An admission diagnosis of paranoid schizophrenia was noted in 41 patients of 247 consecutive admissions to an acute-treatment psychiatric inpatient unit. Only two of these 41 satisfied research criteria for schizophrenia, whereas half satisfied research criteria for mania.
The group whose conditions were rediagnosed as manic was compared with a group of schizophrenic and manic patients for whom admission and research diagnoses concurred. Noticeable differences from the former group and almost no differences from the latter group were found for demographic, genetic, phenomenologic, and treatment-response variables.
These data suggest that many patients whose conditions are diagnosed as paranoid schizophrenia actually suffer from an affective illness and rarely satisfy rigorous criteria for schizophrenia.
Abrams R, Taylor MA, Gaztanaga P. Manic-Depressive Illness and Paranoid SchizophreniaA Phenomenologic, Family History, and Treatment-Response Study. Arch Gen Psychiatry. 1974;31(5):640-642. doi:10.1001/archpsyc.1974.01760170040006