<P> Kraepelin acknowledged that "there are many overlaps in this area," that is, the area between schizophrenia and mood disorders . In 1959, psychiatrist Kurt Schneider (1887--1967) began to further refine conceptualizations of the different forms that schizoaffective disorders can take since he observed "concurrent and sequential types". (The concurrent type of illness he referred to is a longitudinal course of illness with episodes of mood disorder and psychosis occurring predominantly at the same time (now called psychotic mood disorders or affective psychosis); while his sequential type refers to a longitudinal course predominantly marked by alternating mood and psychotic episodes .) Schneider described schizoaffective disorders as "cases in - between" the traditional Kraepelinian dichotomy of schizophrenia and mood disorders . </P> <P> The historical clinical observation that schizoaffective disorder is an overlap of schizophrenia and mood disorders is explained by genes for both illnesses being present in individuals with schizoaffective disorder; specifically, recent research shows that schizophrenia and mood disorders share common genes and polygenic variations . </P> <P> Schizoaffective disorder was included as a subtype of schizophrenia in DSM - I and DSM - II, though research showed a schizophrenic cluster of symptoms in individuals with a family history of mood disorders whose illness course, other symptoms and treatment outcome were otherwise more akin to bipolar disorder than to schizophrenia . DSM - III placed schizoaffective disorder in "Psychotic Disorders Not Otherwise Specified" before being formally recognized in DSM - III - R. DSM - III - R included its own diagnostic criteria as well as the subtypes, bipolar and depressive . In DSM - IV, published in 1994, schizoaffective disorders belonged to the category "Other Psychotic Disorders" and included almost the same criteria and the same subtypes of illness as DSM - III - R, with the addition of mixed bipolar symptomatology . </P> <P> DSM - IV and DSM - IV - TR (published in 2000) criteria for schizoaffective disorder were poorly defined and poorly operationalized . These ambiguous and unreliable criteria lasted 19 years and led clinicians to significantly overuse the schizoaffective disorder diagnosis . Patients commonly diagnosed with DSM - IV schizoaffective disorder showed a clinical picture at time of diagnosis that appeared different from schizophrenia or psychotic mood disorders using DSM - IV criteria, but who as a group, were longitudinally determined to have outcomes indistinguishable from those with mood disorders with or without psychotic features . A poor prognosis was assumed to apply to these patients by most clinicians, and this poor prognosis was harmful to many patients . The poor prognosis for DSM - IV schizoaffective disorder was not based on patient outcomes research, but was caused by poorly defined criteria interacting with clinical tradition and belief; clinician enculturation with unscientific assumptions from the diagnosis' history (discussed above), including the invalid Kraepelinian dichotomy; and by clinicians being unfamiliar with the scientific limitations of the diagnostic and classification system . </P>

When was schizoaffective disorder added to the dsm
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