Association Between Greenness Surrounding Schools and Kindergartens and Attention-Deficit/Hyperactivity Disorder in Children in China

Abstract

IMPORTANCE Few studies have investigated the association between greenness and childhood attention-deficit/hyperactivity disorder (ADHD). OBJECTIVE To evaluate the association between greenness surrounding schools or kindergartens and symptoms of ADHD in children. DESIGN, SETTING, AND PARTICIPANTS This population-based cross-sectional study was performed between April 2012 and January 2013 in 7 cities in northeastern China. This analysis included 59 754 children (aged 2-17 years) from 94 schools and kindergartens, who had resided in the study area for 2 years or longer. Data were analyzed from April 15, 2019, to October 10, 2019. EXPOSURES Greenness surrounding each child's school or kindergarten was estimated using 2 satellite image-derived vegetation indexes: the normalized difference vegetation index and the soiladjusted vegetation index. MAIN OUTCOMES AND MEASURES Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) scales were used to measure ADHD symptoms (9 inattention symptoms and 9 hyperactivityimpulsivity symptoms). Parents or guardians rated the frequency of each of 18 ADHD symptoms during the preceding 6 months. Children with 6 or more symptoms of either inattention or hyperactivity-impulsivity were defined as having ADHD symptoms. Generalized linear mixed models were applied to estimate the association between greenness and ADHD symptoms. RESULTS The mean (SD) age of the 59 754 study participants was 10.3 (3.6) years, and 29 494 (49.4%) were girls. A total of 2566 participants (4.3%) had ADHD symptoms. Greenness levels differed substantially across schools and kindergartens. The normalized difference vegetation index within 500 m of a school or kindergarten ranged from −0.09 to 0.77. Greater greenness levels were associated with lower odds of ADHD symptoms. In covariate-adjusted models, a 0.1-unit increase in normalized difference vegetation index or soil-adjusted vegetation index within 500 m of a school or kindergarten was significantly associated with lower odds of ADHD symptoms (odds ratios, 0.87 [95% CI, 0.83-0.91] and 0.80 [95% CI, 0.74-0.86], respectively; P < .001 for both). The associations were robust in a series of sensitivity analyses. CONCLUSIONS AND RELEVANCE These findings suggest that there may be a beneficial association between school-based greenness and ADHD symptoms in Chinese children. Future longitudinal and mechanistic studies are needed to confirm the findings of this cross-sectional analysis and further explore potential mechanisms of this association.

The Association between Residential Green Space in Childhood and Development of Attention Deficit Hyperactivity Disorder: A Population-Based Cohort Study

“…These findings indicate that living in a residential area with higher density of green space in early life may lower the risk of developing ADHD. Our results are supported by previous studies, which also found associations between higher levels of residential green space and lower risk of ADHD (Amoly et al 2014;Donovan et al 2019;Markevych et al 2018;Yang et al 2019) and lower severity of ADHD symptoms (Amoly et al 2014).…”

“…2019 ; Markevych et al. 2018 ; Yang et al. 2019 ) and lower severity of ADHD symptoms ( Amoly et al.…”

“…A third study found that greater residential proximity to city parks was associated with fewer ADHD symptoms in children (Balseviciene et al 2014), and a more recent study by Markevych et al found that residential green space was associated with a reduced risk of a diagnosis of ADHD (Markevych et al 2018). Finally, a longitudinal cohort study by Donovan et al suggested that increased minimum greenness was associated with a lower risk of developing ADHD (Donovan et al 2019), and a cross-sectional study by Yang et al found that greater levels of greenness near schools or kindergartens were associated with lower odds of ADHD in Chinese children (Yang et al 2019).…”

“…2019 ), and a cross-sectional study by Yang et al. found that greater levels of greenness near schools or kindergartens were associated with lower odds of ADHD in Chinese children ( Yang et al. 2019 ).…”

Emerging Insights Into the Association Between Nature Exposure and Healthy Neuronal Development

“…Although ADHD symptoms were only ascertained from parents, the pattern of phenotypic findings is consistent with other epidemiological results in ADHD, supporting the overall validity of their phenotypic strategy. 1 As Yang et al 1 which features exert which effects at what periods of the life span. 5 Individuals' experience of nature should also be considered, including the types of interaction (eg, swimming in the ocean vs walking in a city park), dose-response of nature exposure, and how personal characteristics affect response.…”