Characteristics of Performance according to Type of Semantic Lexical Task in Normal Elderly and Individuals with Subjective Memory Impairment

Purpose: For comparison of a semantic knowledge processing of the elderly, particularly the normal individuals and individuals with subjective memory impairment, this study aims to clarify what factors of semantic knowledge task could sensitively discriminate between the two groups by conducting various types of tasks and analyzing the aspects. Methods: High/low frequency category fluency test, concrete/abstract noun word defining test, and semantic association task were performed by 30 normal subjects and 30 subjective memory impaired subjects over 65 years old. Total and each subcategory scores were assessed for the category fluency test and word defining test, and correct response and reaction time were measured for the semantic association task. Results: It was found that there were significant differences between the two groups in the total score of the category fluency task (p < 0.001), low-frequency category score, abstract noun word defining task score (p < 0.05), and reaction time of semantic association task (p < 0.01). Conclusion: The result showed that in case of a target word with lower contact frequency and more abstract concept, the elderly with subjective memory impairment have difficulties in neural-networking activation of semantic knowledge and control of interruption stimulation when approaching a target word, with increased reaction time. This findings demonstrate that a semantic and lexical task has a clinical significance in discriminating a subjective memory impairment group.