Taxis in New York City photo by Bonnie Hulkower
With more than 50% of the world's population currently living in cities and 70% of the world population expected to live in a city by 2050, neurologists are starting to map out the impact of living in cities on one's mental health. City living has many virtues that have been extolled on this website, including some health benefits. Yet researchers say living in a city increases the risk of developing a mental disorder, including depression and schizophrenia. Recent research by McGill University scientists maps out regions of the brain where urban dwelling study participants showed signs of increased stress, stimulated by city living. The scientists' findings, published in Nature, may lead to discussions and strategies on how to improve both the mental health and quality of life of city dwellers.
Previous studies have shown that risk for anxiety disorders is 21% higher for people from the city, who also have a 39% increase for mood disorders. Experts also say the incidence of schizophrenia among those who are born and raised in cities is double that of people born and raised in non-urban areas. These numbers are a cause for concern.
Director of McGill University's Centre for Studies in Aging in Montreal, Jens Pruessner, co-author of the Nature study, said the study is the first to show that two distinct brain regions that regulate emotion and stress are affected by city living. Research showed that urban upbringing and city living have impacts on stress processing in humans and that these impacts could continue long after one has left the city.
Study MethodologyThe study took place in Germany. Pruessner's participants were asked to do mathematical calculations, while researchers took pictures of their brains using imaging technology, and then compared the brain images of healthy volunteers who came from a city of more than 100,000 residents to those of volunteers who lived in rural areas. Researchers used an fMRI in three independent experiments. While in the fMRI scanner, volunteers heard a researcher criticize their performance, saying it was disappointing, and telling the volunteers they might not be skilled enough to participate.
Initial Study FindingsAn initial study of 32 volunteers found differences between the urban and rural volunters in two brain areas: the amygdala and the cingulate cortex. The bigger the city, the more the impacts were observed. A city of more than 100,000 showed more activation of the amygdala than participants from towns with 10,000 - 100,000. Those smaller cities in turn showed more activation than people from rural areas. Researchers found that current city living was associated with a greater stress response in the amygdala, which is involved with emotional regulation and mood. Urban upbringing affected the cingulate cortex, a region that regulates negative mood and stress.
What Role Did Researcher's Criticism Play?But when a third group of 37 adults did mental tasks without being criticized for poor performance, they showed no urban-rural differences. That shows the effect comes from the criticism rather than just doing the mental task, the researchers said.
These findings may further provoke new connections between social sciences, neurosciences and public policy addressing the major health challenges of urbanization.
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