Residential green space and behavioral and mental health outcomes in early childhood

Marnie Hazlehurst | 2021

Advisor: Catherine Karr

Research Area(s): Environmental & Occupational Health, Psychiatric Epidemiology

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Natural environments, including urban green spaces, have been associated with a range of health outcomes across the life course. Green space may promote healthy development, even early in childhood. The aim of this study was to investigate the relationships between residential green space exposures and child behavioral and mental health in a socio-demographically diverse cohort in Memphis, TN. We also explored the relationship of green space measures to a broad set of neighborhood conditions, including socioeconomic and education resources.
We assessed three green space exposures—residential surrounding greenness, tree cover, and park proximity—within the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) cohort. Behavioral and mental health outcomes at age 4, including both externalizing and internalizing behaviors, were assessed via parent-report on the Child Behavior Checklist (CBCL). Linear regression models adjusted for individual, household, and neighborhood-level confounders across multiple domains, were fit to assess the relationship between green space and child behavior. Effect modification by neighborhood socioeconomic opportunity and child sex were explored using multiplicative interaction terms.
Higher residential surrounding greenness was associated with lower internalizing behavior scores. Observed associations were generally robust across a suite of sensitivity analyses, including adjustment for potential mediators. In secondary analyses, these associations were most consistent for the anxious/depressed and somatic complaints syndrome scales. We did not find any associations with externalizing behaviors or attention problems. In this study, residential surrounding greenness and tree cover were higher in neighborhoods with a higher homeownership rate, more early childhood education resources, and a lower percentage of Black residents.
Findings from this dissertation add to the accumulating evidence of a protective effect of residential green space for mental health in early childhood. Strengths of this study include the spatial resolution of green space measures and the assessment of behavior outcomes across a continuum. Future work may improve our understanding of these relationships by incorporating child care or school-based exposures and assessing time spent in green spaces. This research can inform the design of new green spaces or the conservation and management of existing urban green spaces, including improving access to nature features such as trees within historically underserved communities, as well as interventions targeting families with young children.