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Schizophrenia Health Center

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Schizophrenia and Schizoaffective Disorder

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What Causes Schizoaffective Disorder?

While the exact cause of schizoaffective disorder is not known, researchers believe that genetic, biochemical, and environmental factors are involved:

  • Genetics (heredity): A tendency to develop schizoaffective disorder may be passed on from parents to their children.
  • Brain chemistry: People with schizophrenia and mood disorders may have abnormalities in the functioning of brain circuits that regulate mood and thinking.
  • Environmental factors: Theories suggest that certain environmental factors -- such as a viral infection, poor social interactions or highly stressful situations -- may trigger schizoaffective disorder in people who have inherited a tendency to develop the disorder. However, the relationships between biological and environmental factors that may lead to schizoaffective disorder are not well understood.

Who Gets Schizoaffective Disorder?

Schizoaffective disorder usually begins in the late teen years or early adulthood, often between the ages of 16 and 30. It seems to occur slightly more often in women than in men and is rare in children.

How Common Is Schizoaffective Disorder?

Because people with schizoaffective disorder have a combination of symptoms reflecting two separate mental illnesses, it is often misdiagnosed. Some people may be misdiagnosed as having schizophrenia, and others may be misdiagnosed with a mood disorder. As a result, it is difficult to determine exactly how many people actually are affected by schizoaffective disorder. However, it is believed to be less common than either schizophrenia or affective disorder alone. Estimates suggest that about one in every 200 people (0.5%) develops schizoaffective disorder at some time during his or her life.

How Is Schizoaffective Disorder Diagnosed?

If symptoms of schizoaffective disorder are present, the doctor will perform a complete medical history and physical exam. Although there are no laboratory tests to specifically diagnose schizoaffective disorder, the doctor may sometimes use various tests -- such as brain imaging (e.g., MRI scans) and blood tests -- to rule out a physical illness as the cause of the symptoms.

If the doctor finds no physical reason for the symptoms, he or she may refer the person to a psychiatrist or psychologist, mental health professionals who are trained to diagnose and treat mental illnesses. Psychiatrists and psychologists use specially designed interview and assessment tools to evaluate a person for a psychotic disorder. A diagnosis of schizoaffective disorder is made if a person has periods of uninterrupted illness and has, at some point, an episode of mania, major depression or a mix of both, while also having symptoms of schizophrenia. In addition, to diagnose the illness, the person must display a period of at least two weeks of psychotic symptoms without the mood symptoms.

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