Vegetated land cover near residence is associated with reduced allostatic load and improved biomarkers of neuroendocrine, metabolic and immune functions
Citation:
Egorov, A., S. Griffin, R. Converse, J. Styles, E. Sams, A. Wilson, L. Jackson, AND Tim Wade. Vegetated land cover near residence is associated with reduced allostatic load and improved biomarkers of neuroendocrine, metabolic and immune functions. ENVIRONMENTAL RESEARCH. Academic Press Incorporated, Orlando, FL, 158:508-521, (2017).
Impact/Purpose:
This manuscript presents information on health-promoting community-level characteristics that supplements previous and ongoing ORD research on green spaces under the Sustainable and Healthy Communities research program. An inter-laboratory (NHEERL and NERL) team of researchers used a PIP stage 1 award to conduct an observational study in the Durham-Chapel Hill metropolitan area involving analysis of serum and saliva samples for multiple biomarkers of health effect. The results demonstrate that greater amount of vegetation near residence is linked with reduced risk of chronic stress-related physiological dysregulation known as allostatic load. This biomarker-based information on subclinical health benefits of urban green spaces is novel. The findings are important because allostatic load has been linked with increased risks of cardiovascular diseases, mental disorders, diabetes, and premature death.
Description:
Abstract Background: Greater exposure to urban green spaces has been linked to reduced risks of depression, cardiovascular disease, diabetes and premature death. Alleviation of chronic stress is a hypothesized pathway to improved health. Previous studies linked chronic stress with biomarker-based measures of physiological dysregulation known as allostatic load. This study aimed to assess the relationship between vegetated land cover near residences and allostatic load. Methods: This cross-sectional population-based study involved 204 adult residents of the Durham-Chapel Hill, North Carolina metropolitan area. Exposure was quantified using high-resolution metrics of trees and herbaceous vegetation within 500 m of each residence derived from the U.S. Environmental Protection Agency’s EnviroAtlas land cover dataset. Eighteen biomarkers of immune, neuroendocrine, and metabolic functions were measured in serum or saliva samples. Allostatic load was defined as a sum of biomarker values dichotomized at specific percentiles of sample distribution. Regression analysis was conducted using generalized additive models with two-dimensional spline smoothing function of geographic coordinates, weighted measures of vegetated land cover allowing decay of effects with distance, and geographic and demographic covariates. Results: An inter-quartile range increase in distance-weighted vegetated land cover was associated with 37% (46%; 27%) reduced allostatic load; significantly reduced adjusted odds of having low level of serum norepinephrine, dopamine, and dehydroepiandrosterone, high level of epinephrine, fibrinogen, vascular cell adhesion molecule-1, interleukin-8, and salivary α-amylase; and previously diagnosed depression. Conclusions: The observed effects of vegetated land cover on allostatic load and individual biomarkers are consistent with prevention of depression, cardiovascular disease and premature mortality.
