Most people now live in cities, and spend much less time enjoying nature that people did in previous generations. Research shows urban dwellers have a higher risk for anxiety, depression and other mental illnesses, compared to people living in rural settings. Now a new study has shown that walking in nature actually changes your brain.
A growing body of research has shown that urban dwellers who have limited access to green spaces have higher levels of psychological problems that people living near the parks. Other research shows that residents of the city who visit natural environments have lower levels of stress hormones when measured their levels immediately after, make people who have not been out in nature.
Until recently, however, did not understand the mechanism by which being in nature decreased stress levels. That intrigued mechanism Bratman Gregory, a graduate in the Emmett Interdisciplinary Program in Environment and Resources at Stanford University student. Bratman has focused on the psychological effects of urban environments where residents.
In a previous study published last month, he and his team found that volunteers who took a walk through a lush natural green campus of Stanford were happier and more attentive, compared to other volunteers who walked near heavy traffic. But the study did not explore the neurological processes that are caused by exposure to nature.
In their new study, published last week in Proceedings of the National Academy of Sciences Bratman and his team decided to examine the effects of a walk on the nature of the tendency of an individual breeding. Melancholic, that cognitive scientists call morbid rumination, is a state of worry that can sometimes lead to depression. It is disproportionately common among urban dwellers compared to people living outside cities.
Scientists know that morbid rumination is also strongly linked to increased activity in the part known as the subgenual prefrontal cortex brain. The researchers decided if they could track activity on that area of the brain, which would be able to better understand the physiology involved.
Bratman and colleagues enlisted 38 healthy adult urban residents, and had to complete a questionnaire to assess their normal level of morbid rumination. brain activity is checked by monitoring the blood flow through the brain. Greater blood flow to any area of the brain shows increased activity in that area.
Half the participants were randomized to walk for 90 minutes through a green and quiet natural portion of the Stanford campus, while others were assigned to walk alongside one busy highway several lanes aloud in Palo Alto. Participants walked alone with the music out, at their own pace chosen.
As soon as they had completed their tours, participants returned to the laboratory and the questionnaire and brain scan is repeated. As you can imagine, volunteers who walked along the road they found the experience relaxing. Broodiness their scores remained the same, and blood flow to the prefrontal cortex subgenual remained high.
By contrast, volunteers who had walked through the nature showed small but significant improvements in their mental health, as determined by scores on the questionnaire. They cared less. They also experienced less blood flow to the prefront subgenual cortex, which shows that part of their brains were quieter.
Bratman says the data “strongly suggest that out in natural environments” can be a quick and easy way to improve mood immediately for city dwellers.