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The experience of natural spaces, filled with greenish light, the smell of soil and quiet whispers of leaves in the wind, can reassure our vibrant modern life. It's as if our cells can breathe out in the environment, relaxing our bodies and minds. Some people seek to maximize the predicted therapeutic effects of contact with the unhealthy environment, starting swimming sessions in the woods, slowing down and becoming reasonably immersed in nature.
But in a rapidly developing world, green areas are shrinking as our cities grow and grow. Scientists are working to understand how green spaces or their absence can affect our mental health.
A study published on Monday in the journal PNAS details what scientists consider to be the largest association study between green spaces and mental health. Researchers at the University of Aarhus in Denmark have found that growing near vegetation is associated with a 55% lower risk of adult mental illness. Christine Engemann, the biologist who led the study, united decades of satellite imagery with extensive medical and demographic data from the population of Denmark to explore the impact of mental health growing near the green.
"The scale of this study is something like that," says Kelly Lambert, a neuroscientist at the University of Richmond who studies the psychological effects of natural spaces. Fewer studies hinted that the lack of greenery increases the risk of mood disorders and schizophrenia and may even affect cognitive development. mental health Rich people, for example, can afford to live in areas with greater access to nature, and have access to other resources that are rich in wealth that can enhance the development of childhood. To isolate the effects of nature from many potential mixing factors, a large and rich set of data is required. The Danish citizens registration system is exactly that.
Established in 1968, the system provides a personal identification number to every Danish citizen and records the gender, place of birth and parent's PIN. The PIN addresses individuals in several databases, including mental health records, and is updated by changes in the place of residence. "This is an incredibly rich source of data," says Engemann. The final set of researchers' data was about 1 million Danes who were born between 1985 and 2003 and for whom they had long records of mental health, social and economic status and place of residence.
vegetation density around each habitat. Unfortunately, these data do not allow to distinguish the forest array from the overgrown field, but in general, the more greens packed in the land, the higher the density of vegetation.
Armed with this data, the researchers compared the risk of developing 16 different psychiatric disorders in adulthood with how many green spaces surrounded the residence of each child. And since they had annual income, work history and education, they could weed out the relative contribution of green space to the socio-economic policies of parents and neighbors.
After taking into account these potential mixed factors, researchers found that growing close to the greenery was associated with a lower risk of development of mental illness in adulthood from 15% to 55%, depending on the specific disease. For example, alcoholism was most closely related to the lack of green planting, and the risk of developing intellectual deficiency was not associated with green spaces.
The association between green space and the risk of mental disorder was similar to other factors that are known to affect mental health as a socio-economic status . According to Engemann, roughly 20 percent of the adult population in Denmark will suffer from poor mental health during any given year, making these minor changes in risk potentially important.
is powered by other well-known effects on mental health, such as the history of mental health disorders in the seven or socio-economic status, "Engemann says. Moreover, the effect of green plantations was "dose-dependent" – the more childhood you spent close to the green, the less risk of mental problems in adulthood.
Engemann warns that research has a limitation: purely correlative, so we can not quite say that growing near greenery reduces the risk of mental illness. Establishing the causes and consequences for such variables is incredibly difficult, Engemann says. However, the breadth and depth of the data used for this analysis are added to the indirect evidence of green space and mental health. "The effect is wonderful," says Lambert. "If we talked about a new drug that would have such an impact, then the buzz would be huge, but these results show that the ability to go for a walk in the park as a child is equally impressive."
Greens Association for the Best Mental Health, conducted in both rural and urban areas of Denmark. "You could grow in very urban areas, but you still have a lower risk if you are surrounded by greenery," Engemann says.
The study also can not decide how different types of green plantations – and how people use it – affect mental health. Are forests more vulnerable than parks? Do you need to actively use these spaces, or is it just enough to grow near the green? These questions, which Enemmann hopes, can provide an answer to future research
. What is it about growing near trees, shrubs and grasses that seems to increase resistance to the development of mental problems?
Lambert suggests that the explanation can be deep, evolutionarily speaking. She says that we have evolved around green spaces, and something about our "native" environment can have powerful physiological and psychological consequences. In addition, more green spaces can simply encourage more social interaction, exercise, or reduce air pollution and noise, all of which are known to affect mental health. Even the impact on a wider variety of microbes in a child may play a role
"There are many potential mechanisms for further work, but as a rule, this study is extremely important," says Lambert. "This suggests that something is as simple as better planning a city can have a profound effect on the mental health and well-being of all of us."
Jonathan Lambert is a trainee at the scientific department of NPR. You can follow it on Twitter: @evolambert