Formal thought disorder in schizophrenia. Linguistic, attentional, and intellectual correlates.

Formal thought disorder (i.e., abnormal utterances and communication problems) is a prominent feature of schizophrenia. To investigate the hypothesis that formal thought disorder in schizophrenics represents a disturbance of language functioning, we compared 21 thought-disordered and 16 non-thought-disordered schizophrenics on the Porch Index of Communicative Ability. The thought-disordered schizophrenics were significantly more impaired. We also examined nonlinguistic factors potentially impacting language performance in schizophrenics (e.g., disturbed attention, intellect, and/or thought content). Reduced attention was the best predictor of language performance in the thought-disordered group, whereas low intellect and reduced attention were predictive of language dysfunction in the non-thought-disordered group. Disturbed thought content was not predictive of language impairment in either group. These findings provide partial support for the idea that formal thought disorder in schizophrenics represents defective language functioning.