Working memory and verbal memory's relationship to discourse comprehension in patients with amnestic mild cognitive impairment and with Alzheimer's disease

Abstract

Objectives: Impairment of story comprehension ability is known to appear in the early stages of Alzheimer's disease (EAD). The main purpose of this study was to identify performance differences in story comprehension among healthy elderly adults, patients with amnestic mild cognitive impairment (aMCI), and patients in EAD in order to see working memory and verbal memory's relationship to discourse comprehension in the three groups. Methods: Thirty healthy elderly adults, 30 patients with aMCI, and 30 patients with EAD participated in this study. They took part in a story comprehension task, a working memory test (forward/backward Digit Span Test) and a verbal memory test (Seoul Verbal Learning Test [SVLT]). Results: The results were as follows. First, there were significant differences in story comprehension performance among all groups (healthy elderly>aMCI>EAD). Second, there was a significant correlation between story comprehension performance, scores of the backward Digit Span Test, and scores of the SVLT in healthy elderly adults and the EAD group. Third, there was only significant correlation between story comprehension performance and delayed recall scores of SVLT in the aMCI group. Conclusion: These results suggest that impairment of story comprehension ability appear in the aMCI stage and that working memory and verbal memory's relationship to discourse comprehension differ in the progression of AD.