Recent brain research, reported a year ago in The New York Times, is affirming a truth that William Wordsworth discovered long ago: walking in nature is a powerful means of treating depression.
Writing in the Times’s “Well” column, Gretchen Reynolds noted,
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 head of the study is Stanford University student Gregory Bratman at the Emmett Interdisciplinary Program in Environment and Resources. Bratman came to his insights while studying the psychological impact of urban living. There are indeed causes of concern:
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.
In the first phase of his study, Bratman discovered 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.”
In the second phase, he looked at the impact of nature walks on people who 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 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.
Examining the brain, Bratman discovered that, for those walking by the highway, “[b]lood flow to their subgenual prefrontal cortex was still high and their broodiness scores were unchanged. By contrast,
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.
They also had less blood flow to the subgenual prefrontal cortex. That portion of their brains were quieter.
Wordsworth was definitely a brooder and he describes urban living as being damaging to his mental health. In Tintern Abbey he talks of living in “lonely rooms” and being disturbed by “the din of towns and cities.” He experiences “the heavy and the weary weight of all this unintelligible world” and later mentions “the fretful stir unprofitable, and the fever of the world” and “the dreary intercourse of daily life.”
Luckily, he has visited the Wye River and so has memories he can fall back on—“emotion recollected in tranquility” as he describes the process in the preface to Lyrical Ballads:
I have owed to them [my memories],
In hours of weariness, sensations sweet,
Felt in the blood, and felt along the heart;
And passing even into my purer mind
With tranquil restoration…
To them I may have owed another gift,
Of aspect more sublime; that blessed mood,
In which the burthen of the mystery,
In which the heavy and the weary weight
Of all this unintelligible world,
Is lightened:—that serene and blessed mood,
In which the affections gently lead us on,—
Until, the breath of this corporeal frame
And even the motion of our human blood
Almost suspended, we are laid asleep
In body, and become a living soul:
While with an eye made quiet by the power
Of harmony, and the deep power of joy,
We see into the life of things.
Think of this as another way of saying that the brain is quieter because there is “less blood flow to the subgenual prefrontal cortex.” Guess which articulation I prefer.
Like a good scientist, Bratman acknowledges that we don’t yet know what precisely about nature walks changes the brain. He wonders how long must a walk be, what within the walk we find the most soothing, and whether it matters if we are alone or accompanied. With regards to this final question, Wordsworth has something to say.
While many of his walks are solitary, something is added when he visits the Wye with his sister Dorothy, whom he describes as his “dear, dear Friend.” Being with her, he says, enhances the experience:
[Nor] wilt thou then forget
That on the banks of this delightful stream
We stood together and that I, so long
A worshipper of Nature, hither came
Unwearied in that service: rather say
With warmer love—oh! with far deeper zeal
Of holier love. Nor wilt thou then forget,
That after many wanderings, many years
Of absence, these steep woods and lofty cliffs,
And this green pastoral landscape, were to me
More dear, both for themselves and for thy sake!
So go out and take a walk. Alone or with someone else