Residential green space structures are associated with a lower risk of bipolar disorder: A nationwide population-based study in Taiwan

Hao-Ting Chang; Chih-Da Wu; Jung-Der Wang; Po-See Chen; Huey-Jen Su

doi:10.1016/j.envpol.2020.115864

Residential green space structures are associated with a lower risk of bipolar disorder: A nationwide population-based study in Taiwan

Environ Pollut. 2021 Aug 15:283:115864. doi: 10.1016/j.envpol.2020.115864. Epub 2020 Oct 15.

Authors

Hao-Ting Chang¹, Chih-Da Wu², Jung-Der Wang³, Po-See Chen⁴, Huey-Jen Su⁵

Affiliations

¹ Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan.
² Department of Geomatics, College of Engineering, National Cheng Kung University, Tainan, 70101, Taiwan; National Institute of Environmental Health Sciences, National Health Research Institutes, Miaoli, 350, Taiwan.
³ Department of Public Health, National Cheng Kung University, College of, Medicine, Tainan, 70101, Taiwan.
⁴ Department of Psychiatry, National Cheng Kung University Hospital, College of, Medicine, National Cheng Kung University, Tainan, 70101, Taiwan; Institute of Behavioral Medicine, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan; Department of Psychiatry, National Cheng Kung University Hospital, Dou-Liou Branch, Yunlin, 64000, Taiwan.
⁵ Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan. Electronic address: hjsu@mail.ncku.edu.tw.

PMID: 33857883
DOI: 10.1016/j.envpol.2020.115864

Abstract

Although many researchers have identified the potential psychological benefits offered by greenness, the association between green space structures and mental disorders is not well understood. The purpose of this study was to identify associations between green space structures and the incidence of bipolar disorder. To this end, we investigated 1,907,776 individuals collected from Taiwan's National Health Insurance Research Database. After a follow-up investigation from 2005 to 2016, among those with no history of bipolar disorder, 20,548 individuals were further found to be diagnosed with bipolar disorder. A geographic information system and landscape index were used to quantify three indices of green space structures: mean patch area (area and edge), mean fractal dimension index (shape), and mean proximity index (proximity). Additionally, greenness indices, the normalized difference vegetation index, and the enhanced vegetation index were used to confirm the association between greenness and incidence of bipolar disorder. These five indices were used to represent the individual's exposure according to the township of the hospital that they most frequently visited with symptoms of the common cold. Spearman's correlation analysis was performed to select variables by considering their collinearity. Subsequently, the frailty model for each index was used to examine the specific associations between those respective indices and the incidence of bipolar disorder by adjusting for related risk factors, such as socioeconomic status, metabolic syndrome, and air pollution. A negative association was identified between the mean patch area and the mean proximity index, and the incidence of bipolar disorder. In contrast, a positive association was found between the mean fractal dimension index and the incidence of bipolar disorder. We observed similar results in sensitivity testing and subgroup analysis. Exposure to green spaces with a larger area, greater proximity, lower complexity, and greener area may reduce the risk of bipolar disorder.

Keywords: Bipolar disorder; Frailty models; Green space structures; Greenness index; Incidence.

MeSH terms

Air Pollution*
Bipolar Disorder* / epidemiology
Humans
Parks, Recreational
Residence Characteristics
Taiwan / epidemiology