Exposure to Nature May Improve City-Dwellers' Mental Health

A new study by German researchers suggests that exposure to urban green space may reduce the risk of mental health issues among city dwellers.

Experts explain that the noise, pollution, and high population density of typical city life can cause chronic stress. As such, city dwellers are at a higher risk of psychiatric illnesses such as depression, anxiety disorders, and schizophrenia than country dwellers.

Investigators at the Max Planck Institute for Human Development studied the brain area called the amygdala, a central region in the brain that plays an important role in stress processing and reactions to danger. Comparisons show higher activity levels in city dwellers’ than in country dwellers’ amygdala.

Taking this information, a research team led by psychologist Dr. Simone Kühn searched for factors that could have a protective influence in relieving the stress. They examined how nature located near people’s homes such as forest, urban green, or wasteland influences stress-processing brain regions such as the amygdala.

“Research on brain plasticity supports the assumption that the environment can shape brain structure and function. That is why we are interested in the environmental conditions that may have positive effects on brain development.

“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,” explains Kühn, the first author and leader of the study.

Indeed, the researchers found a relationship between place of residence and brain health: those city dwellers living close to a forest were more likely to show indications of a physiologically healthy amygdala structure und were therefore presumably better able to cope with stress.

This effect remained stable when differences in educational qualifications and income levels were controlled for. However, it was not possible to find an association between the examined brain regions and urban green, water, or wasteland.

With these data, it is not possible to distinguish whether living close to a forest really has positive effects on the amygdala or whether people with a healthier amygdala might be more likely to select residential areas close to a forest. Based on present knowledge, however, the researchers regard the first explanation as more probable. Further longitudinal studies are necessary to accumulate evidence.

Researchers studied participants from the Berlin Aging Study II (BASE-II), a large longitudinal study examining the physical, psychological, and social conditions for healthy aging. In total, 341 adults aged 61 to 82 years took part in the present study.

Apart from carrying out memory and reasoning tests, the structure of stress-processing brain regions, especially the amygdala, was assessed using magnetic resonance imaging (MRI).

In order to examine the influence of nature close to peoples’ homes on these brain regions, the researchers combined the MRI data with geoinformation about the participants’ places of residence. This information stemmed from the European Environment Agency’s Urban Atlas, which provides an overview of urban land use in Europe.

Source: Max Planck Institute