Long Term Exposure to Green Spaces Affects Children’s Cognitive Development

There is more evidence green does a brain good.

School aged children who have long term exposure to green space are less distracted and experience improved memory, according a recently published study co-authored by UCLA researchers.

The new research links for the first time the improved cognitive function of a child exposed to nature to structural changes in the developing brain. The study’s results could have global implications, as half of the world’s population live in urban areas where access to nature can be scarce.

In the study, which was published Friday in the journal Environmental Health Perspectives, researchers from the Barcelona Institute for Global Health and the UCLA Fielding School of Public Health used MRI data and proximity to green space culled from 253 schoolchildren from the BREATHE project in Barcelona to figure out how being raised in greener neighborhoods affects brain development.

Lifelong exposure to green space - parks, grass, trees and other vegetation - was estimated using satellite imagery of the children’s homes from birth through 2012, the time of the study. The research, led by Dr. Payam Dadvand, a researcher with the Institute for Global Health, was conducted over the span of one year. The children were evaluated every three months, using MRIs and computerized tests to track their working memory and inattentiveness.

The team of researchers found the children raised in homes surrounded by the natural environment had more activity in the regions of their brain associated with learning and the ability to engage with others. Those children also experienced less distraction and a sharpened memory, key indicators to a child’s ability to be successful academically and socially.

The study adds further biological evidence to the belief that exposure to green space is essential for brain development in children. A previous study had similar results. It showed children who attended schools with significant green space were more focused than those who went to schools with less green space.

"We’re not just trying to find association between greenery and cognitive function, but showing there’s a biological mechanism that could be leading to these kinds of changes in early childhood development,” said Dr. Michael Jerrett, co-author of the study and department chair and professor of Environmental Health Sciences at the UCLA Fielding School of Public Health.

But why exposure to greenery has beneficial effects on the brain is anybody’s guess.  “Lower levels of noise and air pollution [could be factors],” said Jerrett who co-authored a study in 2015 that found a reduction in traffic-related air pollution, which has been negatively linked to cognitive development, accounted for 20-65% of the estimated links between school greenness and cognitive development.

"People who have better access to parks and green areas tend to be more physically active and have lower levels of mental illness, depression and anxiety,” said Jerrett of the existing body of literature that links green space to psychological benefits.  

The "biophilia" hypothesis suggests humans have developed an innate tendency toward nature throughout the course of evolution. Proponents of the hypothesis argue nature affords children the opportunity to be creative and take risks while also providing opportunities for psychological restoration - all believed to have positive effects on brain development. 

Evidence overwhelmingly shows that children who grow up surrounded by green space fare better overall, leaving children growing up in Los Angeles’ park poor inner city neighborhoods at odds.  

Forty-five percent of Angelenos living in low-income neighborhoods do not have walkable access to a park. These are the same blighted neighborhoods where most of the city’s 22,600 vacant lots are located.

"Low-income communities and communities of color lack access to parks and are disproportionately affected by health problems like diabetes and heart disease, but these disparities and inequities are not accidental," said Robert Garcia, founding director and counsel of the City Project, who attributes the disparities to a legacy of discriminatory housing and land use practices in Los Angeles.

Although public funding for parks and habitat restoration projects has created more green space in areas developers deem as prime for development, like the Los Angeles River, it has mostly been in gentrified or gentrifying neighborhoods.

Environmental justice advocates saw the passage of Measure A in 2016 as a step towards closing the gap in disparities. The measure raises $94.5 million a year in parcel taxes to expand the number of parks and update existing facilities, giving priority to low-income communities and communities of color, following a park needs assessment by the County Department of Parks and Recreation.

"As we get more and more of this evidence, it’s the duty of policy makers and urban planners to start looking at nature as a very positive solution to many urban problems. One that’s going to have many health benefits to children and as they mature into adults," said Jerrett.   

Top Image: South Park | Courtesy of Fletcher Studio