Living in the city is harmful for your health?

Where you live affects brain activity

Brain scans show that people living in cities have brain functions different from those in rural areas, according to a study by scientists. Researchers found that two brain regions involved in regulating emotions and anxiety become overactive in urban dwellers when they are stressed, suggesting that these differences may be responsible for the increased incidence of mental health problems in urban areas^[1].

Previous studies have shown that people living in cities have a 21% increased risk of anxiety disorders and a 39% increased risk of mood disorders. In addition, those born and raised in cities are twice as likely to suffer from schizophrenia as those living in rural areas^[2].

Professor Andreas Meyer-Lindenberg from the University of Heidelberg in Germany scanned the brains of more than 50 healthy volunteers who lived in locations ranging from rural areas to large cities as they performed complex mental arithmetic tasks. The experiment was designed to make groups of volunteers feel anxious about their performance.

The results, published in the journal Nature, showed that the cerebral amygdala of participants living in urban areas were overactive in stressful situations^[3].

"We know what the amygdala does; it is the brain's danger sensor and is therefore linked to anxiety and depression," said Mejer-Lindenberg.

Another region, the cingulate cortex, was also the most active in participants who were born in cities. Experts know that the cingulate cortex is important for controlling emotions and dealing with environmental adversities.

Different levels of activity affect health

This excessive activity may be the cause of the mental health problems recorded, said Mejer-Lindenberg. "We think that stress may be the primary cause of such disorders, but these are assumptions that we cannot confirm with our own research. On the other hand, they are based on the fact that this specific area of the brain is very sensitive to stress. If animals stress you, you may even have structural abnormalities in that area, which can be permanent and cause constant anxiety when seeing animals. We believe that these things are caused by stress and that when they occur later, they increase the risk of mental illness," said the psychiatrist.

It is predicted that by 2050, almost 70% of people will live in cities. On average, city dwellers are "richer, with better sanitation, nutrition, contraception and healthcare," the Nature researchers wrote. But urban living is also associated with "an increased risk of chronic disorders, a more demanding and stressful social environment, and greater social inequalities. The biological components of this complex landscape of risk and protective factors are largely absent."

Comfort comes at a price

In a commentary in Nature, Dr Daniel Kennedy and Prof Ralph Adolphs, both of the California Institute of Technology, said that people's aspirations for and ability to cope with comfortable urban living vary widely^[4].

"Some people are comfortable in New York City; others would happily trade it for a desert or an island. Psychologists have found that a key factor in this variability is the degree of control people perceive they have over their daily lives. Social threats, lack of control and lack of subordination are likely to be key factors influencing individual and differential acceptance of the effects of stressful urban life," they pointed out.

The next step towards a better understanding of the impact of urban areas on people's mental health is to identify which factors in the city primarily cause stress. Mejer-Lindenberg said this could include social fragmentation, persistent noise or overcrowding. "There is previous evidence that if someone invades your personal space, gets close to you, it is that cingulate circuit in the amygdala that is triggered so that it could be something as simple as the sheer volume of people," he said, hinting that such research could be useful for designing the cities of the future. We can try to make cities better places to live regarding mental health. Unfortunately, there is still a lack of data to tell city planners what would be good and bad.