Exposure to heavy metals and neurocognitive function in adults: a systematic review

Exposure of individuals to heavy metals (HMs) is a growing concern with far-reaching implications for human health. HMs encompass a diverse range of elements that, when present in excess or in particular chemical forms, have the potential to elicit adverse effects on the central nervous system and cognitive function. This systematic review aims to comprehensively investigate the relationship between exposure to HMs and neurocognitive function in adults. The methodological framework for this review adheres rigorously to the Meta-analyses Of Observational Studies in Epidemiology (MOOSE) guidelines. A meticulous and extensive search strategy was executed within PubMed and Web of Science, specifically targeting articles published in the English language until the cutoff date of December 5, 2023. The evaluation of the retrieved studies was systematically conducted by employing the assessment approach outlined by (Gascon et al. in Environ Int 86 60 67, 2016). The initial search yielded a substantial pool of 1573 articles, culminating in a refined selection comprising eight pertinent studies, collectively enrolling a participant cohort totalling n = 1,828,126. Notably, the studies under review predominantly manifested a cross-sectional or cohort design and were geographically situated within the continents of North America and Asia. Furthermore, it is imperative to underscore that a predominant and recurring observation emanating from the majority of the scrutinized investigations underscores a significant correlation between exposure to cadmium (Cd) and mercury (Hg) and deleterious neurocognitive outcomes in the adult population. In summary, our systematic review postulates that exposure to HMs through various routes of exposure harbors the potential for adverse effects on adult neurocognitive function; however, it is incumbent upon future research endeavors to validate and corroborate these findings through further empirical exploration.