The effect of language production manipulations on negative thought disorder and discourse coherence disturbances in schizophrenia

This study was designed to test the following hypotheses about the mechanisms underlying language disturbances in schizophrenia: (1) negative thought disorder (reduced verbosity and syntactic complexity, increased pausing) reflects a deficit generating a discourse plan; and (2) discourse coherence disturbances (tangential responses, loss of goal, derailment, non-sequiturs, distractible speech) reflect a deficit maintaining a discourse plan. Thirty-nine participants with DSM-III-R schizophrenia listened to two stories and answered a series of questions after each story. We manipulated two factors: (1) the presence of context before the stories (to influence generating a discourse plan); and (2) question type (structured vs. unstructured; designed to influence maintaining a discourse plan). Consistent with our hypotheses, low context was associated with less verbose and syntactically complex speech. In addition, patients produced more discourse coherence disturbances when responding to unstructured than when responding to structured questions.