Repetition Priming in Dementia of Alzheimer's Type in Japanese

Abstract

Background: Memory is profoundly impaired in patients with dementia of Alzheimer's type (DAT). However, the study of priming, which is thought to be implicit memory, is relatively scarce in DAT. In Japan there is only one study, which investigated repetition priming in DAT and the relationship between the severity of dementia and repetition priming in DAT has never been examined. Therefore, we studied repetition priming in patients with various severity of DAT from the standpoint of familiarity of words. Method: A new repetition priming task, which is constructed of 3 syllable Japanese Kana nouns and which contains high familiarity words and low familiarity words according to Chihara was used for an implicit memory task. The task was carried out by normal controls and patients with DAT. Each group was matched by age, sex, and educational level. Results: A clear repetition priming effect was found among the control and dementia groups both in low and high familiarity words. The priming effects of a high familiarity task demonstrated no statistical differences among the control and dementia group. However, the priming effect of the low familiarity task in the severe dementia group was revealed to be significantly low compared with that of the control group (p<0.01), mild (p<0.01) and moderate group (p<0.05), and there was also statistical significance between the normal control and moderate dementia group (p<0.05). Conclusion: These results indicate that dementia severity and word familiarity influences repetition priming in DAT.