From ants to cities
More on the work of E. O. Wilson
Yesterday, I introduced a 50-minute film concerning the famous biologist E O Wilson, Lord of the Ants which, as well as being a wonderful tribute to Prof. Wilson, also allowed us humans to have a better understanding of our deeper human issues.
Coincidentally, around the same time of watching that film, I saw an article on the Grist website that referred to some research published in Nature magazine. This what I read, first from Grist, reprinted with the kind permission of Libby S., Senior Marketing Manager of Grist.
Scientists have been doing studies for years that show you are more likely to suffer from mental illness if you live in a city. What they haven’t figured out is why.
Now, researchers in Germany have conducted experiments that they believe might begin to get at the neuroscience behind the crazy-making nature of urban areas.
Publishing in the journal Nature, a group led by Andreas Meyer-Lindenberg of the University of Heidelberg’s Central Institute of Mental Health in Mannheim, Germany, looked at how social stress affected the minds of subjects, some city-dwellers and some not.
If we then turn to that article in Nature (to get access you will need to arrange prior free sign-up) we get to read this,
City living marks the brain
Neuroscientists study social risk factor for mental illness.
Epidemiologists showed decades ago that people raised in cities are more prone to mental disorders than those raised in the countryside. But neuroscientists have avoided studying the connection, preferring to leave the disorderly realm of the social environment to social scientists. A paper in this issue of Naturerepresents a pioneering foray across that divide.
Using functional brain imaging, a group led by Andreas Meyer-Lindenberg of the University of Heidelberg’s Central Institute of Mental Health in Mannheim, Germany, showed that specific brain structures in people from the city and the countryside respond differently to social stress (see pages 452 and 498). Stress is a major factor in precipitating psychotic disorders such as schizophrenia.
The work is a first step towards defining how urban life can affect brain biology in a way that has a potentially major impact on society — schizophrenia affects one in 100 people. It may also open the way for greater cooperation between neuroscientists and social scientists. “There has been a long history of mutual antipathy, particularly in psychiatry,” says sociologist Craig Morgan at the Institute of Psychiatry in London. “But this is the sort of study that can prove to both sides that they can gain from each others’ insights.”
I feel uncomfortable about reproducing more of this fascinating study without some formal permission to do so, therefore, if you want to read the full article then do sign up for access at the Nature website.
Back to the article from Grist written by Sarah Goodyear, Grist’s cities editor,
I called Dr. Meyer-Lindenberg to ask him more about the implications of his experiment, and what he thought might be the cause of heightened sensitivity to social stress among urban dwellers.
“On the neural level, we find two things,” he told me. “A, the neural effects are completely dissociated, so current urban living only affects the amygdala, urban upbringing only affects the cingulate. And B, these areas are associated with these illnesses. The amygdala is sort of a danger center, and it’s critically important for fear. And it is clear that the amygdala is a major player in depression. The cingulate is a prefrontal area regulating negative emotion, and it’s known to be one of the earliest areas affected by schizophrenia.”
So what accounts for the hyperactivity of the amygdala-cingulate circuit in urban dwellers? “That exact circuit that we found hyperactive has also shown to be activated when someone comes too close to you and crowds your personal space,” Meyer-Lindenberg told me.
But he cautioned against inferring that mere density of population is at fault. “It’s still speculation,” he said. “There could be myriad components of the urban experience that might or might not be bad for you from the point of your risk for mental illness. No one really knows. People are annoyed by noise or by traffic, or it could also be lead, or air pollution, but there’s no evidence base to say this is an important factor, this is not an important factor. Therefore there’s no basis for urban planning that’s grounded in human biology, at least with regard to mental illness.”
Later in the Grist article, Dr. Meyer-Lindenberg told Sarah Goodyear,
“Social status is closely linked to socioeconomic variables. What we found in our imaging studies is that if your social status becomes labile, and especially if you are in danger of losing it, a very similar brain circuit becomes active. There is a convergence of socially relevant risk factors on that circuit.”
Different types of urban environments might also affect people in different ways. “It’s very different if you live in Manhattan and you sort of live in a series of overlapping villages, if you will, or if you live in a city like Sao Paolo, in which no such microstructure is immediately available to you, or if you live in a large spread-out area,” said Meyer-Lindberg.
The social connections that are fostered in more walkable neighborhoods could help city dwellers from losing it. “A previous study found that that the size of your social support network is actually correlated to the size of the exact brain circuit we found in this study,” Meyer-Lindenberg said. “So that’s a protective factor. The more friends you have, the bigger those brain structures are.”
Already, more than half the human population lives in cities. That proportion will only increase. New cities are springing up all over the developing world, some built to order, some completely unplanned. The form they take could be crucial.
More knowledge about what exactly drives people could lead to concrete solutions that would make for better mental health — the same way the discovery of how disease was spread by waterborne germs finally ended the scourge of cholera in London.
“I think it would be important to make cities better, given that we can’t escape cities, given the dynamics of urbanization,” said Meyer-Lindenberg. “That’s a reality that we’re not going to get rid of.”
Fascinating article made doubly interesting by E O Wilson’s lifetime study of ants!
Written by Paul Handover
August 5, 2011 at 00:00