Longitudinal Changes in Semantic Concreteness in Semantic Variant Primary Progressive Aphasia (svPPA)

Area of Science:

• Neuroscience
• Neurology
• Linguistics

Background:

• Semantic variant primary progressive aphasia (svPPA) is characterized by a loss of concrete noun knowledge.
• Previous studies link this deficit to left ventral temporal lobe atrophy.
• The longitudinal progression of this impairment and its relation to brain atrophy remain unclear.

Purpose of the Study:

• To investigate longitudinal changes in noun concreteness in svPPA.
• To correlate these changes with longitudinal gray matter (GM) changes observed via MRI.
• To compare noun concreteness progression in svPPA with behavioral variant frontotemporal dementia (bvFTD).

Main Methods:

• Elicited naturalistic speech samples at two time points from svPPA (n=11) and bvFTD (n=15) patients.
• Assessed the concreteness of spoken nouns in these samples.
• Measured longitudinal GM changes using MRI in a subset of svPPA patients (n=7).

Main Results:

• svPPA patients showed a significant decrease in noun concreteness over time, unlike bvFTD patients whose speech remained concrete.
• Longitudinal GM decline was observed in temporal and frontal regions in svPPA patients.
• Atrophy in the right fusiform/parahippocampal gyri and left superior temporal gyrus correlated with reduced noun concreteness.

Conclusions:

• Progressive atrophy of the ventral temporal lobe in svPPA contributes to the decline in concrete noun production.
• This study provides longitudinal evidence for the progression of semantic impairment in svPPA.
• Findings highlight the link between specific neuroanatomical changes and language deficits in svPPA.