Abstract

Background

Brain-derived neurotrophic factor (BDNF) is critical for enhancing the survival and growth of neurons and modulating the synaptic plasticity. BDNF levels have been demonstrated to be changed in plasma and cerebrospinal fluid (CSF) following brain insults such as inflammation or ischemia or infection in several studies. Currently, there is no systematic review regarding BDNF levels in encephalitis or encephalopathy patients. Considering inconsistency between studies, we aimed to pool the data from existing studies to determine whether blood or CSF levels of BDNF are different in patients with encephalopathy/encephalitis.

Methods

We comprehensively searched Web of Science, PubMed, Scopus, and Embase databases to identify eligible studies. The last search occurred in December 2022.

Results

12 studies met our inclusion criteria and ten studies including 283 patients and 323 healthy controls were enrolled in this meta-analysis. In comparison to controls, patients with encephalitis/encephalopathy had higher levels of BDNF in their CSF [standardized mean difference (SMD) = 1.48, 95% CI 0.18–2.77; P = 0.03)], while their blood levels of BDNF did not differ significantly [standardized mean difference (SMD) = 0.27, 95% CI = − 0.71 to 1.25; P = 0.58)]. Moreover, regarding the heterogeneity among studies reporting BDNF blood levels, we performed two subgroup analyses based on the disease etiology and the specimen (plasma and serum); none of them indicated statistically significant difference in BDNF levels between the subgroups (P = 0.41 and 0.20, respectively).

Conclusion

Meta-analysis provides evidence that patients with encephalopathy/encephalitis have higher CSF levels of BDNF compared to controls.

中文翻译：

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脑病/脑炎患者血液和脑脊液中脑源性神经营养因子的水平：系统评价和荟萃分析

摘要

背景

脑源性神经营养因子（BDNF）对于增强神经元的存活和生长以及调节突触可塑性至关重要。多项研究已证明，在炎症、缺血或感染等大脑损伤后，血浆和脑脊液 (CSF) 中的 BDNF 水平会发生变化。目前，尚无关于脑炎或脑病患者的 BDNF 水平的系统评价。考虑到研究之间的不一致，我们的目的是汇集现有研究的数据，以确定脑病/脑炎患者的血液或脑脊液中 BDNF 水平是否不同。

方法

我们全面检索了 Web of Science、PubMed、Scopus 和 Embase 数据库，以确定符合条件的研究。最后一次搜索发生在 2022 年 12 月。

结果

12 项研究符合我们的纳入标准，其中 10 项研究纳入了本次荟萃分析，其中包括 283 名患者和 323 名健康对照。与对照组相比，脑炎/脑病患者的脑脊液中 BDNF 水平较高[标准化平均差 (SMD) = 1.48，95% CI 0.18–2.77；P  = 0.03)]，而他们的血液 BDNF 水平没有显着差异[标准化平均差 (SMD) = 0.27，95% CI = − 0.71 至 1.25；P  = 0.58）]。此外，关于报告 BDNF 血液水平的研究之间的异质性，我们根据疾病病因和样本（血浆和血清）进行了两个亚组分析；它们均未表明亚组之间 BDNF 水平存在统计学显着差异（P 分别为 0.41 和 0.20）。

结论

荟萃分析提供的证据表明，与对照组相比，脑病/脑炎患者的脑脊液中 BDNF 水平较高。