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Impaired comprehension of metaphorical expressions in very mild Alzheimer’s disease

Authors Fujimoto N, Nakamura H, Tsuda T, Wakutani Y, Takao T

Received 6 November 2018

Accepted for publication 25 January 2019

Published 20 March 2019 Volume 2019:15 Pages 713—720


Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 2

Editor who approved publication: Dr Taro Kishi

Norimasa Fujimoto,1 Hikaru Nakamura,2 Tetsuya Tsuda,3 Yosuke Wakutani,4 Takeo Takao4

1Department of Rehabilitation, Kurashiki Heisei Hospital, Kurashiki, Okayama, Japan; 2Department of Health and Welfare Science, Okayama Prefectural University, Soja, Okayama, Japan; 3Department of Communication Sciences and Disorders, Prefectural University of Hiroshima, Mihara, Hiroshima, Japan; 4Department of Neurology, Kurashiki Heisei Hospital, Kurashiki, Okayama, Japan

Background: Brain-damaged patients often have difficulty understanding non-literal language. However, whether patients with Alzheimer’s disease (AD) have comprehension deficits of metaphorical expressions, in contrast with non-metaphorical (literal) expressions, remains unclear.
Patients and methods: The subjects were 40 AD patients; 20 had mild AD (17–23 points on the Mini-Mental State Examination [MMSE]), and 20 had very mild AD (≥24 points). Twenty normal elderly controls were also enrolled as a control group. Thirty sentences that contained novel similes (Items) were prepared. For each Item, four explanatory choices, consisting of one correct response and three foils, were provided. The participants were asked to choose the written statement that best represented the Item’s meaning. In addition, all the subjects completed the Token Test.
Results: The patients with mild AD had significantly lower scores than the normal controls on both the simile comprehension test and the Token Test. However, the patients with very mild AD exhibited significantly lower scores on the simile comprehension test, but not on the Token Test. The distributions of error types for the simile test differed between the mild AD group and the other groups. The mild AD patients made more errors that were “far” from the correct responses.
Conclusion: Patients with AD are more likely to have comprehension deficits of metaphorical expressions than comprehension deficits of non-metaphorical expressions. Pragmatic language dysfunction may precede formal language dysfunction during the progression of AD.

Keywords: non-literal language, simile, multiple-choice, pragmatics

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