The Differential Diagnosis of Schizoaffective Disorder
John M. Kane, MD
Department of Psychiatry, The Zucker Hillside Hospital, Glen Oaks, and the Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx, New York
Initial Psychiatric Interview
The initial psychiatric interview is critical in making an accurate diagnosis of schizoaffective disorder.1 This interview should include a history of the patient’s chief complaint, details of the present illness, a past psychiatric history, a review of systems, and a mental status examination.
Obtaining an accurate history can be difficult because patients often do not recall the duration and time course of specific signs and symptoms of their disorder and may have problems remembering exactly what their mood was during a psychotic episode. One tool clinicians might use to help obtain an accurate record is a structured diagnostic interview tool, such as the SCID-CV.2 Details should also be gathered from family members whenever possible, and prior medical and psychiatric records can sometimes be helpful.
Careful completion of a mental status examination is an essential component in making a differential diagnosis. Clinicians should take particular note of the presence of mood disturbances and psychotic signs and symptoms, determine their duration and intensity, and evaluate the extent to which these symptom domains have been apparent, either concurrently or separately, over time.
Conceptual Framework of Schizoaffective Disorder
The relevance of obtaining an accurate record becomes acutely apparent when clinicians try to place a patient’s symptoms within the conceptual framework of schizoaffective disorder in either the DSM-IV-TR3 or the ICD-10.4 Differing definitions of the disorder in the DSM-IV-TR and ICD-10 may result in varying diagnoses for patients.5
DSM-IV-TR criteria. The DSM-IV-TR3 criterion A for schizoaffective disorder states that, during the course of illness, patients must have experienced an uninterrupted mood episode concurrently with schizophrenic symptoms for a significant portion of a 1-month period. Criterion B states that, during the same period of illness, either delusions or hallucinations occurred for at least 2 weeks without prominent mood symptoms being present. However, criterion C requires that mood symptoms must also occupy a substantial portion of the total duration of the illness.
Using DSM-IV-TR criteria, the diagnosis of schizoaffective disorder can be subdivided into either bipolar or depressive type. The bipolar type includes a manic or mixed episode, or a manic or mixed episode and a major depressive episode. The depressive subtype can be specified if only major depressive episodes occur.
ICD-10 criteria. The ICD-104 guidelines for schizoaffective disorder state that affective and schizophrenic symptoms develop together, are equally prominent, and occur within the same episode. The affective and schizophrenic symptoms should preferably occur simultaneously but can occur within a few days of each other. The schizoaffective diagnosis should not be used if the schizophrenic and affective symptoms occur only in separate episodes of the illness.
Subtypes of schizoaffective disorder specified in ICD-10 include manic type, depressive type, and mixed type. For all subtypes, at least 1 and preferably 2 of the following schizophrenic symptoms should be clearly present during the mood episodes: thought interference; delusions of control, influence, or passivity, or delusional perception; hallucinatory voices; or other persistent delusions that are culturally inappropriate or humanly impossible.
In the manic type, prominently elevated mood, or elevated mood accompanied by increased irritability or excitement, should occur within the same episode as symptoms of schizophrenia. In the depressive type, schizophrenic symptoms and depressed mood are both prominent in the same episode and must be accompanied by at least 2 other depressive symptoms or behavioral abnormalities. The mixed type of schizoaffective disorder can be diagnosed when the patient has had at least 1 manic, hypomanic, or mixed episode and currently has either a mixture of or rapidly alternating manic, hypomanic, and depressive symptoms.
Common diagnostic mistakes. Most clinicians will recognize DSM-IV-TR criterion A, but many will omit criterion B and/or criterion C. Omitting these criteria can lead to a misdiagnosis of the symptoms as major depressive disorder with psychotic features, bipolar disorder, or schizophrenia.
Differentiating Schizoaffective Disorder From Schizophrenia and Other Disorders
Because schizoaffective disorder shares symptoms with both mood and other psychotic disorders, making a differential diagnosis can be difficult. Although cognitive impairments might help to differentiate between schizoaffective disorder and other psychotic disorders, unique patterns of cognitive dysfunction to distinguish patients with these differential diagnoses have not yet been clearly identified.6 However, schizophrenia and schizoaffective disorder appear to have similar patterns of cognitive deficits, and these patterns seem to differ from those seen in major depression, bipolar disorder
(AV 1),7 and Alzheimer's dementia.8
Schizophrenia. Kendler and colleagues9 examined disorder severity and suggested that, compared with patients with schizophrenia, patients with schizoaffective disorder have more prominent depressive and manic symptoms, less severe negative symptoms and hallucinations, and better overall functioning (P ≤ .05 for all). Examining symptom frequency, Benedetti and colleagues10 found fewer hallucinations and first-rank psychotic symptoms, significantly fewer catatonic symptoms (P < .01), and significantly fewer negative symptoms (P < .001) in patients with schizoaffective disorder compared with those with schizophrenia (AV 2). Regarding family history, affective illness in first-degree relatives is much more common in those with schizoaffective disorder than in those with schizophrenia (P = .03), although the rate of schizophrenia in relatives is similar between the 2 groups.9
Mood disorders with psychotic features. When delusions or hallucinations occur exclusively during periods of mood disturbance, the diagnosis of mood disorder with psychotic features may be used.3 In terms of severity, patients with schizoaffective disorder have significantly worse negative symptoms (P < .001, see AV 2),10 more severe depression (P < .05)11 and worse overall functioning (P ≤ .01)9 than those with psychotic affective illness. Additionally, psychotic symptoms last longer in schizoaffective disorder than they do in mood disorders.12 A family history of schizophrenia is more frequent in patients with schizoaffective disorder than in those with mood disorders (P = .02).9
Schizophreniform disorder. Symptoms of schizophreniform disorder meet DSM-IV-TR criterion A for schizophrenia but do not meet the duration criteria for schizophrenia, ie, symptoms last at least 1 month but less than 6 months. Impairment of social and occupational functioning is not required.
Brief psychotic disorder. Brief psychotic disorder involves the sudden onset of at least 1 of the following symptoms: delusions, hallucinations, disorganized speech, or grossly disorganized or catatonic behavior.3 An episode lasts at least 1 day but less than 1 month, and the patient eventually returns to his or her premorbid level of functioning.
Delusional disorder. When a patient has delusional disorder, the only psychotic symptoms are delusions and, thus, do not meet criterion A for schizoaffective disorder.3 The delusions should not be bizarre (ie, the delusions involve real-life or plausible situations). Tactile and olfactory hallucinations may be present if they relate to the delusions. Delusions should persist for at least 1 month.
Substance-induced psychotic disorder. When prominent hallucinations or delusions are the direct result of the physiologic effect of a drug of abuse, a medication, or exposure to a toxin, the diagnosis of substance-induced psychotic disorder is appropriate. Two subtypes can be used: with delusions or with hallucinations.
Psychotic disorder not otherwise specified. When delusions, hallucinations, disorganized speech, and/or grossly disorganized or catatonic behavior are present but do not meet criteria for other disorders, or when insufficient information exists, the most appropriate diagnosis may be psychotic disorder not otherwise specified.
Re-evaluation of Diagnosis Over Time
Longitudinal studies5,13 of patients with schizoaffective disorder indicate that the diagnosis may change over time; in addition, studies14,15 have shown inter-rater reliability for diagnosing schizoaffective disorder to be low. Because the distinguishing features of the disorder emerge over time, making an accurate diagnosis depends on eliciting an accurate history of signs and symptoms, as well as documenting the duration, intensity, and time course of symptoms. Documentation of the history and symptoms is also crucial for treating the patient at a later date, as a clear idea of the basis on which the diagnosis was made is needed by the clinician to either maintain the diagnosis or to recognize new information that might result in a change of diagnosis.
For Clinical Use
- Take a careful history of the patient’s symptoms (including duration, intensity, and co-occurrence), involving informants and previous medical records, if possible, and document your findings
- Place your findings within the framework of the DSM-IV-TR or ICD-10 criteria, and differentiate schizoaffective disorder from other psychotic diagnoses
- Re-evaluate your diagnosis over time
CPT = Continuous Performance Test
DSM-IV-TR = Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision
NR = not reported
ICD-10 = International Classification of Diseases, Tenth Revision
SCID-CV = Structured Clinical Interview for DSM-IV Axis I Disorders–Clinician Version
- McIntyre KM, Norton JR, McIntyre JS. Psychiatric interview, history, and mental status examination. In: Sadock BJ, Sadock VA, Ruiz P, eds. Kaplan & Sadock's Comprehensive Textbook of Psychiatry, Vol I. 9th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009:886–906.
- First MB, Spitzer RL, Gibbon M, et al. Structured Clinical Interview for DSM-IV Axis I Disorders: Clinician Version (SCID-CV). Washington, DC: American Psychiatric Press, Inc; 1996.
- American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision. Washington, DC: American Psychiatric Association; 2000.
- World Health Organization. The ICD-10 Classification of Mental and Behavioural Disorders: Clinical Descriptions and Diagnostic Guidelines. Geneva, Switzerland: World Health Organization; 1992. http://www.who.int/classifications/icd/en/bluebook.pdf. Accessed September 15, 2010.
- Malhi GS, Green M, Fagiolini A, et al. Schizoaffective disorder: diagnostic issues and future recommendations. Bipolar Disord. 2008;10(1, pt 2):215–230.
- Keefe RS, Fenton WS. How should DSM-V criteria for schizophrenia include cognitive impairment? Schizophr Bull. 2007;33(4):912–920.
- Jabben N, Arts B, van Os J, et al. Neurocognitive functioning as intermediary phenotype and predictor of psychosocial functioning across the psychosis continuum: studies in schizophrenia and bipolar disorder. J Clin Psychiatry. 2010;71(6):764–774.
- Buchanan RW, Davis M, Goff D, et al. A summary of the FDA-NIMH-MATRICS workshop on clinical trial design for neurocognitive drugs for schizophrenia. Schizophr Bull. 2005;31(1):5–19.
- Kendler KS, McGuire M, Gruenberg AM, et al. Examining the validity of DSM-III-R schizoaffective disorder and its putative subtypes in the Roscommon Family Study. Am J Psychiatry. 1995;152(5):755–764.
- Benedetti A, Pini S, de Girolamo G, et al. The psychotic spectrum: a community-based study. World Psychiatry. 2009;8(2):110–114.
- Reichenberg A, Harvey PD, Bowie CR, et al. Neuropsychological function and dysfunction in schizophrenia and psychotic affective disorders. Schizophr Bull. 2009;35(5):1022–1029.
- Ghaemi SN. Mood Disorders: A Practical Guide. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2008.
- Abrams DJ, Rojas DC, Arciniegas DB. Is schizoaffective disorder a distinct categorical diagnosis? a critical review of the literature. Neuropsychiatr Dis Treat. 2008;4(6):1089–1109.
- Sprock J. Classification of schizoaffective disorder. Compr Psychiatry. 1988;29(1):55–71.
- Maj M, Pirozzi R, Formicola AM, et al. Reliability and validity of the DSM-IV diagnostic category of schizoaffective disorder: preliminary data. J Affect Disord. 2000;57(1–3):95–98.