Rhetorical Relations in the Speech of Alzheimer’s Patients and Healthy Elderly Subjects: An Approach from the RST

Abstract

The study is aimed to extract discourse relations patterns in conversational speech of subjects with Alzheimer’s Disease (AD) and adults with healthy aging processes using the Rhetorical Structure Theory (RST). By means of the RST, we analyzed semi-structured interviews of native Spanish speakers. Seven subjects were in the mild, moderate or advanced stages of AD, and 6 were cognitively intact individuals. The procedure involved the segmentation of each conversational discourse into Semantic Dialog Units (SDUs), the labeling of their rhetorical relations and the construction of tree diagrams. We perform acorrelation analysis to determine the significance of the use of rhetorical relations for each group. We found a significantly (p-value < .05) lower rhetorical relations production density in subjects with AD. We also observed that most rhetorical relations used by healthy older subjects were Elaboration, Concession, Interpretation, Non-Volitional Cause, Solutionhood and Volitional Result.