A wide number of social factors have been linked to an increased incidence of schizophrenia including poverty, living in the inner-city and coming from an ethnic-minority background. A two-year study of 33 wards in South-East London looked at a number of different variables to see how they affected people's chances of developing the condition. The researchers found that low voter turn-out and ethnic segregation both increased the risk of developing schizophrenia. There was also some evidence that ethnic minority individuals were at greater risk of schizophrenia in areas with smaller proportions of minority groups.
Kirkbride, James B. ... [et al] - Neighbourhood-level effects on psychoses : re-examining the role of context Psychological Medicine 2007, 37, 1413-1425