Comparative studies of thought disorders. I. Mania and schizophrenia.

Thought disorder in 20 manic and 43 schizophrenic patients was examined using the Thought Disorder Index. To ensure the inclusion of patients with unambiguous mania and schizophrenia, the patients met Research Diagnostic Criteria, DSM-III criteria, and Washington University (St Louis) criteria. While the quantity of thought disorder did not differ significantly between the two groups, there were distinct qualitative differences. The thought disorder of manic patients was extravagantly combinatory, usually with humor, flippancy, and playfulness. The thought disorder of schizophrenic patients appeared disorganized, confused, and ideationally fluid, with many peculiar words and phrases.