Pathways from the Campus Neighborhood Built Environment to Chinese University Students' Depression: Urban vs. Suburban Campuses

University students, a highly active demographic group in society, face substantial mental health challenges due to academic, employment, and social pressures. Existing studies suggest that the built environment is an important intervention for mental health. However, limited attention has been paid to the mechanisms through which the built environment influences depression via behavioral mediators among university students, and the spatial heterogeneity of these effects between urban and suburban areas remains underexplored. Based on data from the 2018 Chinese College Student Epidemiological Survey, this study employed a grouped path analysis model to examine the mediating effects of individual behaviors (active travel, exercise, unhealthy diet, and social interactions) on the relationship between the campus neighborhood-built environment and depression among university students in urban and suburban areas. The results indicate that campus neighborhood-built environment factors, including land-use mix, intersection density, normalized difference vegetation index (NDVI), proximity to parks, and the density of sports facilities, food delivery outlets, and fast-food outlets, indirectly affect depression by influencing individual behavior. In urban areas, an unhealthy diet mediates the relationship between campus neighborhood-built environment and depression, whereas active travel, unhealthy diet, and social interactions mediate this relationship in suburban areas. Specifically, in urban areas, intersection density, proximity to parks, and the density of sports facilities indirectly appear to influence depression by affecting an unhealthy diet. In suburban areas, the NDVI and the density of sports facilities and food delivery outlets indirectly affect depression by influencing active travel. NDVI and the density of food delivery and fast-food outlets indirectly affect depression by influencing an unhealthy diet. Land-use mix, NDVI, and the density of food delivery outlets indirectly affect depression by influencing social interactions. Additionally, campus neighborhood-built environmental factors directly affect depression among university students. Land-use mix, intersection density, and the density of food delivery outlets have considerable direct effects on depression in urban areas, while intersection density, proximity to parks, and the density of sports facilities and fast-food outlets show substantial direct effects in suburban areas. This study elucidated the mechanisms through which campus neighborhood-built environments influence depression among university students via behavioral mediators, providing empirical support for addressing inequalities in living and learning environments and mental health between urban and suburban university students. Based on this, the present study proposes two strategies— environment-behavior interventions and direct environmental interventions—to optimize the neighborhood-built environment on urban and suburban campuses and promote mental health of college students.