Causes of Schizophrenia

According to the National Institute of Mental Health (NIMH), approximately 2.2 million adults have schizophrenia. There is no known single cause of the disease. Scientists do not yet understand what causes schizophrenia, but believe it may be a combination of genes, environment, behavior, and other factors. Researchers are investigating all of these factors to learn the cause.

Is Schizophrenia Hereditary?

People who have a close relative with schizophrenia are more likely to develop the disorder than people who do not have a relative with the illness. For example, an identical twin of a person with schizophrenia has the highest risk — 40% to 50% — of developing the illness. A child whose parent has schizophrenia has about a 10% chance. The risk of schizophrenia in the general population is about 1%.

Scientists think that there are several genes that may make a person more likely to develop schizophrenia. Environmental factors, such as prenatal illness or birth complications, may also influence the development of schizophrenia. Even with this information, doctors are not yet able to predict who will develop the illness.

Is Schizophrenia Associated With a Chemical Defect in the Brain?

Substances that allow communication between nerve cells in the brain, called neurotransmitters, are thought to be involved in the development of schizophrenia. The disorder may be associated with an imbalance of the complex chemical systems of the brain, affecting these neurotransmitters.

Is Schizophrenia Caused by a Physical Abnormality in the Brain?

Many studies of people with schizophrenia have found small differences in brain structure, such as an enlargement of the fluid-filled cavities, called the ventricles, in the interior of the brain. Others have shown a decreased size of certain brain regions or decreased activity in certain brain regions.

Visit the NIMH Web site for more detailed information on the possible causes of schizophrenia.

Talk to Your Doctor

If you have additional questions or concerns about this topic, talk to your doctor.