Summary: Children who grew up in residential areas with greater surrounding green space had a lower likelihood of receiving an ADHD diagnosis compared with children raised in environments with limited access to nature.
Source: Aarhus University
New research from iPSYCH indicates that the amount of vegetation near a child’s home during early childhood may influence their risk of developing attention-deficit/hyperactivity disorder (ADHD).
Researchers at Aarhus University examined the relationship between residential green space and the later diagnosis of ADHD in children and adolescents. Their population-based analysis reveals a clear association: lower exposure to green surroundings in early childhood is linked to a higher risk of receiving an ADHD diagnosis.
“Children who experienced less green space around their homes up to age five showed an increased risk of being diagnosed with ADHD compared to those who lived in the greenest residential areas,” says Malene Thygesen, one of the study’s authors.
ADHD is among the most common psychiatric diagnoses in childhood and presents with a variety of symptoms and severities. While genetics play a known role, environmental factors are also under investigation. Prior studies have suggested that access to nature supports children’s mental health and cognitive development, prompting researchers to explore whether green space could be one of several factors influencing ADHD risk.
A robust, population-based analysis
Although a single study cannot establish causation, this research complements earlier findings and benefits from comprehensive data and careful adjustments for potential confounders. The team accounted for child sex, age, birth year, parental psychiatric diagnoses, parental socio-economic status, neighborhood socio-economic characteristics, and urbanicity. Clinical ADHD diagnoses used in the study were made by specialists, strengthening the validity of the outcome measurements.
Implications and directions for further study
The findings, published in Environmental Health Perspectives, highlight green space as a potential protective factor worth further investigation. Future research can build on these results to explore mechanisms—such as opportunities for physical activity, social interaction, stress reduction, and reduced exposure to air pollution—that might explain how natural environments benefit developing children.
“The possibility that growing up in greener surroundings could lower a child’s risk of ADHD is an important hypothesis for public health and urban planning,” adds Thygesen, underscoring the need for more studies to verify the association and to investigate causal pathways.
Methodology
The study analyzed residential address data for more than 814,000 individuals born in Denmark from 1992 through 2007, tracking clinical ADHD diagnoses from age five through 2016. Researchers measured vegetation around each residence using the normalized difference vegetation index (NDVI). For each address, NDVI was calculated within a square area of 210 meters by 210 meters centered on the home. Individual green space exposure was defined as the average NDVI across each child’s residential addresses from birth until their fifth birthday.
Statistical models estimated incidence rate ratios (IRRs) for ADHD across NDVI-based exposure levels while adjusting for calendar year, age, sex, parental socioeconomic status, neighborhood socioeconomic status, and urbanicity. Children living in the lowest decile of NDVI—areas with sparse vegetation—had a notably higher risk of ADHD compared with those in the highest decile. The unadjusted IRR was 1.55 (95% CI: 1.46–1.65); after adjusting for confounders the association remained statistically significant (IRR=1.20; 95% CI: 1.13–1.28).
About this ADHD research news
Source: Aarhus University
Contact: Press Office – Aarhus University
Image: The image is in the public domain
Original Research: Open access. “The Association between Residential Green Space in Childhood and Development of Attention Deficit Hyperactivity Disorder: A Population-Based Cohort Study” by Malene Thygesen et al. Published in Environmental Health Perspectives.
Abstract
The Association between Residential Green Space in Childhood and Development of Attention Deficit Hyperactivity Disorder: A Population-Based Cohort Study
Background:
Access to green space has been proposed to benefit children’s mental health and cognitive development. Potential mechanisms include psychological restoration, opportunities for physical activity and social interaction, and reductions in harmful environmental exposures such as air pollution.
Objectives:
This nationwide cohort study examined whether residential green space in early childhood is associated with a clinical diagnosis of ADHD.
Methods:
The cohort included 814,689 individuals born in Denmark between 1992 and 2007 who were followed for ADHD diagnoses from age five during 1997–2016. NDVI measured greenness within 210m × 210m squares centered on each residence. Individual exposure was the average NDVI from birth to the fifth birthday. Multilevel models estimated incidence rate ratios for ADHD across exposure levels, adjusting for calendar time, age, sex, parental socioeconomic factors, neighborhood socioeconomic status, and urbanicity.
Results:
Children living in the areas with the lowest vegetation (lowest NDVI decile) had a higher risk of ADHD compared to those in the highest NDVI decile (IRR=1.55; 95% CI: 1.46–1.65). After adjusting for confounders, the association persisted but was attenuated (adjusted IRR=1.20; 95% CI: 1.13–1.28).
Conclusion:
The results suggest that lower levels of residential green space during early childhood may be associated with an increased risk of developing ADHD. Further research is needed to explore causality and underlying mechanisms.