Abstract

Individuals with mild cognitive impairment (MCI) can often progress into Alzheimer’s Disease (AD). Research suggests that decline in episodic memory and semantic memory, as well as functional abilities, can be sensitive in predicting disease progression. This study aimed to (a) investigate episodic and semantic memory performance differences between AD and MCI, (b) determine if memory performance predicts observation-based activities of daily living (ADLs), and (c) explore whether semantic memory mediates the relationship between episodic memory and ADLs. Fifty-eight AD, 53 MCI, and 72 healthy control participants were administered the Rey-O, California Verbal Learning Test, Animal Fluency Test, Boston Naming Test, and Direct Assessment of Functional Status (DAFS). The results revealed, first, that AD participants performed significantly lower than the MCI participants across semantic memory and episodic memory tasks, with the exception of the Boston Naming Test. Second, hierarchical-stepwise regression analyses found that semantic memory significantly predicted DAFS orientation, communication, and financial skills in AD, but episodic memory predicted shopping skills. Furthermore, semantic memory significantly predicted DAFS transportation skills in AD and MCI. Third, within the overall sample, semantic memory mediated the relationship between episodic memory and ADLs. Taken together, the findings suggest decline in semantic memory (as measured by confrontational naming and category fluency) and episodic memory (as measured by list and complex visual design learning and recall) may lead to decline in different and specific aspects of functional abilities in AD and MCI.

摘要

患有轻度认知障碍 (MCI) 的人通常会发展为阿尔茨海默病 (AD)。研究表明，情景记忆和语义记忆以及功能能力的下降在预测疾病进展方面可能很敏感。本研究旨在 (a) 调查 AD 和 MCI 之间的情景和语义记忆表现差异，(b) 确定记忆表现是否能预测基于观察的日常生活活动 (ADL)，以及 (c) 探讨语义记忆是否介导两者之间的关系。情景记忆和 ADL。58 名 AD、53 名 MCI 和 72 名健康对照参与者接受了 Rey-O、加利福尼亚语言学习测试、动物流利度测试、波士顿命名测试和功能状态直接评估 (DAFS)。结果显示，首先，AD 参与者在语义记忆和情景记忆任务上的表现明显低于 MCI 参与者，波士顿命名测试除外。其次，分层逐步回归分析发现，语义记忆显着预测 AD 中的 DAFS 定向、沟通和财务技能，但情景记忆预测购物技能。此外，语义记忆显着预测了 AD 和 MCI 中的 DAFS 运输技能。第三，在整个样本中，语义记忆介导了情景记忆与 ADL 之间的关系。综合起来，