Making the Diagnosis
No diagnostic test exists for schizophrenia. Instead, the disease is identified (usually by a psychiatrist) by the symptoms. This specialist will ask a person about his or her ability to work, socialize, or function. Family and friends might also be called upon to answer questions about the person's behavior.
Your doctor (usually a psychiatrist) will diagnose schizophrenia if your symptoms meet the criteria (based on experiencing certain symptoms for a certain period of time) for a diagnosis. Other possible causes for the symptoms must be ruled out. Psychosis-like behavior can occur with mood disorders, some neurological diseases (e.g., brain tumors), some metabolic or autoimmune diseases, Huntington's disease, liver disease, or reactions to particular medications. Substance abuse can also be responsible for certain behaviors that are similar to the symptoms of schizophrenia.
To investigate further, a doctor might perform computed tomography (CT) or magnetic resonance imaging (MRI) scans. These create detailed images of the brain and can be used to exclude diseases other than schizophrenia. While not diagnostic, CT and MRI changes do occur in some people with schizophrenia.