Nonlinear Effects of the Neighborhood Environments on Residents' Mental Health

Lin Zhang; Suhong Zhou; Lanlan Qi; Yue Deng

doi:10.3390/ijerph192416602

Nonlinear Effects of the Neighborhood Environments on Residents' Mental Health

Int J Environ Res Public Health. 2022 Dec 10;19(24):16602. doi: 10.3390/ijerph192416602.

Authors

Lin Zhang¹, Suhong Zhou^{2

3}, Lanlan Qi⁴, Yue Deng⁵

Affiliations

¹ Institute of Studies for the Greater Bay Area (Guangdong, Hong Kong, Macau), Guangdong University of Foreign Studies, Guangzhou 510006, China.
² School of Geography and Planning, Sun Yat-sen University, Guangzhou 510006, China.
³ Guangdong Provincial Engineering Research Center for Public Security and Disaster, Guangzhou 510275, China.
⁴ School of Management, Guangdong Industry Polytechnic, Guangzhou 510300, China.
⁵ School of Architecture and Civil Engineering, Chengdu University, Chengdu 610106, China.

Abstract

In the context of rapid urbanization and the "Healthy China" strategy, neighborhood environments play an important role in improving mental health among urban residents. While an increasing number of studies have explored the linear relationships between neighborhood environments and mental health, much remains to be revealed about the nonlinear health effects of neighborhood environments, the thresholds of various environmental factors, and the optimal environmental exposure levels for residents. To fill these gaps, this paper collected survey data from 1003 adult residents in Guangzhou, China, and measured the built and social environments within the neighborhoods. The random forest model was then employed to examine the nonlinear effects of neighborhood environments on mental health, evaluate the importance of each environmental variable, as well as identify the thresholds and optimal levels of various environmental factors. The results indicated that there are differences in the importance of diverse neighborhood environmental factors affecting mental health, and the more critical environmental factors included greenness, neighborhood communication, and fitness facility density. The nonlinear effects were shown to be universal and varied among neighborhood environmental factors, which could be classified into two categories: (i) higher exposure levels of some environmental factors (e.g., greenness, neighborhood communication, and neighborhood safety) were associated with better mental health; (ii) appropriate exposure levels of some environmental factors (e.g., medical, fitness, and entertainment facilities, and public transport stations) had positive effects on mental health, whereas a much higher or lower exposure level exerted a negative impact. Additionally, this study identified the exact thresholds and optimal exposure levels of neighborhood environmental factors, such as the threshold (22.00%) and optimal exposure level (>22.00%) of greenness and the threshold (3.80 number/km²) and optimal exposure level (3.80 number/km²) of fitness facility density.

Keywords: built and social environments; mental health; nonlinear relationships; random forest; thresholds.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Mental Health*
Neighborhood Characteristics
Residence Characteristics
Social Environment*

Grants and funding

This research was funded by the National Natural Science Foundation of China (42101247, 41871148, 42101246), the Guangdong Basic and Applied Basic Research Foundation (2020A1515110623), and the Characteristic Innovation Project of Colleges and Universities in Guangdong Province (2021WTSCX023).