20 ABCD Study Environmental Correlates of Gray Space on Cognitive Performance Among Youth via NIH Toolbox
Authors: Harris Julia C , Cardenas-Iniguez Carlos , Lisdahl Krista M 
Published: December 2023

Objective:Evidence has shown that the environment is an often overlooked social determinant of health (SDoH) of emotional, neural, and cognitive development. Aspects of the built environment relate to health factors and equity in living conditions, and may contribute to racial, ethnic, or economic health disparities. For example, urbanicity is linked with negative factors including less access to green space (i.e. gray space), increase in air pollution, temperatures, and socio-economic inequalities. While there is existing research on access to green space on some mental health and cognitive outcomes, there is limited research on the presence of gray space linked with cognitive functioning in youth. While some studies have shown that aspects of the neighborhood environment (e.g. access to healthy food, air pollution, heat exposure, and walkability) can impact neural and cognitive functioning, few to date have disentangled unique contributions of these factors in a large, national cohort. Therefore, the aim of the present study was to identify the best fitting model testing multiple SDoHs related to gray space on overall cognitive functioning in youth enrolled in the Adolescent Brain Cognitive Development (ABCD) Study.Participants and Methods:Using baseline data (n = 8,802) from ABCD 4.0 data, this study used environmental measures and linked external databases to characterize SDoH variables predicting youths’ cognitive functioning via the NIH Toolbox (e.g. total cognitive composite score). This study used geospatial mapping to estimate exposure to air pollutants and heat. Additionally, the National Walkability Index was linked to assess walkability of neighborhood. Exposure to gray space (e.g. impervious surfaces) and access to healthy food were assessed via the Child Opportunity Index 2.0. An exhaustive search for the best subsets of these variables (gray space, access to healthy food, walkability, air pollution, and heat exposure) predicting cognitive performance was run to examine the best fitting model based on adjusted R2, using the 'leaps’ package in R. Then, a multiple linear mixed effects regression model, using the lmer package in R, was fitted adjusting for various and relevant demographic factors.Results:The results of the regression indicated that walkability index (F(1, 1322.4) = 11.07, p < 0.001) and heat exposure (F(1, 81.1) = 5.54, p < 0.001) explained a significant amount of the variance (Adjusted R2 = 20%) predicting total cognitive performance while controlling for sex, age, household income, parent education, marital status, family relatedness, and site.Conclusions:Findings suggest that walkability of the neighborhood and heat exposure may play a role in cognitive development over and above other SDoHs and demographic factors. However, this study was limited to baseline assessment and a single measurement of total composite cognitive score, thus it is crucial for future research to investigate relationships over the life course across cognitive domains to further clarify these findings. The present study can help inform future public policy on improving lived and built environments, which may aid in supporting cognitive development in youth. These findings identify key factors, walkability and heat exposure, to consider when investigating the interaction between poverty, health, and environmental justice.