This is Your Brain on Trees

Researchers from the Max Planck Institute for Human Development in Berlin, Germany, noticed that more and more research is showing that living close to nature is good for our mental health. They wondered how individual brains differ depending upon where their owners live relative to the natural world. They didn’t look at the more stark urban/rural dichotomy. Instead they looked at variations in surroundings of people that lived in Berlin compared to their brain health. They wanted to know what kind of an urban environment would provide enrichment for people.  ‘Enrichment’ being positive changes in the brain.

They looked at the brain health of 341 elderly Berlin residents and compared the results to the conditions surrounding their homes.  The researchers examined three parts of each brain (amygdala, perigenual anterior cingular cortex, and dorsolateral prefrontal cortex) using three different parameters and three imaging techniques (grey matter volume derived by means of voxel-based morphometry, mean diffusivity from a diffusion tensor imaging sequence, and magnetisation-transfer ratio).  They identified four environment types (urban green, forest, water, and wasteland).

Once they understood the situation in their subjects brains and the environment in which those individuals lived, they could apply some statistics to see if there were any relationships. They said, “Our results reveal a significant positive association between the coverage of forest and amygdala integrity.”

While it could be that living in a forest environment helps the brain,  it may also be that people with more healthy brains tend to choose to live near trees.  Other research has shown that mental health improves after moving to greener areas so, the scientists assumed that it was in fact the environment helping the brain.

Urban green areas, that is small areas of trees or green space, did not help brains.

Given their findings and the limitations of the study, the researchers concluded:

“Therewith, the results of our study may suggest that forests in and around the cities are a valuable resource that should be promoted. However future longitudinal studies are needed to investigate the causal directionality of the effect in order to disentangle whether more forest in ones habitat facilitates brain structural integrity or potentially those people with better brain structural integrity choose to live closer to forests. Moreover we need to investigate whether living close to the forest is associated with an absence of risk factors such as noise, air pollution or stress and thereby has beneficial effects or whether the forest itself constitutes a salutary factor that promotes well-being.”

If you want to get into more details,  you can read the full report:

Simone Kühn, Sandra Düzel, et al. In search of features that constitute an “enriched environment” in humans: Associations between geographical properties and brain structure.  Scientific Reports 7. 2017.