Time and time again studies show that getting out in nature can be good for your health. But this new research paper by Stanford’s Gregory Bratman and several colleagues from the United States and Sweden, shows that walking in nature can be good for cognitive health too. They used brain scans after walking in urban enviroments and in nature to see what the difference was.
In the past several months, a bevy of studies have added to a growing literature on the mental and physical benefits of spending time outdoors. That includes recent research showing that short micro-breaks spent looking at a nature scene have a rejuvenating effect on the brain — boosting levels of attention — and also that kids who attend schools featuring more greenery fare better on cognitive tests.
And Monday, yet another addition to the literature arrived — but this time with an added twist. It’s a cognitive neuroscience study, meaning not only that benefits from a nature experience were captured in an experiment, but also that their apparent neural signature was observed through brain scans.
The paper, by Stanford’s Gregory Bratman and several colleagues from the United States and Sweden, was published Monday in the Proceedings of the National Academy of Sciences. In it, 38 individuals who lived in urban areas, and who had “no history of mental disorder,” were divided into two groups — and asked to take a walk.
Half walked for 90 minutes through a natural area near the Stanford campus. The other half walked along a very busy road in downtown Palo Alto, Calif. (along El Camino Real, for those who know the area). Before and also after the walk, the participants answered a questionnaire designed to measure their tendency toward “rumination,” a pattern of often negative, inward-directed thinking and questioning that has been tied to an increased risk of depression, and that is assessed with questionnaire items like “My attention is often focused on aspects of myself I wish I’d stop thinking about,” and “I spend a great deal of time thinking back over my embarrassing or disappointing moments.”
Finally, both before and after the walk, the participants had their brains scanned. In particular, the researchers examined a brain region called the subgenual prefrontal cortex — which the study calls “an area that has been shown to be particularly active during the type of maladaptive, self-reflective thought and behavioral withdrawal that occurs during rumination.”
The result was that individuals who took the 90-minute nature walk showed a decrease in rumination — they actually answered the questionnaire differently, just a short period of time later. And their brain activity also showed a change consistent with this result. In particular, the scans showed decreased activity in the subgenual prefrontal cortex, the region of interest………….
What’s particularly valuable is that the brain scans allowed for the examination of a potential cognitive mechanism by which nature experiences help our mental states. Without such evidence, psychological research can in effect only speculate on occurrences within actual regions of the brain. “That’s why we wanted to push and get at neural correlates of what’s happening,” said Bratman.
Granted, brain scan research can be controversial – and it’s not as if conditions like depression have a single, simple cause. So as with all research, this work will need to be extended and verified by future studies………..
But a key question raised by this is, precisely how would an urban environment worsen — or at least, fail to protect against — a mental behavior like rumination?
The idea seems to be that living in an urban area “is associated with many kinds of stressors, whether it be noise, increased social interactions, traffic,” said Bratman, which in turn increases rumination and anxiety — though he admits that this link in the study’s chain of logic needs further demonstration.
The researchers also tie their results to a large literature on so-called “ecosystem services” — valuable benefits, such as carbon sequestration or water purification, provided by natural environments. The work suggests that on top of these benefits, there may also be “psychological ecosystem services” as well……..