A Systematic Review and Meta-Analysis Investigating the Relationship between Exposures to Chemical and Non-Chemical Stressors during Prenatal Development and Childhood Externalizing Behaviors.

Frances M Nilsen,Jessica Frank,Nicolle S Tulve

doi:10.3390/ijerph17072361

Frances M Nilsen, Jessica Frank + Show 1 more

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https://doi.org/10.3390/ijerph17072361

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Abstract

Childhood behavioral outcomes have been linked to low quality intrauterine environments caused by prenatal exposures to both chemical and non-chemical stressors. The effect(s) from the many stressors a child can be prenatally exposed to may be influenced by complex interactive relationships that are just beginning to be understood. Chemical stressors influence behavioral outcomes by affecting the monoamine oxidase A (MAOA) enzyme, which is involved in serotonin metabolism and the neuroendocrine response to stress. Non-chemical stressors, particularly those associated with violence, have been shown to influence and exacerbate the externalizing behavioral outcomes associated with low MAOA activity and slowed serotonin metabolism. The adverse developmental effects associated with high stress and maternal drug use during pregnancy are well documented. However, research examining the combined effects of other non-chemical and chemical stressors on development and childhood outcomes as a result of gestational exposures is scarce but is an expanding field. In this systematic review, we examined the extant literature to explore the interrelationships between exposures to chemical and non-chemical stressors (specifically stressful/traumatic experiences), MAOA characteristics, and childhood externalizing behaviors. We observed that exposures to chemical stressors (recreational drugs and environmental chemicals) are significantly related to externalizing behavioral outcomes in children. We also observed that existing literature examining the interactions between MAOA characteristics, exposures to chemical stressors, and traumatic experiences and their effects on behavioral outcomes is sparse. We propose that maternal stress and cortisol fluctuations during pregnancy may be an avenue to link these concepts. We recommend that future studies investigating childhood behaviors include chemical and non-chemical stressors as well as children’s inherent genetic characteristics to gain a holistic understanding of the relationship between prenatal exposures and childhood behavioral outcomes.

Highlights

The developmental origins of childhood mental and behavioral health outcomes have been an area of increasing research interest over the last 20 years [1,2,3,4]
In 1980, the American Psychological Association (APA) changed the name and definition of hyperkinetic impulse disorder to attention deficit disorder (ADD) with subtypes relating to hyperactivity, and later to attention deficit hyperactivity disorder (ADHD) with no subtypes
Forty-five references examining externalizing behaviors related to prenatal exposures to chemical and non-chemical stressors and/or monoamine oxidase A (MAOA) genotype were included in this systematic review and meta-analysis

Summary

Introduction

The developmental origins of childhood mental and behavioral health outcomes have been an area of increasing research interest over the last 20 years [1,2,3,4]. Childhood outcomes research evolved from the developmental origins of adult disease (DOHaD) hypothesis, which states that numerous adult diseases can be programmed in utero [5,6]. Many adverse childhood outcomes have been attributed to. Res. Public Health 2020, 17, 2361; doi:10.3390/ijerph17072361 www.mdpi.com/journal/ijerph

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