Regulation of Interleukin-6 and Leptin in Schizophrenia Patients: A Preliminary Analysis

OBJECTIVE: Immune-inflammatory mediators play a pivotal role in brain signaling and have been increasingly associated with the pathophysiology of schizophrenia. Many studies have indicated an increased level of immune-inflammatory interleukin-6 (IL-6) in schizophrenia. IL-6 is a well-known chief stimulator of inflammation. Of late leptin has also been implicated in the inflammatory pathway of schizophrenia. In this study we measured and compared serum levels of IL-6 and leptin in patients with schizophrenia to healthy controls, and investigated the relationship between IL-6 and leptin. METHODS: Serum IL-6 and leptin were determined in 20 patients diagnosed with schizophrenia and in 19 healthy controls matched by gender, age and body mass index (BMI) using commercial Bioplex assays. RESULTS: Using Mann-Whitney U-test, significantly increased IL-6 levels were found in the patients but there was no significant difference in leptin levels though a trend towards higher leptin was observed in the patients. Spearman correlations did not show any correlation between IL-6 and clinical variables except antipsychotic dosage. Leptin significantly correlated with gender and BMI. A large effect size correlation was observed between IL-6 and leptin in the patients but not in the controls. Multiple regression analysis performed on patients, after adjusting for gender and BMI, revealed there was no significant association between IL-6 and leptin. CONCLUSION: IL-6 and leptin levels may reflect the chronic inflammatory state associated with schizophrenia but further evaluation is required. Also, it is important to consider the confounding effects of obesity in any examination of relationships between groups with regard to cytokines and adipokines.

Waist circumference is a potential indicator of metabolic syndrome in Singaporean Chinese

<p><b>INTRODUCTION</b>Metabolic Syndrome (MetS) is associated with cardiovascular morbidity and mortality. Studies proposed that waist circumference (WC) and body mass index (BMI) are good indicators of MetS. In this study, we examined and compared the predictive utility of clinical measures such as WC, blood pressure and BMI and determined the cutoff points in which these measures are most reliable in identifying MetS in Singaporean Chinese.</p><p><b>MATERIALS AND METHODS</b>Two hundred and forty-four subjects aged between 21 and 50 years of Chinese ethnicity were recruited into the study. Sociodemographic, height, weight and blood pressure information were obtained. High-density lipoprotein cholesterol (HDL-C), triglycerides (TG) and glucose levels were evaluated. Presence of MetS was examined according to American Heart Association (AHA)/National Heart, Lung and Blood Institute (NHLBI) guidelines. Predictive utility of BP, WC and BMI was examined using receiver operating curve and discriminant indices were determined accordingly.</p><p><b>RESULTS</b>Forty-one (16.8%) subjects were identified to have MetS. Our analysis revealed that waist circumference was most accurate in identifying MetS (area under the curve (AUC) = 0.88, 95% confidence interval (CI), 0.83 to 0.93, P <0.001) followed by BMI (AUC = 0.84, 95% CI, 0.77 to 0.91, P = 0.035), systolic BP (AUC = 0.83, 95% CI, 0.76 to 0.90, P = 0.036) and diastolic BP (AUC = 0.80, 95% CI, 0.71 to 0.88, P = 0.042). Waist circumference cut-off values of >92.5 cm in males and >86.5 cm in females were found to be most sensitive and specific in discriminating MetS.</p><p><b>CONCLUSION</b>Our finding has immediate and significant clinical implications as WC can be easily obtained. However, as the study included only Singaporean Chinese, findings cannot be generalised for other ethnic groups.</p>

A Review of Brain-derived Neurotrophic Factor as a Candidate Biomarker in Schizophrenia

Brain-derived neurotrophic factor (BDNF), a neurotrophin known to be responsible for development, regeneration, survival and maintenance of neurons has been implicated in the pathophysiology of schizophrenia. This review seeks to complement previous reviews on biological roles of BDNF and summarizes evidence on the involvement of BDNF in the pathophysiology of schizophrenia with an emphasis on clinical relevance. The expressions of BDNF were altered in patients with schizophrenia and were found to be correlated with psychotic symptomatology. Antipsychotics appeared to have differential effects on expression of BDNF but did not restore BDNF expression of patients with schizophrenia to normal levels. In addition, evidence suggests that BDNF is involved in the major neurotransmitter systems and is associated with disruptions in brain structure, neurodevelopmental process, cognitive function, metabolic and immune systems commonly associated with schizophrenia. Besides that, BDNF has been demonstrated to be tightly regulated with estrogen which has also been previously implicated in schizophrenia. Evidence gathered in this review confirms the relevance of BDNF in the pathophysiology of schizophrenia and the potential utility of BDNF as a suitable biomarker for diagnostic and prognostic purposes for disease outcome and other co-morbidities. However, further investigations are warranted to examine the specificity of BDNF in schizophrenia compared to other neurodegenerative disorders and other neuropsychiatric illness. Longitudinal prospective studies will also be of added advantage for evaluation of prognostic utility of BDNF in schizophrenia.

Prevalence of metabolic syndrome among patients with schizophrenia in Singapore

<p><b>INTRODUCTION</b>Schizophrenia has been associated with an increased risk of cardiometabolic morbidity and mortality. Metabolic syndrome (MetS), a reliable predictor of cardiovascular-related morbidity and mortality, has also been shown to be more prevalent in patients with schizophrenia. In this study, we investigated the prevalence of MetS in a sample of patients with schizophrenia in Singapore, and the potential risk factors associated with it.</p><p><b>MATERIALS & METHODS</b>One hundred patients with schizophrenia and 300 community controls were recruited. All subjects provided a fasted sample of venous blood to measure high-density lipoprotein cholesterol (HDL-C), triglycerides and glucose levels. Weight, height and waist circumference were measured. Presence of MetS was assessed according to the American Heart Association and the National Heart, Lung and Blood Institute (AHA/NHLBI) guidelines.</p><p><b>RESULTS</b>The prevalence of MetS in patients with schizophrenia was 46.0%. The adjusted odds ratio (OR) for MetS among patients was 2.79 (CI, 1.50 to 5.20, P = 0.001) when compared with controls. Increasing body mass index (BMI) was identifi ed to be signifi cantly associated with the prevalence of MetS.</p><p><b>CONCLUSION</b>This study found a high prevalence of MetS in Singapore patients with schizophrenia, and that BMI might be a risk factor in the development of MetS. This information is clinically relevant as BMI is routinely measured in psychiatric practice today, and could be used to monitor for development of MetS in schizophrenia.</p>