Text: Jean-Christophe Piot
Photo: Adamquest

Running rampant in the city: psychosis

Several studies have confirmed that schizophrenia is more common in urban than in rural areas. So what are the mechanisms involved?

Is the city bad for mental health? The idea is not new. “The observation of a higher number of schizophrenics in urban areas dates back to 1939,” says Philippe Conus, chief of the Department

of Psychiatry at Lausanne University Hospital (CHUV). This hypothesis has been confirmed in recent research from the Institute of Psychiatry at King’s College London. The findings are conclusive. Schizophrenia, like other psychotic disorders, is twice as common in urban environments. With half of the world’s population living in cities these days, the implications are huge.

Understanding the causes of this correlation is not easy. “Epidemiological studies have their limits,” the psychiatrist admits. Hence the idea of launching a study with an original approach, at the crossroads between human sciences and life sciences. Led by the Department of Psychiatry at the CHUV and the Institute of Geography at the University of Neuchâtel, with the support of the Swiss National Research Foundation, this project initiated by Philippe Conus and geographer Ola Söderström will,
in its first stage, cover about forty patients who have recently developed early signs of the illness.

How can we distinguish between specifically urban factors, genetic, biological or psychological predisposition and external stress factors?

Its aim? To pinpoint the specific factors that contribute to the development of the disease, and the solution that could isolate their impact in the emergence of this complex, multi-faceted pathology. How can we distinguish between specifically urban factors, genetic, biological or psychological predisposition and external stress factors? How can we account for the fact that city dwellers are more often diagnosed with the disease than their fellow citizens from rural areas?

“We don’t know if the size of the city plays a part in the prevalence of schizophrenia,” says Philippe Conus, “but it is understood that the risk increases with the number of years spent in the city, especially in childhood. And this effect persists, even after correcting the potential impact of other more common risk factors in the city, such as the use of cannabis.”

By filming their reactions over a series of journeys through the city, researchers expect to identify which areas are experienced by these patients as safe and which are stressful. All of these factors will then be analysed against epidemiological data compiled by psychiatrists. Supported by the Swiss branch of the International Society for Psychological and Social Approaches to Psychosis (ISPS), this first phase will help define various hypotheses which will then be verified in broader patient groups over the next three years. This should result in valuable insight into better understanding the disease.