Washington: Taking a walk in natural surroundings could lead to a lower risk of depression, a new study has found.
Researchers at Stanford University found that people who walked for 90 minutes in a natural area showed decreased activity in a region of the brain associated with a key factor in depression, as opposed to participants who walked in a high-traffic urban setting.
"These results suggest that accessible natural areas may be vital for mental health in our rapidly urbanising world," said co-author Gretchen Daily, a senior fellow at the Stanford Woods Institute for the Environment.
"Our findings can help inform the growing movement
Worldwide to make cities more livable, and to make nature more accessible to all who live in them," Daily said.
More than half of the world's population lives in urban settings, and that is forecast to rise to 70 per cent within a few decades.
Just as urbanisation and disconnection from nature have grown dramatically, so have mental disorders such as depression.
In the study, two groups of participants walked for 90 minutes, one in a grassland area scattered with oak trees and shrubs, the other along a traffic-heavy four-lane roadway.
Before and after, the researchers measured heart and respiration rates, performed brain scans and had participants fill out questionnaires.
The researchers found little difference in physiological conditions, but marked changes in the brain. Neural activity in the subgenual prefrontal cortex, a brain region active during rumination ? repetitive thought focused on negative emotions ? decreased among participants who walked in nature versus those who walked in an urban environment.
"This finding is exciting because it demonstrates the impact of nature experience on an aspect of emotion regulation ? something that may help explain how nature makes us feel better," said lead author Gregory Bratman, a graduate student in Stanford's Emmett Interdisciplinary Program in Environment and Resources.
"These findings are important because they are consistent with, but do not yet prove, a causal link between increasing urbanisation and increased rates of mental illness," said co-author James Gross, a professor of psychology at Stanford.