The telling of a story is a complex action. In pragmatic, social terms, it places a burden on the narrator to establish the point of the story that makes it a well-formed narrative. In neurolinguistic terms, it places demands on executive resources, working memory, lexical access, and control of syntax and pragmatics. The present study is designed to investigate the effects of neurodegenerative disease on neurological functioning through the medium of this linguistic task.

We studied three subgroups of patients with frontotemporal dementia (FTD), including those with semantic dementia (SD, n=10) who have naming and comprehension difficulty; those with progressive nonfluent aphasia (PNFA, n=8), who exhibit effortful speech; and those who exhibit executive and/or social impairments but who are not aphasic (Non-Aphasic, n=8). We also studied age- and education-matched controls.

The subjects were asked to relate a story from a children's book consisting of a sequence of drawings with no printed words, Frog, Where Are You?, by Mercer Mayer. Before speaking, the subjects looked through the book to familiarize themselves with the story. Then they paged through the book again, recounting the story as they went, and the narrations were digitally recorded and subsequently transcribed. The narratives were scored for accuracy of reported content, as measured against the linguistic analysis of the narrative into its essential components. They were also scored for "connectedness," at both the local (item-by-item) and global levels, and for maintenance throughout the narrative of the overall theme.

All the patient groups demonstrate significant deficits as compared to control subjects, but they differ in the nature of the deficits. SD patients exhibit word-finding difficulty and excessive use of general terms (e.g., animal) in place of specific ones (e.g., frog). PNFA patients demonstrate the effect of their effortful speech with a reduced rate of speaking, shortened utterance length, and a high proportion of missing items. While the aphasic groups are largely able to communicate the overall sense of the story, the Non-Aphasic patients show the greatest deficit in maintaining cohesion of the discourse at the levels of both local and global connectedness. The findings characterize and quantify the nature of dysfunctional narrative performance in populations of patients with neurodegenerative disease.