The dynamics of auditory working memory impairment in logopenic aphasia and Alzheimer’s disease

Abstract

AbstractBackgroundImpaired auditory verbal working memory is a diagnostic hallmark and integral driver of the clinical phenotype in logopenic aphasia. However, the physiology of the working memory buffer in this syndrome is poorly characterised. Here we addressed the temporal dynamics of auditory verbal working memory in patients with logopenic aphasia and typical Alzheimer’s disease.MethodIn a cohort of patients with logopenic aphasia and typical Alzheimer’s disease and in healthy age‐matched controls, we assessed how temporal manipulations of standard auditory verbal working memory tasks (forward and reverse digit span and phrasal repetition) affected performance. We varied tempo of delivery and inter‐trial gap and performed a detailed analysis of error types. Participants also had pure tone audiometry to assess peripheral hearing function and a comprehensive general neuropsychological assessment.ResultCompared with healthy controls, patients with logopenic aphasia and Alzheimer’s disease showed increased sensitivity to temporal manipulation of auditory verbal working memory tasks and error profiles suggesting a dynamic physiological lesion of the working memory buffer. These effects were particularly marked in the logopenic group.ConclusionOur findings open a novel physiological window on working memory dynamics in Alzheimer’s disease syndromes. Further work is warranted to assess how this dynamic deficit impacts communication in patients’ daily lives, how it can best inform management interventions and its potential as a novel, rapid read‐out of neural function in the era of disease‐modifying therapies.