Original Research ARTICLE
The Persistence of the Self over Time in Mild Cognitive Impairment and Early Alzheimer’s Disease
- 1School of Psychology, University of Auckland, New Zealand
- 2Centre for Brain Research, University of Auckland, New Zealand
- 3Brain Research New Zealand, University of Auckland, New Zealand
Diachronic unity is the belief that, despite changes, we are the same person across the lifespan. We propose that diachronic unity is supported by the experience of remembering the self over time during episodic recall (i.e., phenomenological continuity). However, we also predict that diachronic unity is also possible when episodic memory is impaired, as long as the ability to construct life narratives from semantic memory (i.e., semantic continuity) is intact. To examine this prediction, we investigated diachronic unity in Alzheimer’s Disease (AD) and amnestic mild cognitive impairment (aMCI), two conditions characterised by disrupted phenomenological continuity. If semantic continuity is also altered in these conditions, there should be an associated deterioration in diachronic unity. Participants with AD, aMCI and healthy controls (HC) completed a self persistence interview measuring diachronic unity (beliefs about self persistence, explanations for stability/change). Semantic continuity was assessed with a life-story interview measuring autobiographical reasoning (self-event connections), and coherence (temporal/thematic/causal) of narratives. Our results highlight a complex relationship between semantic continuity and diachronic unity and revealed a divergence between two aspects of diachronic unity: AD/aMCI groups did not differ from HC in continuity beliefs, but AD explanations for self persistence were less sophisticated. Semantic continuity was most impaired in AD: their narratives had fewer self-event connections (vs. HCs) and lower temporal/thematic coherence (vs. HC/aMCI), while both AD/aMCI groups had lower causal coherence. Paradoxically AD participants who scored higher on measures of beliefs in the persistence of the core self, provided less sophisticated explanations for their self persistence and were less able to explore persistence in their life narratives. These findings support the importance of semantic continuity to diachronic unity, but suggest a more nuanced and multifaceted relationship than originally proposed in our model. In AD, diminished life narratives that retain features of cultural life scripts are sufficient for strong subjective beliefs of self persistence, but not for sophisticated explanations about persistence. Better semantic continuity, with the ability to weave high-quality life narratives, may scaffold the capacity to understand and explain one’s diachronic unity, but this produces less surety about self persistence.
Keywords: Self persistence, Diachronic unity, Alzheimer’s disease, amnestic mild cognitive impairment (aMCI), narrative identity, phenomenological continuity, semantic continuity
Received: 16 Nov 2017;
Accepted: 22 Jan 2018.
Edited by:Rossella Guerini, University of Trento, Italy
Reviewed by:Liliann Manning, Université de Strasbourg, France
Jane E. Aspell, Anglia Ruskin University, United Kingdom
Copyright: © 2018 Tippett, Prebble and Addis. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Dr. Lynette J. Tippett, University of Auckland, School of Psychology, Auckland, New Zealand, email@example.com