The course and outcome of cycloid psychosis.

Thirty patients with cycloid psychosis were found among 244 general psychotic and schizo-affective patients studied in London. The main clues to the diagnosis were the presence of "confusion', a pleomorphic clinical picture or an acute onset. Most of the patients were classified as schizophrenic by British psychiatrists and the Catego system, and as schizo-affective or mood-incongruent affective psychotics by the American Research Diagnostic Criteria and DSM-III. There was little overlap between the cycloids and any Anglo-American category, and cycloid psychosis is not synonymous with schizo-affective psychosis. The outcome of the cycloids was better than that of psychotic patients as a whole, and much better than schizophrenia as defined by Catego, Schneider's, Langfeldt's or Carpenter's rules, or by the guidelines set by the International Classification of Diseases. Compared with manic-depressive patients (defined by the presence of mania at some stage), cycloids had more schizophrenic and fewer depressive and manic symptoms. There was a negligible concordance between the diagnosis of cycloid psychosis and the final diagnosis of manic-depressive disease. It is concluded that these patients should not be diagnosed as schizophrenic, but that the relation of cycloid psychosis to manic-depressive disease is not yet resolved.