Community severance and mental health-related hospital visits in New York City

Background: Mental health disorders are more prevalent in urban areas; urban living has been linked to increased risk of anxiety, mood, and schizophrenia disorders. These associations may be partially explained by the social and physical urban environment. While traffic-related exposures such as air pollution and noise have been linked to adverse mental health outcomes, the role of road infrastructure and traffic in severing communities and breaking down the social fabric-termed community severance-remains understudied. Methods: We conducted ZIP code-level analyses (2011-2014) to investigate the association between mental health hospital visits and community severance in New York City (NYC), using annual counts of mood-, anxiety-, adjustment-, and schizophrenia-related hospital visits from the New York State Department of Health Statewide Planning and Research Cooperative System database. Community severance was quantified using the community severance index (CSI). We employed generalized additive mixed models to characterize potentially nonlinear associations, adjusting for potential confounders. In secondary analyses, we further adjusted for black carbon to obtain traffic pollution-independent CSI estimates and evaluated potential effect modification by age through stratified analyses. Results: Each interquartile range increase in CSI was associated with higher rates of schizophrenia-related hospital visits (rate ratio [RR] = 1.13, 95% confidence interval [CI] = 1.00, 1.27). Associations for mood (RR = 1.07; 95% CI = 0.98, 1.16), anxiety (RR = 1.06; 95% CI = 0.99, 1.14), and adjustment disorders (RR = 1.07; 95% CI = 0.97, 1.19) were also positive. Results were similar after black carbon adjustment. We found no clear evidence of effect modification by age. Conclusion: Our findings indicate an association between higher levels of community severance and schizophrenia-related hospital visits in urban areas, independent of traffic-related air pollution.