Schizophrenia is a devastating brain disorder—the most chronic and disabling of the severe mental illnesses. The first signs of schizophrenia, which typically emerge in young people in their teens or twenties, are confusing and often shocking to families and friends. Hallucinations, delusions, disordered thinking, unusual speech or behavior and social withdrawal impair the ability to interact with others. Most people with schizophrenia suffer chronically or episodically throughout their lives, losing opportunities for careers and relationships. 1 They often are stigmatized by lack of public understanding about the disease. However, several new antipsychotic medications developed within the last decade, which have fewer side effects than the older medications, in combination with psychosocial interventions have improved the outlook for many people with schizophrenia. 2

Some Facts About Schizophrenia

  • In the U.S., approximately 2.2 million adults 3 , or about 1.1 percent of the population age 18 and older in a given year 4 , have schizophrenia.
  • Rates of schizophrenia are very similar from country to country—about 1 percent of the population.5
  • Schizophrenia ranks among the top 10 causes of disability in developed countries worldwide.6
  • The risk of suicide is serious in people with schizophrenia.7

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 Most people with schizophrenia, however, are not violent toward others but are withdrawn and prefer to be left alone.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.8,9

Research Findings

  • Family studies indicate that genetic vulnerability is a risk factor for schizophrenia.10 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.11,12
  • Research suggests that schizophrenia may be a developmental disorder resulting from impaired migration of neurons in the brain during fetal development.13
  • 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.14
  • Schizophrenia can appear in children, though it is very rare. Neuroimaging research of childhood-onset schizophrenia has shown evidence of progressive abnormal brain development.15

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.

Treatments for Schizophrenia

The newer medications for schizophrenia—the atypical antipsychotics—are very effective in the treatment of psychosis, including hallucinations and delusions, and may also help treat the symptoms of reduced motivation or blunted emotional expression.16 Intensive case management, cognitive-behavioral approaches that teach coping and problem-solving skills, family educational interventions, and vocational rehabilitation can provide additional benefit.2 Evidence suggests that early and sustained treatment involving antipsychotic medication improves the long-term course of schizophrenia.17 Over time, many people with schizophrenia learn successful ways of managing even severe symptoms.

Because schizophrenia sometimes impairs thinking and problem solving, some people may not recognize they are ill and may refuse treatment. Others may stop treatment because of medication side effects, because they feel their medication is no longer working, or because of forgetfulness or disorganized thinking. People with schizophrenia who stop taking prescribed medication are at high risk for a relapse of illness.18 A good doctor-patient relationship may help people with schizophrenia continue to take medications as prescribed.19 Developing safer and more effective medications, as well as identifying strategies to enhance the acceptability of currently available treatments, are important NIMH priorities.

Present and Future Research Directions

In addition to the development of new treatments, NIMH research is focusing on the relationships among genetic, behavioral, developmental, social and other factors to identify the cause or causes of schizophrenia. Utilizing increasingly precise imaging techniques, scientists are studying the structure and function of the living brain. New molecular tools and modern statistical analyses are enabling researchers to close in on the particular genes that affect brain development or brain circuitry involved in schizophrenia. Scientists are continuing to investigate possible prenatal factors, including infections, which may affect brain development and contribute to the development of schizophrenia.

New Clinical Trial

NIMH is funding a large-scale clinical trial to compare the effectiveness of the newer, atypical antipsychotic medications for the treatment of schizophrenia. For more information about this study—the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) project—and others, visit the Clinical Trials page of the NIMH Web site.

For More Information

National Institute of Mental Health (NIMH)
Office of Communications and Public Liaison
Public Inquiries: (301) 443-4513
Media Inquiries: (301) 443-4536
Web site:

All material in this fact sheet is in the public domain and may be copied or reproduced without permission from the Institute. Citation of the source is appreciated.

NIH Publication No. 01-4599


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Updated: January 01, 2001