A new study suggests that putting more green spaces at schools is beneficial in the mental development of children.

Earlier studies found that green spaces help improve the well-being of city dwellers, keep one from being sad, increase birth weight, improve the symptoms of ADHD and deliver lasting mental health benefits. Now, a new study led by Dr. Payam Dadvand from the Center for Research and Environmental Epidemiology in Barcelona, Spain, found that green spaces within and around schools can boost the mental development, particularly the short-term memory, of schoolchildren. The study, published in the June 15 issue of Proceedings of the National Academy of Sciences, is the first to observe this kind of impact.

The researchers studied 2,593 kids, between the ages of 7 and 10, in 36 schools in Spain. The team changed the degree of greenness in their school areas, and assessed the participants' mental development every three months to see if it was affected.

After a year of follow-ups, the researchers observed that the schoolchildren's overall working memory (short-term memory) improved by 23 percent, while their superior working memory (ability to update memories and information) was enhanced by 15 percent. The children's inattentiveness decreased by 19 percent, according to the Guardian.

"Natural environments, including green spaces, provide children with unique opportunities such as inciting engagement, risk-taking, discovery, creativity, mastery and control, strengthening sense of self, inspiring basic emotional states (including sense of wonder) and enhancing psychological restoration," wrote the authors of the study. "Our findings suggest a beneficial impact of green space exposure on cognitive development, with part of this effect resulting from buffering against such urban environmental pollutants."

The researchers recommend changes to the school's environment, like adding more green spaces, planting trees and using less concrete.

"The results fit with previous findings that views of nature help children and adults lower stress and perform mental tasks better," said Sally Augustin, a psychologist in La Grange Park, Ill., to the Washington Post. She was not part of the study.