A walk in the park may soothe the mind and, in the process, change the workings of our brains in ways that improve our mental health, according to an interesting new study of the physical effects on the brain of visiting nature. Most of us today live in cities and spend far less time outside in green, natural spaces than people did several generations ago.
People who live in cities also have a higher risk for anxiety, depression and other mental illnesses than people living outside urban centers, studies show.These developments seem to be linked to some extent, according to a growing body of research. Various studies have found that urban dwellers with little access to green spaces have a higher incidence of psychological problems than people living near parks and that city dwellers who visit natural environments have lower levels of stress hormones immediately afterward than people who have not recently been outside.
But just how a visit to a park or other green space might alter mood has been unclear. Does experiencing nature actually change our brains in some way that affects our emotional health? That possibility intrigued Gregory Bratman, a graduate student at the Emmett Interdisciplinary Program in Environment and Resources at Stanford University, who has been studying the psychological effects of urban living.
Perhaps most interesting for the purposes of Mr. Bratman and his colleagues, however, such rumination also is strongly associated with increased activity in a portion of the brain known as the subgenual prefrontal cortex. Mr. Bratman and his colleagues first gathered 38 healthy, adult city dwellers and asked them to complete a questionnaire to determine their normal level of morbid rumination.Then he randomly assigned half of the volunteers to walk for 90 minutes through a leafy, quiet, parklike portion of the Stanford campus or next to a loud, hectic, multi-lane highway in Palo Alto. The volunteers were not allowed to have companions or listen to music. They were allowed to walk at their own pace.
As might have been expected, walking along the highway had not soothed people’s minds. Blood flow to their subgenual prefrontal cortex was still high and their broodiness scores were unchanged. But the volunteers who had strolled along the quiet, tree-lined paths showed slight but meaningful improvements in their mental health, according to their scores on the questionnaire. They were not dwelling on the negative aspects of their lives as much as they had been before the walk.