The Japanese journal of neuropsychology

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ArticleTitle	False recognition in patients with Alzheimer's disease: A study using a word recognition task
Language	J
AuthorList	Shotaro Murata¹⁾, Atsushi Sato²⁾, Takuya Sato²⁾ and Toru Imamura¹⁾³⁾
Affiliation	¹⁾Department of Speech Therapy, School of Health Sciences, Niigata University of Health and Welfare ²⁾Division of Speech Therapy, Department of Rehabilitation, Niigata Rehabilitation Hospital ³⁾Department of Neurology, Niigata Rehabilitation Hospital
Publication	Japanese Journal of Neuropsychology: 24 (2), 170-176, 2008
Received	Dec 20, 2006
Accepted	Mar 11, 2008
Abstract	Background: Recent studies on of memory distortion and false recognition in patients with Alzheimer's disease (AD) showed that, in word recognition tasks, the level of false recognition of semantically unrelated distracters was higher in AD patients than in normal controls. Objective: To assess the effect of other cognitive deficits on the score of false recognition in a word recognition task in AD patients. Subjects: We studied 189 AD patients in the memory clinic of Niigata Rehabilitation Hospital. All the patients were assessed with the Mini-Mental State Examination (MMSE) and the Alzheimer's Disease Assessment Scale (ADAS). The mean age of the patients was 80.2±6.4 years, the mean MMSE score was 17.8±4.5, and the mean ADAS scores was 21.7±9.3. Methods: We conducted an analysis of multivariate linear regression to assess the effect of the scores of cognitive tests on false recognition score. The statistical model contained the score of false recognition for the semantically unrelated distracters in the recognition subtest of ADAS as the dependent variable, and the scores of MMSE, digit span, subtests of ADAS (word recall, following commands, constructions, ideational praxis, orientation and word recognition) as the independent variables. Results: We obtained significant coefficients for the scores of orientation subtest (β=.25, p<.01) and word recognition subtest (β=-.54, p<.01). That is, the patients with worse score on the orientation subtest and the patients with better score on the word recognition subtest showed worse score of false recognition. Conclusion: We consider that false recognition of semantically unrelated distracters in AD patients has two independent bases. One is a trend toward positive response to the items with general familiarity. Because of this, trend "yes" responses, irrespective to a target or a distracter, increase in the word recognition task. The other is a trend toward confabulatory responses to questions in cognitive tasks. This trend may lead to an increase in the number of incorrect responses both to the questions in the orientation tasks and to the distracter words in the word recognition task.
Keywords	false recognition, word recognition task, ADAS, Alzheimer's disease, confabulation