Kraepelin-oriented research-diagnosable schizophrenia, mania, and depression in Schneider-negative schizophrenics.

The rigorous neo-Kraepelinean research criteria of the St. Louis/Iowa and Taylor groups were applied to case record data of 116 first admissions of Schneider-negative schizophrenics--that is, those without first-rank symptoms (FRSs)--hospitalized in a strongly Schneider-oriented German University Psychiatric Clinic from 1962 to 1971. This sample had a total of 45.7% (53 cases) of psychiatric illness diagnosable by research methods. Indeed, only 31% (36 cases) of Schneider-negative schizophrenics turned out to have research-positive Kraepelin-oriented schizophrenia; and of these, 21 fulfilled both sets of research criteria for schizophrenia. It is important that 14.6% (17 cases) of Schneider-negative schizophrenia consisted of research-diagnosable affective disorder, with mania making up 5.2% and depression 9.4% of this figure. The findings suggest that a sample of Schneider-oriented schizophrenia without FRSs as routinely diagnosed in Germany does not seem to represent a clear-cut homogeneous and 'uncontaminated' group of schizophrenics.