Emergency department visits for mental disorders and the built environment: Residential greenspace and historical redlining

Abstract

The built environment has been increasingly shown to impact mental health. However, little is known about how and the extent to which exposure to greenspace in the residential environment is associated with emergency department visits for mental disorders. In addition, despite recent findings highlighting the links between historical discriminatory housing policies and health outcomes, no evidence is available regarding historical redlining and mental health. We aimed to investigate the extent to which the availability of greenspace in residential surroundings and historical redlining was associated with risks of mental disorder-related emergency department visits. In this ecological study, we analyzed state-wide data on emergency room visits for mental health in all metropolitan areas in Texas between 2016 and 2019. Greenspace coverage was determined using the National Land Cover Database. Historical redlining was defined as the type C (definitely declining) or D (hazardous) designations according to the 1930 s Home Owners’ Loan Corporation (HOLC) Security Maps. We fitted a conditional autoregressive spatial model with zero truncated negative binomial distribution to assess associations among emergency department visits, greenspace availability, and redlining, adjusted for risk and protective urban and social-demographic factors. We found that, with a 1% increase in greenspace coverage in a zip code area, the risk of emergency department visits due to mental health disorders was expected to decrease by 0.16% (IRR = 0.9984, 95% CI: 0.9971–0.9997). Meanwhile, a 1% increase of historically redlining zones was associated with a 0.88% increase (IRR = 1.0088, 95% CI: 1.0056-1.0120) in the risk of emergency department visits for mental health disorders. Our findings support the notion that exposure to natural environments is linked to lower risks of emergency department visits for mental disorders. They also indicate that systematic segregation institutionalized by historical housing policies might be related to present-day mental health-related emergency department visits. This study offers novel insights into the built environmental correlates of mental health and provides planning and policy implications related to mental health and health equity promotion.