Ideational and semantic contributions to narrative production in adults with dementia of the Alzheimer's type .

The narrative production of adults with probable dementia of Alzheimer's type (DAT) was investigated to determine the extent to which cognitive or linguistic deficits might explain the breakdown of discourse production. The structure of narrative tasks was manipulated so that the relationships among task structure and language production corresponded to predictions about the suspected origin of deficit. Sixteen DAT and 16 normal control subjects were administered four narrative tasks that were controlled for the amount of content and picture format display. The DAT subjects exhibited reduced content in terms of propositions and lexical items, shorter sentence lengths with more sentence fragments and reference errors. The mode of picture display failed to influence the amount of target content, or the grammatical performance of subjects. However, when compared to the normal controls, the amount of information pictorially represented significantly influenced the content provided by the DAT subjects; they performed better when the message to be related contained relatively less information. These findings support the contributions of both semantic-lexical and ideational systems to narrative discourse to narrative discourse production.