Which statement correctly differentiates AOS from nonfluent PPA based on speech features?

• A. AOS shows motor planning errors and groping with relatively preserved linguistic content, while nonfluent PPA shows language formulation deficits with apraxia-like errors and more global language impairment.
• B. AOS primarily affects comprehension; nonfluent PPA primarily affects articulation.
• C. AOS has consistent errors across utterances.
• D. Nonfluent PPA is characterized by rapid, natural speech.

Answer: (A)

Differentiating AOS from nonfluent PPA hinges on what each condition disrupts: motor planning for speech versus language formulation. In AOS, the core issue is planning and programming the sequence of movements needed for speech. This leads to motoric errors, distorted sounds, and groping as the speaker searches for the right motor plan, while the linguistic content—vocabulary and meaning—remains relatively intact, especially early on.

Nonfluent PPA, by contrast, is a progressive language disorder. Speech is slow and effortful because the language production system itself is deteriorating, producing apraxia-like articulation errors within a broader language impairment that often includes agrammatism. Comprehension is typically preserved in the early stages but can become more affected as the disease advances.

So, the statement that highlights motor planning errors with preserved linguistic content for AOS, and language formulation deficits with apraxia-like errors and broader language decline for nonfluent PPA, best captures the distinction.