URBANA, Ill. – As modern societies become increasingly urban, sedentary, and screen-oriented, people are spending less time in nature. We’re also more likely than ever to suffer from mental illnesses. A new article in Science Advances links the two phenomena, suggesting that adding natural elements to urban landscapes could improve mental health.
The article, co-authored by 26 of the world’s top experts on nature’s effects on human health and well-being, describes nature’s ability to improve mental health in much the same way that it improves water quality, sequesters carbon dioxide, and prevents floods. Such “ecosystem services” are routinely considered during city planning initiatives, but the link between natural elements and mental health has been overlooked, the scientists say.
“I felt it was time to address the disconnect between what the science tells us cities should be doing for mental health and what cities are doing,” says Ming Kuo, associate professor in the Department of Natural Resources and Environmental Sciences at the University of Illinois, explaining her involvement in the study. “Almost one in five adults in the U.S. lives with a mental illness, and the statistics are similar worldwide. I felt we couldn’t remain silent. The group wanted to offer a consensus statement on what the science is telling us and how to actually put that into practice in designing better cities.”
The group synthesized multiple lines of evidence and hundreds of academic studies – including many by Kuo and her students -- to arrive at their consensus statement. Kuo notes the process wasn’t easy but the group was finally able to boil down the scientific evidence into a summary “we could all agree with.” In essence, as people are increasingly losing contact with nature, the evidence suggests this may be undermining their mental health.
In developing its statement, the team considered evidence on both positive and negative mental health outcomes, as well as risk factors for mental illness. Kuo explains, “Nature experiences are tied to signs of optimal health and functioning such as greater happiness, better learning and cognitive performance, and more social ties. They’re also tied to lower levels of mental illness, including lower rates of depression and anxiety disorders.”
The scientists note that while much of the evidence is correlative, some is based on longitudinal or experimental studies, considered the gold standard in science. For example, a study by Kuo and her then-student, Andrea Faber Taylor, randomly assigned children with ADHD to 20-minute walks in different settings, and found their concentration was better after a walk in a park than a walk in pleasant, but less “green” surroundings.
In addition to offering a consensus statement, the group suggests a systematic, four-step approach to considering the mental health ecosystem services of natural features and views, taking into account the types and amounts of natural features, the exposure and experiences people are likely to have, and then making evidence-based projections of the likely effects on mental health.
The team envisions a scenario in which a city planner could incorporate mental health considerations into decisions about new public parks. In the future, those planners might even be able to determine where the park should go, how big the park should be, and what natural elements—like trees, grass, or a restored river—would maximize the potential mental health benefits to the community.
"In the future, if we can find low-cost ways that help to introduce and conserve nature while simultaneously working to address psychological well-being and mental health, then this can be a win-win solution in many cases," says Greg Bratman, an assistant professor at the University of Washington School of Environmental and Forest Sciences and lead author of the paper.
Kuo adds that greening low-income neighborhoods may pay especially big dividends. “In cities worldwide, the poorest neighborhoods are also the ones most lacking in street trees, landscaping, and parks. The difference is so large that you can see poverty from space – the barren neighborhoods jump out at you. We’re trying to give planners, mayors, and city councils a way to count the potential mental health costs of those missing trees.”
The article, “Nature and mental health: An ecosystem service perspective,” is published in Science Advances [DOI: 10.1126/sciadv.aax0903]. Kuo’s home department, natural resources and environmental sciences, is part of the College of Agricultural, Consumer and Environmental Sciences at the University of Illinois.