Epidemiology and risk factors

There is a large literature on the epidemiology of schizophrenia, but a number of key points are particularly pertinent. The incidence of schizophrenia is highest among males and certain ethnic minority groups. An urban birth and upbringing is a risk factor for schizophrenia, but the size of this effect at the individual level is small. Early motor, language and cognitive developmental impairments appear to be specific to schizophrenia-related disorders, whereas childhood social, emotional and behavioural problems are associated with a wide range of psychiatric disorders in adulthood. Many prenatal and perinatal risk factors for schizophrenia have been identified although their causal mechanism of action awaits elucidation. In addition, a strong link between cannabis use, particularly in adolescence, and later development of schizophrenia has been established. It is likely that schizophrenia is due to a complex interaction of genetic and non-genetic risk factors of small effect.