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By Guadalupe Manrique

A new statistical mathematical model of depression highlights the connection between urbanization and mental health and predicts lower depression rates in larger cities. 

Living in cities is associated with an increased risk for some major mental illnesses. Urban environments are frequently linked to higher rates of pollution, noise pollution, and more physical threats. Consequently, there is an increase in stress levels with negative effects on mental health. 

Although evidence has shown that cities are associated with an increased risk for depression, a research team at the University of Chicago has been studying how depression risks change between cities. The study, published in the Proceedings of the National Academy of Sciences (PNAS) describes a mathematical theory that was developed to determine how the built urban environment influences depression risk. Thus, the team proposed a model of depression that is driven by an individual’s accumulated experience through social networks and brings together socioeconomic network structure with individual risk of depression. Interestingly, researchers found that “a larger number of connections in larger cities entails a qualitatively different experience because it is driven by the need to obtain support, goods, and services in environments with deep divisions of knowledge and labor.”

The authors also described a statistical relationship between depression and city size. For this purpose, they analyzed four independent datasets for consistent assessments of cases of depression across different urban areas in the United States. The team demonstrated that this relationship is consistent in larger cities across the four datasets that were analyzed, and across a decade. This was independent of the different ways in which depressive symptoms were measured and the different ways that the data were collected. Taken together, their results indicated that depression rates are substantially lower in larger US cities, contrary to that expected but in line with the mathematical model the authors developed. Although this theoretical model might be only applicable to larger urban areas in the United States, this study suggests that larger city environments and urbanization provide social stimulation and connections that may play a role against depression. 

Overall, researchers demonstrated that their model fits empirical data across four large-scale datasets in US cities and indicated that “If our model captures some of the underlying causal mechanisms, then these results suggest that depression within cities can be understood, in part, as a collective ecological phenomenon mediated by human social networks and their relationship to the urban built environment.” 


  1. Gruebner O, Rapp MA, Adli M, et al. Cities and Mental Health. Dtsch Arztebl Int. 2017;114(8):121-127.

  2. Stier AJ, Schertz KE, Rim NW, et al. Evidence and theory for lower rates of depression in larger US urban areas. Proc Natl Acad Sci U S A. 2021;118(31): e2022472118

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