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Han, KyungHun (2009): Mental images in episodic memory: Comparison between patients with Alzheimer's disease and healthy control sucjects. Dissertation, LMU München: Faculty of Medicine
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Abstract

Episodic memory, i.e. memorization of information within a spatiotemporal environment, is affected by Alzheimer's disease (AD) but its loss may also occur in the normal aging process. The purpose of this study is to analyze and evaluate episodic memory in patients with AD by examining their cognitive skills in episodic memory through the introspection technique. A new method was used, wherein we assessed mental images of the subject's own past recalled in the mind like projected pictures and movies. Experiment 1 is designed to determine the effect and process of normal and pathological aging on cognitive skills in episodic memory using the introspection technique. Two groups were observed towards this purpose: 21 patients with AD and 19 normal control subjects. All subjects were chosen from ages from 55 to 70 and were administered standardized neuropsychological tests (K-DRS and MMSE-K). All subjects were asked to retrieve their episodic memory of the previous day, week, month, and a day remote from testing day. The answers were analyzed, focusing on their specific features such as emotional state, color, and time order. In the following day, the subjects were tasked to recall again all images that they reproduced in the previous day's test in order to observe impairment of anterograde memory. Results showed that patients failed to arrange the retrieved images in time order and their images of the previous day were unclear in color and were stationary like photographs, even when they reproduced the mental images at as much quantity as controls. They also could not remember particular events of yesterday, only their general occurrence. These results suggest that in the early stage of AD, difficulties in the retrieval of recent episodic memory begin to occur, and qualitative impairment happens earlier than quantitative. The third chapter supports these results with further evidence, analyzing from a clinical viewpoint 3 patients with AD, 1 patient with mild depression and 2 controls. In Experiment 2 the emotional intensity of episodic memory within different categories of memory (yesterday, week, month, and remote) was investigated by comparing healthy elderly people and AD patients. The subjects’ voice intonations were estimated by 8 valuators. As a result, the emotional intensity of AD patient was evaluated lower than controls. It appears that patients in the early stage of AD are impaired in the ability to express emotions during emotional episodic memory retrieval compared to healthy elderly adults.