Discriminant and canonical variate analyses were performed using 302 patients, on whom ratings of lifetime psychopathology and course of illness has been made. DSM-III diagnoses were used to form the criterion groups. Bipolar disorder emerged as a distinct grouping, but there are reasons for dissatisfaction with its definition. The remaining patients formed a 'schizodepressive continuum', but this also had a tendency to bimodality. It is possible that the distinction between schizophrenia and depression was obscured by inadequacies in the data and the inclusion of excessive numbers of patients with schizoaffective depression in this study.

SummaryIn an empirical study on the classification of the psychoses, 302 patients were rated using the Longitudinal Psychopathology Schedule. The data were condensed by factor analysis, which yielded 10 factors - mania and schizomania, depression and suicidal activity, and 6 factors concerned with psychotic symptoms (verbal hallucinosis/passivity, delusion formation, defect symptoms, social decline, cycloid symptomatology and a factor loading depressive auditory hallucinations and visual hallucinations). Provisional diagnostic groups were obtained using DSM III. Discriminant function analyses showed that the only clearly distinct diagnostic group was bipolar disorder, and this was true for various definitions. Canonical variate analyses were performed using 3- and 4-criterion groups. These showed that a group corresponding approximately to cycloid psychosis also met criteria for being a distinct group. The most detailed examination pf the data, using 4-criterion groups and serial reclassification, suggested that the psychoses might fall into 5 groups - bipolar disorder, cycloid psychosis, depression, defect states and schizoaffective depression.

SynopsisA schedule is described for rating the symptoms of mental illness over a period of time which includes several episodes. The reliability was measured in a study involving six raters. The sources of information required were studied, in 20 patients, by comparing an interview with the patient, a similar interview with an informant and an analysis of the case records. A synopsis of interview and record data are necessary to obtain adequate information about longitudinal psychopathology and ‘lifetime’ diagnosis.

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