BERLIN — Linking city living and mental health issues through brain imaging, a new study also finds evidence that residing in a metropolitan area that’s not too far from a forest can help combat the problem.
The recent research, out of the Max Planck Institute for Human Development, was conducted in an effort to better urban planning as more and more people move into cities across the world. Studying 341 older adults who were already participating in the larger Berlin Aging Study II, the researchers found city dwellers showed heightened activity in their amygdalae compared to country dwellers. The amygdala is a part of the brain that processes stress and reacts to danger.
“Studies of people in the countryside have already shown that living close to nature is good for their mental health and well-being. We therefore decided to examine city dwellers,“ says the study’s first author Simone Kühn in a press release.
Kühn, alongside fellow researchers, examined the effects of features such as forest, urban green space, water, or wasteland on the amygdala and other stress-processing brain regions.
“Research on brain plasticity supports the assumption that the environment can shape brain structure and function,” says Kühn. “That is why we are interested in the environmental conditions that may have positive effects on brain development.”
Exploring this, researchers did indeed find an environmental condition that has positive effects — city dwellers living close to a forest seem to have healthier amygdalae than other urbanites.
“Our results reveal a significant positive association between the coverage of forest and amygdala integrity,” the researchers write.
This remained true when the researchers controlled for differences in education and income. While the researchers didn’t rule out the possibility that people with healthier amygdalae chose to live closer to forests, they said the evidence points to the forest causing the brain health changes.
They didn’t find associations in this study between the amygdala (or other stress-processing regions) and urban green space, water, or wasteland.
In addition to giving memory and reasoning tests to assess the effects of the different environments, the researchers also used MRI (magnetic resonance imaging) scans to get actual images of the subjects’ brains at work.
In previous studies linking exposure to nature and brain health, researchers also used MRI machines to look at exactly how nature sounds induced relaxation in subjects.
Another recent study found that being regularly exposed to a significant amount of foliage and birds in a neighborhood was associated with lowered depression, stress, and anxiety.
Noting that about 70 percent of the world’s population is expected to live in cities by 2050, the Max Planck researchers say further studies in the area will be important for helping urban planners mitigate the dangerous effects of cities on mental health.
Their research paper was published last month in the journal Scientific Reports.
Use of the phrase “enriched environment” in the title is especially interesting, as it is a term generally used in animal studies.
“Enriched environments elicit brain plasticity in animals,” the study authors write, explaining their intentions for the study. “In humans it is unclear which environment is enriching.”