Stressed Brains Respond Poorly to City Living

November 12, 2012

Stressed Brains Respond Poorly to City Living

Why do urban settings increase the risk of Depression and Anxiety?

A joint study from researchers in Canada and Germany has recently been published in the journal Nature. It has found that if you reside in a rural setting then your brain reacts less strongly to stress than those who live in a city or other suburban setting. The findings may help to understand why urban dwellers are more susceptible to mood disorders, which can include depression to the more serious mental illnesses such as schizophrenia when compared to people who live in a rural setting.

The study investigated adults from four separate groups; those who lived in cities, those dwelling in mid size towns, people in small towns and those who lived in a rural setting. The study consisted of recording each individual’s brain activity whilst subjecting them to a form of stress by making them do difficult mathematical problems. To add to the stress the individuals were criticized by the researchers for having inferior skills. Because the participants are struggling with one problem and being criticized, social stress is generated irrespective of mental ability.

During the test it was found that people who lived in cities had more activity in an almond shaped part of the brain known as the amygdala when they were subjected to stress when compared to those who lived their lives in a more rural setting. The reason that this finding is important is that the amygdala is the area of the brain which deals with or has an effect on fear, self protection and emotional processing. In previous research it has been linked with mental conditions as diverse as post traumatic stress disorder to autism, anxiety, phobias and depression.

The researchers also found what they believe to be an indication that early life experiences can also have a bearing on how the brain responds. The researchers noted that people who were now living in a rural area but had grown up in a city in their younger lives exhibited higher activity in the anterior cingulate cortex. This area has a regulatory effect on the amygdala, and suggests that experiences from the past may affect the brain’s development.

Study researcher Jens C. Pruessner, PhD, director of the Douglas Mental Health Institute at McGill University in Montreal says of the finding, “It’s a stronger response of those areas that typically regulate fear and emotion”. He also believes that it is an indication, “that living in big cities with many, many people surrounding you sensitizes you to respond more strongly to stress”.

Why do brains react in this way?

Although the study is a useful work in its own right it does not prove that certain areas within the brain work when subjected to stress because of the environment the person lives in. Although proof is evasive the researchers point out that even after all other influences were accounted for, such as anxiety displayed by participants in the initial phase, or socioeconomic status or size of the participant’s social group, then there was still an association between areas of the brain being activated when city dwellers were subjected to periods of stress.

Andreas Meyer-Lindenberg, MD, PhD, director of the Central Institute of Mental Health in Mannheim and professor of psychiatry at Heidelberg University, in Germany is a study researcher and he comments, “I think there’s a lot to the story that our environment is important to how we function and also what our mental health is like”.

He goes on to elaborate that the aim is now to identify which factors of city living cause this response to stress. Meyer-Lindenberg is now looking at people who have lived in a city for a long time compared to migrants and is comparing readings from their brains. He says, “They have a different social environment, but same city environment”.

Marc Berman, PhD, is a research fellow at the University of Michigan and was not involved in the research. He and other experts commend the use of neuroscience as a tool to identify and understand the environmental influences which cause brains to function in the manner that they do. He says, “I hope more scientists try to do this where they combine basic kinds of neuroscience with these kinds of bigger, broader problems, that’s very commendable. But it’s one study, and it’s correlational, so we need a lot more work in this area.”

There have been previous studies detailing the effects of living environments and how the brain functions. In 2008, Berman and colleagues carried out a piece of research.

The researchers requested that their participants, all healthy adults, to walk through a town or city, or walk through the countryside. Immediately after their walk the participants took part in a test to measure working memory. The test involved the researchers giving them a list of numbers verbally and the participants had to repeat them in reverse order.

The study found that after a walk in the countryside the participants had a 20% improvement in their memory function than those who had just completed a walk in the city.

Again no proof was found as to why being in the city should produce less positive results. However researchers speculate that the urban environment may react poorly with the brain because of the magnitude of sights, smells and noises in some way stop the brain from focusing on any one area. They go on to consider natural settings where they say that the brain does not tire so readily because it can have time to focus.

Berman understands that it is early days and says what we all know, “I wouldn’t draw the conclusion from these studies that city living is bad or urban living is bad and we should all move into the country. We need to figure out what elements about the city are harmful to us, what things we can change, what things we can add to the city to make it more restorative and better for cognitive functioning”.

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