From Streets to Synapses: Exploring the Impact of the Neighborhood Environment on the Developing Brain

Abstract

Neighborhood disadvantage is associated with multiple maladaptive youth outcomes, including lower academic achievement, mental disorders, and behavioral problems. Neighborhood disadvantage may lead to worse outcomes by getting “under the skin” and altering underlying neurobiological mechanisms, however many important questions remain underexamined. This dissertation addresses critical questions about the impact of the neighborhood environment on youth brain outcomes and resilience. Specifically, it explores whether neighborhood features cluster together to impact youth brain outcomes, whether historic structural racism is linked to youth brain outcomes, and the neural correlates of resilience to environmental risk. Study 1 examines the structural brain correlates of resilience among youth exposed to neighborhood disadvantage and varying levels of cumulative risk. Using a large sample of adolescent twins, this study investigates associations between brain structure and resilience across psychological, social, and academic domains. Findings suggest that greater gray matter volume is associated with psychological adaptation, while smaller surface area in the caudal middle frontal gyrus predicts social adaptation. Importantly, these associations vary depending on the level of cumulative adversity, with greater brain structure more strongly linked to resilience among youth exposed to higher cumulative risk. Additionally, cognitive ability emerged as a mediator in the association between brain structure and academic adaptation, suggesting that brain structure may indirectly support academic functioning via increased cognitive ability. Study 2 takes a multidimensional approach to characterizing the neighborhood environment, identifying distinct profiles based on physical, social, and resource-based neighborhood features. These profiles were then linked to youth functional brain network organization. The results highlight two distinct neighborhood profiles: one characterized by high risk and low resources, and another by low risk and high resources, highlighting that neighborhood disadvantage clusters together with other neighborhood-level adversities, including worse school quality, higher levels of community violence exposure and disorder, increased risk of toxicant exposure, and diminished social resources. However, no significant associations were found between the identified neighborhood profiles and youth functional network organization, underscoring the need for future studies to further interrogate how complex neighborhood factors influence youth brain outcomes. Study 3 investigates the enduring impact of historic redlining, a form of structural racism, on adolescent functional brain network organization. Using a sample enriched for adversity, discrimination, and marginalization, the study shows that youth living in neighborhoods previously subjected to redlining exhibit altered functional brain network organization, including greater network segregation and decreased between-network integration across the whole brain and within networks critical for higher-order cognitive and socioemotional processes. Interestingly, historic redlining was not associated with present-day neighborhood disadvantage, and neighborhood disadvantage was also not associated with youth functional brain network architecture. These findings provide preliminary evidence that a form of structural racism, implemented nearly a century ago, may contribute to adolescent brain development today, illustrating the long-term impact of historic redlining in the United States. Together, these studies offer a comprehensive exploration of how the neighborhood environment may influence adolescent brain and behavioral outcomes, emphasizing different levels of analysis that complement one another. The findings illustrate that youth brain development and resilience are linked to both individual differences and broader environmental contexts, particularly the historical legacy of structural racism. By integrating these findings, the research underscores the complex interplay between individual neurobiological characteristics, current neighborhood conditions, and enduring historical inequities in shaping adolescent brain and behavioral development.