This study confirmed marked heterogeneity in risk for psychotic disorders by person and place, including higher rates in younger men, racial/ethnic minorities, and areas characterized by a lower percentage of owner-occupied houses.

Recent years have seen considerable progress in epidemiological and molecular genetic research into environmental and genetic factors in schizophrenia, but methodological uncertainties remain with regard to validating environmental exposures, and the population risk conferred by individual molecular genetic variants is small. There are now also a limited number of studies that have investigated molecular genetic candidate gene-environment interactions (G × E), however, so far, thorough replication of findings is rare and G × E research still faces several conceptual and methodological challenges. In this article, we aim to review these recent developments and illustrate how integrated, large-scale investigations may overcome contemporary challenges in G × E research, drawing on the example of a large, international, multi-center study into the identification and translational application of G × E in schizophrenia. While such investigations are now well underway, new challenges emerge for G × E research from late-breaking evidence that genetic variation and environmental exposures are, to a significant degree, shared across a range of psychiatric disorders, with potential overlap in phenotype.

Background-Despite increasing evidence suggesting that childhood maltreatment is significantly associated with psychosis, the specific role of bullying in the onset of psychotic disorders is still unclear. This study aimed to examine whether bullying was more prevalent amongst individuals presenting to services for the first time with a psychotic disorder than in unaffected community controls.Methods-Data on exposure to bullying, psychotic symptoms, cannabis use and history of conduct disorder were collected cross-sectionally from 222 first-presentation psychosis cases and 215 geographically-matched controls. Bullying victimisation was assessed retrospectively as part of the Brief Life Events schedule. Logistic regression was used to examine associations between exposure to bullying and case-control status, while controlling for potential confounders.Results-Psychosis cases were approximately twice as likely to report bullying victimisation when compared to controls. No significant interactions between bullying and either gender or cannabis use were found. Controls reporting being a victim of bullying were approximately twice as likely to also report at least one psychosis-like symptom.Conclusions-Our results extend previous research by suggesting that bullying victimisation may contribute to vulnerability to develop a psychotic disorder in some individuals.

IntroductionIntroductionaaAlthough childhood abuse is a recognised risk factor for depression, post-traumatic stress disorder, and substance misuse, its role in the aetiology of psychotic disorder remained controversial. This is in part because the putative effect of childhood trauma on psychosis has been mostly evaluated by small, cross sectional, uncontrolled studies that raised methodological issues.MethodsPapers concerning the association between childhood trauma and psychotic disorders (to November, 2011) were identified using a comprehensive search of PubMed, Psychinfo, and Scopus and analysing reference list of relevant papers. A narrative synthesis was used to summarise results.ResultsAn association between childhood abuse and psychotic symptoms was consistently reported by large cross sectional surveys with an effect ranging from 1.7 to 15. However, we cannot conclude that the relationship is causal as lack of longitudinal studies prevent us from fully excluding alternative explanations such as reverse causality. Gender, cannabis use, and depressive and post-traumatic stress disorder symptoms appear to moderate the effect of childhood trauma on psychotic disorders. However, specificity of childhood abuse in psychotic disorders and, particularly, in schizophrenia has not been demonstrated.ConclusionAlthough the association between childhood abuse and psychosis has been replicated, the etiological role of such early adversity has yet to be fully clarified. So far none of the studies reported support the hypothesis that childhood abuse is either sufficient or necessary to develop a psychotic disorder. It seems likely that any effect of childhood abuse on schizophrenia needs to be understood in terms of genetic susceptibility and interaction with other environmental risk factors.