A research team led by the Mannheim-based (Germany) Central Institute for Mental Health was able to show that green spaces directly improve the wellbeing of city dwellers in their everyday lives. Also, they investigated brain function to identify the people who benefit most from them.
According to the United Nations, more people have been living in cities than in rural areas for a few years now. It is estimated that by 2050 around two-thirds of all humans will live in cities. Earlier studies have shown that people who grew up in the city and are currently living in the city react differently to stress than people living in rural areas and have a significantly higher risk of depression, schizophrenia or anxiety disorders.
An interdisciplinary research team headed by Prof. Dr. Andreas Meyer-Lindenberg and Prof. Dr. Dr. Heike Tost, as well as the significant participation of Dr. Urs Braun, all from the Clinic for Psychiatry and Psychotherapy at the Central Institute for Mental Health (German: Zentralinstitut für Seelische Gesundheit or ZI) in Mannheim, Germany, has now been able to show that green spaces in cities, such as inner-city trees, lawns, flower beds or parks, can be regarded as an important protective factor. In a study published in the journal Nature Neuroscience, they found that the proportion of green spaces around people has a direct effect on their well-being in everyday life. Surprisingly, people who spend most of their time in urban neighborhoods with little green space and reduced brain capacity to regulate negative emotions benefit from this effect.
"For the first time, we were able to confirm the positive effect of green spaces in cities on well-being directly in urban everyday life and relate it to brain function," says ZI researcher Prof. Dr. Heike Tost. To this end, 33 healthy city-dwellers were initially asked to evaluate their mood nine times a day within a week with the help of specially equipped smartphones. During this time, the participants followed their everyday lives as usual. Using geoinformatics methods, the distances covered by the participants were traced and characteristics of the routes, especially visible green areas, were determined. This information was linked to the recorded mood.
It turned out that the participants displayed a higher sense of well-being in situations in which they were surrounded by a higher proportion of green spaces in the city. In the second step, 52 other young adults were asked to assess their mood in everyday life in the same way. In addition, after the seven-day evaluation phase, the participants were subjected to functional magnetic resonance imaging (fMRI).
The results of the first round were confirmed by the second group. In addition, the researchers observed reduced activity in the dorsolateral prefrontal cortex (DLPFC) in people who reacted particularly positively to green spaces in their daily lives.
"These results suggest that green spaces are particularly important for people whose capacity to regulate negative emotions is reduced," says Prof. Dr. Andreas Meyer-Lindenberg, Chairman of the Board and Medical Director of the Clinic for Psychiatry and Psychotherapy at ZI. "This is particularly interesting with regard to the planning of health-promoting cities," adds Markus Reichert from the Mental mHealth Lab at the Karlsruhe Institute of Technology (KIT) in Karlsruhe, Germany, and one of the main study authors. He suggests that green spaces which are well distributed over a city could unfold a considerable potential for the prevention of mental illness.
The research team led by Meyer-Lindenberg and Tost combined several methods from the fields of epidemiology, psychology, geoinformatics, and neuroimaging. In addition to the ZI researchers, Markus Reichert and Prof. Dr. Ulrich Ebner-Priemer, both from KIT, as well as Prof. Dr. Alexander Zipf and Dr. Sven Lautenbach from the Institute of Geography at the University of Heidelberg, Germany, and the Heidelberg Institute for Geoinformation Technology (HeiGIT) were also in charge of the study.
Tost H, Reichert M, Braun U, Reinhard I, Peters R, Lautenbach S, Hoell A, Schwarz E, Ebner-Priemer U, Zipf A and Meyer-Lindenberg A: Neural correlates of individual differences in affective benefits of real-life urban green space exposure. Nat. Neurosci. 2019. DOI: https://doi.org/10.1038/s41593-019-0451-y