Contributions of a Child’s Built, Natural, and Social Environments to Their General Cognitive Ability: A Systematic Scoping Review

Abstract

The etiology of a child’s cognitive ability is complex, with research suggesting that it is not attributed to a single determinant or even a defined period of exposure. Rather, cognitive development is the product of cumulative interactions with the environment, both negative and positive, over the life course. The aim of this systematic scoping review was to collate evidence associated with children’s cognitive health, including inherent factors as well as chemical and non-chemical stressors from the built, natural, and social environments. Three databases were used to identify recent epidemiological studies (2003–2013) that examined exposure factors associated with general cognitive ability in children. Over 100 factors were evaluated from 258 eligible studies. We found that recent literature mainly assessed the hypothesized negative effects of either inherent factors or chemical exposures present in the physical environment. Prenatal growth, sleep health, lead and water pollutants showed consistent negative effects. Of the few studies that examined social stressors, results consistently showed cognitive development to be influenced by both positive and negative social interactions at home, in school or the community. Among behavioral factors related to diet and lifestyle choices of the mother, breastfeeding was the most studied, showing consistent positive associations with cognitive ability. There were mostly inconsistent results for both chemical and non-chemical stressors. The majority of studies utilized traditional exposure assessments, evaluating chemical and non-chemical stressors separately. Collective evidence from a limited number of studies revealed that cumulative exposure assessment that incorporates multiple chemical and non-chemical stressors over the life course may unravel the variability in effect on cognitive development and help explain the inconsistencies across studies. Future research examining the interactions of multiple stressors within a child’s total environment, depicting a more real-world exposure, will aid in understanding the cumulative effects associated with a child’s ability to learn.

A Systematic Review of the Interplay Between Social Determinants and Environmental Exposures for Early-Life Outcomes

“…Many studies have separately demonstrated that environmental contaminants like air pollution and metals as well as early-life social and psychosocial factors, such as living in poverty and experiences of adversity, have independent and substantial effects on a range of child health outcomes including asthma, cognition and behavior, obesity, and perinatal risks like being born low birth weight [2][3][4][5]. Fewer studies have considered explicitly the accumulation of risk and potential synergies between social and environmental risks as determinants of child health outcomes.…”

Children’s Exposure to Environmental Contaminants: An Editorial Reflection of Articles in the IJERPH Special Issue Entitled, “Children’s Exposure to Environmental Contaminants”

“…The onus of responsibility is on the researchers to represent limitations and bias within any study, along with potential variability across space and time and any potential uncertainty in measurements and modelling computations. Underlying biological mechanisms and confounding factors (e.g., gene variants, multiple exposures, poverty, poor nutrition, predisposing and enabling factors natural, built and social aspects) can provide the audience with a broader understanding of the complexity of certain health outcomes [53,59]. Certainly, attention must be paid to how we represent data and communicate the risks to the public [60].…”

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

“…The childhood well-being framework may aid in the identification of other stressors that can be related to prenatal exposure to recreational drugs [44]. A previous study examined contributing factors from the built, natural, and social environments that may be linked to prenatal exposure to recreational drugs [118]. Parental lifestyle factors, part of the social environment, are directly related to parental drug use during pregnancy.…”

“…The desire to examine the synergistic effects of chemical and non-chemical stressors with inherent characteristics to gain a more comprehensive understanding of children's health outcomes is gaining momentum in the literature [44,118,147]. However, there is still a paucity of studies that examine these factors collectively.…”