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

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.

Protein Succinylation and Malonylation as Potential Biomarkers in Schizophrenia

Two protein post-translational modifications, lysine succinylation and malonylation, are implicated in protein regulation, glycolysis, and energy metabolism. The precursors of these modifications, succinyl-CoA and malonyl-CoA, are key players in central metabolic processes. Both modification profiles have been proven to be responsive to metabolic stimuli, such as hypoxia. As mitochondrial dysfunction and metabolic dysregulation are implicated in schizophrenia and other psychiatric illnesses, these modification profiles have the potential to reveal yet another layer of protein regulation and can furthermore represent targets for biomarkers that are indicative of disease as well as its progression and treatment. In this work, data from shotgun mass spectrometry-based quantitative proteomics were compiled and analyzed to probe the succinylome and malonylome of postmortem brain tissue from patients with schizophrenia against controls and the human oligodendrocyte precursor cell line MO3.13 with the dizocilpine chemical model for schizophrenia, three antipsychotics, and co-treatments. Several changes in the succinylome and malonylome were seen in these comparisons, revealing these modifications to be a largely under-studied yet important form of protein regulation with broad potential applications.

Association between variants of MTHFR genes and psychiatric disorders: A meta-analysis

Background

Psychiatric disorders have seriously affected human life, one of the risk genes related to psychosis is the methylenetetrahydrofolatereductase (MTHFR) gene. This gene has a potential role in psychiatric disorders. Therefore, a meta-analysis is conducted to investigate the correlations between two prevalent MTHFR single nucleotide polymorphisms (SNPs), MTHFR C677T, A1298C, severe psychological disorders (schizophrenia, major depression, bipolar disorder).

Methods

A total of 81 published studies were screened and selected by a search of electronic databases up to April 2022. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the association between MTHFR polymorphism and psychiatric disorders susceptibility by using random effect models.

Results

We found that MTHFR C677T polymorphism is significantly related to schizophrenia and major depression in the overall population. MTHFR C677T has been linked to an increased risk of bipolar disorder in the recessive model (TT vs. CT + CC). Ethnic subgroup analysis shows that schizophrenia and major depression significantly correlate with MTHFR C677T and A1298C in Asian populations but not Caucasians. Besides, schizophrenia is correlated substantially with MTHFR C677T in the African population. However, the MTHFR A1298C polymorphism is only marginally linked to major depression.

Conclusion

Findings of the current study revealed that MTHFR may contribute to the common pathogenesis of psychiatric diseases and that its variants may be essential in controlling the expression of psychosis-related genes. This study could help the researchers and health specialists in the early diagnosis and treatment of psychiatric disorders.

Association between MTHFR (677C>T and 1298A>C) polymorphisms and psychiatric disorder: A meta-analysis

Recent studies showed that genetic polymorphism of 5,10-methylenetetrahydrofolate reductase (MTHFR) is related to attention-deficit hyperactivity disorder (ADHD), bipolar disorder (BD) and schizophrenia (SCZ). However, no consistent conclusion has been determined. This meta-analysis aims to interrogate the relationship between MTHFR gene polymorphisms (677C>T and 1298A>C) and the occurrence of ADHD, BD and SCZ. We retrieved case-control studies that met the inclusion criteria from the PubMed database. Associations between MTHFR polymorphisms (677C>T and 1298A>C) and ADHD, BD and SCZ were measured by means of odds ratios (ORs) using a random effects model and 95% confidence intervals (CIs). Additionally, sensitivity analysis and publication bias were performed. After inclusion criteria were met, a total of five studies with ADHD including 434 cases and 670 controls, 18 studies with BD including 4167 cases and 5901 controls and 44 studies with SCZ including 16,098 cases and 19913 controls were finally included in our meta-analysis. Overall, our meta-analytical results provided evidence that the MTHFR 677C>T was associated with occurrence of BD and SCZ, while the 1298A>C polymorphism was related to ADHD and BD, and additionally the sensitivity analysis indicated these results were stable and reliable. This may provide useful information for relevant studies on the etiology of psychiatric disorders.

Risk factors for metabolic syndrome in individuals with recent-onset psychosis at disease onset and after 1-year follow-up

Metabolic syndrome (MetS) is a cluster of parameters encompassing the most dangerous heart attack risk factors, associated with increased morbidity and mortality. It is highly prevalent in recent-onset psychosis (ROP) patients. In this pilot study, we evaluated MetS parameters (fasting glucose, high-density lipoprotein (HDL) cholesterol (HDL-c), fasting triglycerides, waist circumference, and systolic and diastolic blood pressure), clinical symptoms, pharmacological treatment, lifestyle, and inflammatory markers in 69 patients with ROP and 61 healthy controls (HCs). At baseline, waist circumference (p = 0.005) and fasting triglycerides (p = 0.007) were higher in patients with ROP than in HCs. At the 1-year follow-up, patients showed clinical improvement, with a reduction in the positive and negative syndrome scale (PANSS) score (p < 0.001), dietary intake (p = 0.001), and antipsychotic medication dose (p < 0.001); however, fasting glucose (p = 0.011), HDL-c (p = 0.013) and waist circumference worsened (p < 0.001). We identified sex, age, BMI, dietary intake, physical activity, daily tobacco use, daily cannabis use, and antipsychotic doses as risk factors contributing to baseline MetS parameters. After 1-year follow-up, those factors plus the PANSS and Calgary Depression Scale for Schizophrenia (CDSS) scores were associated with MetS parameters. Further studies are needed to understand the contributions of the studied risk factors in patients with ROP at onset and during disease progression.

Evaluation of mRNA expression level of the ATP synthase membrane subunit c locus 1 (ATP5G1) gene in patients with schizophrenia

Background

Schizophrenia is a serious, complex mental disorder. The impairment of oxidative phosphorylation has a detrimental consequence on CNS function. Different ATP synthase subunits have been involved in the pathological process of various neurodegenerative disorders. Our goal was to evaluate the mRNA expression level of the ATP synthase membrane subunit c locus 1 (ATP5G1, also named ATP5MC1) gene in patients with schizophrenia.

Methods

Determination of the expression levels of ATP5G1 in plasma and peripheral blood mononuclear cells (PBMCs) were performed by real-time PCR in 90 controls and 90 patients with schizophrenia.

Results

Patients had significantly decreased ATP5G1 mRNA expression levels in both plasma and PBMCs compared to controls. The receiver operating characteristic curve was applied to detect a cut-off value of ATP5G1 expression in plasma and PBMCs. The ATP5G1 relative expression in PBMCs had better performance with a cut-off value ≤ 21 (AUC = 0.892, P < 0.001), sensitivity of 94.44%, and specificity of 72.22% in discriminating between schizophrenic patients. ATP5G1 expression in PBMCs was an independent predictor in schizophrenia.

Conclusion

This study revealed a down-regulation of ATP5G1 expression in schizophrenia, precisely expression in PBMCs. That might give insight into the role of ATP5G1 gene in the pathogenesis of schizophrenia.

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This study revealed a down-regulation of ATP5G1 expression in schizophrenia, precisely expression in PBMCs, which was found as an independent risk factor.

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This might give insight into the role of the ATP5G1 gene in the pathogenesis of schizophrenia.

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Further studies are needed to evaluate the role of ATP5G1 in schizophrenia and their impact on ATP production in these patients.

The Effects of Plasma Homocysteine Level on the Risk of Three Major Psychiatric Disorders: A Mendelian Randomization Study

BACKGROUND

Higher homocysteine (Hcy) level has been suggested to be associated with major psychiatric disorders (MPDs), such as schizophrenia (SCZ), bipolar disorder (BD), and major depressive disorder (MDD). We investigated the causal relationships between plasma Hcy level and MPDs risks using the Mendelian randomization (MR) method.

METHODS

We selected 18 loci associated with plasma Hcy level from a large-scale genome-wide association study (GWAS) as genetic instruments. Genetic associations with SCZ, MDD, BD and BD subtypes (BD-I and BD-II) were extracted from several GWAS datasets from the Psychiatric Genomics Consortium. We used the Generalized Summary-data-based Mendelian Randomization (GSMR) method to estimate the associations of genetically predicted plasma Hcy levels with MPDs risks. We also performed inverse variance-weighted (IVW) analysis to verify the GSMR results and used MR-Egger regression and leave-one-out analysis to test the assumptions for a valid MR analysis.

RESULTS

Genetically predicted plasma Hcy levels were associated with risks of SCZ (odds ratio [OR] = 1.12, P _GSMR = 1.73 × 10^-3) and BD-I (OR = 1.14, P _IVW = 5.23 × 10^-3) after Bonferroni correction. These associations were statistically significant when using IVW analysis (SCZ: OR = 1.11, P _IVW = 2.74 × 10^-3; BD-I: OR = 1.13, P _IVW = 9.44 × 10^-3). Furthermore, no significant horizontal pleiotropy was found by sensitivity analysis, and leave-one-out analyses showed no specific SNP affected the overall estimate. However, genetically determined plasma Hcy levels were not causally associated with MDD, BD, or BD-II risks.

CONCLUSION

Our results suggest that elevated plasma Hcy levels may increase the risk of SCZ or BD-I. Further randomized clinical trials are warranted to validate the MR findings in our study.

Associations of Genetic Variants of Methylenetetrahydrofolate Reductase and Serum Folate Levels with Metabolic Parameters in Patients with Schizophrenia

The one-carbon metabolism pathway is a suitable candidate for studying the genetic and epigenetic factors contributing to metabolic abnormalities in patients with schizophrenia. We recruited 232 patients with schizophrenia and analyzed their serum folate, vitamin B12, and homocysteine levels and metabolic parameters to investigate the associations of genetic variants of methylenetetrahydrofolate reductase (MTHFR) and folate levels with metabolic parameters. MTHFR C677T and MTHFR A1298C were genotyped. Results showed that MTHFR 677T allele carriers had lower levels of total cholesterol and low-density lipoprotein cholesterol than those with the 677CC genotype. Metabolic parameters did not differ between MTHFR 1298C and 1298AA carriers. Patients with a low folate level had a lower high-density lipoprotein cholesterol level than those with a normal folate level, but the effect disappeared after adjustment for age, sex, and types of antipsychotics used. We found significant interactions between MTHFR A1298C and the folate level status (low vs. normal) in terms of body mass index and waist circumference. In conclusion, genetic variants in one-carbon metabolism might play a role in antipsychotic-induced metabolic abnormalities. Prospective studies on drug-naïve, first-episode patients with schizophrenia are warranted to identify key regions of DNA methylation changes accounting for antipsychotic-induced metabolic abnormalities.

Evidence for the atherogenic index of plasma as a potential biomarker for cardiovascular disease in schizophrenia

BACKGROUND

Schizophrenia is known to be accompanied with increased cardiovascular mortality, which causes reduced life expectancy.

AIM

The aim of the current study was to investigate if atherogenic index of plasma (AIP) could be a good marker in assessing cardiovascular disease (CVD) risk in patients with schizophrenia.

METHODS

Patients with schizophrenia (n = 328) and healthy controls (n = 141) were recruited. Schizophrenia patients were evaluated according to the presence of antipsychotic (AP) drug use as AP(+)Sch group and AP(-)Sch group. Atherogenic indices, such as AIP, Castelli's risk index-I (CRI-I), Castelli's risk index-II (CRI-II), and atherogenic coefficient (AC), were calculated according to the laboratory examination of serum lipid parameters.

RESULTS

According to the comparison of serum lipid levels, triglyceride (TG) levels were found to be highest and high-density lipoprotein-cholesterol levels were lowest in AP(+)Sch group than AP(-)Sch group and control group (CG) (p < 0.001). AIP, CRI-I, and CRI-II scores were found to be significantly higher in AP(+)Sch group than AP(-)Sch group, and in AP(-)Sch than healthy controls (p < 0.001). Mean AC scores were higher in AP(+)Sch group than both AP(-)Sch and CG and were similar in AP(-)Sch and control subjects (p < 0.001). According to the correlation analysis, AIP scores were positively correlated with duration of disease (r = 0.235; p = 0.002) and age (r = 0.226; p = 0.003) in AP(+)Sch group but not in drug-free subjects. In all groups, atherogenic indices of CRI-I, CRI-II, and AC scores were found to be positively correlated with AIP scores (p < 0.001).

CONCLUSION

Our results suggest that AIP is an easily calculable and reliable marker for determining the CVD risk in both drug-free schizophrenia patients and patients under AP treatment.

Subsequent Dyslipidemia and Factors Associated with Mortality in Schizophrenia: A Population-Based Study in Taiwan

Background: Persons with schizophrenia are at greater risk of developing subsequent medical conditions. To date, few studies have examined comprehensively the risks, mortality and survival rates in schizophrenia and subsequent dyslipidemia over different time periods. The objective of this study was to evaluate the occurrence of subsequent dyslipidemia after the diagnosis of schizophrenia, and factors associated with mortality and survival rate in patients with schizophrenia. Methods: We used a population-based cohort from Taiwan National Health Insurance Research Database, to investigate in patients whom were first diagnosed with schizophrenia during the period from 1997 through 2009, the risk of subsequent dyslipidemia during follow-up. Cumulative incidences and hazard ratios after adjusting for competing mortality risks were calculated. Results: A total of 20,964 eligible patients were included. Risks (i.e., comorbidity) and protective factors (i.e., statin use) have significant impacts on mortality. The mortality exhibits a U-shaped pattern by age. After 50, the risk of death increases with age. Risk of mortality before 50 increases with a decrease in age. Risks differed by the duration time to subsequent dyslipidemia after schizophrenia. Mean duration was 63.55 months in the survive group, and 43.19 months in the deceased group. The 5-, 10-, and 15-year survival rates for patients with schizophrenia and subsequent dyslipidemia were 97.5, 90, and 79.18%, respectively. Conclusion: Early occurrence of subsequent dyslipidemia is associated with increased overall mortality in patients with schizophrenia.

Sex-Specific Effect of Serum Lipids and Body Mass Index on Psychotic Symptoms, a Cross-Sectional Study of First-Episode Psychosis Patients

Background: Schizophrenia is a disorder with considerable heterogeneity in course and outcomes, which is in part related to the patients' sex. Studies report a link between serum lipids, body mass index (BMI), and therapeutic response. However, the role of sex in these relationships is poorly understood. In a cross-sectional sample of first-episode psychosis (FEP) patients, we investigated if the relationship between serum lipid levels (total cholesterol, HDL-C, LDL-C, and triglycerides), BMI, and symptoms differs between the sexes. Methods: We included 435 FEP patients (males: N = 283, 65%) from the ongoing Thematically Organized Psychosis (TOP) study. Data on clinical status, antipsychotics, lifestyle, serum lipid levels, and BMI were obtained. The Positive and Negative Syndrome Scale (PANSS) and the Calgary Depression Scale for Schizophrenia (CDSS) were used to assess psychotic and depressive symptoms. General linear models were employed to examine the relationship between metabolic variables and symptomatology. Results: We observed a female-specific association between serum HDL-C levels and negative symptoms (B = -2.24, p = 0.03) and between triglycerides levels (B = 1.48, p = 0.04) and BMI (B = 0.27, p = 0.001) with depressive symptoms. When controlling for BMI, only the association between serum HDL-C levels and negative symptoms remained significant. Moreover, the HDL-C and BMI associations remained significant after controlling for demography, lifestyle, and illness-related factors. Conclusion: We found a relationship between metabolic factors and psychiatric symptoms in FEP patients that was sex-dependent.

Metabolic Dysregulation and Psychosocial Stress in Patients with Schizophrenia Spectrum Disorders: A Case-Control Study

Patients with schizophrenia spectrum disorders have a reduced life expectancy, which is largely the consequence of a high co-occurrence of cardiovascular diseases. To date, several intrinsic and environmental factors underlying this phenomenon have been found. However, the association with psychosocial stress has not been extensively addressed. In this study, we tested the relationship between a history of adverse childhood experiences (ACEs), lifetime stressors, perceived stress and metabolic parameters in patients with schizophrenia spectrum disorders and in healthy controls. The participants included 85 inpatients with schizophrenia spectrum disorders and 56 healthy controls. Serum levels of glucose, insulin, low- and high-density lipoproteins (LDL and HDL), triglycerides, total cholesterol and high-sensitivity C-reactive protein (hsCRP) were determined. After adjustment for potential confounding factors, patients had significantly higher levels of glucose (F = 4.856, p = 0.030), triglycerides (F = 4.720, p = 0.032) and hsCRP (F = 7.499, p = 0.007) as well as significantly lower levels of HDL (F = 5.300, p = 0.023) compared to healthy controls. There were also significant effects of interactions between diagnosis and a history of ACEs on the levels of insulin (F = 4.497, p = 0.036) and homeostatic model assessment of insulin resistance (HOMA-IR) (F = 3.987, p = 0.048). More specifically, the levels of insulin and HOMA-IR were significantly higher in the subgroup of patients with schizophrenia spectrum disorders and a positive history of ACEs compared to other subgroups of participants. No significant associations between lifetime stressors and perceived stress with metabolic parameters were found. Our findings indicate that a history of ACEs might be associated with insulin resistance in patients with schizophrenia spectrum disorders. Therapeutic strategies targeting early-life stress should be considered with early interventions that aim to manage cardiometabolic comorbidity in patients with schizophrenia spectrum disorders.

Impaired hormonal regulation of appetite in schizophrenia: A narrative review dissecting intrinsic mechanisms and the effects of antipsychotics

Cardiometabolic diseases are the main contributor of reduced life expectancy in patients with schizophrenia. It is now widely accepted that antipsychotic treatment plays an important role in the development of obesity and its consequences. However, some intrinsic mechanisms need to be taken into consideration. One of these mechanisms might be related to impaired hormonal regulation of appetite in this group of patients. In this narrative review, we aimed to dissect impairments of appetite-regulating hormones attributable to intrinsic mechanisms and those related to medication effects. Early hormonal alterations that might be associated with intrinsic mechanisms include low levels of leptin and glucagon-like peptide-1 (GLP-1) together with elevated insulin levels in first-episode psychosis (FEP) patients. However, evidence regarding low GLP-1 levels in FEP patients is based on one large study. In turn, multiple-episode schizophrenia patients show elevated levels of insulin, leptin and orexin A together with decreased levels of adiponectin. In addition, patients receiving olanzapine may present with low ghrelin levels. Post mortem studies have also demonstrated reduced number of neuropeptide Y neurons in the prefrontal cortex of patients with schizophrenia. Treatment with certain second-generation antipsychotics may also point to these alterations. Although our understanding of hormonal regulation of appetite in schizophrenia has largely been improved, several limitations and directions for future studies need to be addressed. This is of particular importance since several novel pharmacological interventions for obesity and diabetes have already been developed and translation of these developments to the treatment of cardiometabolic comorbidities in schizophrenia patients is needed.

Homocysteine, but not MTHFR gene polymorphism, influences depressive symptoms in patients with schizophrenia

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) is the key enzyme of folate metabolism in the process of one-carbon cycle and its deficiency results in elevated homocysteine concentration. In this study, we hypothesized that MTHFR C677T polymorphism and homocysteine concentration may play important roles in the development of depressive symptoms in schizophrenia.

METHODS

We recruited 715 patients with stable schizophrenia, and among them, 197 schizophrenia patients under olanzapine monotherapy were enrolled for homocysteine concentration analysis. The Positive and Negative Syndrome Scale (PANSS) and Calgary Depression Scale for Schizophrenia (CDSS) were employed to evaluate psychiatric and depressive symptoms.

RESULTS

When the 715 schizophrenia patients were evaluated by CDSS, 326 individuals (45.6%) had depressive symptoms. No significant differences were observed in C677T genotype and allele distributions between the schizophrenia with or without depression groups. Schizophrenia patients with depression have higher levels of homocysteine than those without depression (P = 0.019). There was a positive correlation between the homocysteine levels and CDSS score (r = 0.22, P = 0.002).

CONCLUSION

Our findings suggested that higher levels of homocysteine may be a risk factor for the development of depressive symptoms in schizophrenia patients.

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.

Glucose metabolism dysregulation at the onset of mental illness is not limited to first episode psychosis: A systematic review and meta-analysis

AIM

To compare the differences of glucose metabolism outcomes between treatment-naïve, patients with first episode psychosis (FEP) and mood disorders.

METHODS

We conducted a systematic review and meta-analysis of glucose intolerance in treatment-naïve, first episode patients with severe mental illnesses (SMIs).

RESULTS

We identified 31 eligible studies. Compared to healthy controls, FEP group have higher insulin and insulin resistance levels, and both groups have higher glucose tolerance test results. No significant differences were found in glucose metabolism outcomes between FEP and mood disorder groups.

CONCLUSIONS

Our results highlight impaired glucose metabolism at the onset of SMIs, suggesting both patients with psychosis and mood disorders are high-risk groups for diabetes development.

Increased Dietary Inflammatory Index Is Associated with Schizophrenia: Results of a Case-Control Study from Bahrain

BACKGROUND

Several studies have indicated that chronic low-grade inflammation is associated with the development of schizophrenia. Given the role of diet in modulating inflammatory markers, excessive caloric intake and increased consumption of pro-inflammatory components such as calorie-dense, nutrient-sparse foods may contribute toward increased rates of schizophrenia. This study aimed to examine the association between dietary inflammation, as measured by the dietary inflammatory index (DII^®), and schizophrenia.

METHODS

A total of 120 cases attending the out-patient department in the Psychiatric Hospital/Bahrain were recruited, along with 120 healthy controls matched on age and sex. The energy-adjusted DII (E-DII) was computed based on dietary intake assessed using a comprehensive food frequency questionnaire (FFQ). Logistic regression was used to estimate odds ratios and 95% confidence intervals, adjusting for potential confounders including age, sex, body mass index, education, employment, diabetes, hypertension, and cardiovascular disease with E-DII expressed both as a continuous variable and categorized as quartiles.

RESULTS

The mean E-DII score for the entire sample was 1.79 ± 1.52, indicating a generally pro-inflammatory diet. The cases with schizophrenia appeared to have a higher E-DII score compared to controls: 1.99 ± 1.39 vs. 1.60 ± 1.38, respectively (p = 0.009). For every one unit increase in the E-DII score, the odds of having schizophrenia increased by 62% (OR 1.62; 95% CI 1.17-2.26). Similarly, increased risk was observed when the E-DII was used as quartiles, with participants in most pro-inflammatory quartile 4 being nearly 6 times more likely to be schizophrenic than participants in the most anti-inflammatory group quartile 1 (OR 5.96; 1.74-20.38; p-trend = 0.01).

CONCLUSIONS

The data suggest that a pro-inflammatory diet, as indicated by increasing E-DII score, is associated with schizophrenia. This is the first study to examine the association between the DII and schizophrenia in a Middle Eastern population. Although these results are consistent with findings from research conducted in depression, additional studies are required before generalizing the findings to other populations.

Interactions between genetic variants involved in the folate metabolic pathway and serum lipid, homocysteine levels on the risk of recurrent spontaneous abortion

Background

The interaction between folate pathway gene polymorphisms and homocysteine, serum lipid leverls are poorly understood in patients with recurrent spontaneous abortion (RSA). The aim of this study is to explore the effects of folate pathway gene polymorphisms (the 5–10-methylenetetrahydrofolate reductase, MTHTR C677T, MTHFR A1298C and the methionine synthase reductase, MTRR A66G) and their interactions with homocysteine on serum lipid levels in patients with RSA.

Methods

A total of 403 RSA women and 342 healthy women were randomly selected. Genotyping of the MTHFR C677T, A1298C and MTRR A66G were performed by TaqMan-MGB technique. Serum homocysteine, folate, fasting glucose, fasting insulin, Interleukin 6, Tumor necrosis factorα (TNFα) and lipid profiles were measured according to the kits. Continuous variables were analyzed using 2-sample t-tests. Categorical variables were analyzed and compared by χ² or Fisher’s exact tests. Unconditional logistic regression model was applied to test the interactions of gene polymorphisms on RSA.

Results

The distribution of genotype of CC, CT TT and T allele of MTHFR C677T, genotype of AA and C allele of MTHFR A1298C, and genotype of AA, AG and G allele of MTRR A66G were different between cases and controls (all p were < 0.05). There were significant interactions between MTHFR C677T-A1298C and MTHFR A1298C-MTRR A66G in RSA group and control group, with ORs of 1.62 (95%CI: 1.28–2.04, p < 0.001) and 1.55 (95%CI: 1.27–1.88, p < 0.001), respectively. Serum TNFα level and insulin resistant status (HOMR-IR) were higher in RSA group than in control group (p = 0.038, 0.001, respectively). All the three gene SNPs except MTRR 66AG gene variant had detrimental effects on HOMA-IR (all p were < 0.05). RSA group who carried the MTHFR 677CT, TT, CT/TT genotypes and MTRR 66AG, AG/GG genotypes had detrimental effects on serum homocysteine levels, the MTHFR 677CT, CT/TT genotype carriers had favorable effects on serum folate levels, the MTHFR 677TT, CT/TT, 1298 AC, AC/CC genotype carriers had detrimental effects on serum low-density lipoprotein cholesterol (LDL-C) levels, and the MTRR 66AG genotype carriers had lower high-density lipoprotein cholesterol (HDL-C) levels than the AA genotype carriers (all p were < 0.05).

Conclusions

Interaction between the MTHFR C677T, A1298C and MTHFR A1298C, MTRR A66G are observed in our RSA group. Besides, all the three gene SNPs except MTRR 66AG gene variant had detrimental effects on HOMA-IR. MTHFR C677T and MTRR A66G gene variants had detrimental effects on serum homocysteine levels and insulin resistance status, while MTHFR C677T, A1298C and MTRR A66G gene variants had detrimental effects on certain serum lipid profiles.

Appetite regulating hormones in first-episode psychosis: A systematic review and meta-analysis

We aimed to perform a systematic review and meta-analysis of appetite regulating hormones in patients with first-episode psychosis (FEP). Meta-analyses were conducted using random-effects models with Hedges' g as the effect size estimate. We identified 31 eligible studies, investigating the levels of 7 appetite regulating hormones (adiponectin, insulin, leptin, ghrelin, orexin, resistin and visfatin) in 1792 FEP patients and 1364 controls. The insulin levels in FEP patients were higher than in controls (g = 0.34, 95%CI: 0.19 - 0.49, p < 0.001), even considering only antipsychotic-naïve patients (g = 0.39, 95%CI: 0.12 - 0.66, p = 0.005). The severity of negative symptoms was positively associated with the effect size estimates (β = 0.08, 95%CI: 0.01 - 0.16, p = 0.030). Moreover, we found lower levels of leptin in antipsychotic-naïve FEP patients (g = -0.62, 95%CI: -1.11 - 0.12, p = 0.015). Impaired appetite regulation, in terms of elevated insulin levels and decreased leptin levels, occurs in early psychosis, before antipsychotic treatment. Hyperinsulinemia might be related to negative symptoms.

First-episode schizophrenia is associated with a reduction of HERV-K methylation in peripheral blood

Human endogenous retroviruses (HERV) have been widely associated with schizophrenia etiology. Aberrant epigenetic processes may play a role in the etiology of schizophrenia. In this study, we tested whether schizophrenia patients at different stages of illness might present alterations in the levels of HERV-K methylation. We recruited 49 first-episode schizophrenia (FES) patients with 47 age- and sex-matched healthy controls (HCs), and 100 multi-episode schizophrenia (MES) patients with 50 age- and sex-matched HCs. Based on the Schedule for Deficit Schizophrenia, patients with MES were also divided into two subgroups: deficit (D-SCZ) and non-deficit schizophrenia (ND-SCZ). DNA methylation levels of HERV-K sequences were examined in peripheral blood leukocytes. We found significantly lower levels of HERV-K methylation in FES patients compared to HCs. Patients with MES and matched HCs had similar levels of HERV-K methylation. There was a significant positive correlation between chlorpromazine equivalent dosage and HERV-K methylation levels in MES patients, but not in FES individuals. No significant differences in HERV-K methylation levels between D-SCZ and ND-SCZ as well as HCs were found. Our results indicate lower HERV-K methylation levels at early stages of schizophrenia. This difference might normalize with subsequent exacerbations of schizophrenia, likely due to the effects of antipsychotics.

Association between olanzapine treatment and brain cortical thickness and gray/white matter contrast is moderated by cholesterol in psychotic disorders

Altered cortical brain morphology is observed in psychotic disorders. Despite the importance of lipid homeostasis for healthy brain functioning, knowledge about its role in cortical alterations in psychosis is limited. In a sample of patients with psychotic disorders, we investigated the relationship between treatment with olanzapine (OLZ), and cortical thickness and gray/white matter intensity contrast, and the association between these measures and serum lipid levels. We included 33 OLZ users, 19 unmedicated psychotic patients and 76 healthy controls (HC). Data on serum lipids and cortical measures based on MR brain images processed with FreeSurfer were analyzed with General Linear Models. We found that intensity contrast was similar in OLZ users as compared to HC and that the cortex (frontal, orbitofrontal, medial temporal) was thinner in OLZ users (p < 0.05, Bonferroni corrected). An OLZ-specific HDL interaction effect was further found for the pericentral cortical thickness measure (p < 0.05, Bonferroni corrected). Additionally, nominally significant findings indicated similar OLZ-specific interaction effects for cortical thickness in several regions, and an OLZ-specific interaction with LDL for occipital lobe contrast (p < 0.05, uncorrected). Our findings may suggest a drug-related lipid-effect on brain myelination. Experimental studies and replications in different study samples are needed to clarify these complex relationships further.

Antipsychotics-induced metabolic alterations: Recounting the mechanistic insights, therapeutic targets and pharmacological alternatives

Atypical antipsychotics (AAPs) are the drug of choice in the management of mental illnesses by virtue of their advantage over typical antipsychotics i.e. least tendency of producing extrapyramidal motor symptoms (EPS) or pseudoparkinsonism. Despite the clinical efficacy, AAPs produces troublesome adverse effects, particularly hyperphagia, hyperglycemia, dyslipidemia weight gain, diabetes mellitus, insulin resistance and QT prolongation which further develops metabolic and cardiac complications with subsequent reduction in life expectancy, poor patient compliance, and sudden death. AAPs-induced weight gain and metabolic alterations are increasing at an alarming rate and became an utmost matter of concern for psychopharmacotherapy. Diverse underlying mechanisms have been explored such as the interaction of AAPs with neurotransmitter receptors, alteration in food reward anticipation behavior, altered expressions of hypothalamic orexigenic and anorexigenic neuropeptides, histamine H₁ receptor-mediated hypothalamic AMP-activated protein kinase (AMPK) activation, increased blood leptin, ghrelin, pro-inflammatory cytokines. Antipsychotics induced imbalance in energy homeostasis, reduction in energy expenditure which is linked to altered expression of uncoupling proteins (UCP-1) in brown adipose tissue and reduced hypothalamic orexin expressions are emerging insights. In addition, alteration in gut-microbiota and subsequent inflammation, dyslipidemia, obesity, and diabetes after AAPs treatment are also associated with weight gain and metabolic alterations. Oral hypoglycemics and lipid-lowering drugs are mainly prescribed in the clinical management of weight gain associated with AAPs while many other pharmacological and nonpharmacological interventions also have been explored in different clinical and preclinical studies. In this review, we critically discuss the current scenario, mechanistic insights, biomarkers, and therapeutic alternatives for metabolic alterations associated with antipsychotics.

Profiling inflammatory signatures of schizophrenia: A cross-sectional and meta-analysis study

We aimed to profile a broad panel of inflammatory markers in patients with schizophrenia and healthy controls. Additionally, we performed a meta-analysis of chemokine alterations that have not been subjected to quantitative synthesis so far. We recruited 78 patients with schizophrenia and 78 healthy controls, and measured inflammatory markers using the Luminex technology. After adjustment for multiple testing, we found elevated levels of interleukin (IL)-1 receptor antagonist (IL-1RA), IL-6, IL-7, IL-8, IL-9, IL-10, IL-13, interferon-γ, eotaxin-1, granulocyte-macrophage colony-stimulating factor (GM-CSF), monocyte chemoattractant protein-1 (MCP-1), platelet-derived growth factor with two B subunits (PDGF-BB), macrophage inflammatory protein (MIP)-1α, MIP-1β, vascular endothelial growth factor A (VEGF-A) and RANTES in multiple-episode schizophrenia (MES) patients. These differences, except for the difference in eotaxin-1 levels, appeared to be significant after co-varying for the dosage of antipsychotics. There were no significant differences in the levels of immune markers between first-episode schizophrenia (FES) patients and controls. Our meta-analysis revealed elevated levels of MCP-1 in first-episode psychosis (FEP) patients and MES individuals. Other chemokine alterations (elevated levels of IL-8, eotaxin-1 and MIP-1β) were present only in MES patients. Our results indicate that dysregulation of immune response in schizophrenia develops with illness progression or appears as a long-term medication effect. Chemokine alterations are another example of aberrant immune response in schizophrenia patients. Elevated levels of MCP-1 might represent trait markers since these alterations were found in FEP and MES patients. Other chemokine alterations might be the markers of disease progression or might represent medication effects.

Increase in serum HDL level is associated with less negative symptoms after one year of antipsychotic treatment in first-episode psychosis

BACKGROUND

A potential link between increase in total cholesterol and triglycerides and clinical improvement has been observed during antipsychotic drug treatment in chronic schizophrenia patients, possibly due to drug related effects on lipid biosynthesis. We examined whether changes in serum lipids are associated with alleviation of psychosis symptoms after one year of antipsychotic drug treatment in a cohort of first-episode psychosis (FEP) patients.

METHODS

A total of 132 non-affective antipsychotic-treated FEP patients were included through the Norwegian Thematically Organized Psychosis (TOP) project. Data on antipsychotic usage, serum lipids (total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol and triglycerides (TG)), body mass index (BMI) and clinical state were obtained at baseline and after 12months. The Positive and Negative Syndrome Scale (PANSS) was used to assess psychotic symptoms. Mixed-effects models were employed to examine the relationship between serum lipids and psychotic symptoms while controlling for potential confounders including BMI.

RESULTS

An increase in HDL during one year of antipsychotic treatment was associated with reduction in PANSS negative subscores (B=-0.48, p=0.03). This relationship was not affected by concurrent change in BMI (adjusted HDL: B=-0.54, p=0.02). No significant associations were found between serum lipids, BMI and PANSS positive subscores.

CONCLUSION

We found that an increase in HDL level during antipsychotic treatment is associated with improvement in negative symptoms in FEP. These findings warrant further investigation to clarify the interaction between lipid pathways and psychosis.

Quantitative Analysis of l-Arginine, Dimethylated Arginine Derivatives, l-Citrulline, and Dimethylamine in Human Serum Using Liquid Chromatography-Mass Spectrometric Method

ABSTRACT

Nitric oxide (NO) is a small molecule involved in the regulation of many physiological processes. It plays a crucial role in the regulation of nervous system, immune and inflammatory responses, and blood flow. NO is synthesized by nitric oxide synthase (NOS) during two-step oxidation of l-arginine to l-citrulline. Intermediates and derivatives of NO metabolism, such as l-arginine, l-citrulline, asymmetrical dimethylarginine (ADMA), symmetrical dimethylarginine (SDMA), and dimethylamine (DMA), are investigated as potential biomarkers. In this article, we present a novel analytical method that allowed for simultaneous analysis of l-arginine, ADMA, SDMA, l-citrulline, and DMA, in a single-step extraction and derivatization using benzoyl chloride. In brief, aliquots of serum were mixed with internal standard solution mixture (50 µM D6-DMA, 20 µM D7-ADMA, and 100 µM D7-arginine) and 0.025 M borate buffer, pH 9.2 (10:1:5). The derivatization process was performed at 25 °C for 5 min using 10% benzoyl chloride. A reverse phase column was used for chromatographic separation. Quantitation was performed using following ions (m/z): 279.1457, 286.1749, 307.1717, 314.2076, 280.1297, 150.0919, and 156.1113 for l-arginine, D7-arginine, ADMA, SDMA, D7-ADMA, l-citrulline, DMA, and D6-DMA, respectively. The method was validated, and its assay linearity, accuracy and precision, recovery, and limits of detection (1.7 µM l-arginine, 0.03 µM ADMA, 0.02 µM SDMA, 0.36 µM l-citrulline, 0.06 µM DMA) and quantification (3.2 µM l-arginine, 0.08 µM ADMA, 0.05 µM SDMA, 1.08 µM l-citrulline, 0.19 µM DMA) were determined. The method is sensitive, reliable, repeatable, and reproducible. It can be applied in the routine clinical/diagnostic laboratory.

GRAPHICAL ABSTRACT

Association between B vitamins and schizophrenia: A population-based case-control study

To explore the association between schizophrenia and six types of B vitamins, including choline, biotin, riboflavin, pyridoxamine, pyridoxine and nicotinamide, based on the hydrophilic interaction liquid chromatography column (HILIC) Liquid Chromatography-Mass Spectrometry (LC-MS) platform. We conducted the case-control study between November 2015 and September 2016 in Weifang, Shandong Province, China. Blood samples from 128 cases of schizophrenia and 101 controls were collected, and B vitamin were measured by LC-MS coupled with HILIC. The HILIC UPLC-MS based analysis of serum B vitamins levels from 128 cases (30 cases with first-episode, 98 cases with relapse) and 101 controls were performed. The results indicated that lower pyridoxine level and schizophrenia was related. (total cases versus controls: β= -0.215, 95% CI: -0.271, -0.125, p < 0.001; first-episode cases versus controls: β = -0.190, 95% CI: -0.277, -0.103, p < 0.001). Higher nicotinamide level was also associated with schizophrenia after adjusting confounders (β = 0.343, 95% CI: 0.022, 0.664, p = 0.036). Other four B vitamins, including biotin, riboflavin, pridoxamine and choline, were showed no statistically difference in cases versus controls, first episode cases versus relapse cases. Two types of B Vitamins, pyridoxine and nicotinamide, show significant association with the schizophrenia.

Lipid profile disturbances in antipsychotic-naive patients with first-episode non-affective psychosis: A systematic review and meta-analysis

BACKGROUND

Dyslipidaemia is one of the most prevalent metabolic disturbances observed in schizophrenia patients and has been largely attributed to the effects of poor lifestyle habits and adverse effects of antipsychotic treatment. However, less is known whether patients with first-episode non-affective psychosis (FENP) present subthreshold indices of dyslipidaemia. Therefore, we tested the hypothesis whether subclinical lipid profile alterations occur already in antipsychotic-naïve FENP patients.

METHODS

In this systematic review and meta-analysis we adhered to the PRISMA guidelines and searched PubMed, CINAHL Complete, Academic Search Complete, ERIC and Health Source: Nursing/Academic Edition from database inception to Dec 12, 2016, for case-control studies measuring the levels of total cholesterol, low- and high-density lipoproteins (LDL and HDL) and triglycerides in patients with FENP and controls. W calculated effect size (ES) estimates as Hedges' g and pooled data using random- or fixed-effects models depending on heterogeneity. Our study was registered in the PROSPERO database (CRD42016051732).

RESULTS

Out of 2466 records identified, 19 studies representing 1803 participants were finally included in our systematic review and meta-analysis. Pooled analysis revealed that FENP patients had significantly lower levels of total cholesterol [ES=-0.16 (95% CI: -0.27, -0.06), p=0.003], LDL [ES=-0.13 (95% CI: -0.24, -0.01), p=0.034] and HDL [ES=-0.27 (95% CI: -0.49, -0.05), p=0.018] as well as significantly higher levels of triglycerides [ES=0.22 (95% CI: 0.11, 0.32), p<0.001] compared to controls. After removing single studies in sensitivity analysis, ES estimate for LDL levels was insignificant.

CONCLUSIONS

Antipsychotic-naïve patients with FENP present subclinical dyslipidaemia. Future studies should disentangle whether our findings reflect disease-specific mechanisms.

Cholesterol and triglyceride levels in first-episode psychosis: systematic review and meta-analysis

BackgroundThe extent of metabolic and lipid changes in first-episode psychosis (FEP) is unclear.AimsTo investigate whether individuals with FEP and no or minimal antipsychotic exposure show lipid and adipocytokine abnormalities compared with healthy controls.MethodWe conducted a meta-analysis of studies examining lipid and adipocytokine parameters in individuals with FEP and no or minimal antipsychotic exposure v. a healthy control group. Studies reported fasting total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides and leptin levels.ResultsOf 2070 citations retrieved, 20 case-control studies met inclusion criteria including 1167 patients and 1184 controls. Total cholesterol and LDL cholesterol levels were significantly decreased in patients v. controls, corresponding to an absolute reduction of 0.26 mmol/L and 0.15 mmol/L respectively. Triglyceride levels were significantly increased in the patient group, corresponding to an absolute increase of 0.08 mmol/L. However, HDL cholesterol and leptin levels were not altered in patients v. controls.ConclusionsTotal and LDL cholesterol levels are reduced in FEP, indicating that hypercholesterolaemia in patients with chronic disorder is secondary and potentially modifiable. In contrast, triglycerides are elevated in FEP. Hypertriglyceridaemia is a feature of type 2 diabetes mellitus, therefore this finding adds to the evidence for glucose dysregulation in this cohort. These findings support early intervention targeting nutrition, physical activity and appropriate antipsychotic prescription.

Visceral Fat Dysfunctions in the Rat Social Isolation Model of Psychosis

Medication with neuroleptics has been associated with adipose tissue dysfunctions and, in particular, with increased visceral fat amount. However, several studies suggested that antipsychotic treatment might not be the main responsible of fat mass accumulation, as this has been also described in not treated psychotic patients. One of the most used “drug-free” rodent models of psychosis is the social isolation rearing of young adult rats, which provides a non-pharmacologic method of inducing long-term alterations reminiscent of symptoms seen in psychotic patients. Recent data highlighted a crucial role of redox imbalance in adipose tissue dysfunctions, in terms of decreased antioxidant defense and increased reactive oxygen species (ROS). Here, we investigated possible oxidative stress-related biomolecular alterations associated with visceral fat increase in 7 week isolated rats. To this purpose, we quantified total and visceral fat amount by using dual-energy X-ray (DEXA) absorptiometry. On visceral fat, we analyzed the expression of specific ROS-producer genes (Nox1, Nox4, Hmox-1), antioxidant enzymes (Prdx1 and Ucp-1) and oxidative stress-induced damage markers (Cidea, Slc2a4, and Acacb). The impact of oxidative stress on beta3-adrenergic receptors (Adrb3), at both mRNA and protein level, was also assessed. We found that 7 weeks of social isolation induced an increase in total and visceral fat, associated with a decrease in Prdx1 (mRNA and protein) as well as Ucp-1 mRNA levels and an enhanced expression of Nox1 (mRNA and protein) and Hmox-1 mRNA. No differences were detected in Nox4 mRNA levels between grouped and isolated animals. Elevations in Cidea, Slc2a4, and Acacb expression in visceral fat of isolated animals accounted for oxidative stress-related damage in this tissue, further associated with a significant increase in Adrb3 mRNA and protein. Our results provide a novel understanding of the pathological link existing among psychosocial stress-induced psychosis, adipose tissue dysfunctions and redox imbalance, opening new therapeutic perspectives for the treatment of alterations in peripheral tissues associated with this mental disorder.

Germline genetic variants with implications for disease risk and therapeutic outcomes

Genetic testing has multiple clinical applications including disease risk assessment, diagnosis, and pharmacogenomics. Pharmacogenomics can be utilized to predict whether a pharmacologic therapy will be effective or to identify patients at risk for treatment-related toxicity. Although genetic tests are typically ordered for a distinct clinical purpose, the genetic variants that are found may have additional implications for either disease or pharmacology. This review will address multiple examples of germline genetic variants that are informative for both disease and pharmacogenomics. The discussed relationships are diverse. Some of the agents are targeted for the disease-causing genetic variant, while others, although not targeted therapies, have implications for the disease they are used to treat. It is also possible that the disease implications of a genetic variant are unrelated to the pharmacogenomic implications. Some of these examples are considered clinically actionable pharmacogenes, with evidence-based, pharmacologic treatment recommendations, while others are still investigative as areas for additional research. It is important that clinicians are aware of both the disease and pharmacogenomic associations of these germline genetic variants to ensure patients are receiving comprehensive personalized care.

Genetic Basis of Positive and Negative Symptom Domains in Schizophrenia

Schizophrenia is a highly heritable disorder, the genetic etiology of which has been well established. Yet despite significant advances in genetics research, the pathophysiological mechanisms of this disorder largely remain unknown. This gap has been attributed to the complexity of the polygenic disorder, which has a heterogeneous clinical profile. Examining the genetic basis of schizophrenia subphenotypes, such as those based on particular symptoms, is thus a useful strategy for decoding the underlying mechanisms. This review of literature examines the recent advances (from 2011) in genetic exploration of positive and negative symptoms in schizophrenia. We searched electronic databases PubMed, Web of Science, and Cumulative Index to Nursing and Allied Health Literature using key words schizophrenia, symptoms, positive symptoms, negative symptoms, cognition, genetics, genes, genetic predisposition, and genotype in various combinations. We identified 115 articles, which are included in the review. Evidence from these studies, most of which are genetic association studies, identifies shared and unique gene associations for the symptom domains. Genes associated with neurotransmitter systems and neuronal development/maintenance primarily constitute the shared associations. Needed are studies that examine the genetic basis of specific symptoms within the broader domains in addition to functional mechanisms. Such investigations are critical to developing precision treatment and care for individuals afflicted with schizophrenia.

Meta-analysis of glucose tolerance, insulin, and insulin resistance in antipsychotic-naïve patients with nonaffective psychosis

BACKGROUND

Some studies have suggested that antipsychotic-naïve patients with nonaffective psychosis (NAP) have glucose intolerance.

AIMS

To conduct a systematic review and meta-analysis of fasting glucose (FG), two hour values in the oral glucose tolerance test (2HG), fasting insulin concentration (INS), and insulin resistance (IR).

METHOD

We identified possibly relevant studies, then selected studies, following usual guidelines, with two authors reviewing the manuscripts. We required studies to include subjects with nonaffective psychosis and control subjects.

RESULTS

There were 911 patients and 870 control subjects in the analysis of FG; their average ages were respectively 28.7 and 29.5years. Significant differences were found for all four variables, with effect size estimates ranging from 0.21 to 0.58.

CONCLUSIONS

As a group, at the time of first clinical contact for psychosis, people with NAP have a slight increase in FG, which most of them maintain in the normal range despite a small increase in IR by secreting additional INS. When faced with a physiological challenge such as a glucose tolerance test or antipsychotics, they are no longer able to maintain a normal glucose concentration.

Genetic Variation in One-Carbon Metabolism and Changes in Metabolic Parameters in First-Episode Schizophrenia Patients

BACKGROUND

In this study, we aimed to investigate the effects of polymorphisms in genes encoding 1-carbon metabolism enzymes on differential development of metabolic parameters during 12 weeks of treatment with second-generation antipsychotics in first-episode schizophrenia patients.

METHODS

The following polymorphisms in 1-carbon metabolism genes were genotyped: MTHFR (C677T and A1298C), MTHFD1 (G1958A), MTRR (A66G), and BHMT (G742A). A broad panel of metabolic parameters including body mass index, waist circumference, total cholesterol low and high density lipoproteins, triglycerides, homocysteine, folate, and vitamin B12 was determined.

RESULTS

There was a significant effect of the interaction between the MTHFR C677T polymorphism and time on body mass index and waist circumference in the allelic and genotype analyses. Indeed, patients with the MTHFR 677CC genotype had higher increase in body mass index and waist circumference compared with other corresponding genotypes or the MTHFR 677T allele carriers (CT and TT genotypes). In addition, patients with the MTHFR 677TT genotype had higher waist circumference in all time points. Similarly, patients with the MTHFR 677TT genotype had higher body mass index in all time points, but this effect was not significant after correction for multiple testing.

CONCLUSIONS

Our results indicate that the MTHFR C677T polymorphism may predict antipsychotic-induced weight gain. Effects of the MTHFR C677T polymorphism might be different in initial exposure to antipsychotics compared with long-term perspective.

Gender-specific interactions of MTHFR C677T and MTRR A66G polymorphisms with overweight/obesity on serum lipid levels in a Chinese Han population

Background

Little is known regarding the interactions of methylenetetrahydrofolate reductase (MTHFR) C677T and methionine synthase reductase (MTRR) A66G polymorphisms with overweight/obesity on serum lipid profiles. The aim of the current study was to explore interactions between the two polymorphisms and overweight/obesity on four common lipid levels in a Chinese Han population and further to evaluate whether these interactions exhibit gender-specificity.

Methods

A total of 2239 participants (750 females and 1489 males) were enrolled into this study. The genotypes of the MTHFR C677T and MTRR A66G were determined by a TaqMan assay. Overweight and obesity were defined as a body mass index between 24 and 27.99 and ≥ 28 kg/m², respectively. The interactions were examined by factorial design covariance analysis, and further multiple comparisons were conducted by Bonferroni correction.

Results

There was no significant difference in the genotypic and allelic frequencies between females and males (MTHFR 677 T allele: 54.47 % for females and 54.40 % for males; MTRR 66G allele: 24.73 % for females and 24.71 % for males). Interaction between the MTHFR C677T polymorphism and overweight/obesity on serum triglyceride levels, and interaction between the MTRR A66G polymorphism and overweight/obesity on serum high-density lipoprotein cholesterol levels were detected in women (P = 0.015 and P = 0.056, respectively). For female subjects with overweight/obesity, the serum triglyceride levels in MTHFR 677TT genotype [1.09 (0.78–1.50) mmol/L] were significantly higher as compared with MTHFR 677CC genotype [0.90 (0.60–1.15) mmol/L, P = 0.007], and the MTRR 66GG genotype carriers had higher serum high-density lipoprotein cholesterol levels than those with MTRR 66AG genotype (1.46 ± 0.50 vs. 1.19 ± 0.31 mmol/L, P = 0.058). Furthermore, in male subjects with overweight/obesity, the MTHFR 677CT genotype carriers had higher low-density lipoprotein cholesterol levels than those with MTHFR 677TT genotype (2.96 ± 1.07 vs. 2.74 ± 0.88 mmol/L, P = 0.015).

Conclusions

Our results indicate that there exist interactive effects of the MTHFR C677T and MTRR A66G polymorphisms with overweight/obesity on some lipid traits in Chinese Han population, and the effects were gender-specific.