Quantifying grammatical impairments in primary progressive aphasia: Structured language tests and narrative language...

Area of Science:

• Neurolinguistics
• Cognitive Neuroscience
• Clinical Linguistics

Background:

• Primary progressive aphasia (PPA) encompasses neurodegenerative conditions affecting language.
• Understanding grammatical production deficits is crucial for PPA diagnosis and management.
• Differentiating PPA subtypes based on linguistic features aids in understanding underlying neuropathology.

Purpose of the Study:

• To examine grammatical production in PPA using structured tests and narrative samples.
• To quantify the relationship between grammatical measures across different tasks.
• To identify factors influencing these cross-task grammatical relationships.

Main Methods:

• 77 participants with PPA (including PPA-G, PPA-L, PPA-S subtypes) underwent grammatical testing and provided narrative samples.
• Accuracy scores and grammatical diversity were analyzed for both tests and narratives.
• Principal components analysis and multiple regression explored cross-task measure relationships.

Main Results:

• PPA-G participants showed lower accuracy in sentence production and verb morphology compared to PPA-L and PPA-S.
• Narrative grammatical accuracy predicted test performance in PPA-G; narrative diversity predicted it in PPA-L.
• Severe grammatical impairments showed robust associations between morphology and argument structure errors across tasks.

Conclusions:

• Narrative grammatical production is a strong predictor of structured test performance in PPA.
• Distinct narrative production patterns (accuracy vs. diversity) characterize PPA-G and PPA-L subtypes.
• Grammatical diversity measures are vital for analyzing language production, especially in non-agrammatic PPA variants.