Serum and plasma BDNF levels in major depression: a replication study and meta-analyses.

OBJECTIVES: Alterations of BDNF signalling in major depression (MD) are supported by studies demonstrating decreased levels of the neurotrophin serum and plasma content in MD patients. We conducted a replication study and we performed two meta-analyses on studies analysing serum and plasma BDNF levels in MD patients. METHODS: The samples were composed by 489 patients/483 controls for the meta-analysis on serum and by 161 patients/211 controls for that on plasma levels. We performed also subgroup analyses to examine whether the decrease in BDNF levels in MD was influenced by gender. RESULTS: In the replication study we found decreased serum BDNF levels in MD patients (P<0.01) and we demonstrated that is down-regulated the mature form of the neurotrophin (mBDNF). No significant difference was evidenced for plasma BDNF levels. The meta-analyses showed a reduction of both BDNF serum (P<0.0001) and plasma levels (P=0.02) in MD. No difference in the effect size on serum BDNF was observed between males and females (P=0.18). CONCLUSIONS: In conclusion, our results provide evidence of peripheral BDNF alteration in MD and support the rationale for further investigation aiming to the identification of biomarkers for differential diagnosis and personalization of therapies in this disorder.

VEGF serum levels in depressed patients during SSRI antidepressant treatment.

Recent evidence indicates that the vascular endothelial growth factor (VEGF) may be involved in the neuronal mechanisms underlying both the depression aetiology and the response to pharmacological and non pharmacological antidepressant treatments. To investigate whether VEGF peripheral levels are altered in depression and are modulated by antidepressant therapies, we analyzed the serum VEGF concentrations in 25 subjects affected by major depression (MD) before (T0) and after 8 (T8) and 12 (T12) weeks of escitalopram treatment. No significant alterations in VEGF serum levels were found at T0, even considering possible effects of confounders such as gender and smoking habit (r2=0.227 p=0.74). No changes appeared during the treatment (F(1.83, 43.86)=0.962; p=0.383) and there was no correlation between percentage VEGF variations at T12 and symptoms improvements (p=0.823). The present work represents the first report on the evaluation of serum VEGF levels in MD patients. However, before discarding serum VEGF as a biochemical marker in the diagnosis and treatment of depression, our negative results need to be confirmed in larger patient samples stratified for clinical characteristics, co-morbidities, cardiovascular diseases and confounding factors.