Abstract
Objective : To examine the nature of false recall in a common word-list recall task and its relation to other cognitive deficits in patients with Alzheimer's disease (AD) . Subjects : We studied 77 AD patients who underwent the Mini-Mental State Examination (MMSE) and the Alzheimer's Disease Assessment Scale (ADAS) . The mean age of the patients was 80.1 ± 6.4 years and the mean MMSE score was 18.7 ± 4.6. Methods : We collected falsely recalled words from the responses of each patient in the Word Recall subtest of ADAS, and examined the relation between the falsely recalled words and the target words. We also conducted analyses of logistic regression to assess the effect of the scores of other cognitive tests on the presence or absence of false recall. Results : Twenty-four of the 77 patients showed false recall. The mean number of falsely recalled words in all patients was 1.1 ± 2.6. Among a total of 19 falsely recalled words,13 words (68%) belonged to one of the four semantic categories of the target words. We obtained a significant odds ratio for scores on the Word Recognition subtest of ADAS (p < .05) , that is, patients with better scores on the Word Recognition subtest were more likely to show false recall in the word recall task. Conclusion : AD patients with impaired memory encoding may show worse scores on word recognition tasks. We consider that patients of this type fail to encode semantically related words which are activated during the presentation of the targets in the word recall task, and are less likely to show false recall. These results suggest that the mechanism of false recall in AD patients on the Word Recall subtest of ADAS is similar to that of healthy subjects.
