Peripheral brain-derived neurotrophic factor in autism spectrum disorder: a systematic review and meta-analysis.

Zhen Zheng,Tingting Zhu,Jichong Huang,Dezhi Mu,Li Zhang,Yi Qu

doi:10.1038/srep31241

Abstract

Brain-derived neurotrophic factor (BDNF) regulates neuronal survival and growth and promotes synaptic plasticity. Recently, researchers have begun to explore the relationship between peripheral BDNF levels and autism spectrum disorder (ASD), but the findings are inconsistent. We undertook the first systematic review and meta-analysis of studies examining peripheral BDNF levels in ASD compared with healthy controls. The PubMed, Embase, and Cochrane Library databases were searched for studies published before February 2016. Fourteen studies involving 2,707 participants and 1,131 incident cases were included. The meta-analysis provided evidence of higher peripheral BDNF levels in ASD compared with controls [standardized mean difference (SMD) = 0.63, 95% confidence interval (95% CI) = 0.18–1.08; P = 0.006]. Subgroup analyses revealed higher BDNF levels in ASD compared with controls for both serum [SMD = 0.58, 95% CI = 0.11–1.04; P = 0.02] and plasma [SMD = 1.27, 95% CI = 0.92–1.61; P < 0.001]. Studies of childhood yielded similar cumulative effect size [SMD = 0.78, 95% CI = 0.31–1.26; P = 0.001], while this was not true for the studies of adulthood [SMD = 0.04, 95% CI = −1.72–1.80; P = 0.97]. This meta-analysis suggests that peripheral BDNF levels are a potential biomarker of ASD.

Highlights

The concept of the “periphery as a window to the brain” has led to an ever-increasing number of clinical studies assessing peripheral BDNF levels in Autism spectrum disorder (ASD)
Some studies have reported that serum BDNF is significantly reduced in ASD compared with healthy controls[12,13], while other studies have reported higher serum BDNF levels in children with ASD compared with controls[14,15,16]
We undertook a systematic review of studies assessing peripheral BDNF levels in ASD and controls, followed by a series of meta-analyses to provide an overall estimate of the effect size and between-study heterogeneity of the association between peripheral BDNF levels and ASD

Summary

Introduction

The concept of the “periphery as a window to the brain” has led to an ever-increasing number of clinical studies assessing peripheral BDNF levels in ASD. Reports of peripheral BDNF levels in ASD are inconsistent. Some studies have reported that serum BDNF is significantly reduced in ASD compared with healthy controls[12,13], while other studies have reported higher serum BDNF levels in children with ASD compared with controls[14,15,16]. Two studies that have examined BDNF levels in neonatal specimens from individuals later diagnosed with ASD have yielded inconsistent results[17,18]. We undertook a systematic review of studies assessing peripheral BDNF levels in ASD and controls, followed by a series of meta-analyses to provide an overall estimate of the effect size and between-study heterogeneity of the association between peripheral BDNF levels and ASD

Methods

Results

Conclusion