Schizophrenia - Diagnosis

There are currently no laboratory tests by which schizophrenia can be diagnosed. Some imaging techniques, such as computed tomography (CT) scans, which use X rays to create a picture of internal organs, can be helpful in showing abnormal structures in the brain. CT scans are also sometimes called computerized axial tomography (CAT) scans. For the most part, however, doctors must observe a patient's behavior to decide if he or she is schizophrenic.

The first step in this process is to rule out other physical and mental disorders. Some diseases and disorders of the brain cause symptoms similar to those of schizophrenia. Encephalitis (see encephalitis entry), or brain fever, is one such disease. Encephalitis is caused by a virus and must be treated very differently from schizophrenia.

Psychiatrists also try to distinguish various types of mental disorders from each other. While many disorders have symptoms similar to those of schizophrenia, they may require quite different treatments.

Psychiatrists usually rely on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) in diagnosing a mental disorder. DSMIV is a standard reference book that lists all recognized mental disorders. It also lists the basis on which each disorder is diagnosed. The standards used for diagnosing schizophrenia are as follows:

• A patient must have two or more of the following symptoms during a one-month period: delusions, hallucinations, disorganized speech, disorganized behavior, or lack of normal behaviors (such as the ability to speak).
• The patient shows a decline in social, personal, or occupational functions, including the ability to care for him or herself.
• The disturbed behavior must last for at least six months.
• Other physical and mental problems must be ruled out as causes of the abnormal behavior.