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Tests and diagnosis

By Mayo Clinic staff

When doctors suspect someone has schizophrenia, they typically ask for medical and psychiatric histories, conduct a physical exam, and run medical and psychological tests and exams. These tests and exams generally include:

  • Laboratory tests. These may include a complete blood count (CBC), other blood tests that may help to rule out other conditions with similar symptoms, screening for alcohol and drugs, and imaging studies, such as an MRI or CT scan.
  • Psychological evaluation. A doctor or mental health provider will check mental status by observing appearance and demeanor and asking about thoughts, moods, delusions, hallucinations, substance abuse, and potential for violence or suicide.

Diagnostic criteria for schizophrenia

To be diagnosed with schizophrenia, a person must meet the criteria spelled out in the Diagnostic and Statistical Manual of Mental Disorders (DSM). This manual is published by the American Psychiatric Association and is used by mental health providers to diagnose mental conditions.

Diagnosis of schizophrenia involves ruling out other mental health disorders and determining that symptoms aren't due to substance abuse, medication or a medical condition. In addition, a person must:

  • Have at least two of the common symptoms of the disorder — delusions, hallucinations, disorganized speech, disorganized or catatonic behavior, or presence of negative symptoms for a significant amount of time during one month
  • Experience significant impairment in the ability to work, attend school or perform normal daily tasks
  • Have had symptoms for at least six months

There are several subtypes of schizophrenia, but not everyone easily fits into a specific category. The five most common subtypes are:

  • Paranoid. Characterized by delusions and hallucinations, this type generally involves less functional impairment and offers the best hope for improvement.
  • Catatonic. People with this subtype don't interact with others, get into bizarre positions, or engage in meaningless gestures or activities.
  • Disorganized. Characterized by disorganized thoughts and inappropriate expressions of emotion, this type generally involves the most functional impairment and offers the least hope for improvement.
  • Undifferentiated. This is the largest group of people with schizophrenia, whose dominant symptoms come from more than one subtype.
  • Residual. This type is characterized by extended periods without prominent positive symptoms, but other symptoms continue.
Treatments and drugs Preparing for your appointment
References
  1. Schizophrenia and other psychotic disorders. In: Diagnostic and Statistical Manual of Mental Disorders DSM-IV-TR. 4th ed. Arlington, Va.: American Psychiatric Association; 2000. http://www.psychiatryonline.com. Accessed Nov. 26, 2011.
  2. Minzenberg MJ, et al. Schizophrenia. In: Hales RE, et al. The American Psychiatric Publishing Textbook of Psychiatry. 5th ed. Washington, D.C.: American Psychiatric Publishing; 2008. http://www.psychiatryonline.com/resourceToc.aspx?resourceID=5. Accessed Nov. 26, 2011.
  3. Schizophrenia. National Institute of Mental Health. http://www.nimh.nih.gov/health/publications/schizophrenia/complete-index.shtml. Accessed Nov. 26, 2011.
  4. Fischer BA, et al. Schizophrenia: Clinical manifestations, course, assessment, and diagnosis. http://www.uptodate.com/home/index.html. Accessed Nov. 26, 2011.
  5. Jibson MD. Schizophrenia: Epidemiology and pathogenesis. http://www.uptodate.com/home/index.html. Accessed Nov. 26, 2011.
  6. Stroup TS, et al. Pharmacotherapy for schizophrenia: Acute and maintenance phase treatment. http://www.uptodate.com/home/index.html. Accessed Nov. 26, 2011.
  7. Aripiprazole. U.S. National Library of Medicine. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000221/. Accessed Nov. 26, 2011.
  8. Risperidone. U.S. National Library of Medicine. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000944/. Accessed Nov. 26, 2011.
  9. Hall-Flavin DK (expert opinion). Mayo Clinic, Rochester, Minn. Nov. 30, 2011.
  10. Wall CA (expert opinion). Mayo Clinic, Rochester, Minn. Dec. 20, 2011.
DS00196 Jan. 27, 2012

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