Core auditory processing deficits in primary progressive aphasia.

Area of Science:

• Neuroscience
• Audiology
• Linguistics

Background:

• The contribution of non-linguistic auditory processing deficits to primary progressive aphasia (PPA) phenomenology is not well-established.
• PPA encompasses various subtypes, including semantic, non-fluent/agrammatic, and logopenic variants, each with distinct clinical presentations.

Purpose of the Study:

• To investigate auditory processing deficits in pitch, timing, and timbre using non-linguistic stimuli in patients with PPA.
• To determine if these deficits correlate with speech, language, and neuropsychological profiles across different PPA variants.

Main Methods:

• Psychoacoustic tasks assessing pitch, timing, and timbre were administered to 18 PPA patients (8 semantic, 6 non-fluent, 4 logopenic) and 28 healthy controls.
• Performance was analyzed at the group level and correlated with clinical and neuropsychological assessments.

Main Results:

• PPA patients exhibited significant group-level impairments in all three auditory domains (pitch, timing, timbre).
• The most pronounced deficits were observed in rhythm processing for short tone sequences, especially in the non-fluent variant.
• Logopenic variant patients showed no significant impairments; semantic variant patients had less severe deficits.

Conclusions:

• A core central auditory impairment for non-linguistic stimuli exists in PPA, particularly affecting the non-fluent and semantic variants.
• Deficits in auditory timing may underlie impairments in both auditory perception and speech production, potentially involving auditory working memory in the non-fluent variant.