Correlation Between Hippocampal Volume and Autobiographical Memory Depending on Retrieval Frequency in Healthy Individuals and Patients with Alzheimer’s Disease

Article type: Research Article

Authors: Liechti, Caroline^{a; d; 1} | Caviezel, Marco P.^{a; 1} | Müller, Stephan^{b; 1} | Reichert, Carolin F.^a | Calabrese, Pasquale^c | Linnemann, Christoph^a | Melcher, Tobias^{a; 2} | Leyhe, Thomas^{a; d; *; 2}

Affiliations: [a] University of Basel, Centre of Old Age Psychiatry, Psychiatric University Hospital, Basel, Switzerland | [b] Department of Psychiatry and Psychotherapy, University Hospital of Tübingen, Tübingen, Germany | [c] University of Basel, Neuropsychology and Behavioural Neurology Unit, Basel, Switzerland | [d] University of Basel, Geriatric Psychiatry, University Department of Geriatric Medicine FELIX PLATTER, Basel, Switzerland

Correspondence: [*] Correspondence to: Thomas Leyhe, University of Basel, Center of Old Age Psychiatry, Psychiatric University Hospital (UPK), Wilhelm Klein-Strasse 27, CH-4002 Basel, Switzerland. Tel.: +41 (0)61 325 53 53; E-mail: thomas.leyhe@upk.ch.

Note: [1] These authors contributed equally to this work.

Note: [2] These authors share the senior authorship.

Abstract: The hippocampus plays an indispensable role in episodic memory, particularly during the consolidation process. However, its precise role in retrieval of episodic memory is still ambiguous. In this study, we investigated the correlation of hippocampal morphometry and the performance in an autobiographical memory task in 27 healthy controls and 24 patients suffering from Alzheimer’s disease (AD). Most importantly, correlations were defined separately and comparatively for memory contents with different retrieval frequency in the past. In healthy subjects, memory performance for seldom retrieved autobiographical events was significantly associated with gray matter density in the bilateral hippocampus, whereas this correlation was not present for events with high retrieval frequency. This pattern of findings confirms that retrieval frequency plays a critical role in the consolidation of episodic autobiographical memories, thereby making them more independent of the hippocampal system. In AD patients, on the other hand, successful memory retrieval appeared to be related to hippocampal morphometry irrespective of the contents’ retrieval frequency, comprising events with high retrieval frequency, too. The observed differences between patients and control subjects suggest that AD-related neurodegeneration not only impairs the function, but also decreases the functional specialization of the hippocampal memory system, which, thus, may be considered as marker for AD.

Keywords: Alzheimer’s disease, autobiographical memory, cognitive impairment, episodic memory, gray matter, hippocampus, historic events, magnetic resonance imaging, medial temporal lobe, voxel-based morphometry

DOI: 10.3233/JAD-190047

Journal: Journal of Alzheimer's Disease, vol. 72, no. 4, pp. 1341-1352, 2019