Deprivation–schizophrenia link accounted for by crime, low education

By Sarah Pritchard, medwireNews Reporter

Study results indicate that the association between area deprivation and first-onset schizophrenia could be accounted for by high crime and low education levels.

The findings emerge from research undertaken in a highly urban area of London, UK, and show that, overall, deprivation scores can predict incidence of schizophrenia after adjusting for ethnicity, ethnic density, population density and population turnover.

Furthermore, high levels of crime and low levels of education emerged as significant individual predictors, suggesting a possible means to reduce schizophrenia incidence because “both of these are potentially modifiable,” remark the researchers.

The team used the Index of Multiple Deprivation (IMD) 2004 to calculate area-level deprivation in the London borough of Lambeth, in which 405 patients aged 16 to 35 years with first-onset schizophrenia presented to mental health services between 2000 and 2007 and were included in the study.

The IMD takes into account seven domains of deprivation, explain Vishal Bhavsar (Institute of Psychiatry, London) and colleagues, including income deprivation, employment deprivation, health deprivation and disability and education.

They completed a regression analysis predicting incidence rate ratios (IRR) for schizophrenia using deprivation scores for super output areas – a geographic area with an average population of 1500 – of which Lambeth has 177. These are nested in 21 electoral wards, which allows analysis of incidence rates at both SOA and ward leve.

The IRR of schizophrenia associated deprivation in SOAs was similar to that in electoral wards, at 1.03 and 1.04, respectively, representing a respective 3% and 4% increased risk of schizophrenia onset per unit increase of deprivation in the area.

The team subsequently tested six of the seven IMD domains individually and found that three were significantly associated with schizophrenia incidence after adjusting for age and gender alone: crime, at an IRR of 1.28, education deprivation, at an IRR of 1.02, and unemployment, at an IRR of 7.61.

However, after adjusting their model further to account for population density and the proportion of ethnic minorities in the area, only crime and education deprivation significantly predicted schizophrenia incidence, with respective IRRs of 1.26 and 1.02.

Bhavsar and co-authors suggest that there is an ongoing challenge in their area of research to develop valid methods to measure the social environment and investigate which aspects are of particular importance in relation to schizophrenia incidence.

“The importance of these findings is that they point towards modifiable population level risk factors for a severe and costly mental illness”, they conclude in Schizophrenia Research.

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