Ability to Select AAC Graphic Symbols by Severity of Alzheimer’s Disease and Number of Symbols

Abstract

Purpose: This study aimed to examine the graphic-symbol selection ability of patients with dementia of Alzheimer's type (DAT) based on the severity of dementia by conducting symbol identification and symbol discrimination tasks with increasing numbers of symbols. These tasks were performed with both normal elderly individuals and DAT patients to explore how cognitive load affects them differently.Methods: A total of 21 normal elderly individuals, 17 mild DAT patients, and 20 moderate to severe DAT patients were assessed. They performed symbol identification and symbol discrimination tasks using the Augmentative and Alternative Communication Symbol Assessment Tool. The number of symbols increased in six steps, from 4 to 72. Accuracy and response time were measured for statistical analysis.Results: In the symbol identification task, there was no significant difference in accuracy among the three groups. However, normal group showed significantly faster responses compared to moderate to severe DAT group. In the symbol discrimination task, normal group showed higher accuracy and significantly faster responses than moderate to severe DAT group. As the number of symbols increased, response times increased across all groups, with more time required for the symbol discrimination task.Conclusion: It was confirmed that the greater the severity of DAT, the more cognitive load and impaired information processing were reflected in symbol selection. Findings suggest that response time is a more sensitive indicator of cognitive decline in DAT patients and highlight the need to adjust the number of symbols and presentation methods according to the severity of the patient’s condition in dementia interventions.