Reference Performance and Positive and Negative Thought Disorder: A Follow-Up Study of Manics and Schizophrenics

Abstract

Manic (n = 22) and schizophrenic (n = 28) patients were examined with clinical and linguistic measures of language performance at an acute admission and at a follow-up. It was found that the frequency of incompetent references and the severity of negative thought disorder were stable independent traits of schizophrenics. Furthermore, low levels of verbal productivity, indexed both clinically and linguistically, predicted the likelihood that schizophrenic subjects would be psychotic at follow-up. The language performance of manic patients was not temporally stable, although high levels of reference failures at index predicted psychosis at follow-up. These results are evaluated in terms of their implications for differentiating state-specific aspects of speech competence from potential vulnerability markers in these two types of patients.