Pediatric Exposures to Neurotoxicants: A Review of Magnetic Resonance Imaging and Spectroscopy Findings

Abstract

Heavy metals, including lead and manganese, air pollution, pesticides, environmental tobacco smoke, and flame retardants are among the known and suspected environmental neurotoxicant exposures examined with magnetic resonance imaging (MRI)-based studies of pediatric populations. Many studies feature morphological changes associated with the exposures while others employ magnetic resonance spectroscopy, diffusion imaging, task-based, and resting state functional magnetic resonance imaging to reveal abnormal metabolic concentrations, white matter disorganization, and atypical patterns of activation. Some studies follow pregnant women and their offspring throughout the lifespan with collection of individual specimens as exposure biomarkers. Others innovatively make use of public databases to obtain relevant exposure biomarkers while taking advantage of these studies in their efforts to monitor developmental features in large, population-based, imaging cohorts. As exposures to neurotoxicants in the womb and throughout childhood have life-long impacts on health and well-being, the importance of these innovative neuroimaging investigations is ever increasing.

Topological network properties of resting-state functional connectivity patterns are associated with metal mixture exposure in adolescents

“…Few studies investigated the neural mechanisms of metal neurotoxicity throughout this extended window of vulnerability. Findings from these studies have linked metal exposure with alterations in regional brain volume ( Claus et al, 2012 , 2014 ; Horton et al, 2014 , 2018 ; Levin-Schwartz et al, 2021 ; Heng et al, 2022 ; Migneron-Foisy et al, 2022 ), and brain metabolite concentrations ( Trope et al, 2001 ; Meng et al, 2005 ; Thomason et al, 2019 , 2021 ; Cecil, 2022 ) during this period. This heightened vulnerability may be due to rapid growth and differentiation of the brain throughout childhood.…”

Topological network properties of resting-state functional connectivity patterns are associated with metal mixture exposure in adolescents

“…Our finding that lead and chromium were the top contributing metals in the association between the metal mixture and GE, and chromium contributed most to the association with LE, suggests that these metals may exert a greater influence on global and/or local functional connectivity across/within topological brain networks. Previous human neuroimaging studies have observed associations between lead exposure and altered structural connectivity and functional activation patterns in both children and adults [20][21][22]. In particular, Thomason et al found prenatal lead (Pb) exposure was associated with altered age-related intrinsic functional connectivity patterns in developing fetuses [21].…”

“…Few studies investigated the neural mechanisms of metal neurotoxicity throughout this extended window of vulnerability. Findings from these studies have linked metal exposure with alterations in regional brain volume [14][15][16][17][18][19], and brain metabolite concentrations [20][21][22][23][24] during this period. This heightened vulnerability may be due to rapid growth and differentiation of the brain throughout childhood.…”

Topological network properties of resting-state functional connectivity patterns are associated with metal mixture exposure in adolescents

“…Lead exposure is known for causing the disruption of neuronal activity, in particular to alter the release and storage of neurotransmitters from the presynaptic nerve endings, that may change the developmental processes of synapse formation in children and young adults and results in altered brain functions (Bressler and Goldstein, 1991). Previous human neuroimaging studies have observed associations between lead exposure and altered structural connectivity and functional activation patterns in both children and adults (Thomason et al, 2019(Thomason et al, , 2021Cecil, 2022). In particular, Thomason et al (2019) found prenatal lead (Pb) exposure was associated with altered age-related intrinsic functional connectivity patterns in developing fetuses.…”

“…Few studies investigated the neural mechanisms of metal neurotoxicity throughout this extended window of vulnerability. Findings from these studies have linked metal exposure with alterations in regional brain volume (Claus et al, 2012(Claus et al, , 2014Horton et al, 2014Horton et al, , 2018Levin-Schwartz et al, 2021;Heng et al, 2022;Migneron-Foisy et al, 2022), and brain metabolite concentrations (Trope et al, 2001;Meng et al, 2005;Thomason et al, 2019Thomason et al, , 2021Cecil, 2022) during this period. This heightened vulnerability may be due to rapid growth and differentiation of the brain throughout childhood.…”