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by Mary West
July 04, 2011
from
PreventDisease Website
Spanish version
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.
Sources
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