Central Auditory Dysfunction as a Harbinger of Alzheimer Dementia

Abstract

Objective Confirm that central auditory dysfunction may be a precursor to the onset of Alzheimer’s Disease (AD) Design Cohort study Setting Research study center Participants 274 volunteers from a dementia surveillance cohort were followed for up to 4 years after having complete audiometric assessment. 21 of the participants received a consensus diagnosis of AD after hearing testing. Intervention Three central auditory tests were performed: the Dichotic Sentence Identification, the Dichotic Digits, and the Synthetic Sentence Identification with Ipsilateral Competing Message. Main Outcome Measures A new diagnosis of Alzheimer’s disease using the National Institute of Neurological and Communicative Diseases and Stroke–Alzheimer’s Disease and Related Disorders Association criteria at a consensus conference Results The mean scores on each CAD test were significantly poorer in the incident dementia group. Cox proportional hazards models with age as the time-scale were used to estimate the hazard ratio for incident dementia based on CAD test results. After adjusting for educational level, the hazard ratio for incident dementia in people with severe CAD based on a Dichotic Sentence Identification in free report mode of <50% was 9.9 (95% C.I. 3.6, 26.7). Conclusions In these cases, CAD was a precursor to Alzheimer’s dementia. We recommend evaluating older adults complaining of hearing difficulty with CAD tests. Those with severe CAD should receive a modified rehabilitation program and be considered for referral for neurologic evaluation.

Music Perception in Dementia

“…This contrasts with previous work characterising a generic impairment of auditory scene analysis in AD [33,35,36,[72][73][74][75] and may in part reflect the relatively wide variation in healthy control performance on our tune streaming test (Figure 3). However, it is possible that the analysis of musical scenes benefits to a greater degree than other kinds of auditory scenes from the availability of stored templates, here familiar tunes.…”

“…Musical scene analysis has not been widely studied neuropsychologically in clinical populations but is likely to engage posterior superior temporal and parietal lobe regions and their dorsal projections [68][69][70][71][72]. AD has been shown to produce a generic impairment of auditory scene analysis under diverse listening tasks and conditions, including the streaming of sound sequences that bear some similarities to musical melodies; this has been linked to dysfunction of posterior temporoparietal areas overlapping those involved in music perception [33,35,36,[73][74][75]. On both neuroanatomical and neuropsychological grounds, patients with AD might therefore be anticipated to have difficulties with musical scene analysis; however, this has not been addressed directly in previous work.…”

Donepezil enhances understanding of degraded speech in Alzheimer's disease

“…The relative selectivity of the present effect suggests that the pairing of procholinergic therapy with specific, dynamic auditory stimuli such as degraded speech may be required to train and to measure perceptual benefit. Our findings have clear implications for assessing dynamic perceptual reserve, improving communication and designing interventions and acoustic environments from the early stages of AD 5. Besides corroboration in larger cohorts using a placebo‐controlled design and drug‐naive patients, future work should address the pharmacological, neurophysiological and neuroanatomical correlates of these findings in relation to peripheral hearing, the circadian alertness cycle and other disease factors and the durability and translatability of sinewave speech effects to other adverse listening paradigms.…”

“…Patients with AD frequently struggle to understand spoken information in the presence of background noise or when delivered in unfamiliar accents or voices,2, 3, 4 restricting communication and quality of life. Auditory dysfunction has been identified as a harbinger of incipient dementia in AD 5. The role of acetylcholine in auditory function is highly pertinent, particularly for dynamic perception under difficult or changing listening conditions or where there is a requirement for auditory plasticity 6.…”

Cognitive Decline and Hearing Health Care for Older Adults

“…In fact, dementia is more prevalent in people with hearing loss than in counterparts without hearing loss (Uhlman et al, 1986(Uhlman et al, , 1989. Strikingly, epidemiologic research indicates that scores on tests of auditory central processing (Gates et al, 2002(Gates et al, , 2010(Gates et al, , 2011, and even audiometric thresholds (Lin et al, 2011a(Lin et al, ,b, 2013 . One possibility is that the relationship between hearing loss and incident dementia is mediated by lifestyle factors; e.g., participation in social leisure activities is known to be related to good cognition but is compromised by hearing loss.…”