Association of peripheral manifestation of brain‐derived neurotrophic factor with depression: A meta‐analysis

Abstract

Background:The relationship between brain-derived neurotrophic factor (BDNF) and depression is a hot topic in research as several results of preclinical and clinical studies have shown controversial results. Our meta-analysis aims to evaluate and update the current status of peripheral BDNF with depression. Methods:We performed a meta-analysis by comprehensively searching PubMed and Web of Science for English-language literature from inception to 1st of June 2020. The search terms included brain-derived neurotrophic factor or BDNF in combination with depression, without year restriction. Using STATA software, data were pooled using a random-effects model. Results:In our literature search, 24 studies involving 1130 depressed patients and 1378 healthy individuals met our inclusion criteria. The results of our meta-analysis showed that the peripheral levels of BDNF levels significantly decreased in depression than nondepressed healthy controls (SMD = −0.89, 95% CI = −1.41, −0.38, p < .0001); however, the significant heterogeneity among studies (Q = 740.91, I 2 = 96.8; p < .001) was discovered. Trim-and-fill estimations for the adjustment of publication bias indicated that publication bias had no impact on our results. Our sub-group analysis showed that a history of depression and alcohol consumption had an effect on the level of BDNF. In addition, age and gender did not affect the heterogeneity of BDNF in the meta-analysis. Conclusions:Although decreased peripheral expression of BDNF certainly presents a risk of depression, we cannot find a definite relationship between the peripheral level of BDNF with depression to use BDNF as a reliable biomarker to assess the depression in clinical practice. We propose that future research should consider all the factors affecting BDNF and assess the level of proBDNF and mBDNF separately while evaluating the patients with depression objectively.

Neurotrophin signalling in the human nervous system

“…Given the presence of readily measurable levels of BDNF in human serum, a very large number of studies have attempted to correlate the levels of BDNF with depression. The overall conclusion of metanalyses is that a weak inverse correlation seems to exist between the severity of depressive episodes and the levels of BDNF in serum ( Tiwari et al, 2022 ). Yet it remains difficult to understand the logic of the assumption that BDNF levels in serum may reflect those in the brain, given that it has long been recognized that the main source of BDNF in human serum are circulating blood platelets ( Yamamoto and Gurney, 1990 ).…”

Plasma Brain-Derived Neurotrophic Factor Levels in First-Episode and Recurrent Major Depression and before and after Bright Light Therapy in Treatment-Resistant Depression

“…Apart from the brain, it is also present in the blood, platelets, serum, and plasma. Multiple lines of evidence demonstrated lower peripheral BDNF levels in patients during depressive episode than euthymic patients or healthy controls [ 23 , 24 ]; however, it is not clear if such levels differ between first or recurrent episode, and TRD patients. The effects of various antidepressant interventions on peripheral BDNF levels were also extensively investigated [ 25 ], but very few studies address the influence of BLT on BDNF.…”