There are many theories about the cause of schizophrenia, but none have been proved.

There is some evidence that genetics may play a role. Your chance of developing schizophrenia is 10 times greater if your parent or sibling has the disease.² But having a relative with schizophrenia does not mean you will get this disease. Many people develop schizophrenia who do not have a relative with this condition.

Schizophrenia may also be related to problems experienced during pregnancy, including malnutrition or exposure to a viral infection, that can damage an unborn child's developing brain and nervous system.² Recent evidence suggests that treating a pregnant woman who has high blood pressure with diuretics during the third trimester may put the baby at risk for later developing schizophrenia.³

Another recent study suggests that a child is at greater risk for developing schizophrenia if the father is over the age of 50 when the child is conceived.⁴ Another possible cause is a head injury in a child who has a parent or sibling with schizophrenia-the head injury may trigger this brain disease if the child is genetically already at risk.⁵

Schizophrenia symptoms also have been linked with the use of illegal drugs.

More research is needed to understand the cause(s) of schizophrenia.