New directions in the epidemiology of schizophrenia.

New primary data and systematic reviews have prompted the review of some long-held views about the epidemiology of schizophrenia. The incidence and prevalence of schizophrenia show prominent variation between locations. Males are more likely to develop schizophrenia than females (1.4 : 1). Migrant status, urban birth or residence, and advanced paternal age are associated with an increased risk of developing schizophrenia. Prenatal infection and nutrition are associated with an increased risk of schizophrenia. Individuals with schizophrenia have a 2-3-fold increased mortality risk compared with the general population. This differential mortality gap may have worsened in recent decades. Epidemiology is good for generating candidate exposures but poor at proving them. Cross-disciplinary projects between epidemiology and neuroscience may help us understand the pathways leading to schizophrenia.