The Role of Migration and Acculturation in Moderating Risk of Schizophrenia: An Australian Case-Control Study

Background: Compared to Native Born (NB) populations, elevated rates of schizophrenia have been identified in the First-Generation Migrants (FGMs) and Second-Generation Migrants (SGMs) of numerous countries (‘the migration effect’). However, recent data suggest that FGMs have a reduced risk of psychotic illness in Australia. Methods: Study 1 utilised data from the Australian Schizophrenia Research Bank (ASRB) (N= 1528, cases N=714) and Study 2 consisted of 217 participants recruited from the ASRB (cases N=103). Bivariate and multivariate logistic regression models were employed to examine the effects of migrant status and other psychosocial factors on risk of schizophrenia (expressed as odds ratios (OR)). Results: Overall, FGM status was associated with a significantly reduced relative-risk of schizophrenia compared to NB participants (Study 1 OR = 0.53, p0.05). These effects were moderated by cannabis abuse as well as childhood adversity, which were found to strongly predict schizophrenia in Study 1. Experiences of discrimination increased the odds of schizophrenia in Study 2 (OR=1.27, p<0.05), however this effect was rendered non-significant when substance abuse history was taken into account. Study 2 also found that having a negative affiliation towards mainstream Australian culture and a Marginalised acculturation style more than doubled risk of schizophrenia in the overall sample ((OR = 2.12 and OR = 2.67, p