This study examined speech and language characteristics of three groups of individuals with neurodegenerative disease: (1) primary progressive apraxia of speech (AOS) without aphasia (N=18), (2) agrammatic primary progressive aphasia (agPPA) less severe than AOS (N=10), and (3) agPPA more severe than AOS (N=9). Findings indicate that differences in the predominant characteristics of AOS (predominance of articulatory versus prosodic abnormalities) distributed differently among the three groups, independent of AOS severity. Neuroimaging findings also differed among the groups. Results suggest that neurodegenerative AOS may include perceptually distinguishable subtypes that are related to the presence or absence of aphasia and neuroimaging findings
