‘Walking in nature changes brain, lowers breast cancer risk’
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.
The study was published in Proceedings of the National Academy of Sciences.
Most of us today live in cities and spend far less time outside in green, natural spaces than people did several generations ago.
City dwellers 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. In an earlier study published last month, he and his colleagues found that volunteers who walked briefly through a lush, green portion of the Stanford campus were more attentive and happier afterward than volunteers who strolled for the same amount of time near heavy traffic.
But that study did not examine the neurological mechanisms that might underlie the effects of being outside in nature.
So for the new study, which was published last week in Proceedings of the National Academy of Sciences, Bratman and his collaborators decided to closely scrutinize what effect a walk might have on a person’s tendency to brood.
Brooding, which is known among cognitive scientists as morbid rumination, is a mental state familiar to most of us, in which we can’t seem to stop chewing over the ways in which things are wrong with ourselves and our lives. This broken-record fretting is not healthy or helpful. It can be a precursor to depression and is disproportionately common among city dwellers compared with people living outside urban areas, studies show.
Perhaps most interesting for the purposes of 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.
A two-minute walk may counter the harms of sitting.
With evidence mounting that sitting for long stretches of time is unhealthy, many of us naturally wonder how best to respond. Should we stand up, or is merely standing insufficient? Must we also stroll or jog or do jumping jacks?
Anew study offers some helpful perspective, suggesting that even a few minutes per hour of moving instead of remaining in a chair might substantially reduce the harms of oversitting.
As most of us have heard by now, long bouts of sitting can increase someone’s risk for diabetes, heart disease, obesity, kidney problems and premature death. These risks remain elevated even if someone exercises but then spends most of the rest of his or her waking hours in a chair.
In a representative and sobering study published in Diabetologia, scientists found that every hour that overweight adults spent watching television, which is a handy way to measure sitting time at home, increased their risk of becoming diabetic by 3.4 percent. Most of the participants were watching nearly three hours a day.
But despite such health concerns, simply advising people to abandon their chairs and stand all day is impractical. Many of us who have experimented with standing or treadmill desks have discovered that they can have their own deleterious impacts on typing accuracy, general productivity and our lower backs.
How walking may lower breast cancer risk
Physical activity, even including walking, can substantially reduce a woman’s risk of developing breast cancer, encouraging new science shows, in part, it seems, by changing how her body deals with estrogen.
Evidence has been accumulating for some time that exercise reduces the risk of many types of cancer, including breast malignancies. But the physiological mechanisms involved have not been well characterized, nor have scientists known what kinds and amounts of exercise provide the surest protection.
Which makes the results of two recently published studies of considerable interest to women and those of the remaining gender who love us.
In the newest and largest of these studies, published online in Cancer Epidemiology, Biomarkers & Prevention, researchers with the Epidemiology Research Program at the American Cancer Society began by turning to a huge trove of data maintained by the cancer society. The database includes detailed health and medical information from more than 73,600 postmenopausal women, age 50 to 73, who enrolled in the study in the early 1990s. For almost two decades, they completed follow-up questionnaires every two years.
*Adapted from The New York Times
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