ABSTRACT

Alzheimer’s disease (AD) is the most common form of dementia, impacting global cognitive performance, including episodic memory. Semantic clustering is a learning strategy involving grouping words of similar meaning and can improve episodic memory performance, e.g., list learning. As the APOE ε4 allele is the most validated genetic risk factor for AD, we predicted that its presence would be associated with poorer list learning performance, and we hypothesized that semantic clustering moderates or mediates this association. The sample comprised 699 healthy older adults participating in the CHARIOT PRO Main Study, 169 of whom were APOE ε4 carriers. Participants’ ability to form groups of related stimuli (assessed via a categorization task, CAT), and their use of semantic clustering during list learning, were investigated using the Neuropsychological Assessment Battery (NAB). CAT scores predicted the use of semantic clustering in, and performance on, the list learning task. CAT scores were not significantly lower in APOE ε4 carriers, suggesting that the ability to categorize was preserved. However, APOE ε4 carriers made less use of semantic clustering in list learning. Semantic clustering use partially mediated the relationship between CAT scores and list learning performance, and, in women only, moderated the impact of APOE ε4 on list learning performance. The results suggest that better categorization ability is associated with greater use of mnemonic strategies and better performance on memory tasks regardless of genetic risk, but that APOE ε4 carriers make less use of such strategies. Furthermore, female APOE ε4 carriers may benefit more than their non-carriers from using semantic clustering to aid list learning. Thus, semantic clustering may be a contributing factor of their “cognitive reserve”, compensating for potential deficits in episodic memory.

摘要

阿尔茨海默氏病（AD）是痴呆症的最常见形式，会影响整体认知表现，包括情节性记忆。语义聚类是一种学习策略，涉及对含义相似的单词进行分组，可以提高情景记忆的性能，例如列表学习。由于APOE ε4等位基因是AD的最有效的遗传危险因素，我们预测，它的存在将与较差的名单学习表现相关联，我们假设语义聚合温和派或介导这种关联。样本包括699位健康老年人，他们参与了CHARIOT PRO主要研究，其中169位是APOEε4载波。使用神经心理学评估电池（NAB）调查了参与者形成相关刺激组的能力（通过分类任务CAT评估），以及他们在列表学习过程中语义聚类的使用。CAT分数预测了列表学习任务中语义聚类的使用和性能。CAT分数不显著降低APOE ε4携带者，这表明的能力进行分类被保留下来。然而，APOE ε4携带者做出列表学习较少使用语义聚合的。语义聚类使用部分地介导了CAT分数与列表学习成绩之间的关系，并且仅在女性中减轻了APOE的影响列表学习成绩为ε4。结果表明，更好的分类能力有更大的使用记忆策略也不管遗传风险对记忆任务更好的性能有关，但APOE ε4携带者减少使用这种策略。此外，女性的APOE ε4携带者可以利用语义聚合到援助清单学习中获益超过其非携带者。因此，语义聚类可能是其“认知储备”的促成因素，弥补了情节记忆中的潜在缺陷。