Causes of schizophrenia

Genetic causes

Schizophrenia tends to run in families in a similar way to conditions such as heart disease.

The lifetime risk for schizophrenia is approximately 1%. It has been found that having one parent affected by schizophrenia increases this to 13%. When both biological parents are affected, the lifetime risk goes up to 46%.

Abnormal brain development

Brain scans have shown that people with schizophrenia may have abnormalities of the brain. It has also been found that the volume of certain parts of the brain are increased or reduced in some people with schizophrenia. 

Birth complications

Research has found that complications during pregnancy and birth is associated more with people with schizophrenia than people without.

Psychological triggers

The main psychological triggers that can lead to the onset of symptoms of schizophrenia are stressful life events. These kinds of experiences don’t cause schizophrenia themselves but can trigger its development in someone who is already vulnerable to it.

Substance misuse

Drugs do not directly cause schizophrenia. However, there is evidence consistent with the view that certain drugs such as cannabis can trigger psychosis. This risk is increased when cannabis is used during adolescence. This is a particular risk for those that may already be vulnerable to mental health problems, like those who have a history of mental illness in the family.

More information on what causes schizophrenia can be found in our Schizophrenia factsheet (237 kb)