Assessing differences in episodic and semantic memory in healthy ageing and in people at increased genetic risk for late-onset Alzheimer’s Disease

Sacripante, Riccardo (2025) Assessing differences in episodic and semantic memory in healthy ageing and in people at increased genetic risk for late-onset Alzheimer’s Disease. Doctoral thesis, University of East Anglia.

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Abstract

Cognitive and genetic markers in preclinical Alzheimer’s Disease (AD) represent a promising research ground for early diagnosis and intervention. The genetic variant Apolipoprotein epsilon 4 (APOE ε4) is linked to higher risk of developing AD and research investigating cognitive functioning in people at risk could help identify markers of preclinical AD. Past research observed that episodic memory is usually impaired in APOE ε4 carriers, while semantic memory has received less attention. This thesis aimed to assess whether the cognitive impact of APOE ε4 genotype also affects other aspects of declarative memory, such as personal and general semantic memory. A systematic review was carried out to investigate whether APOE ε4 genotype affects semantic memory functioning in healthy adults at increased genetic risk of developing AD. An empirical study aimed to clarify whether the impact of APOE ε4 on declarative memory is specific to episodic memory, or if it also extends to personal and general forms of semantic memory by using new and traditional autobiographical interview protocols. The results from the systematic review revealed a limited impact of APOE ε4 on semantic memory and highlighted the need for more demanding and sensitive tasks designed to measure semantic memory. The empirical findings of the thesis revealed that APOE ε4 carriers showed reduced production of on-task and off-task episodic details, while carriers and non-carriers showed equal recall of personal and general semantic memory. These findings increase our understanding of how genetic risk for AD affects memory, and reveal the importance of developing new tasks for less ambiguous comparisons of subtypes of declarative memory findings. The limitations are also discussed, along with recommendations for future research prospects. Altogether, these findings suggest that APOE ε4 has a limited impact on semantic memory, and that episodic memory is selectively reduced in healthy older APOE ε4 carriers.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User:	Chris White
Date Deposited:	30 Oct 2025 08:46
Last Modified:	30 Oct 2025 08:46
URI:	https://ueaeprints.uea.ac.uk/id/eprint/100849
DOI:

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