ProBDNF as an Indicator of Improvement among Women with Depressive Episodes

Abstract

Depression is a chronic psychiatric disorder with a heavy socioeconomic burden. Studies on biomarkers are needed to comprehend the pathophysiology of depression and to improve treatment outcomes. Research points to the importance of imbalance between mature brain-derived neurotrophic factor (BDNF) and its precursor, pro-brain-derived neurotrophic factor (proBDNF), in the pathophysiology of mood disorders and the potential neurodegenerative role of calcium-binding protein B (S100B). Our objective was to compare BDNF, proBDNF, and S100B serum levels before and after the treatment of acute depressive episodes and to assess their correlation with the severity of symptoms and history of stress. We also aimed to investigate the differences in BDNF, proBDNF, and S100B levels between depression in the course of bipolar disorder (BD) and major depressive disorder (MDD). We recruited 31 female patients diagnosed with BD or MDD who were hospitalized due to current depressive episodes. The patients had their serum BDNF, proBDNF, and S100B levels evaluated using the ELISA method upon admission and after the symptoms improved, at discharge. We found that proBDNF levels decreased significantly with the treatment (p = 0.0478), while BDNF and S100B levels were not altered significantly. No differences in biochemical parameters between MDD and BD subjects were observed. Consequently, we concluded that a decrease in serum proBDNF levels could be considered a biomarker of recovery from depressive episodes.

Keywords: biomarkers; bipolar disorder; brain-derived neurotrophic factor; depression; mood disorders.

Figure 1

(a) Pro-brain-derived neurotrophic factor serum levels before (proBDNF1) and after (proBDNF2) the treatment of depressive episodes in the studied group overall. (b) Brain-derived neurotrophic factor serum levels before (BDNF1) and after (BDNF2) the treatment of depressive episodes in the studied group overall. Each value is presented as a circle in the first assessment and as a square in the second assessment. *—statistically significant result.

Figure 2

Correlation of biochemical parameters with stress and depressive symptoms overall. HDRS 1—Hamilton Depression Rating Scale before the treatment; BLEQ—Brief Life Event Questionnaire. BDNF—brain-derived neurotrophic factor, proBDNF—pro-brain-derived neurotrophic factor, S100B—calcium-binding protein B. First evaluation of BDNF, proBDNF, and S100B was used in the analysis. The Spearman Rank–Order Correlation Test was performed for all analysis. Statistically significant results were marked with *. (a,c,e)—correlation between BDNF, proBDNF, S100B respectively and the level of stress measured with BLEQ. (b,d,f)—correlation between BDNF, proBDNF, S100B respectively and the level of depressive symptoms measured with HDRS.