Peripheral and central hearing impairment and their relationship with cognition: a review

Association between hearing ability and cortical morphology in the elderly: multiparametric mapping, cognitive relevance, and neurobiological underpinnings

BACKGROUND

Hearing impairment is a common condition in the elderly. However, a comprehensive understanding of its neural correlates is still lacking.

METHODS

We recruited 284 elderly adults who underwent structural MRI, magnetic resonance spectroscopy, audiometry, and cognitive assessments. Individual hearing abilities indexed by pure tone average (PTA) were correlated with multiple structural MRI-derived cortical morphological indices. For regions showing significant correlations, mediation analyses were performed to examine their role in the relationship between hearing ability and cognitive function. Finally, the correlation maps between hearing ability and cortical morphology were linked with publicly available connectomic gradient, transcriptomic, and neurotransmitter maps.

FINDINGS

Poorer hearing was related to cortical thickness (CT) reductions in widespread regions and gyrification index (GI) reductions in the right Area 52 and Insular Granular Complex. The GI in the right Area 52 mediated the relationship between hearing ability and executive function. This mediating effect was further modulated by glutamate and N-acetylaspartate levels in the right auditory region. The PTA-CT correlation map followed microstructural connectomic hierarchy, were related to genes involved in certain biological processes (e.g., glutamate metabolic process), cell types (e.g., excitatory neurons and astrocytes), and developmental stages (i.e., childhood to young adulthood), and covaried with dopamine receptor 1, dopamine transporter, and fluorodopa. The PTA-GI correlation map was related to 5-hydroxytryptamine receptor 2a.

INTERPRETATION

Poorer hearing is associated with cortical thinning and folding reductions, which may be engaged in the relationship between hearing impairment and cognitive decline in the elderly and have different neurobiological substrates.

FUNDING

See the Acknowledgements section.

Prediction Model for Cognitive Impairment among Disabled Older Adults: A Development and Validation Study

Disabled older adults exhibited a higher risk for cognitive impairment. Early identification is crucial in alleviating the disease burden. This study aims to develop and validate a prediction model for identifying cognitive impairment among disabled older adults. A total of 2138, 501, and 746 participants were included in the development set and two external validation sets. Logistic regression, support vector machine, random forest, and XGBoost were introduced to develop the prediction model. A nomogram was further established to demonstrate the prediction model directly and vividly. Logistic regression exhibited better predictive performance on the test set with an area under the curve of 0.875. It maintained a high level of precision (0.808), specification (0.788), sensitivity (0.770), and F1-score (0.788) compared with the machine learning models. We further simplified and established a nomogram based on the logistic regression, comprising five variables: age, daily living activities, instrumental activity of daily living, hearing impairment, and visual impairment. The areas under the curve of the nomogram were 0.871, 0.825, and 0.863 in the internal and two external validation sets, respectively. This nomogram effectively identifies the risk of cognitive impairment in disabled older adults.

An Over-the-Counter Hearing Aid Clinical Trial in Rural Alabama: Project Design and Potential Implications for Pharmacy and Audiology Interprofessional Collaborations

Over-the-counter hearing aids (OTC HAs) have the potential to help adults with perceived mild-to-moderate hearing loss across the US, especially in rural communities, where access to hearing healthcare is extremely limited or non-existent. The purpose of this study was to describe an OTC HA clinical trial being conducted in five rural counties of Alabama and to provide preliminary anecdotal data related to the use and care of these hearing aids by the participants. In brief, for this clinical trial, adults with hearing loss were randomly placed in one of three groups where they received varying levels of support for setting, using, and maintaining their OTC HAs. Listening tests and surveys were administered to assess the extent to which they benefitted from the hearing aids as related to word understanding, communication with others in natural settings, and hearing aid use and care. Currently, anecdotal findings suggested that, although some participants required very little support to successfully use their hearing aids, others had difficulty setting and caring for their devices and could have benefitted from individualized guidance. Future quantitative studies will assess the extent of support needed for successful hearing aid benefit and use. Potentially, collaborations among pharmacy and audiology professionals could lead to increased access to hearing healthcare by supporting the use and purchase of OTC HAs in rural pharmacy settings.

Acoustic reflexes: should we be paying more attention?

OBJECTIVE

The clinical audiology test battery often involves playing physically simple sounds with questionable ecological value to the listener. In this technical report, we revisit how valid this approach is using an automated, involuntary auditory response; the acoustic reflex threshold (ART).

DESIGN

The ART was estimated four times in each individual in a quasi-random ordering of task conditions. The baseline condition (referred to as Neutral) measured the ART following a standard clinical practice. Three experimental conditions were then used in which a secondary task was performed whilst the reflex was measured: auditory attention, auditory distraction and visual distraction tasks.

STUDY SAMPLE

Thirty-eight participants (27 males) with a mean age of 23 years were tested. All participants were audiometrically healthy.

RESULTS

The ART was elevated when a visual task was performed at the same time as the measurements were taken. Performing an auditory task did not affect the ART.

CONCLUSIONS

These data indicate that simple audiometric measures widely used in the clinic, can be affected by central, non-auditory processes even in healthy, normal-hearing volunteers. The role of cognition and attention on auditory responses will become ever more important in the coming years.

Adjunct Methods for Alzheimer's Disease Detection: A Review of Auditory Evoked Potentials

The auditory afferent pathway as a clinical marker of Alzheimer's disease (AD) has sparked interest in investigating the relationship between age-related hearing loss (ARHL) and AD. Given the earlier onset of ARHL compared to cognitive impairment caused by AD, there is a growing emphasis on early diagnosis and intervention to postpone or prevent the progression from ARHL to AD. In this context, auditory evoked potentials (AEPs) have emerged as a widely used objective auditory electrophysiological technique for both the clinical diagnosis and animal experimentation in ARHL due to their non-invasive and repeatable nature. This review focuses on the application of AEPs in AD detection and the auditory nerve system corresponding to different latencies of AEPs. Our objective was to establish AEPs as a systematic and non-invasive adjunct method for enhancing the diagnostic accuracy of AD. The success of AEPs in the early detection and prediction of AD in research settings underscores the need for further clinical application and study.

Bidirectional associations between hearing difficulty and cognitive function in Chinese adults: a longitudinal study

Background

Middle-aged and older adults frequently experience hearing loss and a decline in cognitive function. Although an association between hearing difficulty and cognitive function has been demonstrated, its temporal sequence remains unclear. Therefore, we investigated whether there are bidirectional relationships between hearing difficulty and cognitive function and explored the mediating role of depressive symptoms in this relationship.

Method

We used the cross-lagged panel model and the random-intercept cross-lagged panel model to look for any possible two-way link between self-reported hearing difficulty and cognitive function. To investigate depressive symptoms' role in this association, a mediation analysis was conducted. The sample was made up of 4,363 adults aged 45 and above from the China Health and Retirement Longitudinal Study (CHARLS; 2011-2018; 44.83% were women; mean age was 56.16 years). One question was used to determine whether someone had a hearing impairment. The tests of cognitive function included episodic memory and intelligence. The Center for Epidemiologic Studies Depression Scale, which consists of 10 items, was used to measure depressive symptoms.

Results

A bidirectional association between hearing and cognition was observed, with cognition predominating (Wald χ2 (1) = 7.241, p < 0.01). At the between-person level, after controlling for potential confounders, worse hearing in 2011 predicted worse cognitive function in 2013 (β = -0.039, p < 0.01) and vice versa (β = -0.041, p < 0.01) at the between-person level. Additionally, there was no corresponding cross-lagged effect of cognitive function on hearing difficulty; rather, the more hearing difficulty, the greater the cognitive decline at the within-person level. According to the cross-lagged mediation model, depressive symptoms partially mediates the impact of cognitive function on subsequent hearing difficulty (indirect effect: -0.003, bootstrap 95% confidence interval: -0.005, -0.001, p < 0.05), but not the other way around.

Conclusion

These results showed that within-person relationships between hearing impairment and cognitive function were unidirectional, while between-person relationships were reciprocal. Setting mental health first may be able to break the vicious cycle that relates hearing loss to cognitive decline. Comprehensive long-term care requires services that address depressive symptoms and cognitive decline to be integrated with the hearing management.

Retomando los sonidos: Prevención de la hipoacusia y rehabilitación auditiva en las personas mayores

La hipoacusia representa una de las principales causas de discapacidad a nivel mundial y su prevalencia aumenta a medida que se envejece. Representa un tipo de discapacidad que, en la mayoría de los casos, puede ser potencialmente prevenible y tratable, por lo que su prevención, identificación temprana y rehabilitación integral deberían ser algunos de los puntos de acción a nivel local ya que se ha relacionado con numerosos desenlaces adversos en salud, incluyendo los dominios físico, mental, social y económico de las personas mayores. El objetivo de este artículo es resaltar la importancia de la prevención de la hipoacusia y promover su rehabilitación a lo largo del curso de vida, especialmente en personas mayores, y describir estrategias que se han planteado desde la Organización Mundial de la Salud y la Organización Panamericana de la Salud.

The Association Between Hearing Impairment, Vision Impairment, Dual Sensory Impairment, and Serious Cognitive Impairment: Findings from a Population-Based Study of 5.4 million Older Adults

Background:

Sensory impairments and cognitive impairment are increasing in scope due to the aging population.

Objective:

To investigate the association between hearing impairment, vision impairment, and dual sensory impairment with cognitive impairment among older adults.

Methods:

Secondary analysis of a combination of ten consecutive waves (2008–2017) of the nationally representative American Community Survey. The sample included 5.4 million community-dwelling and institutionalized older adults aged 65 and older. Bivariate and logistic regression models were conducted to examine the association hearing impairment, vision impairment, and dual sensory impairment with cognitive impairment.

Results:

After controlling for age, race, education, and income, older adults with only hearing impairment had more than double the odds of cognitive impairment (OR = 2.66, 95% CI = 2.64, 2.68), while older adults with only vision impairment had more than triple the odds of cognitive impairment (OR = 3.63; 95% CI = 3.59, 3.67). For older adults with dual sensory impairment, the odds of cognitive impairment were eight-fold (OR = 8.16; 95% CI = 8.07, 8.25). Similar trends were apparent in each sex and age cohort.

Conclusion:

Hearing and vision impairment are both independently associated with cognitive impairment. However, dual sensory impairment is associated with substantially higher odds of cognitive impairment, even after controlling for sociodemographic characteristics. Practitioners working with older adults may consider treatment for sensory impairments and cognitive impairment concurrently. Future research is needed to determine if the association is causal, and to investigate the effectiveness of common methods of treatment for sensory impairment for reducing the prevalence of cognitive impairment.

High-Frequency Cochlear Amplifier Dysfunction: A Dominating Contribution to the Cognitive-Ear Link

Objective: The objective of this study was to investigate the role of the high-frequency cochlear dysfunction in the cognitive-ear link.

Methods: Seventy-four presbycusis patients (PC group) and seventy-one age-, sex-, and education-level matched normal hearing controls (NH group) were recruited in this study. Participants underwent a battery of cognitive tests estimated by Montreal Cognitive Assessment (MoCA), Stroop Color-Word Interference Test (Stroop), Symbol Digit Modalities Test (SDMT), Auditory Verbal Learning Test (AVLT), and Trail-Making Test (TMT-A and B), as well as auditory tests including distortion product otoacoustic emission (DPOAE), pure tone (PT) thresholds, and speech reception thresholds (SRT). Data were analyzed using the factor analysis, partial correlation analysis, multiple linear regression models, and mediation models.

Results: Distortion product otoacoustic emission detection amplitudes and PT thresholds performed worse gradually from low to high frequencies in both the NH and PC groups. High-frequency DPOAE (H-DPOAE) was significantly correlated with cognitive domains in the PC group (AVLT: r = 0.30, p = 0.04; SDMT: r = 0.36, p = 0.01; Stroop: r = –0.32, p = 0.03; TMT-A: r = –0.40, p = 0.005; TMT-B: r = –0.34, p = 0.02). Multiple linear regression models showed that H-DPOAE predicted cognitive impairment effectively for aspects of memory (R2 = 0.27, 95% CI, 0.03 to 1.55), attention (R2 = 0.32, 95% CI, –6.18 to –0.40), processing speed (R2 = 0.37, 95% CI, 0.20 to 1.64), and executive function (TMT-A: R2 = 0.34, 95% CI, –5.52 to 1.03; TMT-B: R2 = 0.29, 95% CI, –11.30 to –1.12). H-DPOAE directly affected cognition and fully mediated the relationship between pure tone average (PTA)/SRT and cognitive test scores, excluding MoCA.

Conclusion: This study has demonstrated that the high-frequency cochlear amplifier dysfunction has a direct predictive effect on the cognitive decline and makes a large contribution to the cognitive-ear link.

Stress Response and Hearing Loss Differentially Contribute to Dynamic Alterations in Hippocampal Neurogenesis and Microglial Reactivity in Mice Exposed to Acute Noise Exposure

Noise-induced hearing loss (NIHL) is one of the most prevalent forms of acquired hearing loss, and it is associated with aberrant microglial status and reduced hippocampal neurogenesis; however, the nature of these associations is far from being elucidated. Beyond its direct effects on the auditory system, exposure to intense noise has previously been shown to acutely activate the stress response, which has increasingly been linked to both microglial activity and adult hippocampal neurogenesis in recent years. Given the pervasiveness of noise pollution in modern society and the important implications of either microglial activity or hippocampal neurogenesis for cognitive and emotional function, this study was designed to investigate how microglial status and hippocampal neurogenesis change over time following acoustic exposure and to analyze the possible roles of the noise exposure-induced stress response and hearing loss in these changes. To accomplish this, adult male C57BL/6J mice were randomly assigned to either a control or noise exposure (NE) group. Auditory function was assessed by measuring ABR thresholds at 20 days post noise exposure. The time-course profile of serum corticosterone levels, microglial status, and hippocampal neurogenesis during the 28 days following noise exposure were quantified by ELISA or immunofluorescence staining. Our results illustrated a permanent moderate-to-severe degree of hearing loss, an early but transient increase in serum corticosterone levels, and time-dependent dynamic alterations in microglial activation status and hippocampal neurogenesis, which both present an early but transient change and a late but enduring change. These findings provide evidence that both the stress response and hearing loss contribute to the dynamic alterations of microglia and hippocampal neurogenesis following noise exposure; moreover, noise-induced permanent hearing loss rather than noise-induced transient stress is more likely to be responsible for perpetuating the neurodegenerative process associated with many neurological diseases.

Association of hearing loss with land transport accidents: a nationwide population-based study

OBJECTIVE

This study aimed to investigate the association of prior hearing loss with land transport accidents using a nationwide population-based dataset.

DESIGN

A case-control study.

STUDY SAMPLE

Data for this study were obtained from Taiwan's National Health Insurance Dataset. We retrieved data on 2066 patients who had received a diagnosis of a land transport accident as cases. We used a propensity score-matched method to select 6198 controls.

RESULTS

A Chi-squared test revealed that there was a significant difference in the prevalence of prior hearing loss between cases and controls (6.8% vs. 5.6%, p = 0.046). The odds ratio (OR) of prior hearing loss for cases was 1.128 (95% confidence interval [CI]: 1.003 ∼ 1.503) compared to controls. After adjusting for demographic variables and comorbidities, the OR of hearing loss for cases was 1.238 (95% CI: 1.008 ∼ 1.522) that of controls.

CONCLUSIONS

Our finding suggests that pre-existing hearing loss may be associated with land transport accidents among adults aged 50 years and older. Further study is needed to elucidate the mechanism(s) through which hearing loss may contribute to land transport accidents and examine how the use of hearing rehabilitation devices, for example, hearing aids impacts the observed associations.

Hearing Loss and Dementia: A Meta-Analysis of Prospective Cohort Studies

Background: Consensus is lacking with regard to whether hearing loss is an independent risk factor for dementia. We therefore conducted a meta-analysis to clarify the relationship of hearing loss and dementia.

Methods: Prospective cohort studies investigating the association between hearing loss and the incidence of dementia in a community-derived population were included by searching electronic databases that included PubMed, Embase, and Cochrane's Library. A random-effects model was adopted to combine the results.

Results: Fourteen cohorts including 726,900 participants were analyzed. It was shown that hearing loss was independently associated with dementia [adjusted hazard ratio (HR): 1.59, 95% confidence interval (CI): 1.37 to 1.86, p < 0.001; I² = 86%]. Sensitivity analysis sequentially excluding any of the individual studies included showed similar results. Subgroup analysis according to the diagnostic methods for hearing loss, validation strategy for dementia, follow-up duration, and adjustment of apolipoprotein E genotype also showed consistent results (p-values for subgroup differences all > 0.05). Meta-analysis with five studies showed that hearing loss was also connected to higher risk of Alzheimer's disease (adjusted HR: 2.24, 95% CI: 1.32 to 3.79, p = 0.003; I² = 2%).

Conclusions: Hearing loss may increase the risk of dementia in the adult population. Whether effective treatment for hearing loss could reduce the incidence of dementia should be explored in the future.

Sport as a Factor in Improving Visual Spatial Cognitive Deficits in Patients with Hearing Loss and Chronic Vestibular Deficit

Hearing loss and chronic vestibular pathologies require brain adaptive mechanisms supported by a cross-modal cortical plasticity. They are often accompanied by cognitive deficits. Spatial memory is a cognitive process responsible for recording information about the spatial environment and spatial orientation. Visual-spatial working memory (VSWM) is a kind of short-term working memory that allows spatial information to be temporarily stored and manipulated. It can be conditioned by hearing loss and also well-compensated chronic vestibular deficit. Vestibular rehabilitation and hearing aid devices or training are able to improve the VSWM. We studied 119 subjects suffering from perinatal or congenital hearing loss, compared with 532 healthy subjects and 404 patients with well-compensated chronic vestibular deficit (CVF). VSWM was evaluated by the eCorsi test. The subjects suffering from chronic hearing loss and/or unilateral or bilateral vestibular deficit showed a VSWM less efficient than healthy people, but much better than those with CVF, suggesting a better multimodal adaptive strategy, probably favored by a cross-modal plasticity which also provides habitual use of lip reading. The sport activity cancels the difference with healthy subjects. It is therefore evident that patients with this type of deficit since childhood should be supported and advised on a sport activity or repeated vestibular stimulation.

Selective attention modulates neural envelope tracking of informationally masked speech in healthy older adults

Speech understanding in noisy situations is compromised in old age. This study investigated the energetic and informational masking components of multi‐talker babble noise and their influence on neural tracking of the speech envelope in a sample of healthy older adults. Twenty‐three older adults (age range 65–80 years) listened to an audiobook embedded in noise while their electroencephalogram (EEG) was recorded. Energetic masking was manipulated by varying the signal‐to‐noise ratio (SNR) between target speech and background talkers and informational masking was manipulated by varying the number of background talkers. Neural envelope tracking was measured by calculating temporal response functions (TRFs) between speech envelope and EEG. Number of background talkers, but not SNR modulated the amplitude of an earlier (around 50 ms time lag) and a later (around 300 ms time lag) peak in the TRFs. Selective attention, but not working memory or peripheral hearing additionally modulated the amplitude of the later TRF peak. Finally, amplitude of the later TRF peak was positively related to accuracy in the comprehension task. The results suggest that stronger envelope tracking is beneficial for speech‐in‐noise understanding and that selective attention is an important ability supporting speech‐in‐noise understanding in multi‐talker scenes.