Sentence comprehension in patients with dementia of the Alzheimer's type

Xinmiao Liu; Wenbin Wang; Haiyan Wang; Yu Sun

doi:10.7717/peerj.8181

Sentence comprehension in patients with dementia of the Alzheimer's type

PeerJ. 2019 Dec 3:7:e8181. doi: 10.7717/peerj.8181. eCollection 2019.

Authors

Xinmiao Liu¹, Wenbin Wang², Haiyan Wang³, Yu Sun⁴

Affiliations

¹ School of English for Specific Purposes, Beijing Foreign Studies University, Beijing, China.
² National Research Centre for Foreign Language Education, Beijing Foreign Studies University, Beijing, China.
³ Institute of Language and Brain Science, School of Translation Studies, Qufu Normal University, Rizhao, China.
⁴ Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing, China.

Abstract

Sentence comprehension is diminished in patients with dementia of the Alzheimer's type (DAT). However, the underlying reason for such deficits is still not entirely clear. The Syntactic Deficit Hypothesis attributes sentence comprehension deficits in DAT patients to the impairment in syntactic ability, whereas the Processing Resource Deficit Hypothesis proposes that sentence comprehension deficits are the result of working memory deficiency. This study investigated the deficits in sentence comprehension in Chinese-speaking DAT patients with different degrees of severity using sentence-picture matching tasks. The study revealed a significant effect of syntactic complexity in patients and healthy controls, but the effect was stronger in patients than in healthy controls. When working memory demand was minimized, the effect of syntactic complexity was only significant in patients with moderate DAT, but not in healthy controls or those with mild DAT. The findings suggest that in patients with mild DAT, working memory decline was the major source of sentence comprehension difficulty and in patients with moderate DAT, working memory decline and syntactic impairment jointly contributed to the impairments in sentence comprehension. The source of sentence comprehension deficits varied with degree of dementia severity.

Keywords: Alzheimer’s disease; Chinese; Language comprehension; Language deficit.

Grants and funding

This work was supported by the key project (18AYY003) of the National Social Science Foundation of China, the National Research Centre for Foreign Language Education (MOE Key Research Institute of Humanities and Social Sciences at Universities), Beijing Foreign Studies University, the Post-funded Project by Beijing Foreign Studies University (2019SYLHQ012), the Humanities and Social Sciences Foundation of Ministry of Education of China (18YJA740048), Shandong Social Science Planning Fund (17CQRJ04), the National Key Research and Development Program of China (2016YFC1306300), National Natural Science Foundation of China (61633018, 81430037), and Beijing Municipal Commission of Health and Family Planning (PXM2020_026283_000002). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.