• Cases of unclassified psychosis were assessed with a nine-variable diagnostic measure designed to discriminate schizophrenia and primary affective disorder. As a group, the unclassified cases occupied a midway position between and overlapping with cases of schizophrenia and primary affective disorder. Also, the mean discriminant-function score of the unclassified group was significantly different from the mean scores of the groups with affective disorder and schizophrenia, although one subgroup of unclassified cases was statistically indistinguishable from the group with schizophrenia. While this investigation was essentially unsuccessful in reclassifying unclassified psychosis, it demonstrates a method for reclassifying diagnostic groups. When this procedure is used in conjunction with follow-up and family studies, it provides a basis for modifying diagnostic criteria.
Fowler RC, Mezzich J, Liskow BI, Van Valkenburg C. Schizophrenia-Primary Affective Disorder DiscriminationII. Where Unclassified Psychosis Stands. Arch Gen Psychiatry. 1980;37(7):815-817. doi:10.1001/archpsyc.1980.01780200093011