognitive impairments resistant to drug treatment. According to studies, many biomarkers can affect this disorder. However, there is little information about vitamin D and homocysteine levels in patients with disease complications. We aimed to investigate this relationship in schizophrenia.

METHOD

In this case-control study, 33 patients with schizophrenia and 33 healthy individuals were enrolled from Golestan, the north of Iran, in 2021. Blood samples were taken from all participants to assess vitamin D and homocysteine serum levels. In addition, schizophrenic patients completed the Positive And Negative Syndrome Scale (PANSS) and Simpson-Angus Extrapyramidal Side Effects Scale (SAS). Data analysis was performed at a significance level of 0.05 using SPSS 16 software.

RESULTS

Of the 66 participants, 66.7% had vitamin D deficiency, and 71.2% had normal homocysteine levels. However, the serum level of vitamin D was lower in schizophrenic patients than in controls (p = 0.035), and serum homocysteine levels were higher in the schizophrenic group than in controls (p &lt; 0.001). Vitamin D levels in patients with schizophrenia were significantly correlated with the overall assessment of extrapyramidal symptoms (r = 0.35, p = 0.04). However, no significant relationship existed between vitamin D and homocysteine levels and PANSS results (p &gt; 0.05).

CONCLUSION

Serum levels of vitamin D and homocysteine were significantly lower and higher in schizophrenic patients than in the control group. Improvement of extrapyramidal symptoms in schizophrenic patients had a direct and significant relationship with serum vitamin D.

Treatment-resistant schizophrenia: focus on the transsulfuration pathway

Treatment-resistant schizophrenia (TRS) is a severe form of schizophrenia. The severity of illness is positively related to homocysteine levels, with high homocysteine levels due to the low activity of the transsulfuration pathway, which metabolizes homocysteine in synthesizing L-cysteine. Glutathione levels are low in schizophrenia, which indicates shortages of L-cysteine and low activity of the transsulfuration pathway. Hydrogen sulfide (H2S) levels are low in schizophrenia. H2S is synthesized by cystathionine β-synthase and cystathionine γ-lyase, which are the two enzymes in the transsulfuration pathway. Iron-sulfur proteins obtain sulfur from L-cysteine. The oxidative phosphorylation (OXPHOS) pathway has various iron-sulfur proteins. With low levels of L-cysteine, iron-sulfur cluster formation will be dysregulated leading to deficits in OXPHOS in schizophrenia. Molybdenum cofactor (MoCo) synthesis requires sulfur, which is obtained from L-cysteine. With low levels of MoCo synthesis, molybdenum-dependent sulfite oxidase (SUOX) will not be synthesized at appropriate levels. SUOX detoxifies sulfite from sulfur-containing amino acids. If sulfites are not detoxified, there can be sulfite toxicity. The transsulfuration pathway metabolizes selenomethionine, whereby selenium from selenomethionine can be used for selenoprotein synthesis. The low activity of the transsulfuration pathway decreases selenoprotein synthesis. Glutathione peroxidase (GPX), with various GPXs being selenoprotein, is low in schizophrenia. The dysregulations of selenoproteins would lead to oxidant stress, which would increase the methylation of genes and histones leading to epigenetic changes in TRS. An add-on treatment to mainline antipsychotics is proposed for TRS that targets the dysregulations of the transsulfuration pathway and the dysregulations of other pathways stemming from the transsulfuration pathway being dysregulated.

Combined glyoxalase 1 dysfunction and vitamin B6 deficiency in a schizophrenia model system causes mitochondrial dysfunction in the prefrontal cortex

Methylglyoxal (MG) is a reactive and cytotoxic α-dicarbonyl byproduct of glycolysis. Our bodies have several bio-defense systems to detoxify MG, including an enzymatic system by glyoxalase (GLO) 1 and GLO2. We identified a subtype of schizophrenia patients with novel mutations in the GLO1 gene that results in reductions of enzymatic activity. Moreover, we found that vitamin B6 (VB6) levels in peripheral blood of the schizophrenia patients with GLO1 dysfunction are significantly lower than that of healthy controls. However, the effects of GLO1 dysfunction and VB6 deficiency on the pathophysiology of schizophrenia remains poorly understood. Here, we generated a novel mouse model for this subgroup of schizophrenia patients by feeding Glo1 knockout mice VB6-deficent diets (KO/VB6(−)) and evaluated the combined effects of GLO1 dysfunction and VB6 deficiency on brain function. KO/VB6(−) mice accumulated homocysteine in plasma and MG in the prefrontal cortex (PFC), hippocampus, and striatum, and displayed behavioral deficits, such as impairments of social interaction and cognitive memory and a sensorimotor deficit in the prepulse inhibition test. Furthermore, we found aberrant gene expression related to mitochondria function in the PFC of the KO/VB6(−) mice by RNA-sequencing and weighted gene co-expression network analysis (WGCNA). Finally, we demonstrated abnormal mitochondrial respiratory function and subsequently enhanced oxidative stress in the PFC of KO/VB6(−) mice in the PFC. These findings suggest that the combination of GLO1 dysfunction and VB6 deficiency may cause the observed behavioral deficits via mitochondrial dysfunction and oxidative stress in the PFC.

•

A combination of Glo1 KO and VB6 deficiency induces MG accumulation in the brain.

•

Glo1 KO/VB6(−) mice exhibit schizophrenia-like behavioral deficits.

•

Gene expression related to mitochondria is impaired in the PFC of the Glo1 KO/VB6(−).

•

Mitochondria in the PFC of the Glo1 KO/VB6(−) mice show respiratory dysfunction.

•

Oxidative stress is enhanced in the PFC of the Glo1 KO/VB6(−).

Prevalence and clinical demography of hyperhomocysteinemia in Han Chinese patients with schizophrenia

Previous studies have shown that high homocysteine worsens the occurrence, symptoms, and prognosis of patients with schizophrenia. The purpose of this study was to evaluate the prevalence, clinical correlation, and demographic characteristics of hyperhomocysteinemia in Han Chinese schizophrenia patients. In this study, we enrolled 330 schizophrenia patients and 190 healthy controls. Positive and Negative Syndrome Scale (PANSS) was used to evaluate the psychiatric symptoms of patients with schizophrenia. The plasma homocysteine level was measured by the enzyme cycle method and the concentration of homocysteine > 15 μmol/L was defined as hyperhomocysteinemia. The prevalence of hyperhomocysteinemia in Han Chinese schizophrenia patients and healthy controls was 55.05% and 26.98%, respectively. Schizophrenia patients with hyperhomocysteinemia had more male proportion, older age, higher smoking rate, lower HDL level, higher PANSS total score, and higher negative factor than those patients without hyperhomocysteinemia. Binary logical regression result showed that gender and age were the independent risk factors of hyperhomocysteinemia. Han Chinese patients with schizophrenia had high prevalence hyperhomocysteinemia than healthy controls, and elderly male patients have a higher risk of hyperhomocysteinemia. This study was registered in the China Clinical Trial Registration Center (chiCTR 1800017044).

Involvements of Hyperhomocysteinemia in Neurological Disorders

Homocysteine (HCY), a physiological amino acid formed when proteins break down, leads to a pathological condition called hyperhomocysteinemia (HHCY), when it is over a definite limit. It is well known that an increase in HCY levels in blood, can contribute to arterial damage and several cardiovascular disease, but the knowledge about the relationship between HCY and brain disorders is very poor. Recent studies demonstrated that an alteration in HCY metabolism or a deficiency in folate or vitamin B12 can cause altered methylation and/or redox potentials, that leads to a modification on calcium influx in cells, or into an accumulation in amyloid and/or tau protein involving a cascade of events that culminate in apoptosis, and, in the worst conditions, neuronal death. The present review will thus summarize how much is known about the possible role of HHCY in neurodegenerative disease.

Early-Onset Schizophrenia: A Special Phenotype of the Disease Characterized by Increased MTHFR Polymorphisms and Aggravating Symptoms

BACKGROUND

Patients with early-onset schizophrenia usually exhibit more severe symptoms, revealing a potentially distinctive disease phenotype. Methylenetetrahydrofolate reductase (MTHFR) is a critical enzyme in folate conversion and methylation modification associated with the disease. We aimed to investigate the potential effects of MTHFR polymorphisms and related methylation patterns in patients with early-onset schizophrenia, which implies special phenotypes of schizophrenia.

METHODS

In 177 patients with schizophrenia, MTHFR polymorphism at three sites (C677T, A1298C, and G1793A) and the Positive and Negative Syndrome Scale (PANSS) were tested. Differential methylation positions (DMPs) and enrichment of genes and related pathways were analyzed by testing the genomic methylation level. Catechol-O-methyltransferase (COMT), solute carrier family 6 member 4 (SLC6A4), neuregulin1 (NRG1), and brain-derived neurotrophic factor (BDNF) were selected to evaluate the methylation levels of specific CpG regions by pyrosequencing.

RESULTS

Higher levels of symptom severity and MTHFR polymorphisms and lower levels of global DNA methylation in patients with early-onset schizophrenia were observed in this study. SLC6A4 was hypermethylated, and BDNF was hypomethylated in specific regions of patients with early-onset schizophrenia.

CONCLUSION

Aggravating symptoms, increased MTHFR polymorphisms, and reduced genomic methylation levels may be characteristics and underlying mechanisms of early-onset schizophrenia, which implies a special disease phenotype. Beyond that, specific genes and biological pathways may imply the potential phenotype of schizophrenia.

Homocysteine level, body mass index and clinical correlates in Chinese Han patients with schizophrenia

Obesity is common comorbidity in patients with schizophrenia. Previous studies have reported that homocysteine (Hcy) is increased in schizophrenia. However, no study has reported the association between BMI and Hcy levels in schizophrenia. This cross-sectional naturalistic study aimed to evaluate the relationship between BMI, Hcy and clinical symptoms in Chinese Han patients with chronic schizophrenia. Clinical and anthropometric data as well as plasma Hcy level and glycolipid parameters were collected. Psychopathology was measured with the Positive and Negative Syndrome Scale (PANSS). Our results showed that compared with the low BMI group, the high BMI group had a higher PANSS general psychopathology subscore, higher levels of blood glucose, total cholesterol and high-density lipoprotein (HDL) cholesterol (all p < 0.05). Hcy levels were negatively associated with BMI in patients (p < 0.001). Hcy level, the PANSS general psychopathology subscale, total cholesterol and education (all p < 0.05) were the influencing factors of high BMI. Our study suggest that Hcy level may be associated with BMI in patients with schizophrenia. Moreover, patients with high BMI show more severe clinical symptoms and higher glucose and lipid levels.

Association between serum folate levels and schizophrenia based on sex

AIM

Sex differences in serum folate concentrations are well known, but no studies have investigated the association between serum folate levels and schizophrenia based on sex. With this study in a Japanese population, we examined the difference in serum folate levels between patients with schizophrenia and non-psychiatric controls stratified by sex. The relations among serum folate levels, plasma total homocysteine (tHcy), and serum vitamin B6 (pyridoxal) levels were also examined using data from our previous studies.

METHODS

The serum folate concentrations of 482 patients diagnosed with schizophrenia and 1350 non-psychiatric control subjects were measured. We conducted an analysis of covariance to examine the differences in serum folate levels between the two groups based on sex. Spearman's rank correlation was used to evaluate the relations among folate, tHcy, and vitamin B6 levels.

RESULTS

In the control group, serum folate concentrations were higher in women than in men. Lower levels of serum folate were observed in both male and female patients with schizophrenia. An inverse correlation between serum folate and plasma tHcy and a weak positive correlation between serum folate and vitamin B6 were observed in the combined cohort.

CONCLUSION

Our findings suggest that: (i) a low serum folate level may be associated with schizophrenia regardless of sex; and (ii) folate administration may be beneficial for the treatment of schizophrenia. In schizophrenic patients with low serum folate levels, folate administration might result in improvements in high tHcy and an increase in low vitamin B6 levels.

Regulation of inflammatory pathways in schizophrenia: A comparative study with bipolar disorder and healthy controls

Background

Immune-inflammatory processes have been implicated in schizophrenia (SCH), but their specificity is not clear.

Main aim

To identify potential differential intra-/intercellular biochemical pathways controlling immune-inflammatory response and their oxidative-nitrosative impact on SCH patients, compared with bipolar disorder (BD) patients and healthy controls (HC).

Methods

Cross-sectional, naturalistic study of a cohort of SCH patients (n=123) and their controls [BD (n=102) and HC (n=80)].

Statistical analysis

ANCOVA (or Quade test) controlling for age and gender when comparing the three groups, and controlling for age, gender, length of illness, cigarettes per day, and body mass index (BMI) when comparing SCH and BD.

Results

Pro-inflammatory biomarkers: Expression of COX-1 was statistically higher in SCH and BD than HC (P<0.0001; P<0.0001); NFκB and PGE2 were statistically higher in SCH compared with BD (P=0.001; P<0.0001) and HC (P=0.003; P<0.0001); NLRP3 was higher in BD than HC (P=0.005); and CPR showed a gradient among the three groups. Anti-inflammatory biomarkers: BD patients had lower PPARγ and higher 15d-PGJ2 levels than SCH (P=0.005; P=0.008) and HC (P=0.001; P=0.001). Differences between SCH and BD: previous markers of SCH (NFκB and PGE2) and BD (PPARγ and 15d-PGJ2) remained statistically significant and, interestingly, iNOS and COX-2 (pro-inflammatory biomarkers) levels were statistically higher in SCH than BD (P=0.019; P=0.040).

Conclusions

This study suggests a specific immune-inflammatory biomarker pattern for established SCH (NFκB, PGE2, iNOS, and COX-2) that differentiates it from BD and HC. In future, their pharmacological modulation may constitute a promising therapeutic target.

Evaluation of hyperhomocysteinemia prevalence and its influence on the selected cognitive functions in patients with schizophrenia

There is evidence that hyperhomocysteinemia may be associated with the development of schizophrenia and cognitive impairment. Therefore, the aim of this study was to analyze the relationship between cognitive functions and normal homocysteine concentrations vs. hyperhomocysteinemia in schizophrenia patients before and after supplementation with vitamins B6, B12 and folate. An 8-week prospective, non-randomized study enrolled 122 adult patients with schizophrenia (67F/55M, mean age 43.54 ± 11.94 years). Homocysteine concentrations were measured in all individuals and afterwards hyperhomocysteinemia patients (n = 42) were divided into two subgroups: treated with oral vitamins supplementation (B6 - 25 mg/d, B12 - 20 μg/d, folate - 2,5 mg/d) (n = 22) and without supplementation (n = 20). The assessment of schizophrenia symptoms severity in study group was performed using the Positive and Negative Syndrome Scale (PANSS). Cognitive functions were evaluated using the Stroop test and the Trail Making Test (TMT). We observed a higher prevalence of hyperhomocysteinemia in schizophrenia patients (34.4%) in comparison to the general population. Individuals with schizophrenia and coexisting hyperhomocysteinemia had worse performance on the Stroop and the TMT tests as well as higher PANSS scores. In these patients, supplementation with vitamins effectively decreased the homocysteine concentrations to the normal values, however there was no statistically significant improvement in the PANSS and cognitive test scores, except a significant decrease in the number of the Stroop test errors. We conclude that significant results obtained in this study show that there is a relationship between homocysteine blood concentration and schizophrenia severity. Moreover, homocysteine concentration lowering might be beneficial in schizophrenia patients with hyperhomocysteinemia in terms of cognitive functions improvement.

The Vitamins in Psychosis Study: A Randomized, Double-Blind, Placebo-Controlled Trial of the Effects of Vitamins B12, B6, and Folic Acid on Symptoms and Neurocognition in First-Episode Psychosis

BACKGROUND

Elevated homocysteine is observed in schizophrenia and associated with illness severity. The aim of this study was to determine whether vitamins B₁₂, B₆, and folic acid lower homocysteine and improve symptomatology and neurocognition in first-episode psychosis. Whether baseline homocysteine, genetic variation, sex, and diagnosis interact with B-vitamin treatment on outcomes was also examined.

METHODS

A randomized, double-blind, placebo-controlled trial was used. A total of 120 patients with first-episode psychosis were randomized to an adjunctive B-vitamin supplement (containing folic acid [5 mg], B₁₂ [0.4 mg], and B₆ [50 mg]) or placebo, taken once daily for 12 weeks. Coprimary outcomes were change in total symptomatology (Positive and Negative Syndrome Scale) and composite neurocognition. Secondary outcomes included additional measures of symptoms, neurocognition, functioning, tolerability, and safety.

RESULTS

B-vitamin supplementation reduced homocysteine levels (p = .003, effect size = -0.65). B-vitamin supplementation had no significant effects on Positive and Negative Syndrome Scale total (p = .749) or composite neurocognition (p = .785). There were no significant group differences in secondary symptom domains. A significant group difference in the attention/vigilance domain (p = .024, effect size = 0.49) showed that the B-vitamin group remained stable and the placebo group declined in performance. In addition, 14% of the sample had elevated baseline homocysteine levels, which was associated with greater improvements in one measure of attention/vigilance following B-vitamin supplementation. Being female and having affective psychosis was associated with improved neurocognition in select domains following B-vitamin supplementation. Genetic variation did not influence B-vitamin treatment response.

CONCLUSIONS

While 12-week B-vitamin supplementation might not improve overall psychopathology and global neurocognition, it may have specific neuroprotective properties in attention/vigilance, particularly in patients with elevated homocysteine levels, patients with affective psychosis, and female patients. Results support a personalized medicine approach to vitamin supplementation in first-episode psychosis.

Decreased Serum Oxytocin and Increased Homocysteine in First-Episode Schizophrenia Patients

Schizophrenia (SZ) is a debilitating and heterogeneous disease. We hypothesized that the oxytocin (OXT) system, inflammation and one-carbon metabolism would have a link with SZ. In this study, serum OXT, OXT receptor (OXTR), interleukin-6 (IL-6), high sensitivity CRP (hsCRP) and homocysteine (Hcy) levels were measured in 52 first-episode schizophrenia (FES) patients and 41 healthy controls (HC) from the Second Xiangya Hospital of Central South University. Meanwhile, the mRNA expressions of OXT and OXTR genes were determined by real-time quantitative PCR. Serum OXT and OXTR levels were significantly lower in FES patients (518.96 ± 22.22 and 174.60 ± 17.11 pg/ml) than the HC group (711.58 ± 40.57 and 252.15 ± 20.62 pg/ml). Serum IL-6 and hsCRP levels showed no difference between the two groups (1.82 ± 0.30 vs. 1.69 ± 0.36 pg/ml, 0.66 (0.22, 1.07) vs. 0.31 (0.13, 0.91) mg/L), but serum Hcy levels were significantly higher in FES patients (20.18 ± 1.83 vs. 15.24 ± 0.82 μmol/ml). The FES patients (0.27 ± 0.02 and 0.20 ± 0.02) have relatively higher mRNA expressions of OXT and OXTR genes than the HC group (0.16 ± 0.01 and 0.14 ± 0.01). In summary, our results suggested the possible function of the OXT system and Hcy in the pathogenesis of SZ.

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

INTRODUCTION

Several studies have described increased oxidative stress parameters in patients with schizophrenia. The objectives of the current study were to identify potential oxidative stress biomarkers in stable patients during first 10 years of schizophrenia and determine if they are associated with specific clinical dimensions.

MATERIAL AND METHODS

Seventy-three clinically stable outpatients with schizophrenia and 73 sex and age-matched healthy controls were recruited. Sociodemographic, clinical and biological data were collected at enrollment. Blood biomarkers included homocysteine, the percentage of hemolysis, lipid peroxidation subproducts, and as an antioxidant biomarker, catalase activity in erythrocytes.

RESULTS

Comparative analyses after controlling for smoking and metabolic syndrome evidenced a significant increase in catalase activity in patients. Also, lower lipid peroxidation levels showed an association with negative symptoms.

CONCLUSIONS

In conclusion, compensatory antioxidant mechanisms might be increased in stable patients with schizophrenia at early stages. Furthermore, there may be an inverse relationship between oxidative stress and negative dimension.

Antioxidant and anti-inflammatory nutrient status, supplementation, and mechanisms in patients with schizophrenia

Over 50 million people around the world suffer from schizophrenia, a severe mental illness characterized by misinterpretation of reality. Although the exact causes of schizophrenia are still unknown, studies have indicated that inflammation and oxidative stress may play an important role in the etiology of the disease. Pro-inflammatory cytokines are crucial for normal central nervous development and proper functioning of neural networks and neurotransmitters. Patients with schizophrenia tend to have abnormal immune activation resulting in elevated pro-inflammatory cytokine levels, ultimately leading to functional brain impairments. Patients with schizophrenia have also been found to suffer from oxidative stress, a result of an imbalance between the production of free radicals and the ability to detoxify their harmful effects. Furthermore, inflammation and oxidative stress are implicated to be related to the severity of psychotic symptoms. Several nutrients are known to have anti-inflammatory and antioxidant functions through various mechanisms in our body. The present review evaluates studies and literature that address the status and supplementation of omega-3 polyunsaturated fatty acids, vitamin D, B vitamins (B6, folate, B12), vitamin E, and carotenoids in different stages of schizophrenia. The possible anti-inflammatory and antioxidant mechanisms of action of each nutrient are discussed.

Effect of risperidone on serum homocysteine levels in first-episode, drug-naïve patients with schizophrenia

Some studies have shown that homocysteine (Hcy) levels are increased in patients with schizophrenia, and may be involved in its pathophysiology. The purpose of this study was to investigate the effect of the atypical antipsychotic drug risperidone on serum Hcy levels and to explore the relationship between the changes in Hcy levels and the therapeutic outcome, which, to our best knowledge have not been investigated. Fifty-six first-episode and drug-naïve inpatients with schizophrenia were assigned to a 12-week treatment regime with risperidone. Clinical efficacy was determined with the Positive And Negative Syndrome Scale (PANSS). Serum Hcy levels were measured by sandwich enzyme-linked immunosorbent assay in schizophrenia patients before and after the 12-week treatment, and the values were compared with those of fifty-six age- and gender- matched healthy controls. Serum Hcy levels were significantly higher in first-episode and drug-naïve patients than in control subjects (11.18±4.53 vs. 5.99±3.61μmol/L, F=37.195, df=1, p=1.73×10^-8). Moreover, a significant positive correlation between Hcy levels and PANSS negative sub-score was observed (r=0.515; p=4.81×10^-5). Serum Hcy levels were significantly decreased in patients after risperidone treatment (baseline: 11.18±4.53μmol/L vs. post-treatment: 8.98±4.07μmol/L, t=3.857, p=3.034×10^-4). At post-treatment, there was a significant negative relationship between serum Hcy levels and PANSS negative sub-scores (r=-0.288, p=0.032). High Hcy levels at the onset of psychosis suggests that it may contribute to the pathogenesis of schizophrenia and is related to clinical psychopathology. Serum Hcy levels were significantly decreased in schizophrenia patients after risperidone treatment.

[Psychopathological characteristics and social functioning of the schizophrenic patients with the T allele of the MTHFR677C>T polymorphism]

AIM

To compare the severity of psychopathological symptoms and characteristics of personal and social functioning in patients with schizophrenia, carriers of different alleles of the MTHFR677C>T polymorphism.

MATERIAL AND METHODS

One hundred and fifty patients diagnosed with schizophrenia were genotyped for the MTHFR677C>T polymorphism, some of them were examined using psychometric scales and tests (PANSS, SANS, PSP, CDSS, a battery of cognitive tests etc).

RESULTS AND CONCLUSION

Patients with the MTHFR677T variant had greater severity of negative symptoms regardless of psychometric instruments used in the study, greater severity of schizophrenia disorder in whole measured with the PANSS General psychopathological symptoms subscale, higher scores on the PANSS cognitive cluster and lower levels of personal and social functioning measured with the PSP compared to the patients with the MTHFR677CС genotype. The results of psychometric testing are in line with significant differences of MTHFR677T allele carriers from those with the MTHFR677CС genotype in the number of disable patients and the use of different types of psychiatric services. The differences were not related to sex, age, illness duration and depressive symptoms measured with CDSS and PANSS «depression/anxiety» factor.

Lower folate levels in schizophrenia: A meta-analysis

This meta-analysis aimed to estimate the association between folate level and schizophrenia in order to provide the evidence for the treatment of schizophrenia. Data were extracted from all the studies meeting our inclusion and exclusion criteria. The association between the folate level and schizophrenia was evaluated by the standardized mean difference (SMD) and 95% confidence interval (CI). The 20 published articles of our meta-analysis included 1463 (53.4%) cases and 1276 (46.6%) controls. The folate level was significantly lower in schizophrenia cases than in healthy controls. Subgroup analysis showed the folate level was lower in cases from Asia subgroup than in healthy controls. Sensitivity analysis showed that the current results were credible and reliable and the funnel plots indicated no publication bias in our meta-analysis. Our study indicates that schizophrenia patients may have lower folate levels. More epidemiological and laboratory studies are still needed to confirm whether it is necessary to supplement folate in schizophrenia patients.

Metabolic dysregulation in first-episode schizophrenia patients with respect to genetic variation in one-carbon metabolism

The aim of this study was to investigate the prevalence of metabolic disturbances in patients with first-episode schizophrenia (FES) and test the hypothesis that genetic variation in one-carbon metabolism may account for metabolic dysregulation in early psychosis. We measured fasting glucose, lipid profile parameters, homocysteine, folate and vitamin B12 in 135 patients with FES and 146 healthy controls (HCs). Polymorphisms in the following genes were determined: MTHFR (C677T and A1298C), MTHFD1 (G1958A), MTRR (A66G) and BHMT (G742A). Serum levels of folate and high-density lipoproteins (HDL) were significantly lower in patients with FES compared to HCs. In turn, serum levels of homocysteine and triglycerides were significantly higher in patients with FES than in HCs. Prevalence of hyperhomocysteinemia, low folate and HDL levels together with dyslipidemia was significantly higher in patients with FES compared to HCs. Higher homocysteine levels, lower vitamin B12 levels and the presence of metabolic syndrome were associated with higher severity of negative symptoms. None of studied polymorphisms was associated with schizophrenia risk. Several associations between studied polymorphisms and cardio-metabolic parameters were found. None of them remained significant after Bonferroni correction. Our results indicate that metabolic dysregulation in patients with FES is not associated with genetic variation in one-carbon metabolism.

Serum folate levels in schizophrenia: A meta-analysis

To clarify the relationship between serum folate and schizophrenia (SZ) risk, the meta-analysis was conducted. PubMed, Embase, and Web of Science were searched without language restrictions. Weighted mean difference (WMD) as a summary statistic was used in this meta-analysis. Subgroup analyses by publication language (English and non-English), ethnicity (Caucasian, Asian, African, Latino, and mixed population), duration (acute, chronic, patients including both acute and chronic SZ, and not mentioned about either chronic or acute), measurement time (before drugs using and after drugs using), gender (male and female) and age (<50 years old and >50 years old) were performed. Power analysis was also conducted to detect the reliability of the meta-analyses' results. In summary, the subgroups which failed to detect significant decreased associations were always with lower statistic power and could not be confirmed. The results supported that decreased serum folate was associated with SZ risk in total studies and subgroups of English publications, Caucasians, Asians, acute SZ patients, measurement after drugs using in SZ patients, and age<50 with the great enough powers, respectively. In conclusion, the present meta-analysis found that folate deficiency is associated to SZ, and subgroups which did not reach enough statistical power need further investigation in the future.

Homocysteine levels in schizophrenia patients newly admitted to an acute psychiatric ward

OBJECTIVE

After the discovery of 'homocystinuria syndrome', many studies have suggested that high blood levels of homocysteine may be associated with schizophrenia. The aim of this study was to analyse the association between hyperhomocysteinaemia and schizophrenia.

METHODS

In a population of inpatients suffering from exacerbated schizophrenic disorders (N=100), we evaluated homocysteine levels the day after their admission to an acute psychiatric ward and compared it with that of a non-patient control group (N=110), matched for age and gender. We statistically analysed the correlation between homocysteine levels and selected variables: gender, age, years of illness and number of previous psychiatric admissions as well as Brief Psychiatric Rating Scale, Positive Negative Syndrome Scale and Global Assessment Functioning (GAF) Scores.

RESULTS

We observed elevated homocysteine levels (an increase of 7.84 µM on average per patient) in 32% of the patients, but we did not find any statistically significant difference between the homocysteine levels of our patients and controls. Hyperhomocysteinaemia presented a positive statistically significant correlation with years of illness (p<0.005) and a negative statistically significant correlation with GAF score (p<0.001), but not with other clinical variables.

CONCLUSIONS

Hyperhomocysteinaemia, which occurred in our schizophrenia patients with poor social and relational functioning after many years of illness, could represent an effect of altered lifestyle due to psychosis, but not a specific marker for schizophrenia.

Improvement of Psychotic Symptoms and the Role of Tissue Plasminogen Activator

Tissue plasminogen activator (tPA) mediates a number of processes that are pivotal for synaptogenesis and remodeling of synapses, including proteolysis of the brain extracellular matrix, degradation of adhesion molecules, activation of neurotrophins, and activation of the N-methyl-d-aspartate receptor. Abnormalities in these processes have been consistently described in psychotic disorders. In this paper, we review the physiological roles of tPA, focusing on conditions characterized by low tPA activity, which are prevalent in schizophrenia. We then describe how tPA activity is influenced by lifestyle interventions and nutritional supplements that may ameliorate psychotic symptoms. Next, we analyze the role of tPA in the mechanism of action of hormones and medications effective in mitigating psychotic symptoms, such as pregnenolone, estrogen, oxytocin, dopamine D3 receptor antagonists, retinoic acid, valproic acid, cannabidiol, sodium nitroprusside, N-acetyl cysteine, and warfarin. We also review evidence that tPA participates in the mechanism by which electroconvulsive therapy and cigarette smoking may reduce psychotic symptoms.

Effects of second-generation antipsychotics on selected markers of one-carbon metabolism and metabolic syndrome components in first-episode schizophrenia patients

Purpose

Alterations in one-carbon metabolism (OCM) have been repeatedly reported in schizophrenia. However, there is a scarcity of studies addressing the effects of antipsychotics on selected OCM markers in schizophrenia and provided results are inconsistent.

Methods

We recruited 39 first-episode schizophrenia (FES) patients and determined serum profile of total homocysteine (tHcy), folate, vitamin B12, lipoproteins and glucose at baseline and after 12 weeks of treatment with second-generation antipsychotics (SGA) including olanzapine and risperidone in monotherapy.

Results

After 12 weeks of treatment, all patients had significantly higher body mass index (BMI), serum levels of total cholesterol (TC), low-density lipoproteins (LDL), triglycerides (TG) and tHcy together with significantly lower levels of folate and vitamin B12. The analysis of differences between SGA revealed the same biochemical alterations in patients treated with olanzapine as in the whole group, while those receiving risperidone had no statistically significant changes in serum folate, vitamin B12 and TG. There was a significantly higher increase in BMI and TC in patients treated with olanzapine in comparison with those treated with risperidone. Patients receiving olanzapine had a higher decrease in vitamin B12 than those assigned to the treatment with risperidone. Changes in folate, vitamin B12, tHcy and TC levels were significant only in males, even after Bonferroni correction. Multiple regression analysis revealed that changes in tHcy levels are associated with gender and baseline metabolic parameters (BMI, glucose, TC, LDL and HDL) but not with selected SGA.

Conclusions

These results indicate that SGA may influence OCM, especially in first-episode schizophrenia (FES) males.

Electronic supplementary material

The online version of this article (doi:10.1007/s00228-014-1762-2) contains supplementary material, which is available to authorized users.

Homocysteine levels in schizophrenia and affective disorders-focus on cognition

Although homocysteine (Hcy) has been widely implicated in the etiology of various physical health impairments, especially cardiovascular diseases, overwhelming evidence indicates that Hcy is also involved in the pathophysiology of schizophrenia and affective disorders. There are several mechanisms linking Hcy to biological underpinnings of psychiatric disorders. It has been found that Hcy interacts with NMDA receptors, initiates oxidative stress, induces apoptosis, triggers mitochondrial dysfunction and leads to vascular damage. Elevated Hcy levels might also contribute to cognitive impairment that is widely observed among patients with affective disorders and schizophrenia. Supplementation of vitamins B and folic acid has been proved to be effective in lowering Hcy levels. There are also studies showing that this supplementation strategy might be beneficial for schizophrenia patients with respect to alleviating negative symptoms. However, there are no studies addressing the influence of add-on therapies with folate and vitamins B on cognitive performance of patients with schizophrenia and affective disorders. In this article, we provide an overview of Hcy metabolism in psychiatric disorders focusing on cognitive correlates and indicating future directions and perspectives.

Serum levels of BDNF, folate and homocysteine: in relation to hippocampal volume and psychopathology in drug naïve, first episode schizophrenia

OBJECTIVE

The present study was to examine serum levels of brain-derived neurotrophic factor (BDNF), folate, homocysteine (Hcy), and their relationships with hippocampal volume and psychopathology in drug naïve, first episode schizophrenia.

METHOD

Drug naïve, first episode schizophrenia patients and healthy controls were enrolled in the study. Serum levels of BDNF, folate and Hcy were measured using enzyme-linked immunosorbent assay (ELISA), electrochemiluminescence immunoassay (ECLIA), and enzymatic cycling method respectively. Hippocampus was parcellated and bilateral hippocampal volumes were measured using FreeSurfer.

RESULTS

Forty-six patients with drug naïve, first episode schizophrenia (SZ group) and 30 healthy controls (control group) were enrolled. The SZ group had significantly lower serum levels of BDNF and folate, and significantly higher serum levels of Hcy compared with the control group (p=0.013, p<0.001, p=0.003 respectively). There were no significant differences in hippocampal volumes between the two groups (ps>0.2). Within the SZ group, there were significant positive relationships between serum levels of BDNF and both left and right hippocampal volumes (r=0.327, p=0.026; r=0.338, p=0.022 respectively). In contrast, such relationships did not exist in the control group. Within the SZ group, there were significant negative relationships between serum levels of folate and PANSS-total scores and PANSS-negative symptom scores (r=0.319, p=0.031; r=0.321, p=0.030 respectively); and there was a positive relationship between serum levels of Hcy and PANSS-total scores (r=0.312, p=0.035). Controlling for potential confounding variables resulted in similar findings.

CONCLUSIONS

Drug naïve, first episode schizophrenia presents decreased serum levels of BDNF, folate and increased serum levels of Hcy, which may play an important role in the neurodevelopmental process and clinical manifestation of schizophrenia.

Elevated homocysteine level in first-episode schizophrenia patients--the relevance of family history of schizophrenia and lifetime diagnosis of cannabis abuse

Accumulating evidence indicates that elevated homocysteine (Hcy) level occurs in first-episode schizophrenia (FES) patients. We included 56 FES patients and 53 healthy controls (HC). Plasma level of Hcy was significantly higher in FES patients than HC (p = 0.044). In addition, plasma levels of high-density lipoproteins (HDL) and folate were significantly lower in FES than in HC (p < 0.001). Positive family history of schizophrenia was associated with lower plasma HDL (p = 0.041) and vitamin B12 (p = 0.017), as well as higher level of Hcy (p = 0.017). Patients with FES, who abused cannabis, had higher levels of Hcy (p = 0.017), as well as lower levels of vitamin B12 (p = 0.017) and HDL (p = 0.041). Plasma Hcy negatively correlated with duration of untreated psychosis (r = -0.272, p = 0.042). There was a positive correlation between Hcy level and the severity of negative symptoms (r = 0.363, p = 0.006) and general psychopathology (r = 0.349, p = 0.008) assessed using Positive and Negative Syndrome Scale (PANSS). Vitamin B12 level was negatively associated with the severity of negative symptoms (r = -0.406, p = 0.002), while folate level negatively correlated with general psychopathology score (r = -0.365, p = 0.006) in PANSS. These results indicate that the severity of one-carbon metabolism alterations and HDL deficiency might be associated with family history of schizophrenia and cannabis abuse. Lower vitamin B12 and folate along with elevated Hcy may influence the severity of FES psychopathology.

Meta-analyses of blood homocysteine levels for gender and genetic association studies of the MTHFR C677T polymorphism in schizophrenia

Previous studies suggest that elevated blood homocysteine levels and the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism are risk factors for schizophrenia. However, the effects of gender and MTHFR C677T genotypes on blood homocysteine levels in schizophrenia have not been consistent. We first investigated whether plasma total homocysteine levels were higher in patients with schizophrenia than in controls with stratification by gender and by the MTHFR C677T genotypes in a large cohort (N = 1379). Second, we conducted a meta-analysis of association studies between blood homocysteine levels and schizophrenia separately by gender (N = 4714). Third, we performed a case-control association study between the MTHFR C677T polymorphism and schizophrenia (N = 4998) and conducted a meta-analysis of genetic association studies based on Japanese subjects (N = 10 378). Finally, we assessed the effect of plasma total homocysteine levels on schizophrenia by a mendelian randomization approach. The ANCOVA after adjustment for age demonstrated a significant effect of diagnosis on the plasma total homocysteine levels in all strata, and the subsequent meta-analysis for gender demonstrated elevated blood homocysteine levels in both male and female patients with schizophrenia although antipsychotic medication might influence the outcome. The meta-analysis of the Japanese genetic association studies demonstrated a significant association between the MTHFR C677T polymorphism and schizophrenia. The mendelian randomization analysis in the Japanese populations yielded an OR of 1.15 for schizophrenia per 1-SD increase in plasma total homocysteine. Our study suggests that increased plasma total homocysteine levels may be associated with an increased risk of schizophrenia.

Plasma homocysteine levels in depression and schizophrenia in South Indian Tamilian population

CONTEXT

Hyperhomocysteinemia has been associated with psychiatric diseases in non-Indian populations.

OBJECTIVES

We aimed to determine if total plasma Homocysteine (Hcys) is associated with schizophrenia or depression in South Indian Tamil patients and if so, to correlate their severity and phenomenology to Hcys levels.

SETTINGS AND DESIGN

40 patients each with schizophrenia and depression and 40 healthy controls were recruited from the psychiatry department of a quaternary referral centre. Association between Hcys and psychiatric disorders was determined using a Case- control design. Hcys levels were correlated with age, gender and severity and duration of the disease by appropriate statistical methods using SPSS17.

MATERIALS AND METHODS

Schizophrenia and depression were defined using ICD10 DCR version. Severity of depression was assessed by Hamilton Depression Rating Scale and that of schizophrenia using Positive and Negative Schizophrenia scales (PANSS). Hcys levels were determined using automated chemiluminiscence immunoassay (74-76).

STATISTICAL ANALYSIS

Differences between the mean values of plasma homocysteine levels among schizophrenia, depression and control groups were compared using analysis of variants. The association between the severity and duration of schizophrenia and depression and the plasma homocysteine levels were determine using Pearson correlation.

CONCLUSIONS

In Tamilian population, schizophrenia and depression are associated with total plasma Hcys levels which correlated with the duration and severity of psychosis.

Taurine and glutathione in plasma and cerebrospinal fluid in olanzapine treated patients with schizophrenia

Oxidative stress has been implicated in the pathophysiology of schizophrenia. Taurine and glutathione (GSH) have antioxidant and central nervous system protective properties, and are proposed to be involved in the pathology of schizophrenia. The aim of this study was to compare the blood and cerebrospinal fluid (CSF) levels of taurine and GSH in patients with schizophrenia, medicated with oral olanzapine, compared with controls. In total, 37 patients with schizophrenia and 45 healthy volunteers were recruited. We found the plasma taurine levels to be elevated in patients compared with controls. No differences were, however, found between patients and controls regarding taurine in CSF or GSH concentrations in plasma and CSF. Moreover, in the patient group no correlations between taurine and GSH levels and the symptoms or function of the disorder were found. The higher levels of plasma but not CSF taurine in patients with schizophrenia treated with OLA may implicate the involvement of taurine in the pathophysiology of the disease. The absence of GSH differences both in plasma and CSF between patients and controls is interesting in the perspective of earlier research proposing a dysregulation of GSH metabolism as a vulnerability factor for the development of schizophrenia.

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.

Homocysteine and cognition in first-episode psychosis patients

In the last years, there has been growing evidence linking elevated homocysteine levels with cognitive dysfunction in several neurological and neuropsychiatric diseases. The aim of the present study was to investigate the potential relationship between elevated homocysteine levels and cognitive deficits in first-episode psychosis patients. Plasma levels and cognitive performance of 139 patients and 99 healthy volunteers were compared. Patients were classified as elevated homocysteine (>90 percentile for controls) and normal and compared on 22 cognitive outcome measures grouped into cognitive domains known to be impaired in schizophrenia. Patients had a statistically significant increase in plasmatic homocysteine levels. In addition, they presented with significantly increased cognitive deficits. However, no relationship between homocysteine levels and cognitive impairment was detected. These results suggest the need for further studies to clarify the role of homocysteine in the etiology and prognosis of psychosis.

Risk factors associated with metabolic syndrome in bipolar and schizophrenia subjects treated with antipsychotics: the role of folate pharmacogenetics

Folate has been implicated in cardiovascular disease with atypical antipsychotic (AAPs) use, and individuals with methylenetetrahydrofolate reductase (MTHFR) and catechol-O-methyl transferase (COMT) variants are at greater risk. This study examined the relationship between the MTHFR 677C/T, MTHFR 1298A/C, and COMT Val158Met variants; metabolic syndrome; and lifestyle measures in schizophrenia and bipolar subjects. A total of 237 subjects with bipolar or schizophrenia receiving an antipsychotic for at least 6 months were included in this cross-sectional analysis. Subjects were screened for the metabolic syndrome (National Cholesterol Education Program Adult Treatment Panel III criteria) and MTHFR 677C/T, MTHFR 1298A/C, and Val158Met genotypes. In addition, serum folate and homocysteine were measured along with lifestyle factors. The subject's mean age was 44.7 (SD, 11.7) years; 72% were white, and 51% male; 61% were receiving an AAP; the mean body mass index was 32.6 (SD, 8.2) kg/m, and 48% were current smokers. Overall, 41% met metabolic syndrome criteria (n = 98). There were no differences in age, sex, AAP exposure, or body mass index between genotype groups. Metabolic syndrome was related to age, smoking, and the MTHFR 677T and COMT 158Val alleles (χ = 34.4, P < 0.0001). In addition, AAP use showed a trend association with metabolic syndrome (χ = 3.21, P = 0.07). These data support our previous reports and add more data pointing to folate's role in mediating a link between mental illness and cardiovascular disease. Use of this information clinically may help to reduce the risk for AAP metabolic complications in those whose clinical care necessitates the use of AAPs.

Serum homocysteine and folate levels in korean schizophrenic patients

OBJECTIVE

This study was conducted to confirm the results of the authors' previous research on schizophrenia manifesting high serum homocysteine and low folate levels. This study is anchored on a theory that a high serum homocysteine concentration affects schizophrenia by virtue of a neurotoxic mechanism, and on a report that some schizophrenia patients with high homocysteine levels benefited from high folate ingestion.

METHODS

The serum homocysteine, folate, and vitamin B(12) levels of 236 normal-control-group subjects and 234 schizophrenia subjects who met the diagnostic criteria based on DSM-IV-TR were compared. The homocysteine levels were measured via fluorescence polarization immunoassay, and the folate and vitamin B(12) levels were determined via radioimmunoassay.

RESULTS

The homocysteine levels of the patient group were significantly higher than those of the normal control group. The homocysteine level was more negatively correlated with the folate level in the schizophrenia group than in the control group. The percentages of female and male schizophrenia subjects manifesting high homocysteine levels were 33.8 and 51.5%, respectively. The percentage of schizophrenia subjects with low folate levels was 66.2%. In the low- and normal-folate-level groups, the patient group showed significantly higher homocysteine levels than the normal control group. The low-folate-level patient group particularly showed significantly higher homocysteine levels than the low-folate-level normal control group.

CONCLUSION

Some schizophrenia patients with high serum homocysteine levels may have the genetic defect of having low folate serum levels. In such cases, folate ingestion may be a good management modality for clinical improvement.

One-carbon metabolism and schizophrenia: current challenges and future directions

Schizophrenia is a heterogeneous disease generally considered to result from a combination of heritable and environmental factors. Although its pathophysiology has not been fully determined, biological studies support the involvement of several possible components including altered DNA methylation, abnormal glutamatergic transmission, altered mitochondrial function, folate deficiency and high maternal homocysteine levels. Although these factors have been explored separately, they all involve one-carbon (C1) metabolism. Furthermore, C1 metabolism is well positioned to integrate gene-environment interactions by influencing epigenetic regulation. Here, we discuss the potential roles of C1 metabolism in the pathophysiology of schizophrenia. Understanding the contribution of these mechanisms could yield new therapeutic approaches aiming to counteract disease onset or progression.