Diagnosis of schizophrenia

The diagnosis of schizophrenia is based on criteria in either the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, version DSM-IV-TR, or the World Health Organization's International Statistical Classification of Diseases and Related Health Problems, the ICD-10.^[1] These criteria use the self-reported experiences of the person and reported abnormalities in behavior, followed by a clinical assessment by a mental health professional. Symptoms associated with schizophrenia occur along a continuum in the population and must reach a certain severity before a diagnosis is made.^[2] As of 2009 there is no objective test.^[1]

Criteria

The ICD-10 criteria are typically used in European countries, while the DSM-IV-TR criteria are used in the United States and the rest of the world, and are prevailing in research studies. The ICD-10 criteria put more emphasis on Schneiderian first-rank symptoms. In practice, agreement between the two systems is high.^[3]

According to the revised fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), to be diagnosed with schizophrenia, three diagnostic criteria must be met:^[4]

1. Characteristic symptoms: Two or more of the following, each present for much of the time during a one-month period (or less, if symptoms remitted with treatment).
   • Delusions
   • Hallucinations
   • Disorganized speech, which is a manifestation of formal thought disorder
   • Grossly disorganized behavior (e.g. dressing inappropriately, crying frequently) or catatonic behavior
   • Negative symptoms: Blunted affect (lack or decline in emotional response), alogia (lack or decline in speech), or avolition (lack or decline in motivation)

   If the delusions are judged to be bizarre, or hallucinations consist of hearing one voice participating in a running commentary of the patient's actions or of hearing two or more voices conversing with each other, only that symptom is required above. The speech disorganization criterion is only met if it is severe enough to substantially impair communication.

2. Social or occupational dysfunction: For a significant portion of the time since the onset of the disturbance, one or more major areas of functioning such as work, interpersonal relations, or self-care, are markedly below the level achieved prior to the onset.
3. Significant duration: Continuous signs of the disturbance persist for at least six months. This six-month period must include at least one month of symptoms (or less, if symptoms remitted with treatment).

If signs of disturbance are present for more than a month but less than six months, the diagnosis of schizophreniform disorder is applied.^[4] Psychotic symptoms lasting less than a month may be diagnosed as brief psychotic disorder, and various conditions may be classed as psychotic disorder not otherwise specified. Schizophrenia cannot be diagnosed if symptoms of mood disorder are substantially present (although schizoaffective disorder could be diagnosed), or if symptoms of pervasive developmental disorder are present unless prominent delusions or hallucinations are also present, or if the symptoms are the direct physiological result of a general medical condition or a substance, such as abuse of a drug or medication.

Subtypes

The DSM-IV-TR contains five sub-classifications of schizophrenia, although the developers of DSM-5 are recommending they be dropped from the new classification:^[5][6]

• Paranoid type: Where delusions and hallucinations are present but thought disorder, disorganized behavior, and affective flattening are absent. (DSM code 295.3/ICD code F20.0)
• Disorganized type: Named hebephrenic schizophrenia in the ICD. Where thought disorder and flat affect are present together. (DSM code 295.1/ICD code F20.1)
• Catatonic type: The subject may be almost immobile or exhibit agitated, purposeless movement. Symptoms can include catatonic stupor and waxy flexibility. (DSM code 295.2/ICD code F20.2)
• Undifferentiated type: Psychotic symptoms are present but the criteria for paranoid, disorganized, or catatonic types have not been met. (DSM code 295.9/ICD code F20.3)
• Residual type: Where positive symptoms are present at a low intensity only. (DSM code 295.6/ICD code F20.5)

The ICD-10 defines two additional subtypes:^[6]

• Post-schizophrenic depression: A depressive episode arising in the aftermath of a schizophrenic illness where some low-level schizophrenic symptoms may still be present. (ICD code F20.4)
• Simple schizophrenia: Insidious and progressive development of prominent negative symptoms with no history of psychotic episodes. (ICD code F20.6)

Differential

See also: Dual diagnosis

Psychotic symptoms may be present in several other mental disorders, including bipolar disorder,^[7] borderline personality disorder,^[8] drug intoxication and drug-induced psychosis. Delusions ("non-bizarre") are also present in delusional disorder, and social withdrawal in social anxiety disorder, avoidant personality disorder and schizotypal personality disorder. Schizophrenia is complicated with obsessive-compulsive disorder (OCD) considerably more often than could be explained by pure chance, although it can be difficult to distinguish obsessions that occur in OCD from the delusions of schizophrenia.^[9]

A more general medical and neurological examination may be needed to rule out medical illnesses which may rarely produce psychotic schizophrenia-like symptoms,^[4] such as metabolic disturbance, systemic infection, syphilis, HIV infection, epilepsy, and brain lesions. It may be necessary to rule out a delirium, which can be distinguished by visual hallucinations, acute onset and fluctuating level of consciousness, and indicates an underlying medical illness. Investigations are not generally repeated for relapse unless there is a specific medical indication or possible adverse effects from antipsychotic medication.

"Schizophrenia" does not mean dissociative identity disorder—formerly and still widely known as "multiple personalities"—despite the etymology of the word (Greek σχίζω = "I split").^[2]

Controversies

The scientific validity of schizophrenia, and its defining symptoms such as delusions and hallucinations, have been criticized.^[10][11]

There is an argument that the underlying issues would be better addressed as a spectrum of conditions^[12] or as individual dimensions along which everyone varies rather than by a diagnostic category based on an arbitrary cut-off between normal and ill.^[13] This approach appears consistent with research on schizotypy, and with a relatively high prevalence of psychotic experiences, mostly non-distressing delusional beliefs, among the general public.^[14][15][16] In concordance with this observation, psychologist Edgar Jones, and psychiatrists Tony David and Nassir Ghaemi, surveying the existing literature on delusions, pointed out that the consistency and completeness of the definition of delusion have been found wanting by many; delusions are neither necessarily fixed nor false, and need not involve the presence of incontrovertible evidence.^[17][18][19]

Nancy Andreasen, a leading figure in schizophrenia research, has criticized the current DSM-IV and ICD-10 criteria for sacrificing diagnostic validity for the sake of artificially improving reliability. She argues that overemphasis on psychosis in the diagnostic criteria, while improving diagnostic reliability, ignores more fundamental cognitive impairments that are harder to assess due to large variations in presentation.^[20][21] This view is supported by other psychiatrists.^[22] In the same vein, Ming Tsuang and colleagues argue that psychotic symptoms may be a common end-state in a variety of disorders, including schizophrenia, rather than a reflection of the specific etiology of schizophrenia, and warn that there is little basis for regarding DSM’s operational definition as the "true" construct of schizophrenia.^[12] Neuropsychologist Michael Foster Green went further in suggesting the presence of specific neurocognitive deficits may be used to construct phenotypes that are alternatives to those that are purely symptom-based. These deficits take the form of a reduction or impairment in basic psychological functions such as memory, attention, executive function and problem solving.^[23][24]

The exclusion of affective components from the criteria for schizophrenia, despite their ubiquity in clinical settings, has also caused contention. This exclusion in the DSM has resulted in a "rather convoluted" separate disorder—schizoaffective disorder.^[22] Citing poor interrater reliability, some psychiatrists have totally contested the concept of schizoaffective disorder as a separate entity.^[25][26] The categorical distinction between mood disorders and schizophrenia, known as the Kraepelinian dichotomy, has also been challenged by data from genetic epidemiology.^[27]

References

1. ^ ^{a b} van Os J, Kapur S. Schizophrenia. Lancet. 2009;374(9690):635–45. doi:10.1016/S0140-6736(09)60995-8. PMID 19700006.
2. ^ ^{a b} Picchioni MM, Murray RM. Schizophrenia. BMJ. 2007;335(7610):91–5. doi:10.1136/bmj.39227.616447.BE. PMID 17626963.
3. ^ Jakobsen KD, Frederiksen JN, Hansen T, et al.. Reliability of clinical ICD-10 schizophrenia diagnoses. Nordic Journal of Psychiatry. 2005;59(3):209–12. doi:10.1080/08039480510027698. PMID 16195122.
4. ^ ^{a b c} American Psychiatric Association. Diagnostic and statistical manual of mental disorders: DSM-IV. Washington, DC: American Psychiatric Publishing, Inc.; 2000 [cited 2008-07-04]. ISBN 0-89042-024-6. Schizophrenia.
5. ^ American Psychiatric Association DSM-5 Work Groups (2010) Proposed Revisions – Schizophrenia and Other Psychotic Disorders. Retrieved 17 February 2010.
6. ^ ^{a b} "The ICD-10 Classification of Mental and Behavioural Disorders" (pdf). World Health Organization. p. 26. http://www.who.int/classifications/icd/en/GRNBOOK.pdf. 
7. ^ Pope HG. Distinguishing bipolar disorder from schizophrenia in clinical practice: guidelines and case reports [PDF]. Hospital and Community Psychiatry. 1983 [cited 2008-02-24];34:322–28.
8. ^ McGlashan TH. Testing DSM-III symptom criteria for schizotypal and borderline personality disorders. Archives of General Psychiatry. 1987;44(2):143–8. PMID 3813809.
9. ^ Bottas A. Comorbidity: Schizophrenia With Obsessive-Compulsive Disorder. Psychiatric Times. April 15, 2009;26(4).
10. ^ Boyle, Mary. Schizophrenia: a scientific delusion?. New York: Routledge; 2002. ISBN 0-415-22718-6.
11. ^ Bentall, Richard P.; Read, John E; Mosher, Loren R.. Models of Madness: Psychological, Social and Biological Approaches to Schizophrenia. Philadelphia: Brunner-Routledge; 2004. ISBN 1-58391-906-6.
12. ^ ^{a b} Tsuang MT, Stone WS, Faraone SV. Toward reformulating the diagnosis of schizophrenia. American Journal of Psychiatry. 2000;157(7):1041–50. doi:10.1176/appi.ajp.157.7.1041. PMID 10873908.
13. ^ Peralta V, Cuesta MJ. A dimensional and categorical architecture for the classification of psychotic disorders. World Psychiatry. 2007;6(2):100–1. PMID 18235866.
14. ^ Verdoux H, van Os J. Psychotic symptoms in non-clinical populations and the continuum of psychosis. Schizophrenia Research. 2002;54(1–2):59–65. doi:10.1016/S0920-9964(01)00352-8. PMID 11853979.
15. ^ Johns LC, van Os J. The continuity of psychotic experiences in the general population. Clinical Psychology Review. 2001;21(8):1125–41. doi:10.1016/S0272-7358(01)00103-9. PMID 11702510.
16. ^ Peters ER, Day S, McKenna J, Orbach G. Measuring delusional ideation: the 21-item Peters et al. Delusions Inventory (PDI). Schizophrenia Bulletin. 2005;30(4):1005–22. PMID 15954204.
17. ^ Jones E. The Phenomenology of Abnormal Belief: A Philosophical and Psychiatric Inquiry. Philosophy, Psychiatry and Psychology. 1999;6(1):1–16.
18. ^ David AS. On the impossibility of defining delusions. Philosophy, Psychiatry and Psychology. 1999 [cited 2008-02-24];6(1):17–20.
19. ^ Ghaemi SN. An Empirical Approach to Understanding Delusions. Philosophy, Psychiatry and Psychology. 1999 [cited 2008-02-24];6(1):21–24.
20. ^ Andreasen NC. Schizophrenia: the fundamental questions. Brain Res. Brain Res. Rev.. 2000;31(2–3):106–12. doi:10.1016/S0165-0173(99)00027-2. PMID 10719138.
21. ^ Andreasen NC. A unitary model of schizophrenia: Bleuler's "fragmented phrene" as schizencephaly. Archives of General Psychiatry. 1999;56(9):781–7. doi:10.1001/archpsyc.56.9.781. PMID 12884883.
22. ^ ^{a b} Jansson LB, Parnas J. Competing definitions of schizophrenia: what can be learned from polydiagnostic studies?. Schizophr Bull. 2007;33(5):1178–200. doi:10.1093/schbul/sbl065. PMID 17158508.
23. ^ Green MF, Nuechterlein KH. Should schizophrenia be treated as a neurocognitive disorder?. Schizophr Bull. 1999;25(2):309–19. PMID 10416733.
24. ^ Green, Michael. Schizophrenia revealed: from neurons to social interactions. New York: W.W. Norton; 2001. ISBN 0-393-70334-7. Lay summary: NEJM book review.
25. ^ Lake CR, Hurwitz N. Schizoaffective disorder merges schizophrenia and bipolar disorders as one disease—there is no schizoaffective disorder. Curr Opin Psychiatry. 2007;20(4):365–79. doi:10.1097/YCO.0b013e3281a305ab. PMID 17551352.
26. ^ Malhi GS, Green M, Fagiolini A, Peselow ED, Kumari V. Schizoaffective disorder: diagnostic issues and future recommendations. Bipolar Disorders. 2008;10(1 Pt 2):215–30. doi:10.1111/j.1399-5618.2007.00564.x. PMID 18199238.
27. ^ Craddock N, Owen MJ. The beginning of the end for the Kraepelinian dichotomy. Br J Psychiatry. 2005;186:364–6. doi:10.1192/bjp.186.5.364. PMID 15863738.

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