School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Systematic Review and Meta-analysis Expert Group (SRMEG), Universal Scientific Education and Research Network (USERN), Tehran, Iran.
Acta Neurol Belg. 2024 Apr;124(2):533-542. doi: 10.1007/s13760-023-02442-4. Epub 2024 Jan 24.
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.
We comprehensively searched Web of Science, PubMed, Scopus, and Embase databases to identify eligible studies. The last search occurred in December 2022.
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).
Meta-analysis provides evidence that patients with encephalopathy/encephalitis have higher CSF levels of BDNF compared to controls.
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。多项研究表明，BDNF 水平在脑损伤后如炎症、缺血或感染时会在血浆和脑脊液（CSF）中发生变化。目前，尚无关于脑炎或脑病患者 BDNF 水平的系统评价。考虑到研究之间的不一致性，我们旨在汇总现有研究的数据，以确定 BDNF 水平在脑病/脑炎患者的血液或 CSF 中是否存在差异。
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。最后一次检索时间为 2022 年 12 月。
12 项研究符合纳入标准，10 项研究包括 283 名患者和 323 名健康对照者纳入了本荟萃分析。与对照组相比，脑炎/脑病患者的 CSF 中 BDNF 水平更高[标准化均数差（SMD）=1.48，95%CI 0.18-2.77；P=0.03)]，而其血液 BDNF 水平无显著差异[标准化均数差（SMD）=0.27，95%CI=-0.71 至 1.25；P=0.58)]。此外，对于报告血液 BDNF 水平的研究之间的异质性，我们根据疾病病因和标本（血浆和血清）进行了两项亚组分析；亚组之间的 BDNF 水平均无统计学差异（P=0.41 和 0.20）。
荟萃分析提供了证据，表明与对照组相比，脑病/脑炎患者的 CSF 中 BDNF 水平更高。
