July 2013

Document Type


Degree Name



Dept. of Public Health and Preventive Medicine


Oregon Health & Science University


Background: Depressive disorders are disabling and prevalent in low‐income populations. Improving our understanding of the role of neighborhood environmental factors on depression may suggest modification of specific built environment characteristics that can protect against depression. Canopy cover and walkability are two neighborhood characteristics which may be prevent depressive symptoms, although few studies have examined these associations. We hypothesize that canopy cover and walkability influence depressive symptoms through common causal pathways. Our study aims to help untangle these relationships by considering canopy cover and walkability together. Methods: We use a large study population of low‐income adults who completed extensive mail and in‐person surveys between 2008 and 2010 (n=4121; Portland Metropolitan Area, Oregon). Depression screening used the Patient Health Questionnaire-2. Using geocoded residential locations, we calculated exposure to walkability and canopy cover within 0.25 miles of each study participant’s home. Neighborhood walkability was calculated from density of business, street intersection, and population. Percent canopy cover was calculated using satellite imagery. The association between neighborhood walkability, canopy cover and depression was analyzed using gender-stratified logistic regression models controlling for relevant individual- and neighborhood-level covariates. Results: No association was observed between canopy cover and depression in adjusted models in women (OR=1.00, 95% CI: 0.99-1.01) or men (OR=1.00, 95% CI: 0.99-1.02). Walkability was not related to depression in women (highest vs lowest quartile: OR=1.14, 95% CI: 0.85‐1.52). However, in men there was some indication the odds of depression may be elevated in the third (3rd vs 1st quartile: OR=1.35, 95% CI: 0.96‐1.91) but not fourth (4th vs 1st quartile: OR=0.99, 95% CI: 0.67‐1.46) walkability quartile. Conclusion: Canopy cover was not associated with depression in low-income adults in the Portland Metropolitan Area. Moderately high walkability may be associated with higher odds of depression in men but not women.




School of Medicine



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