Critical period of exposure to mercury and the diagnostic of autism spectrum disorder: A systematic review

• Published in: Journal of neurochemistry 2024-09, Vol.168 (9), p.2092-2104
• Main Authors: Netto, Bruna Bittencourt, Silva, Elica Pizzolo, Aguiar da Costa, Maiara, Rezende, Victória Linden, Bolan, Sofia Januário, Ceretta, Luciane Bisognin, Aschner, Michael, Dominguini, Diogo, Gonçalves, Cinara Ludvig
• Format: Article
• Language: English
• Subjects: Autism; Autism Spectrum Disorder - chemically induced; Autism Spectrum Disorder - diagnosis; autistic; Biological properties; Biological samples; Clinical trials; Detoxification; Environmental Exposure - adverse effects; Environmental factors; Exposure; Female; Heavy metals; Humans; Mercury; Mercury - toxicity; Nervous system; neurodevelopment; Neurotoxicity; Pregnancy; risk factor; Social behavior; Systematic review
• ISSN: 0022-3042; 1471-4159; 1471-4159
• DOI: 10.1111/jnc.16076

Autism spectrum disorder (ASD) is characterized by repetitive behaviors and deficits in social interaction. Its etiology is not completely clear, but both genetic and environmental factors contribute to and influence its development and course. The increased number of autism cases in recent years has been strongly associated with increased exposure to heavy metals. Mercury (Hg) has gained prominence in the scientific literature as a result of its presence as an urban pollutant and well‐described neurotoxicity. This review assessed the relationship between Hg exposure in the pre‐ and post‐natal period and ASD. The systematic review identified observational clinical studies and pre‐clinical trials in journals indexed in the PubMed, Embase, ProQuest, and LILACS databases. The aim of this study was to investigate the association between exposure to Hg and ASD and to define the critical period of exposure. A total of 57 articles were selected for this review, with 35 articles (61.40%) identifying a positive association between ASD and Hg, while 22 articles (38.60%) did not find the same outcome. The biological samples most used to analyze Hg body burdens were hair (36.84%) and blood (36.84%). Most case–control studies found an increase in Hg levels in individuals with ASD who were exposed to a polluted environment in the post‐natal period. Taken together, the studies suggest that these patients have a deficient detoxification system, and this could worsen the symptoms of the disorder. However, new studies addressing the influence of Hg on the post‐natal nervous system and its relationship with ASD should be carried out. Recent autism spectrum disorder (ASD) cases show a notable link to increased heavy metal exposure, particularly mercury (Hg), a recognized neurotoxin found in urban pollution. This review explores the connection between pre‐ and post‐natal Hg exposure and ASD, analyzing 57 articles from databases like PubMed and Embase. Of these, 61.40% confirm a positive association between ASD and Hg. The biological samples most used to analyze Hg body burdens were hair (36.84%) and blood (36.84%), indicating heightened levels in polluted environments during the post‐natal period.