Abstract for: The mechanism underlying depression development in urban context and the role of green infrastructure: a causal loop diagram

Major depressive disorder (MDD) is a result of the combined effect of biological, psychological, social, and environmental determinants. Existing causal loop diagram (CLD) models of depression dynamics have mapped reinforcing feedback mechanisms at the individual level, but none integrate the urban physical environment as an endogenous component of the system. Building on the two foundational CLD frameworks of we extended the system boundary to incorporate urban environmental stressors and urban green infrastructure (UGI) as endogenous variables. Variables and causal links were selected through a targeted literature synthesis, with evidence quality assessed using an adapted GRADE schema. The CLD was constructed in Vensim® PLE 8.0.7. Seven reinforcing feedback mechanisms were identified. Four mechanisms describe how urban stressors (air pollution, heat, noise, and artificial light) drive depression through behavioural withdrawal, which in turn suppresses demand for the green infrastructure that could mitigate those same stressors. Two virtuous reinforcing loops describe conditions under which green infrastructure activates protective dynamics. UGI reduces depression risk only when people are able to access and use it, a condition that depression itself undermines. Socioeconomic disadvantage simultaneously intensifies pathological dynamics and raises the threshold for activating protective ones, identifying equity of access as a structural property of the system rather than an external consideration. Claude.ai for text review and improvement