Research Review: Environmental exposures, neurodevelopment, and child mental health – new paradigms for the study of brain and behavioral effects

Abstract

Background Environmental exposures play a critical role in the genesis of some child mental health problems. Methods We open with a discussion of children’s vulnerability to neurotoxic substances, changes in the distribution of toxic exposures, and co-occurrence of social and physical exposures. We address trends in prevalence of mental health disorders, and approaches to the definition of disorders that are sensitive to the subtle effects of toxic exposures. We suggest broadening outcomes to include dimensional measures of autism spectrum disorders, attention deficit hyperactivity disorder, and child learning capacity, as well as direct assessment of brain function. Findings We consider the impact of two important exposures on children’s mental health: lead and pesticides. We argue that longitudinal research designs may capture the cascading effects of exposures across biological systems and the full-range of neuropsychological endpoints. Neuroimaging is a valuable tool for observing brain maturation under varying environmental conditions. A dimensional approach to measurement may be sensitive to subtle sub-clinical toxic effects, permitting the development of exposure-related profiles and testing of complex functional relationships between brain and behavior. Questions about the neurotoxic effects of chemicals become more pressing when viewed through the lens of environmental justice. Conclusions Reduction in the burden of child mental health disorders will require longitudinal study of neurotoxic exposures, incorporating dimensional approaches to outcome assessment and measures of brain function. Research that seeks to identify links between toxic exposures and mental health outcomes has enormous public health and societal value.

Developmental Dieldrin Exposure Alters DNA Methylation at Genes Related to Dopaminergic Neuron Development and Parkinson’s Disease in Mouse Midbrain

“…In this study, there was no overlap between the DMCs and DMRs detected in the adult and developmental exposure models, and the largest effects of dieldrin exposure were seen in the female developmental exposure. Supporting this data, previous studies have shown that the developing brain is particularly sensitive to environmental perturbations (Rauh and Margolis, 2016;Rice and Barone, 2000), and that environmental chemicals can act as potent neurotoxicants during development (Miodovnik, 2011;Heyer and Meredith, 2017). Furthermore, developmental exposures have the potential to modify epigenetic programming, which takes place during embryonic development (Reik et al, 2001;Feng et al, 2010;Marsit, 2015).…”

Ecosystem Approaches to Health and Well‐Being: Navigating Complexity, Promoting Health in Social–Ecological Systems

“…Ecosystems underpin all of our social and economic systems and feed back into them as well. This is demonstrated by a large body of work in the environment and health field that addresses a wide range of environmental determinants of health such as water quality and diarrhea (Levy et al, 2012), schistosomiasis (Stensgaard et al, 2013), exposure to pesticides (Rauh and Margolis, 2016), indoor air quality and respiratory health (Hulin et al, 2012), malaria (Bevilacqua et al, 2015), dengue (Fazidah A. Siregar et al, 2015), helminth-related diseases such as tapeworms and filariasis (Gazzinelli et al, 2012), and zoonoses such as leptospirosis (Mwachui et al, 2015) and avian influenza (Waltner-Toews, 2007).…”

Prenatal exposure to organophosphorus pesticides and childhood neurodevelopmental phenotypes

“…Typically, studies have considered only a single component of neurodevelopment at a time, such as IQ or behavior. However, there are major conceptual advantages in jointly modeling domains of neurobehavioral development (Rauh and Margolis, 2016; Robinson, 2012). Accounting for the interrelations between developmental domains is more clinically relevant because neurological functions are mutually dependent.…”