City Living Intensifies Brain Stress Response and Increases Mental Illness Riskby Mary West, bibliotecapleyades.net
July 4th 2011
from PreventDisease Website
While city living offers many amenities and advantages not found in rural living, it might have a downside in the area of mental health.
City dwellers generally are more stressed and are at a higher risk of developing mental illness than their rural counterparts. Although scientists have been aware of this, they did not know the reason why.
A new study has revealed certain alterations in brain function that could potentially provide the explanation, Time Healthland reports.
Previous research indicates that those who grow up in a city have a two- to three-fold higher likelihood of developing schizophrenia. In addition, earlier studies show that even after reaching adulthood, city living raises the probability of contracting anxiety disorders by 21% and mood illnesses, such as depression, by 39% compared with rural dwellers.
The new study has provided further enlightenment on the issue.
In an international investigation published in the journal Nature, researchers at University of Heidelberg and McGill University report that city dwellers or those who were raised in cities display definite characteristics of activity in specific areas of the brain that are not found in rural dwellers.
The study pinpointed two areas of the brain that seem to be involved in responding to stress.
One structure of the brain that proved to be the culprit is the amygdala, an area that regulates anxiety and fear. This part of the brain is most often utilized in stressful or threatening situations and the study suggests it is more sensitive in city dwellers.
Another part of the brain the study implicated is the anterior cingulate, a region that is a more global regulator of stress. The research found that those raised in the city during their first fifteen yeas of life showed a higher activation of this area. Furthermore, this increased activation seems to be more permanent than in those who moved to cities later in life, states Jens Pruessner, one of the investigation's coauthors.
He explains that since the changes happen in an important period of development, these individuals will become more alert to stressful situations for the rest of their lives.
Lead researcher, Andreas Meyer-Lindenberg, explains that although the two brain structures are separate, they are linked by forming a circuit. According to Discovery News, he characterizes the findings by stating that the areas of the brain connected to mental illness were found to be hyperactive in city dwellers.
In the study, researchers applied stress on volunteers while their brains were being imaged by MRIs in order to determine which areas of the brain were activated by stressful situations. The stress was exerted by having the participants work difficult math problems, either while they were under time pressure or while they were being criticized by investigators for their poor performance.
Following the application of stress, investigators compared the results of the test with the population density of the area where the participants were currently residing, as well as the place where they were raised.
They found the degree of amygdala activation increased with the size of their hometown, with it being highest in the major metropolitan areas and lowest in the rural areas.
Researchers are not suggesting that people vacate the city and move to the country, but if the exact factors of city life responsible for these brain changes are identified it could have implications for city planning. They think the social aspects of urban living, more so than factors such as noise or pollution, are the stressors affecting the brain.
Future brain scanning investigations should help researchers determine the causative agents in the urban environment.
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