We know for a long time that the environments we live in and work affect our physical health – and that we can hurt things we may not realize we are exposed to, such as lead or air pollution.
It's also not a new idea that our natural environment can also weigh our mental health. Back in the 1930s, two sociologists noticed a striking pattern among the people admitted to Chicago's homes. The rhythms of schizophrenia, they said, were unusually high in those born in city districts. Since then, researchers have discovered that mental illness of all kinds is more common in densely populated cities than in greener and more rural areas. In fact, the City Planning and Mental Health Center estimates that city dwellers face a nearly 40% higher risk of depression, 20% higher probability of anxiety and twice the risk of schizophrenia than people living in rural areas.
Some of the mental health costs of city dwellers can be traced to social problems such as loneliness and anxiety of life cheeks with thousands or even millions of other people. But there is something about the natural nature of cities, which also seems to create tension in the emotional well-being of their inhabitants. Life in the City means dealing with stressors such as air pollution and noise from your circulation, construction or neighbors. However, only in recent years scientists have begun to seriously study the mechanisms through which exposure to various environmental pressure factors can injure our mental health, says Andreas Meyer-Lindenberg, director of the Central Institute of Mental Health in Mannheim, Germany. "It's an emerging field," he says.
Meyer-Lindenberg and his associate researcher Matilda van den Bosch, an environmental health researcher at the University of British Columbia in Vancouver, recently reviewed the scientific evidence for them and several other physical pressure factors to see if they contribute to depression. The couple was looking for studies on a wide range of substances and situations that people can run throughout everyday life. They found that while many of these factors were particularly plentiful in cities, they were not limited to urban environments. For example, atmospheric pollution is not just on the border of cities. Another potential risk was pesticides, which come in contact with farmers in particular.
However, an important part of improving mental health will make our cities more lively, says Meyer-Lindenberg, who published the findings this year in the magazine An annual review of public health. More than half of the world's population already live in cities and this figure is expected to grow to almost 70% by 2050.
"The world is becoming increasingly urban, so neighborhoods are opening and changing," says Marianthi-Anna Kioumourtzoglou, assistant professor of environmental health sciences at Columbia University Mailman School of Public Health, who studied the impact of air pollution on mental health. "We must consciously try and do this in a way that promotes mental well-being."
The dangers around us
In their review, Meyer-Lindenberg and van den Bosch found that some potential threats were dealt with more thoroughly than others. For some, including pollen, there was not yet enough information to show a convincing connection to depression. However, the team has found several studies suggesting that heavy metals such as lead, pesticides, common chemicals such as bisphenol A (BPA) and noise can contribute to depression, although further research is needed to confirm that this is happening .
Even more pressing were the elements condemning atmospheric pollution. In addition to causing respiratory and cardiovascular problems that kill millions of people each year, this threat increases the risk of a range of psychiatric problems. Poor air quality has been associated with depression, anxiety and psychotic experiences like paranoia and hearing voices.
In the United States, emissions for many common pollutants have declined sharply in the decades since the Clean Air Act came into force. However, "the fact that the levels have declined does not mean it is safe," says Kioumurtzoglou. "We all breathe and we all have been inadvertently exposed." She and her colleagues have found that women living in very polluted neighborhoods are more likely than others to report symptoms of anxiety and get antidepressants.
Meyer-Lindenberg and van den Bosch also made their mood available for the possible link between living and depression in the city. "Cities are an interesting case," says Meyer-Lindenberg. On average, city dwellers have access to better health care and education than other people. "So cities are good for most aspects of human life … it's just the mental health that shows the other side of cities." Urban areas, he believes, are detrimental both because of lack of greenery and the presence of particularly high levels of toxic exposure such as air pollution.
This does not mean that if you live next to a highway or over a bar you are doomed to develop depression or anxiety. Many people thrive in the cities. And mental illnesses are caused by a complex obstacle of genetics and living conditions. it is rarely possible to pick a subject and call it guilty, says Meyer-Lindenberg. Rather, risks such as air pollution increase the overall risk of an individual, especially for those who are already vulnerable for other reasons. How strongly our natural environment affects this danger is something that scientists have not yet understood. However, for people in poor communities, the impact is probably very strong. not only financial anxiety contributes to depression, but low-income neighborhoods face disproportionately high levels of air pollution, noise and lead exposure.
How exactly these things prepare the brain for depression is not quite clear. Some issues, such as noise pollution and possibly pollen, burden enough to contribute to depression, reducing our mood continually. Our environment hurts us in ways we do not know consciously, perhaps by damaging our neurons or by changing the abundance of chemical messengers like serotonin, according to Meyer-Lindenberg. Air pollution and other substances can cause an inflammatory response that over time takes a toll on the brain, says Meyer-Lindenberg. In children, exposure to these dangers can also prevent brain development normally.
The idea that so many things we face in everyday life could threaten our mental well-being is worrying. But our natural environment can also feed our mental health. There are many studies that show that our risk of depression and other psychiatric disorders is decreasing – you have been in touch with nature. People are more physically active while in nature, and the sights, sounds and scents of the greens and oceans give us joy and give us impetus.
In an experiment, scientists have discovered that after a walk in nature people are less prone to outbreaks, the tendency to guess the mistakes and problems that are a common feature of disorders such as depression and anxiety. The physical walk also touched the activity in several areas of the brain that were involved in the rumination and responded to threats to the feeling that they belonged or feelings that we have made a social harm. One of these areas of the brain – known as the peripherial anterior bark of the vagina, which participates in the regulation of our emotions – may be the key to understanding how our environments can harm or help the mental our health, Meyer-Lindenberg believes.
"Many of the risk factors we are testing tend to hit the same brain system," he says. He and his colleagues have found that this part of the brain responds particularly strongly to socially stressful situations in people growing up in cities. This area also appears to be affected by certain genes associated with sensitivity to depression and other psychiatric illnesses, suggesting that it may be important for our mental health.
Nearly one in five adults in the United States live with a mental illness while depression is considered the leading cause of worldwide disability by the World Health Organization. This makes it vital to learn more about how the world around us shapes our mental health, says van den Bosch. It hopes that this information will give policy makers an incentive to further strengthen the restrictions on air pollution and other harmful products of the human industry.
"We know that many of these things are bad, and do we really need more evidence?" It seems that the answer is yes, "says van den Bosch. Even if the effect on our overall risk for mental illness proves to be small, he says, "It will still have a huge impact on the health of the population."
Kioumurtzoglu also hopes to see the research whether exercise, time in nature or other actions could offset the dangers posed by air pollution and other risks to our mental health. Whatever these steps are, it will probably not be easy or practical for everyone. It is also important that we import green in our cities where many dangers are more concentrated. Not only parks and street trees give the inhabitants of the city a refreshing dose of nature, they also help us with the noise of noise and the absorption of pollutants.
We can not just flatten our cities and rebuild them in wooded utopias, admits Kioumurtzoglou. However, we can take environmental health into consideration when designing new neighborhoods and refurbishing existing ones. "Sometimes it takes a little while to introduce new and more protective regulations – and we need to know what we can do in the meantime to protect ourselves," he says.