Neuropsychological evaluation of narrative discourse patterns in individuals with early stage Vascular Dementia vs. patients with early stage Alzheimer’s Disease

Individuals in the early stage dementia may demonstrate language difficulties. The aim of the study was an evaluation of the differences of narrative discourse abilities in two types of dementia, i.e., Vascular Dementia (VaD) and Alzheimer’s Disease (AD) in comparison to young and old elderly. Four groups included patients presenting an early stage of VaD (N=14), an early stage of AD (N=14), a young control elderly – YE (N=19), and an old control elderly – OE (N=29) were set up. Neuropsychological testing examined the verbal and nonverbal functions classified into the following cognitive domains: verbal memory, executive functions, reasoning, attention/working memory. Narrations were elicited with two tasks of story retelling and were analyzed on the micro-, macro-, and super-structure level of discourse organization. Results: The AD and VaD groups displayed a lower performance than the age-matched YE on tasks involving reasoning. The VaD participants out performed patients with AD in verbal memory and narrative discourse. Discourse macrostructure analyses showed that the VaD reproduced more propositions than the AD participants, but that these were comparable to YE and OE. There were more conjunctions in narratives reproduced by the VaD participants as compared to other groups, although this tendency was only present in story but not tale reproductions. Individuals in the AD group had more difficulties than YE and OE individuals in figuring out the moral of tales. Clinical and control groups reproduced the microstructure and superstructure of texts comparatively well. Discourse recall correlated with performance on verbal memory, attention/working memory, and reasoning. Differences in narrative discourse abilities were found. Alzheimer’s Disease (AD) patients obtained worse results in verbal memory than did Vascular Dementia (VaD) patients. Both groups however obtained worse results than young and old elderly.