What Causes Schizophrenia and How Common Is It?

While schizophrenia is not as common as other psychiatric disorders, about one in every hundred people (1%) develop schizophrenia at some point in their life. It affects men and women at equal rates.

Schizophrenia can affect multiple members within families. It occurs in about 10% of people who have a parent or sibling with the disorder. People who have a second-degree relatives with schizophrenia, like aunts, uncles, grandparents, or cousins, also develop the disorder more often than the general population. The risk is highest for an identical twin of a person with schizophrenia, with a 40 to 65 percent chance of developing the disorder.

What Causes Schizophrenia?

There is no simple answer to what causes schizophrenia because several factors play a part in the onset of the disorder. These factors include:

• A genetic or family history of schizophrenia
• Environmental stressors
• Stressful live events
• Biological factors

Genetic Factors

Research shows that the risk for schizophrenia results from the influence of genes acting together with environmental factors. That means a family history of schizophrenia does not necessarily mean children or other relatives will develop the disorder. However, studies have shown that schizophrenia does run in families.

Environmental Stressors and Life Events

Others believe the environment plays a key role in whether someone will develop schizophrenia. Some of the environmental factors believed to be linked to schizophrenia are malnutrition before birth, obstetric complications, poverty, and substance use. Cannabis use, especially before age 15, has been identified as a big risk factor.

Stressful life events, such as family conflict, early parental loss or separation, and physical or sexual abuse, are also associated with the illness.

Biological Factors

An imbalance of the neurotransmitters dopamine and glutamate is also linked to schizophrenia. Neurotransmitters are brain chemicals that communicate information throughout our brain and body. However, the exact role of these neurotransmitters in schizophrenia is unclear.

Keep Learning and Find Support

The most important thing is to keep learning about schizophrenia and find a safe place to ask questions and feel supported. We offer a free private Facebook group for families with schizophrenia and bipolar disorder. You can also subscribe to receive our newsletter so that you can receive our latest blog posts.

Here are some additional articles you might find helpful:

• Schizophrenia: Overview and Course of the Disorder
• The Symptoms of Schizophrenia
• Antipsychotic Medication: What You Should Know
• Evidence-Based Treatment for Schizophrenia
• Family Support for Schizophrenia: How Family Members Can Help