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.