Is thought disorder in schizophrenia a function of loss of context and impaired working memory?

Abstract

It has been attempted to characterise formal thought disorder in specificabnormalities in cognitive function that can account for the aberrations in language and thought processes. One theory proposes that there is a deficit in semantic memory. The aim of the present study was therefore, to explore the structure of semantic memory and to investigate the 'spreading of activation' in semantic memory in patients with formal thought disorder. Schizophrenic patients with clinically evident formal thought disorder (FrO) were compared with patients without FTD and with matched normal controls . A categorisation task was administered with four levels of semantic-relatedness (typical, atypical. related, unrelated) to assess the structure of semantic memory. A semantic priming (lexical decision) task was used to assess the activation of word representations in semantic memory. Semantic priming was assessed for highly and weakly related words. Preliminary results show that the patients with FrO show overinclusive categorisation. Patients without FrO do not show overinc1usiveness. Patients with FrO showed reaction time slowing, but their semantic priming effectwas not different from other groups. These findings suggest that there is a broadening of semantic categories in FTO patients, but this is not due to a difference in spreading of activation .