Strongest association seen for patients in urban settings
By Lori Solomon HealthDay Reporter
FRIDAY, Nov. 14, 2025 (HealthDay News) — Greenness is statistically associated with lower risks for hospital admissions for mental disorders in several countries, according to a study published online Nov. 5 in The BMJ.
Tingting Ye, Ph.D., from Monash University in Melbourne, Australia, and colleagues examined the association between exposure to greenness and hospital admissions for mental disorders. The analysis included 6,842 locations in seven countries (Australia, Brazil, Canada, Chile, New Zealand, South Korea, and Thailand) and a total of 11.4 million hospital admissions for mental disorders (2000 to 2019).
The researchers found that a 0.1 increase in the normalized difference vegetation index was associated with a 7 percent reduction in the risk for hospital admissions for all-cause mental disorders (relative risk, 0.93) in pooled analyses. Associations varied across countries and disorder types. For example, Brazil, Chile, and Thailand showed consistent protective associations across most disorder categories, while modest adverse associations were seen in Australia and Canada for hospital admissions for all-cause mental disorders and for several specific disorder categories. Generally, there was a monotonic and approximately linear relation without clear thresholds for exposure-response analyses. Associations were generally more consistent in urban settings, where an estimated 7,712 hospital admissions for mental health disorders annually were statistically attributable to observed greenness levels. A 10 percent increase in greenness was associated with reductions in hospital admissions for mental disorders ranging from ~1 per 100,000 in South Korea to ~1,000 per 100,000 in New Zealand.
“The heterogeneity across countries, seasons, and types of mental disorders underscores the need for locally tailored approaches when evaluating the mental health implications of environmental greenness,” the authors write.
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