Scientists find link between urban life, brain’s response to stress

Offering new meaning to the expression “tough town,” German and Canadian neuroscientists have shown that living in a city -- or being raised in one -- is associated with differences in the way the brain handles stress.

The discovery, reported Wednesday in the journal Nature, marks the first time researchers have used functional magnetic resonance imaging (fMRI) to identify specific brain regions that are affected by urban life.

Hooking study subjects up to fMRI machines and stressing them by administering a timed math test (and then criticizing their performance), the researchers found that people who were current city dwellers had increased activity in the amygdala during stress, compared with those raised in small towns or rural areas. Subjects who had been brought up in cities had greater activity in the perigenual anterior cingulate cortex.

Both brain regions are involved in processing stress.

Although the work doesn’t prove that living in the city causes the changes in the brain, it could one day help improve life for city dwellers, co-author Jens Preussner, a researcher at Montreal’s Douglas Mental Health University, said in a statement.

People who live in cities are at higher risk for anxiety, mood disorders and schizophrenia, Preussner noted. The brain pathways identified in the team’s experiment may have something to do with this. Understanding the basic biological mechanisms could lead to strategies to combat mental health problems among city dwellers in the future.

The fact that 70% of the world’s population is projected to live in cities by the year 2050, wrote Caltech neuroscientists Daniel P. Kennedy and Ralph Adolphs in an accompanying article, “highlights the importance of understanding the effects that [urban] living conditions will have on human mental health.”

They wrote that an “obvious next step” would be for scientists to try to identify exactly how various aspects of city living -- population density, housing types, social heirarchies -- might change the way brains operate under stress.

They also called on researchers to look at the positive side of city life, noting that studies have shown higher rates of suicide in rural areas than in cities.