Health Effects of Stress in the City
Does your pace of life in the city impact your health?
Posted Dec 12, 2014
City dwellers are all too familiar with the daily stress of living in a crowded and fast-paced city. There’s the dreaded serpentine Trader Joe’s or post office queue, the unison groan when the train stops on the tracks for a delay, and the impatient taxi drivers honking at the traffic jam. Even the slow-moving tourists seem like buoys with rushed people streaming around them, reminders of how the city runs at a faster pace.
In fact, people in the city are known to move literally faster than their less populated counterparts. Urban walking speeds have been studied as early as 1976, when psychologists discovered that people’s walking speed directly correlated with the population size—a finding that has been replicated in several subsequent studies. New York consistently ranks in the top ten fastest cities in the world (Singapore most recently tops the list). But why do people in larger cities walk faster? Are people protecting themselves from sensory overload by rushing ahead? Is it due to overcrowding of personal space? Earlier theories posited that people in larger cities moved faster because they wanted to avoid “cognitive overload” but later researchers overturned this theory, showing that there were actually economic factors at play. Economic productivity has been associated with a faster pace of life, as measured by work speed and walking speed. Researchers suggested that as cities grow, the wage rate and the cost of living increase, and people thus placed higher premium on their time.
When time becomes more valuable and scarce, it’s easier for that to translate into impatience and urgency. With a higher price on your time, are there costs to your health?
One study of metropolitan areas found that self-reported impatience increased young adults’ risk of developing high blood pressure, a major risk factor for heart and kidney disease. One potential mechanism is that impatience can lead to activation of the fight or flight system, or sympathetic nervous system, resulting in an increased heart rate, blood pressure, and a release of stress hormones like adrenaline, noradrenaline and cortisol into the bloodstream.
Small bursts of the sympathetic nervous system can be helpful by increasing energy and awareness and decreasing your sensitivity to pain. But if you are constantly turning on this stress system throughout the day and weeks, the prolonged and higher level of stress hormones wears down your body and mind. The chronic overactivation of this stress response can over time lead to higher blood pressure, lower immunity, decreased muscle tissue and bone density, as well as decreased cognitive performance. In short, you get worn down both physically and mentally.
Studies have suggested that city living is associated with increased rates of depression, anxiety, and psychosis, with 39% more mood disorders and 21% more anxiety disorders. The reasons for these potential urban-rural differences are complex and may depend on factors such as race, immigrant status, working status, and marital status. Do urban environments cause increased rates of psychological issues or is it a selection bias (i.e., people with these disorders are more likely to live in urban areas or have access health care?) One functional magnetic resonance imaging study in Nature examined the potential differences in neurological processing of the stress of urban living and found that city living was associated with increased amygdala activity, the part of the brain important in emotional learning and behavior.
The question of whether and why these urban-rural differences exist remains controversial. A recently published study in Journal of Psychiatric Research found no such urban-rural differences in the prevalence of depression or other mental disorders. Further studies are needed to examine if there are indeed urban-rural differences in psychological disorders, and, if so, the potential mechanisms behind these differences.
As urban populations grow, the issue of urbanization and mental health becomes increasingly relevant. More than half of the world’s population lives in urban areas. By 2050, two-thirds of the world's population is expected to live in cities. It is increasingly important to understand whether and how the city environment and our pace of life affect our physical and mental health. In the meantime, exploring our ability to prevent and stop the negative psychological effects of city life is equally, if not, more important.
This is a first in a series of articles on the Urban Survival blog, examining how to manage the stress of city living.
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Copyright Marlynn Wei, MD, PLLC 2014