Joint effects of multi-metal exposure on Autism Spectrum Disorder: Associations, related genes, and biological...

Autism Spectrum Disorder (ASD) is a common, multifactorial neurodevelopmental disorder with complex etiology. Aberrant metal exposure has been linked to ASD pathogenesis, but the independent and joint effects of multi-metal exposure remain unclear. This study investigated the associations between metal exposure and ASD in a case-control study involving 214 children aged 3-8 years, with 112 ASD cases and 102 controls. Plasma concentrations of 15 metals were measured using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Logistic regression and restricted cubic spline models (RCS) were used to assess the associations between metals and ASD. The results indicated that higher plasma concentrations of lead (Pb) were independently associated with ASD, whereas selenium (Se) showed an inverse association. These findings were further supported by sensitivity analyses using Firth logistic regression and bootstrap resampling. Bayesian kernel machine regression (BKMR) and quantile g-computation (Qgcomp) models revealed that the joint effect of Pb and nickel (Ni) on ASD was attenuated when Se was included in the analysis. In addition, analysis of public data identified nine candidate genes potentially related to both metal exposure and ASD. RT-qPCR analysis of local samples confirmed the differential expression of the candidate genes, which were functionally linked to neurodevelopment-related pathways, including thyroid hormone signaling, mTOR/AMPK signaling, and synaptic plasticity. Overall, this study suggests that specific plasma metal profiles may be associated with ASD and highlights the potential relevance of considering multi-metal exposure patterns. Further longitudinal studies and experimental investigations are required to determine the temporal relationship and potential biological mechanisms linking metal exposure to ASD. LAY SUMMARY: Autism Spectrum Disorder is thought to involve both genetic and environmental factors. In this case-control study, we measured multiple metals in children's plasma and found that children with ASD had different metal profiles compared with controls, particularly for lead, nickel, and selenium. When metals were considered together, selenium appeared to influence the observed associations involving lead and nickel. We also identified several genes that may be related to both metal exposure and neurodevelopmental processes. These findings suggest that metal exposure patterns may be relevant to ASD, but larger longitudinal and mechanistic studies are needed to clarify these relationships.