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The differential diagnosis of schizophrenia and affective disease: New empirical scales for the MMPI

1 July 1987


A review of the recent literature on the differential diagnosis of schizophrenia suggests that schizophrenia has been overdiagnosed in relation to affective disorders. This tendency to inadequately define schizophrenia in clinical and research endeavors has been due to emphasis on "schizophrenic symptoms" to justify the diagnosis. Evidence suggests that the MMPI has never been successful in the differential diagnosis of schizophrenics. A study by Davies (1984) hypothesized that an unknown, and significant, number of criterion "schizophrenics" used in the construction of Scale 8 were really subjects with affective disorders who had been misdiagnosed as schizophrenic. The Davies study developed three new MMPI subscales to: (a) differentiate schizophrenics from controls, (b) differentiate bipolar manics from controls, and (c) differentiate manics from schizophrenics. The study did not attempt to separate schizophrenics from depressives and it is assumed that the resultant subscale (SCZ-T) remains contaminated with items more indicative of depression than schizophrenia. Just as problems exist in the differential diagnosis of schizophrenia, there are similar problems in diagnosing affective disorders. The ICD-9 and the DSM-III may be of questionable utility in the differential diagnosis of affective disorders. George Winokur (1981) has proposed a new classification schema of primary affective disorders. He makes a major distinction between bipolar and unipolar depression. Unipolar depressions display no history of mania and can be divided into two major groups according to family psychiatric history. Patients with familial pure depressive disease (FPDD) have first degree relatives who suffer from depression but have no significant history of mania, alcoholism or sociopathy. Clients with depressive spectrum disease (DSD) have an excess of psychiatric illness (including depression, alcoholism, or antisocial behavior) in first degree relatives. The purpose of the present study is to build upon the work of Winokur and Davies to develop new MMPI subscales capable of differentially diagnosing: 1) Schizophrenic disorders, 2) Primary depression (unipolar and bipolar), and 3) major subtypes of Primary Unipolar Depression.


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