Some Facts About Schizophrenia
In the U.S., approximately 2.2 million adults, or about 1.1 percent of the population age 18 and older in a given year, have schizophrenia. Rates of schizophrenia are very similar from country to country¿about 1 percent of the population. Schizophrenia ranks among the top 10 causes of disability in developed countries worldwide. The risk of suicide is serious in people with schizophrenia.
News and entertainment media tend to link mental illnesses including schizophrenia to criminal violence. Most people with schizophrenia, however, are not violent toward others but are withdrawn and prefer to be left alone. Drug or alcohol abuse raises the risk of violence in people with schizophrenia, particularly if the illness is untreated, but also in people who have no mental illness.
Research Findings
Family studies indicate that genetic vulnerability is a risk factor for schizophrenia. A person with a parent or sibling with schizophrenia has approximately a 10 percent risk of developing the disorder compared to a 1 percent risk for a person with no family history of schizophrenia. At the same time, among individuals with schizophrenia who have an identical twin, and thus share the exact genetic makeup, there is only a 50 percent chance that both twins will be affected with the disease. Scientists conclude that nongenetic factors, such as environmental stress perhaps occurring during fetal development or at birth, also may contribute to the risk of schizophrenia.Research suggests that schizophrenia may be a developmental disorder resulting from impaired migration of neurons in the brain during fetal development. Advances in neuroimaging have shown that some people with schizophrenia have abnormalities in brain structure consisting of enlarged ventricles, the fluid-filled cavities deep within the brain. Schizophrenia can appear in children, though it is very rare. Neuroimaging research of childhood-onset schizophrenia has shown evidence of progressive abnormal brain development.
While providing clues about the brain regions involved in schizophrenia, these findings are not yet sufficiently specific to schizophrenia to be useful as a diagnostic test.
