Association Between Exposure to Heavy Metals and Dyslexic Risk Among Children: A Narrative Review

Abstract

Context: Developmental dyslexia (DD) is a learning disorder characterized by difficulties in reading due to challenges in sound identification and letter-word association. This study aimed to evaluate the correlation between exposure to heavy metals (HMs) and the risk of dyslexia in children through a narrative review. Evidence Acquisition: The study adopted a narrative review approach, utilizing keywords to search reputable databases like Google Scholar, Scopus, PubMed, and Web of Science. Relevant research meeting specific criteria were selected for analysis. Results: In most studies, metals were measured in children's urine. The results indicated that children with DD had lower levels of essential metals such as zinc (Zn), selenium (Se), and cobalt (Co). In contrast, toxic metals like mercury (Hg), cadmium (Cd), silver (Ag), and lead (Pb) were significantly higher compared to the control group. Based on the results of previous studies, no significant variations were observed in other essential and toxic metals between the case and control groups. Conclusions: Essential metals like Zn, Se, and Co may protect against DD in children, whereas toxic metals such as Pb, Ag, Cd, and Hg could exacerbate the disorder. It is recommended to evaluate essential and toxic metal levels in parents before and during pregnancy and in infants to mitigate dyslexia risk in children.