We all know that living in a city can be quite stressful . Since roughly half of the world’s population lives in cities (and that number is growing every day), cities are going to get noisier and more crowded, which is likely to mean a lot more stress for those who live in cities . Research has linked urban environments with a higher risk of anxiety, depression, and other mental health problems. How to counter such a fast and intense life in the city? Taking a walk in nature can make a difference, a new study concludes.
Fight urban stress
A central region of the brain involved in stress processing, the amygdala, has been shown to be less activated during stress in those living in rural areas compared to those living in cities, suggesting the potential benefits of nature. Visiting nature, even briefly, is associated with multiple mental and physical health benefits, including lower blood pressure, minimized anxiety and depression, improved mood, or better quality of sleep.
“But so far we haven’t been able to unravel the chicken-and-egg problem, that is, whether nature actually caused the effects on the brain, or whether particular individuals chose to live in rural or urban regions,” says Sonja Sudimac , fellow predoctoral fellow at the Lise Meitner Group for Environmental Neuroscience and lead author of the study published in the journal Molecular Psychiatry.
Researchers at the Max Planck Institute for Human Development devised a new study with the help of functional magnetic resonance imaging (fMRI), employing 63 healthy adult volunteers . They were asked to complete questionnaires, perform a working memory task and undergo fMRI scans while answering questions, some of them designed to induce social stress. None knew the purpose of the investigation.
They divided the participants into two groups: one would walk in nature and the other would walk in an urban setting. In both groups, brain activation was measured before and after the walk, using two different tasks in the MRI scanner.
The power of a nature walk
The researchers found that for those who walked the urban route no change in amygdala activity was observed, but for the group of volunteers who walked for an hour in nature, there was a decrease in activity in a specific area of the brain to all post-walk fMRI tasks: amygdala; in particular, the right amygdala (a key structure in the processing of fear and stress).
This finding that amygdala activity is reduced after a walk in nature leads scientists to conclude that a walk in nature can help us recover from the negative effects of stress. It also suggests that it is not walking itself that produces the improvement, but rather time spent in nature.
“The results support the previously assumed positive relationship between nature and brain health, but this is the first study to test the causal link. Interestingly, brain activity after urban walking in these regions remained stable and showed no increases .” , which argues against a common view that urban exposure causes additional stress,” explains Simone Kühn, Director of the Lise Meitner Group for Environmental Neuroscience.
The study confirms again the importance of urban design policies to create accessible green areas in cities to improve people’s mental health and general well-being .
Referencia: Sonja Sudimac, Vera Sale, Simone Kühn. How nature nurtures: Amygdala activity decreases as the result of a one-hour walk in nature. Molecular Psychiatry, 2022; DOI: 10.1038/s41380-022-01720-6
