Nature Experience Reduces Rumination and Subgenual Prefrontal Cortex Activation

This study investigated whether spending time in nature could reduce rumination, which is repetitive negative thinking linked to depression and other mental illnesses. The researchers conducted a controlled experiment where they recruited 38 healthy adults living in urban areas. These participants were randomly divided into two groups. One group took a 90-minute walk in a natural environment, specifically a grassland area with trees. The other group took a 90-minute walk in an urban environment, along a busy street with traffic and buildings. Before and after their walks, all participants completed a questionnaire to measure their level of rumination. Additionally, the researchers used a brain imaging technique called arterial spin labeling (ASL) to measure activity in a specific brain region called the subgenual prefrontal cortex (sgPFC), which has been associated with rumination and mental illness. By comparing the changes in rumination and brain activity between the nature walking group and the urban walking group, the study aimed to understand if and how nature experience might affect this type of negative thinking.

The main finding of the study was that participants who took a 90-minute walk in a natural environment reported a significant decrease in their levels of rumination after the walk, while the group that walked in the urban environment showed no such decrease. Furthermore, the brain imaging data revealed that neural activity in the sgPFC also decreased in the nature walking group but not in the urban walking group. This suggests a potential biological mechanism through which nature experience might improve mental well-being by reducing rumination. The researchers concluded that providing accessible natural areas within urban settings could be an important resource for mental health in increasingly urbanized populations.

Bratman, G.N., Hamilton, J.P., Hahn, K.S. et al. (2015). Nature experience reduces rumination and subgenual prefrontal cortex activation. Proc Nat Acad Sci USA., 112, 8567–72.