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.

So what do we make of those results? Dr. Stanley Zammit, who headed the study out of Cardiff University in Great Britain, emphasized that this is only one study and more research is necessary before drawing too many conclusions.

But in a way, the results make sense. "Non-affective psychosis" refers to diseases in which a person's sense of reality becomes skewed. So it follows that circumstances or environmental factors that disturb a person's view of reality might leave someone more vulnerable to that kind of disorder. And moving, or anything that fragments our accepted social networks, certainly impacts the stability of what is "real" in our lives.

After all, moving isn't called "uprooting" for nothing. All we knew and counted on as "normal" shifts, and we have to learn a new normal. And what that new "normal" is can be harder to discern in a densely populated and diverse community, or one whose norms are different from the ones we knew before.

That's not to say we should all stay in unchanging, segregated communities. Change, integration and diversity have many advantages over parochial segregation. They allow groups to bring a greater variety of approaches and viewpoints to any problem. They offer individuals a greater exposure to the rich breadth of cultures and backgrounds that exist in the world. And to the extent that exposure to different communities, cultures and diversity in general lead to first-hand knowledge and individual friendships among people, it can reduce stereotypical views or fears about people who come from different ethnic, religious, racial or cultural backgrounds.

But diverse and integrated communities are more challenging environments to live in, because we tend to identify most comfortably with people whom we view, for whatever reason, as "like us." It's uncomfortable and unsettling for our views of what's normal to be challenged by others around us who have different customs, expectations, behavior, and bonds that we don't share.

What's "real" or "normal" is also less clear in a diverse environment. And if a person is one of only a few outsiders in that kind of environment, there's not a lot of reinforcement that their own personal reality is valid. So it makes a certain amount of sense that for someone already genetically susceptible to something like schizophrenia, that extra fragmentation or confusion could be a problematic trigger. 

Again, Dr. Zammit's results only represent one study. And his study took place in Sweden, which has a far more homogeneous culture than the United States. But if his conclusions hold up, they certainly argue for the importance of strong neighborhood and community bonds, especially within urban environments. They also suggest that we would do well to look for the pieces of shared human experience that connect us, no matter how much we differ in background, opinions, culture, religion or appearance. Our mental health might well depend upon it.

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