Association between schizophrenia and social inequality at birth: case–control study

Abstract

Background The association between social inequality at birth and subsequent risk of schizophrenia is uncertain. Aims To investigate the relationship between adult-onset schizophrenia and two indicators of social inequality at birth: social class and area of residence. Method A matched case–control design was used with data from birth certificates of first-episode cases and age— and gender-matched controls. Results Risk increased with increasing levels of deprivation at birth. Subjects whose fathers were social class IV–V or who were born in deprived areas were at increased risk of schizophrenia (odds ratio=2.1; 95% Cl=0.8–5.5). Risk was greater in those with both of these indicators (odds ratio=8.1; 95% CI=2.7–23.9). There was some evidence that associations were stronger in older subjects. Exclusion of African–Caribbeans or cases with positive family history somewhat attenuated the association. Conclusions Indicators of social inequality at birth are associated with increased risk of adult-onset schizophrenia, suggesting that environmental factors are important determinants of schizophrenic disorders.