Association of social and environmental exposures at the neighborhood level with child brain volume.

backgroundPrior studies show that neighborhood disadvantage negatively impacts children's cognitive function and brain volume. However, despite their co-occurrence, there is a lack of cohesive examination of the joint effects of environmental and social factors on brain volumes.

objectivesUsing environmental mixture methods, we investigated the association between a child's neighborhood environment and brain volume in regions relevant for cognitive and cognitive-affective function.

methodsWe leveraged a sample of 8574 nine and ten-year-old children from the Adolescent Brain Cognitive Development study. Exposures included 22 social and 7 environmental exposures linked to participants' baseline addresses. Neighborhood exposome profiles were represented using self-organizing maps. Baseline cortical and subcortical volumes in 16 regions were analyzed using linear mixed effects models with neighborhood exposome profile as a categorical exposure, adjusting for individual-level demographic variables and multiple testing. We used Weighted Quantile Sum (WQS) regression to examine the total mixture effect and the relative contribution of each individual exposure to the total mixture effect.

resultsParticipants living in profiles defined by moderate neighborhood deprivation, high ozone, and poor walkability had greater right caudal middle frontal gyrus volumes compared to those in the reference cluster (beta: 0.11; 95% CI: 0.05, 0.17). WQS indicated that this association was primarily driven by home value and ozone concentration. DISCUSSION: We identified multiple social and environmental factors in association with greater right caudal middle frontal gyrus volume. These results provide evidence of how multiple facets of the neighborhood environment can impact the developing brain and potentially increase the risk of future psychopathology.