Association of Redlining and Natural Environment with Depressive Symptoms in Women in the Sister Study
Improving mental health is recognized as a key factor for achieving global development goals. There is strong evidence that neighborhood greenery promotes better mental health. However, there are environmental justice concerns over the distribution of neighborhood greenery. Underlying this concern are present-day consequences of historical racial discriminatory practices, such as redlining established by the U.S. Federal Home Owners’ Loan Corporation (HOLC) in the 1930s. The impacts of redlining on environmental and health disparities have been researched separately. However, the influences of redlining on the associations between environment and health outcomes have not been fully assessed. This study aims to examine whether associations between tree cover and depressive symptoms in women vary across areas that had been evaluated for investment potential by the HOLC. Depressive symptoms were defined by the 10-item Center for Epidemiologic Studies Depression Scale collected during 2008 - 2012 for 3,555 women residing in the historically HOLC cities from the Sister Study cohort. HOLC rating maps were obtained from the Mapping Inequality Project, University of Richmond, with neighborhoods graded as A (best, green), B (still desirable, blue), C (declining, yellow), and D (hazardous, red – known as redlined). Tree cover within 500m and 2000m from homes were estimated using 2011 U.S. Forest Service Percent Tree Canopy Cover. We found that tree canopy was significantly higher in neighborhoods with better historical HOLC grades. A 10% increase in tree cover was associated with reduced odds of having depressive symptoms for the full population (adjusted Odds Ratios [AORs]: 0.93, 95% Confidence Intervals [CIs]: 0.87 – 0.99, and 0.91, 95% CIs: 0.85 – 0.97 for 500m and 2000m buffer, respectively) and across HOLC grades, with strongest associations in redlined neighborhoods (AORs: 0.72, 95% CIs: 0.52 – 0.99 at 500m buffer and 0.63, 95% CIs: 0.45 – 0.90 at 2000m buffer). Findings suggest a remediation strategy focused on neighborhood greenery that would address multiple public health priorities including improved mental health, climate change mitigation, and environmental justice.