Access to Parks for Children Associated with Better Adult Mental Health: Gunshots


A child admires Japanese cherry blossoms at Bispebjerg Cemetery in Copenhagen, Denmark.


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A child admires Japanese cherry blossoms at Bispebjerg Cemetery in Copenhagen, Denmark.


The experience of natural spaces, brimming with greenish light, the smells of soil and the silent quivering of leaves in the breeze can soothe our frenetic modern lives. It's as if our very cells could breathe when they were surrounded by nature, thus relaxing our body and our mind.

Some people seek to maximize the supposed therapeutic effects of contact with the unbuilt environment by embarking on forest bathing sessions, slowing down and soaking in nature.

But in a rapidly urbanizing world, green spaces are shrinking as our cities grow and grow. Scientists are struggling to understand how green spaces, or lack thereof, can affect our mental health.

A study published Monday in the journal PNAS What scientists say is the biggest investigation into the association between green spaces and mental health.

Researchers from the University of Aarhus in Denmark found that growing near vegetation was associated with up to 55% risk of mental health disorders reduced to adulthood. The study's biologist, Kristine Engemann, has combined decades of satellite imagery with extensive health and demographic data on the Danish population to study the effects on mental health of near-green growth.

"The magnitude of this study is quite something," says Kelly Lambert, a neuroscientist at the University of Richmond, who studies the psychological effects of natural spaces. More modest studies have suggested that lack of green space 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 significant effects on mental health. For example, wealthier families may be able to afford to live in neighborhoods with better access to nature and also have access to other wealth-related resources that can enhance development. of their childhood.

Isolating the effects of nature from so many potential confusions requires a large and rich data set. The Danish civil registration system is just that.

Launched in 1968, the system assigns a personal identification number to every Danish citizen and records their PIN, gender, place of birth and parents. A PIN connects people across multiple databases, including mental health records, and is updated with changes of residence. "It's an incredibly rich data source," says Engemann. The final data of the researchers included nearly one million Danes born between 1985 and 2003 and for whom they had longitudinal data on mental health, socio-economic status and place of residence.

Satellite data dating back to 1985 allowed researchers to calculate the density of vegetation around each residence. Unfortunately, these data do not distinguish an old forest from a vegetation-invaded field, but in general, the more greenery there is in a parcel of land, the higher the density of vegetation.

Armed with this data, the researchers compared the risk of developing 16 different mental health disorders in adulthood to the number of green spaces surrounding each child's home. And because they had an annual income, a work history, a level of education, they could weigh the relative contribution of green space to the socio-economic factors of parents and neighborhood.

After taking into account these potential confounding factors, the researchers found that growing near green spaces was associated with a lower risk of developing psychiatric illness in adulthood by 15-55%, depending on the disease. considered. For example, alcoholism was most strongly associated with the lack of growing green spaces and the risk of developing an intellectual disability was not associated with green spaces.

The strength of the association between green spaces and the risk of psychiatric disorders was similar to other factors known to influence mental health, such as socio-economic status. According to Engemann, it is estimated that about 20% of the adult Danish population will suffer from poor psychiatric health in a given year, potentially making these slight changes in risk significant.

"Green spaces seemed to have an association whose strength was similar to other known influences on mental health, such as a history of mental health disorders in the family or socio-economic status," Engemann said. In addition, the effect of green spaces was "dose dependent": the more you spent your childhood near the greenery, the less likely you are to have mental health problems in adulthood.

Engemann warns that the study has limitations: "It's purely correlational, so we can not say definitively that growing near green spaces reduces the risk of mental illness." Establishing a cause-and-effect relationship for such variables is extremely difficult, according to Engemann.

Nevertheless, the breadth and depth of the data used in this analysis add to the circumstantial evidence linking green spaces and mental health. "The effect is remarkable," Lambert says. "If we were talking about a new drug that would produce this type of effect, the buzz would be huge, but these findings suggest that being able to walk around the park as a child has just as much impact."

The association of greenery with better mental health has taken place in rural and urban areas of Denmark. "You could grow in very urban areas while having a reduced risk if you are surrounded by green spaces," Engemann said.

Nor can the study explain how different types of green spaces – and how people use them – affect mental health. Do forests have more impact than green spaces Do you need to actively use these spaces or is it just that you are growing near greenery? These are questions that Engemann hopes to answer in future studies.

A big question remains: why? How does growing near trees, shrubs and grass seem to increase resistance to mental health problems?

Lambert suggests that the explanation could be profound, in terms of evolution. She says that we have evolved in the middle of green spaces and that being exposed to our "native" environment could have powerful physiological and psychological effects.

In addition, a greater number of green spaces could simply encourage more social interactions, the exercise or reduction of air and noise pollution, all known to have an impact on mental health. Even exposure to a greater diversity of microbes during childhood could play a role.

"There are many potential mechanisms to follow, but generally, I think this study is extremely important," Lambert said. "This suggests that something as simple as better urban planning could have profound implications for the mental health and well-being of all."

Jonathan Lambert is an intern at NPR's Science Desk. You can follow him on Twitter: @evolambert.

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