Serum levels of brain-derived neurotrophic factor in patients with schizophrenia and bipolar disorder.

There is evidence that major psychiatric discords such as schizophrenia (SZ) and bipolar disorder (BD) are associated with dysregulation of synaptic plasticity with downstream alterations of neurotrophins. Brain-derived neurotrophic factor (BDNF) is the most widely distributed neurotrophin in the central nervous system (CNS), and performs many biological functions such as promoting the survival, differentiation, and plasticity of neurons. Variants in the BDNF gene increase the risk of SZ and bipolar disorder. Chronic administration of drugs used to treat SZ and BD, such as lithium, valproate, quetiapine, clozapine, and olanzapine, increases BDNF expression in rat brain. To examine serum BDNF, three groups of chronically medicated DSM-IV SZ patients, on treatment with clozapine (n=27), typical (n=14), and other atypical antipsychotics (n=19), 30 euthymic BD patients, and 26 healthy control had 5 ml blood samples collected by venipuncture. Serum BDNF levels were significantly higher in SZ patients (p<0.001) when compared to either controls or euthymic BD patients. Increased BDNF in SZ patients might be related to the course of illness or to treatment variables. Prospective studies are warranted.

Increased serum levels of eotaxin/CCL11 in late-stage patients with bipolar disorder: an accelerated aging biomarker?

BACKGROUND: Bipolar disorder (BD) is commonly comorbid with many medical disorders including atopy, and appears characterized by progressive social, neurobiological, and functional impairment associated with increasing number of episodes and illness duration. Early and late stages of BD may present different biological features and may therefore require different treatment strategies. Consequently, the aim of this study was to evaluate serum levels of eotaxin/CCL11, eotaxin-2/CCL24, IL-2, IL-4, IL-6, IL-10, IL-17, TNF-α, IFNγ, BDNF, TBARS, carbonyl, and GPx in a sample of euthymic patients with BD at early and late stages compared to controls. METHODS: Early-stage BD patients, 12 late-stage patients, and 25 controls matched for sex and age were selected. 10mL of peripheral blood was drawn from all subjects by venipuncture. Serum levels of BDNF, TBARS, carbonyl content, glutathione-peroxidase activity (GPx), cytokines (IL-2, IL-4, IL-6, IL-10, IL-17, TNF-α and IFNγ), and chemokines (eotaxin/CCL11 and eotaxin-2/CCL24) were measured. RESULTS: There were no demographic differences between patients and controls. No significant differences were found for any of the biomarkers, except chemokine eotaxin/CCL11, whose serum levels were higher in late-stage patients with BD when compared to controls (p=0.022; Mann-Whitney U test). LIMITATIONS: Small number of subjects and use of medication may have influenced in our results. CONCLUSION: The present study suggests a link between biomarkers of atopy and eosinophil function and bipolar disorder. These findings are also in line with progressive biological changes partially mediated by inflammatory imbalance, a process referred to as neuroprogression.