This is your brain on stress and city living
Although city life offers many advantages and even some health benefits, meta-analyses indicate that city living is a substantial risk factor for mood and anxiety disorders. Basically, people who live in cities have a higher incidence for these disorders. Also, genetically predisposed individuals are at an even greater risk if they are brought up in cities. In schizophrenia, for example, the incidence is nearly doubled in subjects that were born, raised and currently lived in the city. And let’s not forget that, usually, with city life comes a more stressful social environment, a factor known to exacerbate many psychiatric disorders, particularly the ones mentioned above.
So how is it that being from/living in a certain place can affect how your brain works?
In order to understand this question, Lederborgen et al (2011) used functional magnetic resonance imaging (fMRI) to study the neural responses of subjects taking a social stressor task that consisted of solving math problems under time pressure while also receiving negative feedback from the experimenter. The subjects differed in terms of their living conditions, as they were from urban (+100,000 people), town (+10,000) or rural areas.
The task was an effective stressor as it successfully induced stress, indexed by increases in heart rate, blood pressure, and salivary cortisol (stress hormone) levels. In addition, there was significant activity in brain areas implicated in the stress response, emotion, and social behavior. Of these, 2 major areas exhibited the most robust changes:
- Amygdala: Current city living was associated with increased amygdala activity. Activation positively correlated with the size of the city that the individual currently lived in, with city dwellers having the highest levels of amygdala activation.
- Anterior cingulate cortex: Activation correlated with the upbringing (or how long) a person had lived in a city. Individuals that were entirely brought up in cities showed the greatest perigenual anterior cingulate cortex (pACC) activation. This region is important due to its role in the regulation of amygdala activity during negative affect and stress.
Moreover, the authors show evidence suggesting that there is reduced functional connectivity between the amygdala and specifically, the perigenual anterior cingulate cortex of those participants that were born and raised in cities. Considering that weakened coupling of these areas has also been linked to genetic risk for psychiatric disorders, these findings have important clinical relevance. Now let’s stretch our thinking- with urbanization increasingly becoming the way of life and the very real risk of overcrowding, what does this mean for brain development?
The authors state that the results were not explained by demographic/clinical factors or a number of other variables. They have also been able to replicate their findings in a larger and better distributed sample. However, they recognize that limitations of their work include that their study was purely correlational and they discuss the need for a larger scale study that has ways of identifying and measuring more variables that may be related to city living.
For those of you that live (or were brought up) in cities, cheer up. There are a variety of reasons for choosing to live (and enjoy) the city life. In a way, the city has its way of forcing you into developing coping strategies- which is a good thing, right? Now here’s something to think about: psychologists have even found that one of the factors accounting for the preference of city living is the degree of control that people have (and feel they have) over their lives.
Sources:
Kennedy, DP & Adolphs R. 2011. Stress and the city. Comment on: Nature. 474: 452-3. doi: 10.1038/474452a
Lederborgen et al. 2011. City living and urban upbringing affect neural social stress processing in humans. Nature. 474: 498-500. oi: 10.1038/nature10190
