# Exploring risk and protective urban environmental factors on mental health through exposure network mapping

## TL;DR

This study explores how urban environments and stress affect brain networks linked to mental health and highlights the protective role of sleep.

## Contribution

The study introduces exposure network mapping (ENM) to identify urban environmental factors impacting mental health.

## Key findings

- Urbanicity and stress converge on brain networks involving the orbital gyrus and cingulate regions.
- Sleep-related brain areas show strong correlations with urbanicity and stress networks.
- Healthy lifestyle habits like sleep may protect mental health in urban settings.

## Abstract

Urbanicity has been revealed to carry a higher risk of experiencing mental health issues. However, the factors in urban environments that pose risks or protective impacts on mental health remain unclear.

Based on eight literature-based datasets and one validation dataset, this study introduced a new technique termed exposure network mapping (ENM) to explore the impacts of urbanicity on brain networks, identify the potential risk urban environmental factors, and examine whether healthy lifestyle habits may provide protective effects on mental health.

Using ENM, this study consolidated existing heterogenous coordinates of urbanicity into a common, significant and replicable network, which primarily located in middle frontal gyrus, orbital gyrus and anterior cingulate gyrus. When conducting ENM analysis using coordinates of five representative factors (i.e., air pollution, noise pollution, income, stress, and green space), only seeds derived from stress significantly converged to a common network, highlighting orbital gyrus, caudate, anterior and middle cingulate gyrus, hippocampus and middle frontal gyrus. The ENM-stress map further exhibited the highest correlation with both the ENM-urbanicity map(r = 0.77) and a transdiagnostic map(r = 0.72). Finally, ENM analysis using coordinates of sleep also enriched in a distinct common network, featuring middle cingulate gyrus, orbital gyrus, caudate and putamen, which concurrently demonstrated strong correlations with urbanicity(r = 0.75), stress(r = 0.80), and the transdiagnostic map(r = 0.55).

This study highlights the potential risks of urbanicity and stress on brain networks, as well as the protective role of healthy habitats—particularly sleep—in safeguarding mental health, which may offer new insights for preventing mental health issues in urban environments.