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The role of verb knowledge in sentence comprehension deficits of individuals with Alzheimer's disease and frontotemporal dementia
Dissertation   Open access

The role of verb knowledge in sentence comprehension deficits of individuals with Alzheimer's disease and frontotemporal dementia

Catherine E. Crenshaw Price
Doctor of Philosophy (Ph.D.), Drexel University
Jul 2002
DOI:
https://doi.org/10.17918/etd-75
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Abstract

Comprehension--Testing Alzheimer's disease--Patients Senile dementia
For the present study, three verb roles (transitivity, thematic role, and subject-verb agreement) were investigated with individuals diagnosed with AD and FTD while using a 'real-time,' also known as 'on-line', sentence comprehension task. It was hypothesized that AD patients would be insensitive to agreements that are semantic knowledge based (i.e., thematic) and that FTD patients would be insensitive to agreements that are grammatically based (i.e., transitivity). For the sentence task, AD (n=15), FTD (n=14), and healthy older adult control participants (n=17) were asked to listen for a target word in a sentence. Unbeknownst to participants, the target word, at times, followed an incorrect thematic, transitive, or subject-verb agreement. The control participants performed as expected on the thematic and transitive violations (i.e., it took them significantly longer to respond to a target word when it immediately followed either a transitive or thematic agreement violation compared to coherent agreement, a difference that was not evident when the target word followed the agreement by several syllables.) AD patients demonstrated the same intact processing pattern for the transitive agreement but not the thematic agreements. The FTD group and all FTD subgroups (Progressive Non-Fluent Aphasic, Semantic Dementia, and patients with an Executive Disturbance) were insensitive to both the thematic and transitive agreements. A review of performances as they relate to executive function and language tasks assisted in concluding that AD patients' insensitivity to thematic role knowledge may be due to degradation of the thematic role matrix in verb semantics. FTD patients' insensitivity to both the thematic and transitivity elements of verb knowledge may be due to a degradation of grammatical and semantic verb knowledge or processing impairments. Overall, these findings indicate that verb knowledge has separate semantic and grammatical elements that can influence sentence comprehension in patients with AD and FTD.

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