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The experience of the natural spaces, full of green light, the smell of the soil and the soft flickering of the breeze leaves can soften our frenetic contemporary life. It is as if our cells can exhale when surrounded by nature, relaxing our bodies and minds. Some people strive to maximize the potential therapeutic effects of contact with the untreated environment, embarking on forest bathing sessions, slowing down and becoming carefully submerged in nature.
But in the rapidly urbanizing world, green areas shrink while our cities are growing. Scientists are working to understand how green spaces or their lack can affect our mental health.
A study published Monday in the journal PNAS specifies what scientists say about the largest study of the relationship between green areas and mental health. Researchers at the University of Aarhus in Denmark have found that growing near vegetation is associated with up to 55% less risk of adult mental health disorders. Biologist Kristine Engemann, head of the study, combines decades of satellite imagery with extensive health and demographic data from the Danish population to study the mental health effects of growing near the greenery. “/>
"The scale of this study is quite a thing," says Kelly Lambert, a neuroscientist at Richmond University, who studies the psychological effects of natural spaces. Smaller studies suggest that lack of green areas increases the risk of mood disorders, schizophrenia and may even affect cognitive development. But more practical factors such as socio-economic status, family history of mental illness and urbanization can also have a great effect. on mental health. For example, richer families can afford to live in neighborhoods with greater access to nature and have access to other wealth-related resources that could improve child development. Isolation of the effects of nature from so many potential confusions requires a large and rich set of data. Danish system of civil registration is exactly the same
Began in 1968, the system gives each Danish citizen an individual identification number and records their gender, place of birth and parental PIN. Pin connects individuals to multiple databases, including mental health records, and updates with changes in location. "This is an extremely rich data source," says Engemann. The final data set of researchers includes nearly 1 million Danes born between 1985 and 2003 and for whom they had data on mental health, socio-economic status and residence.
Satellite data from 1985 allows researchers to calculate the density of vegetation around each dwelling. Unfortunately, this data can not distinguish the old plant forest from the overgrown field, but as a whole the more greenery is packed in a plot, the greater the density of the vegetation. to develop 16 different adult psychiatric disorders to how much green space is surrounded by the residence of each child. And since they had annual income, labor history, educational level, they could judge the relative contribution of green areas to the socio-economic situation of parents and neighborhoods. Having considered these potential disorders, researchers have found that growing near green areas is associated with a lower risk of developing mental illness in adulthood from 15 to 55% depending on the specific disease. For example, alcoholism is most strongly associated with the lack of green areas, and the risk of developing intellectual impairment is not related to green areas.
The strength of the relationship between green space and the risk of mental disorder is similar to other factors known to affect mental health, such as social -Economic status. According to Eneman, about 20% of the adult Danish population will suffer from poor mental health within a given year, making these minor changes in risk potentially important. to other known effects on mental health, such as a history of mental disorders in the family or socio-economic status, "says Engemann. Moreover, the effect of green space is "dose-dependent" – the more you have spent your childhood near the greenery, the less the risk of mental problems in adulthood. It is entirely correlated, so we can hardly say that growing near green areas reduces the risk of mental illness. Identifying the cause and effect of such variables is extremely difficult, according to Engemann. However, the breadth and depth of data used for this analysis complement the indirect evidence linking green space and mental health. "The effect is remarkable," says Lambert. "If we talk about a new drug that had such an effect, buzz would be huge, but these results suggest that the opportunity to go for a walk in the park as a child is just as impressive."
A green association with better mental health, conducted both in rural and urban areas of Denmark. "You can grow in many urban areas, but you still have a reduced risk if you are surrounded by green areas," says Engemann.
The study also can not examine how different types of green areas – and how people use it – affect mental health. Are the Parks Are More Harmful? Is it necessary to actively use these spaces, or is it just enough to grow close to the greenery? These are issues where Engemann hopes to respond to future research.
One big question remains: Why? What about growing near trees, shrubs and grass that seems to increase resistance to the development of mental problems?
Lambert offers the explanation to penetrate deeply, evolutionarily. She says we have evolved, surrounded by green areas, and something about being exposed to our "local" environment can have powerful physiological and psychological effects. In addition, more green areas could simply encourage more social interaction, exercise or reduce air and noise pollution, all of which are known for the impact of mental health. Even exposure to a wider variety of microbes in childhood can play a role.
"There are many potential tracking mechanisms, but overall I think this study is extremely important," says Lambert. "This suggests that something as simple as better urban planning could have a major impact on mental health and well-being for all of us." Jonathan Lambert is a trainee at the NPR Science Department. You can follow it on Twitter: @evolambert .