Schizophrenia Risk Factors

Scientists have been studying schizophrenia for a long time, trying to determine what causes this complex and challenging psychiatric disorder. While a specific cause has not yet been determined, most believe that schizophrenia is caused by a combination of things, including genetics and environmental factors.

Family History

With regards to risk factors for developing schizophrenia, a family history of the disorder still ranks highest 1. Although schizophrenia develops in only about 1% of the population, having a parent with schizophrenia increases the risk to 10% 2. The odds increase to 30% to 40% if both parents are schizophrenic 3. Having an identical twin with schizophrenia makes the risk quite high at 40% to 50% 2


There are many environmental factors which have been linked to the development of schizophrenia, although none is considered a “cause” of the disorder. These include, but are not limited to:

  • Traumatic or highly stressful events in childhood
  • Drug use
  • Maternal complications or illnesses during pregnancy
  • Malnutrition during pregnancy
  • Maternal exposure to the toxoplasmosis parasite 3
  • Complications during birth
  • Living in the city
  • Being born during winter months
  • Living in a more developed country

Abnormalities in the brain

Many individuals with schizophrenia have structural or functional anomalies in their brain. These include things such as enlarged ventricles, metabolic differences, and differences in size of certain areas of the brain.

Other potential risk factors

Other potential risk factors for schizophrenia include a drop in childhood IQ scores, having OCD, being left-handed, having an older father, or the presence of epilepsy in one’s family history 4.

written by Dr. Cheryl Lane, PsyD


  1. Schizophrenia: A Review
  2. What Causes Schizophrenia?
  3. Toxoplasmosis Parasite May Trigger Schizophrenia And Bipolar Disorders
  4. Schizophrenia Risk Factors

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