COGNITIVE BASES OF SCHIZOPHRENIC LANGUAGE SYMPTOMS

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A long-term goal of this program of research is to identify pathophysiological processes underlying schizophrenic disordered speech. The heterogeneity of thought and language symptoms has been a problem to investigators in this area. A "natural language" measure has recently been developed that assesses six different types of referential communication failures present in the speech of schizophrenia patients (Communication Disturbances Index (CDI). Preliminary data from stable outpatients suggests that deficits in conceptual sequencing, working memory, and sustained attention underlie some of these forms of disturbance and not others. The proposed study has four specific aims: (1) To replicate findings of elevated frequencies of each of the six different types of referential communication failures measured by the CDI in the speech of severely ill schizophrenia patients; (2) To assess the neuropsychological correlates of specific structure-related types of communication disturbances in severely ill patients in the areas of conceptual sequencing, working memory, and sustained attention; (3) To begin to test whether these associations are specific to schizophrenia, or occur across diagnostic categories; (4) To assess some possible neuropsychological correlates of other, nonstructural types of communication disturbances. Speech samples would be collected from 40 severely ill schizophrenia patients, 40 severely ill mania patients, and 40 matched nonpsychiatric control subjects, and rated using the CDI. Subjects' cognitive functioning also would be assessed in areas hypothesized to be involved in the production of structure-related communication disturbances, with a series of neuropsychological tests specifically designed to measure conceptual sequencing, facets of working memory, low- and high-load sustained attention, and global verbal intelligence. In addition, cognitive functions potentially implicated in nonstructural types of communication disturbances would be assessed. Levels of each type of communication disturbance would be compared between groups. Performance on the cognitive tests would be compared with ratings of the different types of communication disturbances in the speech samples within and between groups, controlling for differences among subjects in global verbal intelligence and severity of illness, to test specific hypotheses about connections between areas of cognitive impairment and particular kinds of language symptoms.