Hair Trace Elements in Children With Autism Spectrum Disorders: Systematic Literature Review

Abstract

(1) Background: The aim of this work was to systematically review the literature on the relation between the levels of elements in hair (toxic elements and trace elements) on the occurrence of autism spectrum disorder. (2) Methods: Search strategy and study selection: Original articles were included if they met the including criteria that report the trace element levels in hair. The following databases were screened: Medline (via PubMed), Scopus, Web of Science, Google Scholar (from 2000.01.01 to 2020.11.11). The main search terms used were “hair element analysis and trace elements and autism”. (3) Results: The papers available describe results of studies undertaken with the use of different methodology: diversified size of experimental groups, different sampling and analytical techniques. Therefore direct comparison of the results is not informative. (4) Conclusions: It was found that pathogenesis of autism spectrum disorder was associated with the exposure to toxic elements (e.g. Hg and Pb) which act as neurotoxicants. Also, the relation between some microelements seem to be significant, in particular the ratio Zn/Cu. Higher level of zinc and level levels of copper play the protectory role.