[Epidemiology of schizophrenic disorders, genetic and environmental risk factors]

Schizophrenia is a relatively common pathology with onset at adolescence or early adulthood, more frequent in men than women. By describing distribution of cases in different populations and the factors that influence this distribution, epidemiology contributes to our understanding of the disease. Several risk factors for schizophrenia have been uncovered both genetic and environmental. The environmental factors can act at individual level (obstetric complications, season of birth, urbanicity, childhood trauma, cannabis, migration) or at population/area levels (socio-economic level, social fragmentation and social capital, ethnic density, etc.). An integrative and dynamic model based on the "vulnerability-persistence-impairment" paradigm is useful in integrating the findings about the risk factors and their complex relationships.