False memory in patients with mild Alzheimer''s disease

• Main Authors: Ting-Wen Cheng, 鄭婷文
• Other Authors: 花茂棽
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/13747210506380565654

碩士 === 國立臺灣大學 === 心理學研究所 === 94 === Normal memory depends upon both adequate verbatim and gist memory functioning. The deficit of episodic memory is one of the early clinical features in patients with Alzheimer’s disease (AD), and literature shows dysfunction of verbatism and gist memory processing in these patients contributing to such memory impairment. However, the issue regarding whether impairment of semantic memory, that is mainly reflected by gist memory functioning, exists in the early stage of AD patients remains unclear. Furthermore, the related issue of whether deficit of gist memory evident in those AD patients is primarily due to a loss of semantic structure or an inability to get access to semantic knowledge is also in question. The Deese-Roediger-McDermot (DRM) paradigm has been one of the important procedures to approach gist memory functioning in the light of manifestation of false memory. Having used this paradigm, researches revealed that an increase of stimulus exposure trials could facilitate AD patients’ gist memory functioning. However, such findings could not be fully confirmed by other investigations with a manipulation of stimulus features, such as using black-and-white line drawings or colored photos as stimulus items. Methodological pitfalls in these studies might account for these inconsistent outcomes. Using the DRM paradigm in which three forms of stimuli were exposed to normal healthy elderly controls and AD patients, the present study was thus to re-explore these controversial issues. Thirty-six mild AD patients and thirty-six normal healthy elderly controls matched for the sex, age, and education level participated in the study. All subjects were given a battery of neuropsychological tests and the false memory tasks in which subjects received three types of stimulus conditions, including auditory words with visual words, with black-and-white line drawings, and with colored photos. The results revealed that AD patients’ false memory index scores on the false memory tasks, involving stimulus conditions of auditory words plus either visual words or black-and-white line drawings were significantly lower than those of their normal counterparts. In contrast, these index scores on the task with the stimulus feature of auditory words plus colored photos were not significantly different between these two subject groups. For the true index score of the task, the patients were remarkably lower than their normal counterparts, irrespective of the stimulus conditions. These patients’ true and false memory index scores varied with stimulus conditions, that is both true and false memory index scores of the stimulus condition involving color photos were the best followed by the condition involving black-and-white line drawings, and words. Nevertheless, the index score differences among these three conditions were not statistically significant. For normal healthy elderly controls, the similar index score pattern was only evident in their true recognition performance. Based on these results, it appeared that mild AD patients did have semantic memory problem. However, auditory memory task items accompanying with their corresponding colored photos, could facilitate mild AD patients’ gist memory functioning. Accordingly, it is thus suggested that at least mild AD patients’ gist memory problem would be mostly like to be associated with an inability to get access to semantic knowledge rather than a loss of semantic structure. Nonetheless, since the current results were merely based on a small sample, further study on a large scale to investigate these issues is necessary.