Spatial determinants of mental health in Seoul: Cycling, income inequality, and access to care

As cities face growing mental health challenges, the role of transport infrastructure in shaping psychological wellbeing remains underexplored. This study investigated how cycling accessibility, mental healthcare provision, and income inequality jointly influence the spatial distribution of severe mental health outcomes in Seoul. Employing a three-stage spatial framework, Geographically Weighted Regression (GWR), Random Forest (RF), and Suitability Analysis (SA), this study assessed the spatial heterogeneity, nonlinear interactions, and district-level intervention priorities. Results from GWR indicate that cycling infrastructure is the most consistent spatial predictor of mental health disparities, with coefficients as high as 0.81 in districts like Gangnam-gu. Healthcare access and income inequality show more localised yet significant associations. RF modelling confirmed these patterns, ranking healthcare (36 %), cycling accessibility (33 %), and income inequality (31 %) as primary contributors. SA highlights districts such as Songpa-gu and Gangnam-gu as high-priority areas for integrated transportation and public health interventions. Anomalies such as Gangseo-gu, where high vulnerability coexists with low model fit, underscore the need for further localised investigation. By integrating spatial analytics with transport equity and health policy perspectives, this study provides a scalable framework for mental health sensitive infrastructure planning. It positions cycling not only as a sustainable mobility solution but also as a key policy lever for advancing urban health equity.