Patterns of speech disorders in schizophrenia and mania.

Formal thought disorder (FTD), defined as abnormal speech, has been associated with schizophrenia and likened to fluent aphasia. Whether FTD differentiates subtypes of schizophrenics and discriminates schizophrenics from other patients is unclear. We studied this issue by analyzing ratings of FTD of 170 schizophrenics and 62 manics. Eighty percent of emotionally blunted schizophrenics had FTD compared with 6.5% of manics. Factor analysis revealed verbiage disturbance and disorganized speech factors (44% of the variance). We assessed the discriminating ability of these factors, and compared these results to those from factors derived from Andreasen's positive/negative FTD construct, and to factors derived from speech and language diagnostic criteria for schizophrenia and mania in the proposed DSM-IV. Overall classifications were similar (91%, 91%, and 88%, respectively). We also found that FTD was related to emotional blunting, but not to other psychopathology.