The linguistic deficit in patients with Alzheimer's Disease: is there a syntactic impairment?

  • The linguistic impairment of patients affected by Alzheimer’s disease (PAD) is defined as a form of fluent aphasia, which is caused by major disruptions in the semantic and lexical domains. Consequently, their discourse is often described as empty, although their speech is fluent. This study aims at enlarging the comprehension of the linguistic deficit in PADs; in particular, it deals with their syntactic competence and it addresses the following questions: 1) Do PADs suffer from syntactic impairment? 2) How can the impairment in PADs be accounted for? 3) At which stage of the disease are PADs affected by syntactic impairment? The syntactic competence of Italian-speaking PADs is investigated under two different perspectives. On one hand, the study considers the syntactic information stored in the lexicon as part of the lexical entry. For this purpose, PADs complete a grammatical gender retrieval task on a list of 100 Italian nouns. On the other hand, the question deals with syntax intended as the capacity to complete the processing of syntactic structures in sentence comprehension and production. The present study focuses on sentence comprehension and includes two sentence-to-picture matching tasks: one on Wh-questions, and one on relative clauses. PADs complete the experiment on grammatical gender retrieval with high accuracy, except for few mistakes on irregular and opaque nouns, thus showing a spared capacity to retrieve the syntactic information, especially when they can rely on the form-driven procedural mechanism, as in the case of regular nouns. Data on the comprehension of Wh-questions and RC reveals that PADs are more sensitive than controls to locality effects. Patients with moderate dementia are impaired at computing dependencies that entail a crossing movement between two arguments whose features are in a relation of inclusion. In contrast, crossing movements are allowed when the involved feature arrays are in a relation of disjunction. In short, patients are spared at using procedural mechanisms for the retrieval of syntactic information, while they are impaired at processing sentences that entail argument extraction. The impairment manifests itself in moderately impaired PADs in the form of enhanced sensitivity to locality effects.

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Author:Irene Caloi
Place of publication:Frankfurt am Main
Referee:Cecilia Poletto, Adriana Belletti
Document Type:Doctoral Thesis
Date of Publication (online):2017/12/18
Year of first Publication:2017
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Granting Institution:Johann Wolfgang Goethe-Universität
Date of final exam:2016/11/16
Release Date:2018/01/11
Page Number:286
Institutes:Neuere Philologien
Dewey Decimal Classification:4 Sprache / 40 Sprache / 400 Sprache
6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Licence (German):License LogoDeutsches Urheberrecht