Many a soul has been known to proclaim, usually in great frustration, that cities make them crazy. Most of those folks, of course, don't mean it in a literal sense. They just mean that they find the crowded streets, noise, traffic, congestion, conflict, dirt, and/or general difficulty of maneuvering that comes with most urban environments frustrating, annoying or a hassle.
It turns out, however, that there may be something real to that complaint. For some time, researchers have noted a higher rate of what they call non-affective psychosis (psychiatric illnesses such as schizophrenia, which aren't based in a person's emotions, as opposed to illnesses such as depression) among urban populations than in rural groups. But it wasn't clear what particular factors led to that difference, or even whether the difference was really due to the urban environment itself, or reflected individual traits of people who tended to live in cities.
But a study published recently by the American Medical Association indicates that certain elements of city living may, indeed, raise a person's risk of developing schizophrenia or other non-affective disorders.
The authors of the study conducted a longitudinal survey of every person born in Sweden in 1972 and 1977. They identified which ones lived in or moved to cities during childhood and which ones contracted non-affective psychiatric illnesses as adults--along with a wide variety of other data, from the ethnicity of each individual and the diversity present in their neighborhoods and schools, to any deprivation or challenging economic circumstances they may have experienced growing up.
The researchers paid particular attention to childhood environments because schizophrenia, one of the main illnesses they were investigating, tends to emerge in young adulthood. And while it appears that genetics play a strong role in a person's risk for schizophrenia, environmental factors may play a role in whether the disease actually manifests itself.
As expected, the people surveyed who lived or had moved to urban environments had a higher rate of schizophrenia and other similar illnesses. But the researchers wanted to know what part of urban living seemed to increase that risk. And interestingly enough, the factor that showed the strongest correlation was something the researchers called "social fragmentation."
In very stable, homogenous communities (as is often the case in more rural environments), the social norms and bonds are very consistent and strong. But in urban environments, where there tends to be much more diversity and movement within communities, social ties are often more fragmented. And that fragmentation is felt most among people who move often, or feel like "outsiders" in a particular community.
The results showed, for example, that someone moving to a new community could have a higher risk of developing schizophrenia. The risk was also higher if they were a member of a minority group in an otherwise homogenous community. If the community reflected their own ethnic background, so they weren't so much of an outsider, the risk was reduced. Likewise, the risk for a member of a majority group in a homogeneous community went up if the community became diverse enough that their group became the minority, instead. Researchers also noted that these risk factors weren't limited to ethnic or racial characteristics. Any characteristic that made a person "different" from the surrounding group, including economic differences, increased their risk of schizophrenia or other "non-affective" disorders.