Which neurodegenerative variant is associated with apraxia of speech in adults?

• A. Alzheimer's disease
• B. Parkinson's disease
• C. Huntington's disease
• D. Primary progressive apraxia of speech (PPAoS)

Answer: (D)

Apraxia of speech in adults is a motor planning problem that can become progressive when the affected brain area degenerates. When this specific, speech-motor difficulty is the main and early feature of a neurodegenerative process, the condition is called primary progressive apraxia of speech. It sits within the spectrum of primary progressive aphasias and is characterized by AOS as the dominant deficit, sometimes with little or no accompanying language impairment early on. By contrast, Alzheimer's disease centers on memory and broader cognitive decline, Parkinson's disease features movement-related symptoms with speech changes rather than a primary, lasting motor planning defect for speech, and Huntington's disease involves chorea and other motor signs with dysarthria rather than a primary apraxia of speech. So the neurodegenerative variant most associated with apraxia of speech in adults is primary progressive apraxia of speech.