Blood and hair copper levels in childhood autism spectrum disorder: a meta-analysis based on case-control studies

Abstract Objectives The association between copper levels and autism spectrum disorder (ASD) has been a controversial topic. This study investigated relationship between copper levels and ASD. Content The following databases are searched until April 2022: PubMed, EMBASE and Web of Science. Combined effect size standardized mean differences (SMD) and 95% confidence intervals (95% CI) were calculated with Stata 12.0. In this meta-analysis, 29 case-control studies were included, which included 2,504 children with ASD and 2,419 healthy controls. The copper levels in hair (SMD: −1.16, 95% CI: −1.73 to −0.58) was significantly lower in ASD children than healthy controls. The copper levels in blood (SMD: 0.10, 95% CI: −0.12 to 0.32) not significantly compare ASD with controls. Summary and outlook Copper may be associated with the development of ASD in children.