Migrant status, age, gender and social isolation in very late-onset schizophrenia-like psychosis

Background: Data from two retrospective first contact studies suggest that the risk of developing very-late onset schizophrenia-like psychosis (SLP) may be raised in older migrant than British-born populations resident in the UK. Objective: To investigate whether the relative excess of SLP observed amongst younger and male migrants in the above studies might have been explained by differences in the age-gender structures of migrant and British-born denominator populations. A secondary aim was to examine the associations of migrant group status and gender with markers of social isolation. Method: Eighty-six new referrals of SLP to the Mile End (1997 - 2003) and Maudsley (1995 - 2000) hospitals were identified from two retrospective case note studies. Local census data were used to estimate the denominator populations and to calculate rate ratios for migrant and British-born cases of SLP. Case notes were re-examined, to assess markers of social isolation in migrant and British-born patients. Results: Migrant patients were more likely to be male (odds ratio = 4.8; CIodds = 1.8 - 13.2) than British-born patients. The ratio of first contact rates for migrant compared to British-born populations were highest amongst men. There was a lower mean age of onset of SLP in migrant than British-born patients (t = 4.30, 95% Cl = 3.78 - 10.27), which was largely explained by a higher mean age of illness onset in British-born women. There were no differences between migrant and British-born patients with respect to markers of social isolation. Male patients were more likely to have never married than women (odds ratio = 0.28; 95% CI odds = 0.09 - 0.89). Conclusion: The age-gender structure of the background population is not sufficient to explain the socio-demographic differences between migrant and British-born patients with SLP. Male patients may be more socially isolated. Copyright (c) 2005 John Wiley & Sons, Ltd.