How Bad are Cities for Your Mental Health?

Until a few decades ago, cities were harder on your physical health than were rural areas. The advent of modern public health and medical technology has essentially turned that around, so that life expectancy is almost uniformly higher in urban areas of developing countries than in rural areas. But what about mental health? As long ago as 1938 Louis Wirth was arguing that the high density and impersonal nature of cities was not good for human existence. Then came Calhoun's famous studies of the rats of NIMH, showing how disruptive high density living can be in the rat kingdom. In an article in this week's Nature, Alison Abbott raises this issue again, but this time looking at specific mental illnesses to see if they might have distinctive urban origins in the way the brain works in different urban environments.

Now, a few scientists are tackling the question head on, using functional brain imaging and digital monitoring to see how people living in cities and rural areas differ in the way that their brains process stressful situations. “Yes, city-stress is a big, messy concept, but I believed it should be possible to at least see if brains of city-dwellers looked somehow different,” says Andreas Meyer-Lindenberg, director of the Central Institute for Mental Health in Mannheim, Germany. And if scientists can work out what aspects of the city are the most stressful, the findings might even help to improve the design of urban areas. “Everyone wants the city to be beautiful but no-one knows what that means,” says Meyer-Lindenberg. Wider streets? Taller buildings? More trees? “Architects theorize a lot, but this type of project could deliver a scientific basis for a city code.”

You can see that this goes beyond the earlier arguments of density being a problem. Here the focus is on the built environment, more than the social world of urban places. New technologies in geographically tracking the activity spaces of people have also allowed people to think in new ways about what we might be able to learn about the brain-environment relationship.

Meyer-Lindenberg is planning an even more technologically ambitious project with geoscientists at the nearby University of Heidelberg, who have generated a high-resolution map of their city, and physicists at the Karlsruhe Institute of Technology in Germany, who have developed a mobile device that allows people to be tracked and tested for a week as they walk and work around Heidelberg. The device can recognize when participants reach a specific location — such as a green space or a particularly noisy intersection — and instantly question them about their state of mind or send them a cognitive test to be completed on the spot. The scientists will then ask the participants to come into the lab for brain-imaging studies that examine how they process stress and emotion. By correlating the imaging data with their states of mind at different locations, the team hopes to trace how different aspects of city life affect the brain — whether, for example, strolling through a park really does have a calming influence on the amygdala and cingulate cortex.

At first blush, these seem like rich city issues, as I have noted before, but one could hope that if this research revealed that specific types of urban environments really were beneficial or detrimental to health, then there would be motivation to do something about them in cities of developing countries as well--those places that will absorb most of the increase in human numbers over the next few decades.