Many studies have indicated that urban dwellers have more than a 20 percent increased risk for anxiety disorders and an increased risk for mood disorders of almost twice that compared to rural citizens. There have also been a significant increase in schizophrenia evident among people born and raised in metropolitan areas.

Recognizing previous results and noting the explosive growth of urban populations throughout the world, a team of German and Canadian researchers from the Douglas Mental Health Institute in Montreal and the Central Institute of Mental Health at the University of Heidelberg sought to explore possible explanations for this phenomenon.

City Stressors

These researchers hypothesized that the association between city living and an increased risk of developing anxiety disorders stems from urban dwellers' unique response to a particular kind of stress known as social evaluative stress. That type of stress refers to interactions people have in daily life, including fears and concerns about others' opinions of them and of making mistakes in public.

The research entailed inducing stress among a group of German study participants from urban and rural areas while conducting functional magnetic resonance imaging (MRI) on them to investigate their neural responses. Specifically, social evaluative stress was simulated by administering the Montreal Imaging Stress Test (MIST), which asked participants to solve mathematical problems within a limited time. Volunteers were repeatedly told they were not performing well and though unbeknownst to them, the test was skewed to ensure that they could not be correct more than 40 percent of the time. Heart, breathing, and hormonal levels were simultaneously being monitored to confirm elevated stress levels.

Living in the City Affects the Amygdala

City dwellers showed the highest levels of activity in the amygdala, with significant changes noted in the anterior cingulate cortex of people raised in urban areas. In contrast, town and village residents experienced the lowest amygdala activity levels.

The amygdala and anterior cingulate cortex are complex brain structures that regulate emotions, store memories and influence human responses to threats. They have been associated with various mental health illnesses including depression, mood disorders and anxiety.

Anxiety disorders encompass a vast number of mental health conditions that interfere with people's daily lives. Their onset may be sudden and triggered by a certain event or situation, or longstanding and with no immediate explanation. They include generalized anxiety disorder, panic attacks, post-traumatic stress disorder, obsessive compulsive disorder, and phobias.

It's a Whole Different Lifestyle in the City

To determine whether or not the results were related to social stress in particular, scientists repeated the test, administering simple memory tests instead of using the MIST. This time, no correlation on social stress processing from city-living resulted.

The findings suggest that urban residents may be more vulnerable throughout their lifetimes to stress and psychological illness as a result of being raised and living in cities. Specific elements of urban living that contributed to the outcome were unclear though, with researchers unsure whether environmental factors such as pollution and noise or repeated stress were responsible.

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