Aberrations in Peripheral Blood Neuron-Specific Enolase Levels in Depression: A Systematic Review and Meta-Analysis

Neuron-specific enolase (NSE) is a type of glycolytic enzyme enolase. As NSE is predominantly localized in endocrine cells and neurons, it is frequently recognized as a specific biomarker for peripheral neuroendocrine cells and neurons. Recently, numerous clinical studies have investigated the correlation between peripheral blood NSE levels and depression; however, the findings remain inconsistent. The objective of this study is to systematically evaluate peripheral blood NSE levels in patients with various types of depression.

We conducted an extensive literature review using various databases such as PubMed, Embase, Cochrane Library, Web of Science, Wanfang, and China National Knowledge Infrastructure (CNKI). A random-effects model was utilized to compute the pooled effect size (ES) (Hedges' g). Sensitivity analysis, assessment of publication bias, and subgroup analysis were conducted using Comprehensive Meta-Analysis software version 3.0 (CMA 3.0) software.

A total of 1175 records were screened for initial eligibility, and 18 reports reported in 18 studies that met the inclusion criteria were included in the meta-analysis. The primary analysis revealed that abnormally elevated levels of NSE in peripheral blood are closely related to the risk of occurrence of major depressive disorder (MDD) or poststroke depression (PSD). Analysis results from different groups on MDD or PSD showed similar outcomes. Sensitivity analysis confirmed the robustness of our findings. The findings on publication bias suggested that this study did not exhibit any significant publication bias.

The findings of our study suggest that abnormally elevated NSE levels in peripheral blood are closely related to the risk of depression, especially MDD and PSD. These findings offer valuable references for the monitoring and early warning of depression. However, the applicability to other subtypes of depression and the clinical translational value requires further validation. In the future, clinical studies with more participants are necessary.