Green Spaces May Decrease Risk of Childhood ADHD

Children living in areas with sparse green spaces have an increased risk of developing attention-deficit hyperactivity disorder (ADHD), according to a study in Environmental Health Perspectives. Researchers believe that greater exposure to nature and green space could reduce the likelihood that a child will have ADHD.

Researchers looked at individuals born in Denmark between 1992 and 2007, encompassing about 800,000 people, and compared diagnoses of ADHD with residence locations. They calculated exposure to green space from birth to 5 years old.

Even after adjusting for factors like parental socioeconomic status and urban living, researchers found that those children living in areas with the least amount of vegetation (like trees, parks, and yards), had an increased risk of being diagnosed with ADHD from age 5 and up. Those with the most access to green space had the lowest rates of ADHD.

Benefits of Green Space

There are several possible reasons why simply being around green space would be a boost to brain health, according to study lead author Malene Thygesen, PhD, of the school of business and social sciences at Aarhus University.

“The reasons why some children develop ADHD are still largely unknown, but it is believed that the development of the condition may be a consequence of an interaction between genetic and environmental risk factors,” she says.

Green space’s advantages in reducing risk include:

• Lower exposure to air pollution
• More physical activity
• Higher social interaction rate
• Lower overall stress levels
• Higher gut microbial diversity
• Less exposure to noise

Even if children already have ADHD, green spaces have been shown to improve their symptoms of inattention, Thygesen adds, because of these specific advantages.

Gut health, in particular, is an intriguing environmental factor that previous studies have investigated, she says. For example, a study in Nutrients found a strong correlation between low microbial diversity in the gut and development of ADHD.

Stress Reduction Remedy

Another factor for mitigating ADHD development is the reduction of stress, and green space can be a significant remedy, especially as we emerge from the COVID-19 pandemic. This is another factor that can not only reduce the development of the condition for young children, but also potentially improve symptoms for those who already have ADHD, no matter what their age.

“Environments that promote stress reduction could be beneficial in relation to a reduction in ADHD symptoms because stress can exacerbate symptoms in individuals with ADHD,” says Thygesen, adding that yet another advantage could be better immune system function from spending time in nature. Overall, this can reduce inflammation and improve brain health, she adds.

Green space also can offer some relief from activities that may already be overstimulating. Amy Morin, psychotherapist and editor-in-chief of Verywell Mind, says, "One big benefit of being in nature means kids aren't staring at their screens. Getting away from digital devices means kids have a chance to enjoy a slower pace of activity in nature."

And this slower pace can have a calming effect that a lot of kids aren't used to, which contributes to a reduction in ADHD symptoms, "Being in nature might be a lot less stimulating for kids. Hearing birds chirp and looking at flowers is much different than playing a loud, fast-paced video game," says Morin.

That doesn’t apply only to children. Other research has consistently found adults can get similar benefits, including:

• Lower risk of chronic conditions, especially cardiovascular issues
• More physical activity
• Improved sleep
• Better concentration and focus
• Stronger immune system
• Lower risk of depression and anxiety

This may be true even if the amount of green space is minimal, or even viewed instead of experienced. For example, a recent study published in Ecological Applications looked at the links between going outside into a natural setting, or even just seeing green space from a window.

Researchers found that exposure to nature in that way lowered anxiety, even in urban environments. That was true across a wide range of age groups and sociodemographic categories.

"Our findings suggest a regular dose of nature can contribute to the improvement of a wide range of mental health outcomes, and that's important right now because of the possible impacts of the COVID-19 pandemic," says the lead author of that study, Masashi Soga, PhD, of the University of Tokyo. "We're in the middle of a very stressful event for humans. This suggests that there can be a 'nature-based solution' that can help."