Zammit also studied individual, school and geographical characteristics that contribute to risk, and found that while the development of psychoses is driven primarily by individual risk factors — such as genetics or personal circumstances — the disconnectedness of urban living could help explain why rates of psychotic disorders were higher in the city than in rural areas. “There are some [city] neighborhoods where there is a lot of migration in and out of those areas and a lot of single parent households,” says Zammit. “We took that as reflecting poorer social networks, areas where there is less social stability.”