New research shows that urban neighborhoods with high levels of deprivation, population density, and inequality have higher rates of schizophrenia.
The researchers used data from the East London first-episode psychosis study. This study was conducted in three inner-city, ethnically diverse boroughs in East London: City & Hackney, Newham, and Tower Hamlets.
The study included 427 people between the ages of 18 and 64, all of whom experienced a first episode of a psychotic disorder in East London between 1996 and 2000.
The researchers assessed their social environment through measures of the neighborhood in which they lived at the time they first presented to mental health services because of a psychotic disorder. Using the 2001 census, they estimated the population in each neighborhood, and then compared the incidence rate between neighborhoods.
The incidence of schizophrenia — and other similar disorders where hallucinations and delusions are the dominant feature — still showed variation between neighborhoods after taking into account age, sex, ethnicity and social class, according to the researchers.
The study showed that three environmental factors predicted risk of schizophrenia: Increased deprivation, which includes employment, income, education and crime; increased population density; and an increase in inequality, i.e., the gap between the rich and poor.
Results from the study suggested that a percentage point increase in either neighborhood inequality or deprivation was associated with an increase in the incidence of schizophrenia and other similar disorders of around 4 percent.
“Although we already know that schizophrenia tends to be elevated in more urban communities, it was unclear why,” said James Kirkbride, Ph.D., lead author of the study from the University of Cambridge.
“Our research suggests that more densely populated, more deprived and less equal communities experience higher rates of schizophrenia and other similar disorders. This is important because other research has shown that many health and social outcomes also tend to be optimal when societies are more equal.”
“Our research adds to a wider and growing body of evidence that inequality seems to be important in affecting many health outcomes, now possibly including serious mental illness,” Kirkbride said. “Our data seems to suggest that both absolute and relative levels of deprivation predict the incidence of schizophrenia.
“East London has changed substantially over recent years, not least because of the Olympic regeneration,” he continued. “It would be interesting to repeat this work in the region to see if the same patterns were found.”
The study also found that the risk of schizophrenia in some migrant groups might depend on the ethnic composition of their neighborhoods.
For black African people, the study found that rates tended to be lower in neighborhoods where there were a greater proportion of other people of the same background.
By contrast, rates of schizophrenia were lower for the black Caribbean group when they lived in more ethnically integrated neighborhoods.
These findings support the possibility that the sociocultural composition of our environment could influence the risk of schizophrenia and other similar disorders.
The research was published in the journal Schizophrenia Bulletin.
Source: University of Cambridge