Auditory post-processing in a passive listening task is deficient in Alzheimer’s disease

• Auditory post-processing in the form of a diminished late negative frontal wave is reduced in patients with Alzheimer’s disease compared to age-matched healthy controls.
• Physiological aging does not affect auditory post-processing as measured activity does not differ between young and elderly healthy controls.
• The amplitude of the late negative frontal wave predicted short-term memory capacity deficits in the patients with Alzheimer’s and could represent a valuable marker for these impairments.

ObjectiveTo investigate whether automatic auditory post-processing is deficient in patients with Alzheimer’s disease and is related to sensory gating.MethodsEvent-related potentials were recorded during a passive listening task to examine the automatic transient storage of auditory information (short click pairs). Patients with Alzheimer’s disease were compared to a healthy age-matched control group. A young healthy control group was included to assess effects of physiological aging.ResultsA bilateral frontal negativity in combination with deep temporal positivity occurring 500 ms after stimulus offset was reduced in patients with Alzheimer’s disease, but was unaffected by physiological aging. Its amplitude correlated with short-term memory capacity, but was independent of sensory gating in healthy elderly controls. Source analysis revealed a dipole pair in the anterior temporal lobes.ConclusionResults suggest that auditory post-processing is deficient in Alzheimer’s disease, but is not typically related to sensory gating. The deficit could neither be explained by physiological aging nor by problems in earlier stages of auditory perception. Correlations with short-term memory capacity and executive control tasks suggested an association with memory encoding and/or overall cognitive control deficits.SignificanceAn auditory late negative wave could represent a marker of auditory working memory encoding deficits in Alzheimer’s disease.