Risk Factors

Schizophrenia is the most common psychotic condition, affecting about 1% of people worldwide.

Age

Schizophrenia can occur at any age, but it tends to first develop (or at least become evident) between adolescence and young adulthood, typically between the ages of 16 - 30 years. It rarely occurs before adolescence or after age 45.

Gender

Schizophrenia affects both men and women. Men are more likely than women to develop schizophrenia at an earlier age and to experience more severe symptoms.

Family History

Schizophrenia often runs in families.

Environmental Factors

Various environmental factors may play a role in the development of schizophrenia, especially for people who already have a genetic predisposition. Environmental factors possibly associated with schizophrenia include:

• Viral infections. Factors that increase exposure to viruses (living in urban environments, large families, winter and spring births) have been associated with higher risk for schizophrenia.
• Prenatal and Perinatal Problems. Maternal exposure to viruses, maternal malnutrition, and birth complications (such as a baby experiencing lack of oxygen during delivery) may be linked to schizophrenia.
• Father’s age. According to some studies, the older a father is when a child is born, the greater the risk is for schizophrenia in his offspring, perhaps because of a greater chance of genetic mutations in the sperm that can be passed on.
• Childhood trauma. Although parental influence is no longer believed to directly lead to the development of schizophrenia, certain types of childhood trauma (including sexual and physical abuse) may play a role.

Review Date: 01/27/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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