C-reactive protein, brain-derived neurotrophic factor, interleukin-2, and stressful life events in drug-naive first-episode and recurrent depression: A cross-sectional study

AIMS: The aim of the study is to assess and compare serum C-reactive protein (CRP), brain derived neurotrophic factor (BDNF), and interleukin-2 (IL-2) levels in patients with first-episode depression (FED), recurrent depressive disorder (RDD), and healthy controls (HCs) and to determine the relationship between the above-specified inflammatory markers, severity of depression, and stressful life events. MATERIALS AND METHODS: Consecutive drug-naive patients with FED and RDD (n = 85) and 50 HCs were studied. Serum concentrations of CRP, brain-derived nerve growth factor (BDNF), and IL-2 were measured. All participants were assessed using Mini-International Neuropsychiatric Interview Plus, Beck's depression inventory, and presumptive stressful life events scale. RESULTS: The FED and RDD groups had statistically significant lower serum concentration of BDNF and higher IL-2 compared to the HC group, whereas no statistically significant difference was observed with regard to CRP level. No statistically significant differences were observed with regard to the severity of depression and serum concentrations of CRP, BDNF, and IL-2 in the FED and RDD groups. No significant correlation was found between severity of depression and serum concentration of CRP, BDNF, and IL-2 in both the groups. Serum CRP concentration was significantly higher in patients with ≥2 stressful life events. No significant difference was observed between number of stressful life events and BDNF and IL-2 in patients with depression. CONCLUSION: FED and RDD are associated with lower serum concentration of BDNF and higher IL-2 compared to the HCs, whereas there appears no difference with regard to CRP level. Multicentric studies are needed to further elucidate the role of inflammatory markers in depression.