Auditory cognition in Alzheimer's Disease

Abstract

Mounting evidence suggests a significant association between hearing loss and an elevated risk of dementia, yet its neurobiological underpinnings remain largely unknown. A decline in the central auditory processing ability, particularly, has been implicated in the increased susceptibility to Alzheimer’s Disease dementia. The research presented in this dissertation highlights the importance of auditory cognitive mechanisms such as speech-in-noise perception and auditory memory, in two demographic cohorts: ageing individuals who are cognitively intact and those afflicted with Alzheimer's disease, which includes those exhibiting mild cognitive impairment and Alzheimer's Disease dementia. Employing an array of different experimental paradigms and methodologies, I present evidence that highlights the critical role of short-term auditory memory (spanning tens of seconds) in speech-in-noise perception, an ability that diminishes across the Alzheimer's Disease continuum. Evaluating this auditory cognitive ability can serve as a valuable instrument for understanding the functionality of the medial temporal lobe, as corroborated by neuropsychological and neuroanatomical work demonstrated in this thesis and functional imaging work conducted in healthy volunteers. To fully substantiate these findings and gauge their generalisability, it is imperative to conduct longitudinal studies to ascertain the validity and reliability of these observations in diverse participant cohorts.