Decrease in brain‐derived neurotrophic factor at plasma level but not in serum concentrations in suicide behavior: A systematic review and meta‐analysis

INTRODUCTION: Suicide is known as a major health concern worldwide. There is evidence for the role of brain‐derived neurotrophic factor (BDNF) in suicide behavior. Therefore, this factor has been proposed as a biomarker for suicide behavior. Clinical studies have measured BDNF concentrations at central and peripheral levels. As a consequence, the aim of this study was to assess BDNF levels in blood plasma and serum to see whether there is a difference in concentrations in patients with suicide behavior when compared to those in controls, using a meta‐analysis approach. METHODS: We conducted a systematic review and meta‐analysis. The search strategy was performed using three databases: PubMed, EBSCO and ScienceDirect. The meta‐analysis included a total of nine case–control studies, six measured the BDNF level in serum and three in plasma in suicide behavior. RESULTS: A decrease in BDNF levels in plasma was observed (d = −0.73, 95% CI −1.42 to −0.03 pg/ml). In the case of serum concentrations, no BDNF differences were encountered between cases and controls (d = 0.09, 95% CI −0.31 to 0.13 ng/ml, p(Q) = .92). CONCLUSIONS: According to the results found in the present meta‐analysis, the plasma BDNF level could be suggest as a potential biomarker in suicide behavior. However, since the number of studies included in the analysis is limited, a larger number is necessary to determine conclusively the role of BDNF as a biomarker in suicide behavior.