The role of the gut microbiome in the associations between lead exposure and child neurodevelopment.

Lead is highly toxic to the developing brain. Given its persistence in the environment, new intervention strategies are needed to mitigate the impacts of lead on child neurodevelopment. The gut microbiome, referring to the bacteria and microorganisms residing in the gastrointestinal system, may be a viable target for intervention. This short review summarizes recent evidence linking the gut-brain axis to child developmental outcomes. We explore how lead-induced effects to the gut microbiome could indirectly affect child neurodevelopment, such that disrupting or offsetting this mediating process could buffer the effects of lead on child developmental outcomes. Unexpected findings with respect to child microbiota diversity and child cognitive and behavioral outcomes as well as lead exposure and adult microbiota diversity are discussed. When possible, we draw connections between observed changes to relative bacterial abundance, proposed bacterial functions, and downstream effects to brain development. We also explore how the gut microbiome might modify the toxicity of lead by impeding the uptake of lead across the gastrointestinal tract or through indirect mechanisms in such ways that the gut microbiome does not fit within a mediating pathway. In this case, promoting the buffering capacity of the gut microbiome may reduce the impacts of lead on child neurodevelopment. The goal of this short review is to bring attention to the potential role of the gut microbiome in the associations between lead exposure and child neurodevelopment with an eye towards intervention.