How is Schizophrenia Diagnosed?

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The symptoms of schizophrenia can be very frightening for the person experiencing them, or for friends and loved ones observing them. If you or someone you care about experiences symptoms that suggest schizophrenia, it’s very important to get advice from a doctor right away. You’ll need to see a psychiatrist to rule out or diagnose schizophrenia. The symptoms may indicate another illness that needs to be treated.

If the diagnosis is schizophrenia it’s very important to begin treatment as soon as possible in order to make the best recovery.

Schizophrenia is a type of mental illness classified as a psychotic disorder. People with schizophrenia have symptoms of psychosis, which make them appear to be out of touch with reality. However, other illnesses may also involve psychotic symptoms. There is no blood test or brain scan to diagnose schizophrenia. Only someone with special training to diagnose mental illness can make an accurate diagnosis of schizophrenia. In order to diagnose schizophrenia, a doctor will perform a variety of interview and psychological tests to determine the patient’s current beliefs and symptoms as well as the history of the patient.

Five Types of Schizophrenia Symptoms

There are five basic types of symptoms of schizophrenia that a doctor will look for when trying to make a diagnosis.

The first four types are described as positive symptoms, and the last type includes all negative symptoms.

In addition to the positive and negative symptoms, a patient may have cognitive symptoms as well. Those symptoms are not specific to the definition of schizophrenia that the doctor will use to make the diagnosis.

Five Types of Schizophrenia

There are five basic subtypes of schizophrenia, which are distinguished by the combination of symptoms a patient experiences. Based on psychological tests and interviews, the formal diagnosis of schizophrenia will specify one of these types.

  • Paranoid Type Schizophrenia. Prominent features of this diagnosis involve hallucinations or delusions fixated on a theme that often involves being plotted against, betrayed or persecuted. Negative symptoms such as flattened affect, catatonia, or disorganized speech are not as prominent as in other types of schizophrenia.
  • Disorganized Type Schizophrenia. This diagnosis describes patients who exhibit disorganized behavior and speech as well as negative symptoms, but relatively fewer hallucinations or delusions.
  • Catatonic Type Schizophrenia. This diagnosis is made when the most prominent symptoms are bizarre behavior and abnormal activity, either very little activity or overly excited behavior.
  • Undifferentiated Type Schizophrenia. These patients show a mixture of psychotic symptoms (delusions, hallucinations, disorganized speech, disorganized behavior, and negative symptoms), with no one type of symptoms dominating the behavior.
  • Residual Type Schizophrenia. This diagnosis is more rarely used than the other four. It describes a patient who at one time met the criteria for one of the other four types but who no longer has significant delusions, hallucinations, disorganized speech or disorganized behavior. To meet this diagnosis, the person will either have negative symptoms like flattened affect or reduced activity or speech, or have greatly reduced, residual positive symptoms like delusions, hallucinations, or disorganized speech or behavior.

Other Psychotic Disorders

Most of the symptoms of schizophrenia are symptoms of psychosis, but it is possible to have psychotic symptoms without having schizophrenia.

Other psychotic disorders include:

  • Schizophreniform Disorder
  • Schizoaffective Disorder
  • Brief Psychotic Disorder
  • Delusional Disorder
  • Shared Psychotic Disorder
  • Psychotic Disorder Due to a General Medical Condition
  • Substance-Induced Psychotic Disorder
  • Psychotic Disorder Not Otherwise Specified

There are also disorders that can have psychosis as a symptom:

  • Mood Disorder with Psychosis
  • Cognitive Disorder with Psychosis
  • Personality Disorders

and disorders that can masquerade as psychosis:

  • Specific Phobia
  • Mental Retardation
  • Somatization Disorder
  • Factitious Disorder
  • Malingering


American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR). Washington, DC: American Psychiatric Association, 2000.

Morrison, J. DSM-IV Made Easy: the Clinician’s Guide to Diagnosis. New York: The Guilford Press, 2006.

Schizophrenia: a detailed booklet that describes symptoms, causes, and treatments, with information on getting help and coping. National Institutes of Mental Health. (2006)

Torrey, E.F. Surviving Schizophrenia: a Manual for Families, Patients and Providers, 5th Edition. New York: HarperCollins Publishers, 2006.

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