Hearing Loss and Cognition: What We Know and Where We Need to Go

Effect of Hearing Intervention Versus Health Education Control on Fatigue: A Secondary Analysis of the ACHIEVE Study

BACKGROUND

Fatigue is a common complaint among older adults with hearing loss. The impact of addressing hearing loss on fatigue symptoms has not been studied in a randomized controlled trial. In a secondary analysis of the Aging and Cognitive Health Evaluation in Elders (ACHIEVE) study, we investigated the effect of hearing intervention versus health education control on 3-year change in fatigue in community-dwelling older adults with hearing loss.

METHODS

Participants aged 70-84 years old with untreated hearing loss recruited across 4 study sites in the United States (Forsyth County, North Carolina; Jackson, Mississippi; Minneapolis, Minnesota; Washington County, Maryland) were randomized (1:1) to hearing intervention or health education control and followed for 3 years. Three-year change in fatigue symptoms was measured by 2 instruments (RAND-36 and PROMIS). We estimated the intervention effect as the difference in the 3-year change in fatigue between intervention and control groups using a linear mixed-effects model under the intention-to-treat principle.

RESULTS

Participants (n = 977) had a mean age (SD) of 76.8 (4.0) years, were 53.5% female and 87.8% White. Over 3 years, a beneficial effect of the hearing intervention versus health education control on fatigue was observed using the RAND-fatigue score (β = -0.12 [95% CI: -0.22, -0.02]). Estimates also suggested beneficial effect of hearing intervention on fatigue when measured by the PROMIS-fatigue score (β = -0.32 [95% CI: -1.15, 0.51]).

CONCLUSIONS

Our findings suggest that hearing intervention may reduce fatigue over 3 years among older adults with hearing loss.

The mediational role of hearing acuity in the association between personality and memory: Evidence from the health and retirement study and the English Longitudinal Study of Ageing

OBJECTIVES

Personality traits (i.e., the enduring patterns of thoughts, feelings, and behaviors) are associated with cognition across adulthood. There is interest in identifying potential mechanisms to explain this association, but none has focused on sensory function. Therefore, the present study examined whether an objective measure of hearing acuity mediates the association between personality and memory.

METHODS

Participants were from the Health and Retirement Study (HRS, N = 5497, 60 % women, Mean age = 65.66, SD = 9.00) and the English Longitudinal Study of Ageing (ELSA, N = 4706, 57 % women, Mean age = 64.47, SD = 7.59). In the HRS, participants had data on personality and demographic variables in 2012/2014, hearing acuity in 2016/2018, and memory in 2020. In ELSA, participants had data on personality and demographic variables measured in 2010/2011, hearing acuity in 2014/2015, and memory in 2018/2019.

RESULTS

In both HRS and ELSA, higher hearing acuity partially mediated the association between lower neuroticism (4 % and 5 % proportion effect mediated), higher conscientiousness (6 % and 15 %) and higher openness (3 % and 7 %) and better memory performances at follow-up.

CONCLUSIONS

The present study provides novel evidence that hearing acuity mediates the association between personality and cognition.

Knowledge, attitudes, and practices of Australian allied hearing-healthcare professionals: survey on comorbid hearing loss and cognitive impairment

Purpose

As hearing loss is a modifiable risk factor of dementia, allied hearing-healthcare professionals (AHHPs) frequently see older patients who are affected by both conditions. However, little is known about how well Australian AHHP's understand the complexities of providing care to patients with comorbid hearing loss and dementia, as well as their associated views and practices. Thus, the current study used a survey to explore the knowledge, attitudes, and practices (KAPs) of Australian AHHPs in managing comorbid patients.

Materials and methods

A cross-sectional design was used, wherein a KAP survey was developed and distributed to eligible AHHPs via Qualtrics. Data were analysed with descriptive statistics and binary logistic regression.

Results

101 Australian AHHPs met inclusion criteria (2.5% of approximately 4,000 invited AHHPs), and participated in the study. Although participants generally possessed a high level of knowledge for the association between hearing loss and cognitive impairment, their specific knowledge and practices in relation to cognitive screening tests and referral pathways was limited. Participants also expressed mostly positive attitudes towards their role in assisting patients with comorbid hearing loss and dementia. Furthermore, our results suggested that some KAPs relevant to comorbid patients differed based on sex, qualification, and ethnicity.

Conclusion

This study identified gaps in the knowledge and practices of Australian AHHPs with regard to the complexities of addressing comorbid cognitive impairment and hearing loss. These findings will help to develop training programs to empower AHHPs to deliver optimal healthcare services to comorbid patients.

The Medicare annual wellness visit: An opportunity to improve health system identification of hearing loss?

BACKGROUND

Hearing loss is prevalent and consequential but under-diagnosed and managed. The Medicare Annual Wellness Visit (AWV) health risk assessment elicits patient-reported hearing concerns but whether such information affects documentation, diagnosis, or referral is unknown.

METHODS

We use 5 years of electronic medical record (EMR) data (2017-2022) for a sample of 13,776 older primary care patients. We identify the first (index) AWV indication of hearing concerns and existing and subsequent hearing loss EMR diagnoses (visit diagnoses or problem list diagnoses) and audiology referrals. For a 20% random sample of AWV notes (n = 474) we compared hearing loss EMR diagnoses to documentation of (1) hearing concerns, (2) hearing loss/aid use, and (3) referrals for hearing care.

RESULTS

Of 3845 (27.9%) older adults who identified hearing concerns (mean age 79.1 years, 57% female, 75% white) 24% had an existing hearing diagnosis recorded. Among 474 patients with AWV clinical notes reviewed, 90 (19%) had an existing hearing loss diagnosis. Clinicians were more likely to document hearing concerns or hearing loss/aid use for those with (vs. without) an existing EMR diagnosis (50.6% vs. 35.9%, p = 0.01; 68.9% vs. 37.5%, p < 0.001, respectively). EMR diagnoses of hearing loss were recorded for no more than 40% of those with indicated hearing concerns. Among those without prior diagnosis 38 (9.9%) received a hearing care referral within 1 month. Subgroup analysis suggest greater likelihood of documenting hearing concerns for patients age 80+ (OR:1.51, 95% confidence interval [CI]: 1.03, 2.19) and decreased likelihood of documenting known hearing loss among patients with more chronic conditions (OR: 0.49, 95% CI: 0.27, 0.9), with no differences observed by race.

CONCLUSION

Documentation of hearing loss in EMR and AWV clinical notes is limited among older adults with subjective hearing concerns. Systematic support and incorporation of hearing into EMR and clinical notes may increase hearing loss visibility by care teams.

The impact of age-related hearing loss on cognitive decline: The mediating role of brain age gap

In recent years, the relationship between age-related hearing loss, cognitive decline, and the risk of dementia has garnered significant attention. The significant variability in brain health and aging among individuals of the same chronological age suggests that a measure assessing how one's brain ages may better explain hearing-cognition links. The main aim of this study was to investigate the mediating role of Brain Age Gap (BAG) in the association between hearing impairment and cognitive function. This research included 185 participants aged 20-79 years. BAG was estimated based on the difference between participant's brain age (estimated based on their structural T1-weighted MRI scans) and chronological age. Cognitive performance was assessed using the Montreal Cognitive Assessment (MoCA) test while hearing ability was measured using pure-tone thresholds (PTT) and words-in-noise (WIN) perception. Mediation analyses were used to examine the mediating role of BAG in the relationship between age-related hearing loss as well as difficulties in WIN perception and cognition. Participants with poorer hearing sensitivity and WIN perception showed lower MoCA scores, but this was an indirect effect. Participants with poorer performance on PTT and WIN tests had larger BAG (accelerated brain aging), and this was associated with poorer performance on the MoCA test. Mediation analyses showed that BAG partially mediated the relationship between age-related hearing loss and cognitive decline. This study enhances our understanding of the interplay among hearing loss, cognition, and BAG, emphasizing the potential value of incorporating brain age assessments in clinical evaluations to gain insights beyond chronological age, thus advancing strategies for preserving cognitive health in aging populations.

Rethinking the Accessibility of Hearing Assessments for Children with Developmental Disabilities

We aim to determine the accessibility of gold-standard hearing assessments - audiogram or auditory brainstem response (ABR) - during the first 3 months of hearing health care for children with and without developmental disabilities. Electronic health records were examined from children (0-18 years) who received hearing health care at three hospitals. Children with developmental disabilities had a diagnosis of autism, cerebral palsy, Down syndrome, or intellectual disability. Assessments from the first 3 months were reviewed to determine if ≥ 1 audiogram or ABR threshold was recorded. To evaluate differences in assessment based on disability status, logistic regression models were built while accounting for age, race, ethnicity, sex, and site. Of the 131,783 children, 9.8% had developmental disabilities. Whereas 9.3% of children in the comparison group did not access a gold-standard assessment, this rate was 24.4% for children with developmental disabilities (relative risk (RR) = 3.79; p < 0.001). All subgroups were at higher risk relative to the comparison group (all p < 0.001): multiple diagnoses (RR = 13.24), intellectual disabilities (RR = 11.52), cerebral palsy (RR = 9.87), Down syndrome (RR = 6.14), and autism (RR = 2.88). Children with developmental disabilities are at high risk for suboptimal hearing evaluations that lack a gold-standard assessment. Failure to access a gold-standard assessment results in children being at risk for late or missed diagnosis for reduced hearing. Results highlight the need for (1) close monitoring of hearing by healthcare providers, and (2) advancements in testing methods and guidelines.

Alpha and theta oscillations on a visual strategic processing task in age-related hearing loss

Introduction

Emerging evidence suggests changes in several cognitive control processes in individuals with age-related hearing loss (ARHL). However, value-directed strategic processing, which involves selectively processing salient information based on high value, has been relatively unexplored in ARHL. Our previous work has shown behavioral changes in strategic processing in individuals with ARHL. The current study examined event-related alpha and theta oscillations linked to a visual, value-directed strategic processing task in 19 individuals with mild untreated ARHL and 17 normal hearing controls of comparable age and education.

Methods

Five unique word lists were presented where words were assigned high- or low-value based on the letter case, and electroencephalography (EEG) data was recorded during task performance.

Results

The main effect of the group was observed in early time periods. Specifically, greater theta synchronization was seen in the ARHL group relative to the control group. Interaction between group and value was observed at later time points, with greater theta synchronization for high- versus low-value information in those with ARHL.

Discussion

Our findings provide evidence for oscillatory changes tied to a visual task of value-directed strategic processing in individuals with mild untreated ARHL. This points towards modality-independent neurophysiological changes in cognitive control in individuals with mild degrees of ARHL and adds to the rapidly growing literature on the cognitive consequences of ARHL.

Progress on early diagnosing Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that affects both cognition and non-cognition functions. The disease follows a continuum, starting with preclinical stages, progressing to mild cognitive and behavioral impairment, ultimately leading to dementia. Early detection of AD is crucial for better diagnosis and more effective treatment. However, the current AD diagnostic tests of biomarkers using cerebrospinal fluid and/or brain imaging are invasive or expensive, and mostly are still not able to detect early disease state. Consequently, there is an urgent need to develop new diagnostic techniques with higher sensitivity and specificity during the preclinical stages of AD. Various non-cognitive manifestations, including behavioral abnormalities, sleep disturbances, sensory dysfunctions, and physical changes, have been observed in the preclinical AD stage before occurrence of notable cognitive decline. Recent research advances have identified several biofluid biomarkers as early indicators of AD. This review focuses on these non-cognitive changes and newly discovered biomarkers in AD, specifically addressing the preclinical stages of the disease. Furthermore, it is of importance to explore the potential for developing a predictive system or network to forecast disease onset and progression at the early stage of AD.

APOE-ε4 is not associated with pure-tone hearing thresholds, visual acuity or cognition, cross-sectionally or over 3 years of follow up in the Canadian Longitudinal Study on Aging

INTRODUCTION

Hearing loss and diminished visual acuity are associated with poorer cognition, but the underlying mechanisms are not understood. The apolipoprotein (APOE) ε4 allelic variant may drive the associations. We tested whether APOE-ε4 allele count (0, 1, or 2) was associated with declines in memory, executive function, pure-tone hearing threshold averages, and pinhole-corrected visual acuity among participants in the Canadian Longitudinal Study on Aging (CLSA).

METHODS

Multivariable linear mixed regression models were utilized to assess associations between APOE-ε4 allele count and each of the outcome variables. For each main effects model, interactions between APOE-ε4 and sex and age group (45-54-, 55-64-, 65-74-, and 75-85 years) respectively, were analyzed.

RESULTS

Significant associations were not observed in main effects models. Models including APOE-ε4 * age (but not APOE-ε4 * sex) interaction terms better fit the data compared to main effects models. In age group-stratified models, however, there were minimal differences in effect estimates according to allele count.

CONCLUSION

APOE-ε4 allele count does not appear to be a common cause of sensory-cognitive associations in this large cohort.

Longitudinal associations between sensory and cognitive functioning in adults 60 years or older in Sweden and Denmark

BACKGROUND

The objective of this study is to explore the bidirectional, longitudinal associations between self-reported sensory functions (hearing/vision) and cognitive functioning among older adults in Sweden and Denmark during the period 2004-2017.

METHODS

The study is based on data from The Survey of Health, Ageing and Retirement in Europe and consists of 3164 persons aged 60 to 93 years. Within-person associations between sensory and cognitive functions were estimated using random intercept cross-lagged panel models.

RESULTS

The results indicated that cognitive and sensory functions were associated within their respective domains over time. The results on the bidirectional associations between sensory functions and cognition over time showed weak and statistically non-significant estimates.

CONCLUSION

Our study showed no clear evidence for cross-lagged effects between sensory functions and cognitive functioning. Important to note, however, is that using longitudinal data to estimate change within persons is a demanding statistical test and various factors may have contributed to the absence of conclusive evidence in our study. We discuss several of these factors.

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.

Effects of Economic Status on Changes in Social Networks and Mental Health after Using Hearing Aids

OBJECTIVES

Hearing impairment affects social networks and mental health. Hearing aids (HA) can improve these deficits. However, their effects might be affected by various factors such as economic status (ES). This study aimed to identify how ES could moderate the effects of HA on social networks, depressive mood, and cognition.

METHODS

A prospective cohort for new HA users was established and classified into two groups based on their ES: a low ES group (LES group) and a medium to high ES group (MHES group). Audiological examination, Lubben social network scale-18 (LSNS-18), Short form of Geriatric Depression Score, Mini-Mental State Examination in the Korean version of the CERAD Assessment Packet, and surveys for satisfaction with HA were conducted before and at six months after wearing HA.

RESULTS

Post-HA application LSNS-18 scores were not improved in the LES group whereas they revealed significant improvement in the MHES group (p = 0.003). The LES group showed lower LSNS-18 score (p = 0.020) and its change (p = 0.042) than the MHES group. Additionally, patients with depressive moods in the MHES group showed better improvements than those in the LES group (p = 0.048). The effects of wearing HA on cognition and satisfaction with HA were not significantly different between the two groups.

CONCLUSIONS

HA did not improve social relationships and depressive moods in the LES group. Comprehensive and multidirectional support as well as hearing rehabilitation may be important for patients with LES.

LEVEL OF EVIDENCE

3 (Nonrandomized controlled cohort/follow-up study) Laryngoscope, 134:2387-2394, 2024.

Associations Between Self-Reported Visual Difficulty, Age of Onset, and Cognitive Function Trajectories Among Chinese Older Adults

Objectives: This study examined the association between self-reported visual difficulty and age-related cognitive declines among older Chinese adults and how the timing of visual difficulty onset plays a role in cognitive trajectories. Methods: Data were drawn from the 2011-2018 wave of the China Health and Retirement Longitudinal Study, involving 9974 respondents aged 60 years or older (mean age 65.44 years, range 60-101 years). Results: At baseline, 14.16% respondents had self-reported visual difficulty. Growth curve models showed that Chinese older adults with visual difficulty experienced a faster decline in cognitive function compared to those without visual difficulty (β = -0.02, p < .01). Older adults who began experiencing visual difficulty between 61 and 75 years of age had steeper cognitive declines compared to those with earlier or later onset (β = -0.05, p < .01). Discussion: Older adults with self-reported visual difficulty experience faster rates of cognitive decline. Future research should explore potential factors that underlie the association between onset timing of visual difficulty and cognitive function.

A study on the relationship between recreational physical activity and audiovisual difficulty for older adults

Audiovisual difficulty are especially common in older adults. Audiovisual difficulty seriously affect the quality of life of older adults in their later years. It is a top priority to find out the related factors, and to intervene and prevent them. The purpose of this study was to explore the relationship between recreational physical activities and audiovisual difficulty in older adults. We hope that older adults can reduce the risk of hearing and visual difficulty through scientific physical activity. A total of 4,886 people were sampled from the National Health and Nutrition Examination Survey (NHANES) from 2013 to 2018. Recreational physical activity was assessed through the Global Physical Activity Questionnaire (GPAQ); Hearing and visual difficulty were assessed using the Disability Questionnaire (DLQ). Chi-square test was used for categorical variables and rank sum test was used for measurement variables. P < 0.05 was considered statistically significant (bilateral test). After univariate analysis, binary Logistic regression analysis was performed with recreational physical activity as the independent variable, statistically significant demographic variable as the covariate, and hearing and visual difficulty as the dependent variable, respectively. (1) After excluding all confounding variables, recreational physical activity was significantly associated with hearing difficulty (P < 0.001), odds ratio (OR) 0.657 (95% CI 0.5899-0.733); (2) Recreational physical activity was significantly associated with visual difficulty (P < 0.001), OR 0.731 (95% CI 0.630-0.849). (1) Recreational physical activity is the protective factor of hearing difficulty in older adults; (2) Recreational physical activity is a protective factor for visual difficulty in older adults.

Umbrella review and Delphi study on modifiable factors for dementia risk reduction

A 2013 systematic review and Delphi consensus study identified 12 modifiable risk and protective factors for dementia, which were subsequently merged into the "LIfestyle for BRAin health" (LIBRA) score. We systematically evaluated whether LIBRA requires revision based on new evidence. To identify modifiable risk and protective factors suitable for dementia risk reduction, we combined an umbrella review of systematic reviews and meta-analyses with a two-round Delphi consensus study. The review of 608 unique primary studies and opinions of 18 experts prioritized six modifiable factors: hearing impairment, social contact, sleep, life course inequalities, atrial fibrillation, and psychological stress. Based on expert ranking, hearing impairment, social contact, and sleep were considered the most suitable candidates for inclusion in updated dementia risk scores. As such, the current study shows that dementia risk scores need systematic updates based on emerging evidence. Future studies will validate the updated LIBRA score in different cohorts. HIGHLIGHTS: An umbrella review was combined with opinions of 18 dementia experts. Various candidate targets for dementia risk reduction were identified. Experts prioritized hearing impairment, social contact, and sleep. Re-assessment of dementia risk scores is encouraged. Future work should evaluate the predictive validity of updated risk scores.

Elderly Individuals Residing in Nursing Homes in Western Romania Who Have Been Diagnosed with Hearing Loss are at a Higher Risk of Experiencing Cognitive Impairment

Purpose

The objective of this research was to determine if there is any correlation between the severity of neurocognitive disorder and hearing impairment in the elderly.

Patients and Methods

This is a population-based observational study that included subjects aged ≥ 65 years. They were evaluated for the existence of cardiovascular risk factors, diabetes, stroke, alcohol abuse, and smoking. Hearing impairment was diagnosed by an audiologist, using behavioral audiometric examination. These evaluations might have been performed in response to concerns about hearing loss, or they could have been a routine component of yearly comprehensive health screenings that included a Mini-Mental State Examination 2nd Edition (MMSE-2) test. According to the results of the MMSE-2 scale, we divided the individuals into two groups, Group I for those who had cognitive impairment and severe neurocognitive disorder, and Group II for those who did not have cognitive impairment.

Results

The study enrolled 203 patients with a mean age of 77 ± 7.5 years (range 65-98), 99 (48%) were males. When comparing the two groups, group I patients presented more often cardiovascular risk factors, stroke, diabetes, and impaired hearing. The univariable logistic regression found that cognitive impairment was significantly more frequent in the elderly with cardiovascular disease, diabetes, and stroke (p<0.0001). The multivariate regression analysis found that stroke (p<0.0001) diabetes (p=0.0008), cardiovascular disease (p=0.0004), and impaired hearing (p=0.0011) were significantly linked to cognitive impairment. The occurrence of hearing impairment in the elderly was related to having an MMSE-2 score of 14 or below.

Conclusion

According to the findings of this research, the elderly who have trouble hearing in addition to other conditions might have an increased risk for severe neurocognitive disorder.

[Relationship Between Hearing Loss and Cognitive Function in Elderly Chinese People: A Study Based on Propensity Score Matching]

Objective

To explore the relationship between hearing loss and cognitive function in the elderly population through propensity score matching method.

Methods

We analyzed the data of 7605 participants aged 60 and above who were included in the 2018 China Health and Retirement Longitudinal Study (CHARLS). The non-substitutable 1∶1 nearest neighbor matching method without caliper value was used for propensity score matching and G-computation was used to estimate the average treatment effect (ATE) of hearing loss on all dimensions of cognitive function.

Results

Before matching, there were 3626 (47.68%) women, with 1409 (18.53%) of whom suffering from hearing loss and 3031 (39.86%) of whom suffering from cognitive impairment. After matching, 1409 subjects were included in the hearing loss group and 1409, in the normal hearing group, with both groups sharing similar distribution of basic demographic characteristics. The results for the average treatment effect of the population indicated that the cognitive function scores of the hearing loss group were lower than those of the normal hearing group, with the overall cognitive function being 0.593 points lower (95% confidence intervel [CI]: －0.916-－0.257, P<0.001), orientation being 0.183 points lower (95% CI: －0.302-－0.055, P=0.004), immediate memory being 0.150 points lower (95% CI: －0.218-－0.085, P<0.001), and language skills being 0.178 points lower (95% CI: －0.303-－0.058, P=0.006). The prevalence of cognitive impairment of the hearing loss group was 4.2% higher than that of the normal hearing group (95% CI: 0.007-0.077, P=0.020).

Conclusion

Hearing loss adversely affects the orientation, memory, and language skills of the elderly population and forms a potential risk factor for cognitive impairment in the elderly population.

Accelerated Brain Atrophy, Microstructural Decline and Connectopathy in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) has recently been linked to cognitive impairment. We hypothesized that AMD modifies the brain aging trajectory, and we conducted a longitudinal diffusion MRI study on 40 participants (20 with AMD and 20 controls) to reveal the location, extent, and dynamics of AMD-related brain changes. Voxel-based analyses at the first visit identified reduced volume in AMD participants in the cuneate gyrus, associated with vision, and the temporal and bilateral cingulate gyrus, linked to higher cognition and memory. The second visit occurred 2 years after the first and revealed that AMD participants had reduced cingulate and superior frontal gyrus volumes, as well as lower fractional anisotropy (FA) for the bilateral occipital lobe, including the visual and the superior frontal cortex. We detected faster rates of volume and FA reduction in AMD participants in the left temporal cortex. We identified inter-lingual and lingual-cerebellar connections as important differentiators in AMD participants. Bundle analyses revealed that the lingual gyrus had a lower streamline length in the AMD participants at the first visit, indicating a connection between retinal and brain health. FA differences in select inter-lingual and lingual cerebellar bundles at the second visit showed downstream effects of vision loss. Our analyses revealed widespread changes in AMD participants, beyond brain networks directly involved in vision processing.

Cholinergic Receptor Muscarinic 1 Co-Localized with Mitochondria in Cultured Dorsal Root Ganglion Neurons, and Its Deletion Disrupted Mitochondrial Ultrastructure in Peripheral Neurons: Implications in Alzheimer's Disease

Background

Loss of Cholinergic Receptor Muscarinic 1 (CHRM1) has been linked to the pathogenesis of Alzheimer's disease (AD). Our recent study found significantly lower CHRM1 protein levels in AD patient cortices, linked to reduced survival. Furthermore, using knockout mice (Chrm1-/-) we demonstrated that deletion of Chrm1 alters cortical mitochondrial structure and function, directly establishing a connection between its loss and mitochondrial dysfunction in the context of AD. While CHRM1's role in the brain has been extensively investigated, its impact on peripheral neurons in AD remains a crucial area of research, especially considering reported declines in peripheral nerve conduction among AD patients.

Objective

The objective was to characterize Chrm1 localization and mitochondrial deficits in Chrm1-/- dorsal root ganglion (DRG) neurons.

Methods

Recombinant proteins tagged with Green or Red Fluorescent Protein (GFP/RFP) were transiently expressed to investigate the localization of Chrm1 and mitochondria, as well as mitochondrial movement in the neurites of cultured primary mouse DRG neurons, using confocal time-lapse live cell imaging. Transmission electron microscopy was performed to examine the ultrastructure of mitochondria in both wild-type and Chrm1-/- DRGs.

Results

Fluorescence imaging revealed colocalization and comigration of N-terminal GFP-tagged Chrm1 and mitochondrial localization signal peptide-tagged RFP-labelled mitochondria in the DRGs neurons. A spectrum of mitochondrial structural abnormalities, including disruption and loss of cristae was observed in 87% neurons in Chrm1-/- DRGs.

Conclusions

This study suggests that Chrm1 may be localized in the neuronal mitochondria and loss of Chrm1 in peripheral neurons causes sever mitochondrial structural aberrations resembling AD pathology.

The Impact of Age-Related Hearing Loss on Working Memory among Older Individuals: An Event-Related Potential Study

Introduction

Age-related hearing loss (ARHL) may affect working memory (WM), which impacts problem-solving, decision-making, language comprehension, and learning. Limited research exists on how ARHL affects WM using N-back tasks, but studying this is crucial for understanding neural markers and associated cognitive processes. Our study explores the impact of ARHL on WM using behavioral and electrophysiological measures and how it correlates with speech-in-noise scores in older individuals with ARHL.

Method

The study involved two groups, each with 20 participants aged 60-80. Group 1 had individuals with mild to moderate sensorineural hearing loss, while Group 2 had age- and education-matched controls with normal or near-normal hearing. Participants underwent audiological assessments and completed cognitive tests, including simple reaction time and N-back tests. During the performance of cognitive tasks, a simultaneous electroencephalography was recorded. Data analysis included behavioral and event-related potentials, source estimation, and functional connectivity analysis.

Results

The study revealed significantly poor accuracy, longer reaction time, and smaller P300 amplitude among individuals with ARHL, even after controlling for general slowing. Individuals with ARHL experience compromised neural activity, particularly in the temporal and parietal regions, which are vital for cognition and WM. Furthermore, individuals with ARHL exhibited poor communication between the superior temporal gyrus and insulae regions among the brain regions mediating WM during the 1-back task. Also, the study found a strong correlation between hearing measures and WM outcomes.

Conclusion

The study findings suggest that individuals with ARHL have impaired WM compared to those with normal hearing. This indicates a potential link between ARHL and cognitive decline, which could significantly affect daily life and quality of life. The widely used WM test with simultaneous EEG recording and source estimation analysis would further validate the usefulness of the study in assessing WM in this population.

Assessing the feasibility of a randomised controlled trial examining the effect of hearing aids on cognitive decline in elderly individuals: a study protocol

INTRODUCTION

Hearing loss is one of the leading potentially modifiable risk factors for dementia. There is growing evidence suggesting that treating hearing loss with hearing aids could be a relatively low-cost intervention in reducing cognitive decline and the risk of dementia in the long term. However, given the current constraints of the limited evidence, it is premature to draw definitive conclusions about the effect of hearing aids on cognitive functioning. More long-term randomised studies examining this effect would be recommended. Prior to embarking on large-scale lengthy randomised controlled trials (RCTs), it is imperative to determine the viability of such studies. Therefore, the purpose of the current study is to assess the feasibility of a RCT that investigates the effect of hearing aids on cognitive functioning in elderly hearing impaired individuals.

METHODS AND ANALYSIS

In this randomised controlled feasibility trial, 24 individuals aged 65 years or older with mild to moderate hearing loss (≥35-<50 dB pure tone average (0.5-4 kHz) unilateral or bilateral) will be included and randomised towards a hearing aid intervention or no intervention. At baseline and at 6-month follow-up, a test battery consisting of cognitive tests and questionnaires will be administered to both groups. The primary outcome of the study is the willingness of hearing impaired individuals to be randomised for hearing amplification in a study regarding cognition. The secondary outcomes are the feasibility of the test battery and the therapy compliance of hearing aid use.

ETHICS AND DISSEMINATION

This research protocol was approved by the Institutional Review Board of the University Medical Centre Utrecht (NL80594.041.22, V.3, January 2023). The trial results will be made accessible to the public in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ISRCTN84550071.

Cognitive functioning and psychosomatic syndromes in a subjective tinnitus sample

Introduction

Tinnitus is the perception of a sound in the absence of any corresponding external sound source. Current research suggests a relationship among emotional, cognitive, and psychosomatic symptoms and the occurrence or maintenance of chronic tinnitus. This study aimed to detect the prevalence and role of psychosomatic conditions, as defined by the Diagnostic Criteria for Psychosomatic Research (DCPR), and cognitive functioning in a group of patients with tinnitus.

Methods

Sixty-two patients with subjective tinnitus and 62 non-tinnitus controls were recruited from the Otorhinolaryngology Unit of the University of Bari. Pure-tone audiometry was performed in all tinnitus subjects, and sound level tolerance was evaluated. Additionally, tinnitus handicap (Tinnitus Handicap Inventory [THI]), psychopathological symptoms (Symptom Checklist-90, Revised [SCL-90-R]), anxiety (State-Trait Anxiety Inventory [STAI-Y1/2]), depression (Beck Depression Inventory [BDI]), cognitive impairment (Mini-Mental State Examination [MMSE]), executive functions (Frontal Assessment Battery [FAB]), and psychosomatic syndromes (DCPR) were evaluated. Parametric and non-parametric tests were used to detect cognitive and symptomatological differences between patients and controls. The predictivity of these factors for tinnitus severity was studied using multiple regression (Backward Elimination). All tests were considered significant at p < 0.05 (family wise error corrected for each comparison).

Results

69.4% tinnitus patients met multiple DCPR criteria, compared to 32.3% of controls. Tinnitus patients exhibited elevated rates of illness denial (ꭓ2 = 9.02; p < 0.009), demoralization (ꭓ2 = 8.05; p < 0.018), somatization (ꭓ2 = 4.92; p < 0.063) and functional symptoms (ꭓ2 = 5.21; p < 0.06) scoring significantly higher on the BDI, STAI-Y1, and STAI-Y2, and SCL-90-R compared to controls. Patients with tinnitus showed lower MMSE scores, compared to controls (t = -2.282; p < 0.001). No association between tinnitus severity and global cognitive impairment emerged. Conversely, executive function deficits were associated to tinnitus severity. Among the cognitive and psychological factors, only trait anxiety, one or more psychosomatic syndromes, and somatization clusters were strongly correlated with tinnitus severity.

Discussion

Our findings suggest a relationship between tinnitus severity, psychological, psychosomatic symptoms, and frontal impairment. Additionally, the influence of tinnitus on cognitive functions paves the way for integrated, multidisciplinary diagnostic and treatment options for patients. Although preliminary, our findings highlight the importance of early cognitive and psychological screening to improve patients' quality of life.

Photobiomodulation Can Enhance Stem Cell Viability in Cochlea with Auditory Neuropathy but Does Not Restore Hearing

Sensorineural hearing loss is very difficult to treat. Currently, one of the techniques used for hearing rehabilitation is a cochlear implant that can transform sound into electrical signals instead of inner ear hair cells. However, the prognosis remains very poor if sufficient auditory nerve cells are not secured. In this study, the effect of mouse embryonic stem cells (mESC) and photobiomodulation (PBM) combined treatment on auditory function and auditory nerve cells in a secondary neuropathy animal model was investigated. To confirm the engraftment of stem cells in vitro, cochlear explants were treated with kanamycin (KM) to mimic nerve damage and then cocultured with GFP-mESC. GFP-mESCs were observed to have attached and integrated into the explanted samples. An animal model for secondary neurodegeneration was achieved by KM treatment and was treated by a combination therapy of GFP-mESC and NIR-PBM at 8 weeks of KM treatment. Hearing recovery by functional testing using auditory brain stem response (ABR) and eABR was measured as well as morphological changes and epifluorescence analysis were conducted after 2 weeks of combination therapy. KM treatment elevated the hearing threshold at 70-80 dB and even after the combination treatment with GFP-mESC and PBM was applied, the auditory function was not restored. In addition, the stem cells transplanted into cochlea has exponentially increased due to PBM treatment although did not produce any malignancy. This study confirmed that the combined treatment with mESC and PBM could not improve hearing or increase the response of the auditory nerve. Nevertheless, it is noteworthy in this study that the cells are distributed in most cochlear tissues and the proliferation of stem cells was very active in animals irradiated with PBM compared to other groups wherein the stem cells had disappeared immediately after transplantation or existed for only a short period of time.

Original Research Clinical attendance rate at a tertiary adult audiological service in South Africa

BACKGROUND

 Clinical non-attendance to audiological appointments may negatively affect early diagnosis and intervention as well as treatment outcomes for adults with hearing impairments.

OBJECTIVES

 This study aimed to explore the attendance rate and factors influencing attendance and non-attendance at an adult audiology diagnostic clinic at a tertiary hospital in Gauteng, South Africa.

METHOD

 A mixed-methods research design, utilising structured questionnaires and a retrospective record review was adopted. A total of 31 adult patients at a diagnostic audiology clinic were interviewed.

RESULTS

 Findings revealed an attendance rate of 47.62%, with 52.38% rate failure to return for follow-up appointments. Key reasons for attendance included understanding the need for appointments (57%), staff attitudes (42%) and appointment reminders (17%), and those for non-attendance included multiple appointments (33%), work commitments (28%), transport (8%) and forgetting about the appointment (8%). Six reasons for non-attendance were prominent in the current study: having multiple appointments (33%), work commitments (28%), forgetting the appointment (8%), transport difficulties (8%), attitudes and/or perceptions of the healthcare system (4%) and sequelae of hearing impairment (8%).

CONCLUSION

 This study reinforces previous research findings while highlighting that health literacy and Batho Pele (people first) ethos by staff positively influence attendance.Contribution: Current findings contribute towards contextually relevant evidence on the attendance rate in this sector for ear and hearing care, as well as additional insights into factors influencing this within the South African context. This information is crucial for clinical services provision planning as well as for policy formulation around resource allocation in the public healthcare sector.

Association between sensation, perception, negative socio-psychological factors and cognitive impairment

Background

Evidence has suggested that sensation and socio-psychological factors may be associated with cognitive impairment separately in older adults. However, the association between those risk factors and cognitive impairment is still unknown.

Objective

To investigate the association between sensation, perception, negative socio-psychological factors, and cognitive impairment in institutionalized older adults.

Methods

From two public aged care facilities, 215 participants were investigated. The Mini-mental State Examination was applied to assess cognitive function. The sensory function was bifurcated into auditory and somatosensory realms which were evaluated using pure tone audiometry and Nottingham Sensory Assessment, respectively. Albert's test, left and right resolution, and visuospatial distribution were used to evaluate perception. Depression and social isolation were selected as negative socio-psychological factors and were evaluated by the Geriatric Depression Scale and the Lubben Social Network Scale. The multivariate analysis was performed utilizing binary logistic regression.

Results

Participants with moderately severe or severe hearing loss exhibited significant cognitive impairment compared to those with mild hearing loss. It was observed that perceptual dysfunction and depression were independently related to cognitive impairment. However, there was no significant association between somatosensory function, social isolation, and cognitive impairment in the institutionalized older adults.

Conclusion

More profound hearing loss, abnormal perception, and depression are associated with cognitive impairment in older adults. Subsequent research endeavors should delve into the causal mechanisms underpinning these associations and explore whether combined interventions have the potential to postpone the onset of cognitive impairment.

Variability in Cochlear Implantation Outcomes in a Large German Cohort With a Genetic Etiology of Hearing Loss

OBJECTIVES

The variability in outcomes of cochlear implantation is largely unexplained, and clinical factors are not sufficient for predicting performance. Genetic factors have been suggested to impact outcomes, but the clinical and genetic heterogeneity of hereditary hearing loss makes it difficult to determine and interpret postoperative performance. It is hypothesized that genetic mutations that affect the neuronal components of the cochlea and auditory pathway, targeted by the cochlear implant (CI), may lead to poor performance. A large cohort of CI recipients was studied to verify this hypothesis.

DESIGN

This study included a large German cohort of CI recipients (n = 123 implanted ears; n = 76 probands) with a definitive genetic etiology of hearing loss according to the American College of Medical Genetics (ACMG)/Association for Molecular Pathology (AMP) guidelines and documented postoperative audiological outcomes. All patients underwent preoperative clinical and audiological examinations. Postoperative CI outcome measures were based on at least 1 year of postoperative audiological follow-up for patients with postlingual hearing loss onset (>6 years) and 5 years for children with congenital or pre/perilingual hearing loss onset (≤6 years). Genetic analysis was performed based on three different methods that included single-gene screening, custom-designed hearing loss gene panel sequencing, targeting known syndromic and nonsyndromic hearing loss genes, and whole-genome sequencing.

RESULTS

The genetic diagnosis of the 76 probands in the genetic cohort involved 35 genes and 61 different clinically relevant (pathogenic, likely pathogenic) variants. With regard to implanted ears (n = 123), the six most frequently affected genes affecting nearly one-half of implanted ears were GJB2 (21%; n = 26), TMPRSS3 (7%; n = 9), MYO15A (7%; n = 8), SLC26A4 (5%; n = 6), and LOXHD1 and USH2A (each 4%; n = 5). CI recipients with pathogenic variants that influence the sensory nonneural structures performed at or above the median level of speech performance of all ears at 70% [monosyllable word recognition score in quiet at 65 decibels sound pressure level (SPL)]. When gene expression categories were compared to demographic and clinical categories (total number of compared categories: n = 30), mutations in genes expressed in the spiral ganglion emerged as a significant factor more negatively affecting cochlear implantation outcomes than all clinical parameters. An ANOVA of a reduced set of genetic and clinical categories (n = 10) identified five detrimental factors leading to poorer performance with highly significant effects ( p < 0.001), accounting for a total of 11.8% of the observed variance. The single strongest category was neural gene expression accounting for 3.1% of the variance.

CONCLUSIONS

The analysis of the relationship between the molecular genetic diagnoses of a hereditary etiology of hearing loss and cochlear implantation outcomes in a large German cohort of CI recipients revealed significant variabilities. Poor performance was observed with genetic mutations that affected the neural components of the cochlea, supporting the "spiral ganglion hypothesis."

Hearing loss, depression, and cognition in younger and older adult CI candidates

Background and Aim

Hearing loss in old age is associated with cognitive decline and with depression. Our study aimed to investigate the relationship between hearing loss, cognitive decline, and secondary depressive symptoms in a sample of younger and older cochlear implant candidates with profound to severe hearing loss.

Methods

This study is part of a larger cohort study designated to provide information on baseline data before CI. Sixty-one cochlear implant candidates with hearing loss from adulthood onwards (>18 years) were enrolled in this study. All had symmetrical sensorineural hearing loss in both ears (four-frequency hearing threshold difference of no more than 20 dB, PTA). Individuals with primary affective disorders, psychosis, below-average intelligence, poor German language skills, visual impairment, and a medical diagnosis with potential impact on cognition (e.g., neurodegenerative diseases,) were excluded. Four-frequency hearing thresholds (dB, PTA, better ear) were collected. Using the Abbreviated Profile of Hearing Aid Benefit, we assessed subjective hearing in noise. Clinical and subclinical depressive symptoms were assessed with the Beck Depression Inventory (BDI II). Cognitive status was assessed with a neurocognitive test battery.

Results

Our findings revealed a significant negative association between subjective hearing in noise (APHAB subscale "Background Noise") and BDII. However, we did not observe any link between hearing thresholds, depression, and cognition. Additionally, no differences emerged between younger (25-54 years) and older subjects (55-75 years). Unexpectedly, further unplanned analyses unveiled correlations between subjective hearing in quiet environments (APHAB) and cognitive performance [phonemic fluency (Regensburg Word Fluency), cognitive flexibility (TMTB), and nonverbal episodic memory (Nonverbal Learning Test), as well as subjective hearing of aversive/loud sounds (APHAB)], cognitive performance [semantic word fluency (RWT), and inhibition (Go/Nogo) and depression]. Duration of hearing loss and speech recognition at quiet (Freiburg Monosyllables) were not related to depression and cognitive performance.

Conclusion

Impact of hearing loss on mood and cognition appears to be independent, suggesting a relationship with distinct aspects of hearing loss. These results underscore the importance of considering not only conventional audiometric measures like hearing thresholds but also variables related to hearing abilities during verbal communication in everyday life, both in quiet and noisy settings.

Comprehension of acoustically degraded speech in Alzheimer's disease and primary progressive aphasia

Successful communication in daily life depends on accurate decoding of speech signals that are acoustically degraded by challenging listening conditions. This process presents the brain with a demanding computational task that is vulnerable to neurodegenerative pathologies. However, despite recent intense interest in the link between hearing impairment and dementia, comprehension of acoustically degraded speech in these diseases has been little studied. Here we addressed this issue in a cohort of 19 patients with typical Alzheimer's disease and 30 patients representing the three canonical syndromes of primary progressive aphasia (non-fluent/agrammatic variant primary progressive aphasia; semantic variant primary progressive aphasia; logopenic variant primary progressive aphasia), compared to 25 healthy age-matched controls. As a paradigm for the acoustically degraded speech signals of daily life, we used noise-vocoding: synthetic division of the speech signal into frequency channels constituted from amplitude-modulated white noise, such that fewer channels convey less spectrotemporal detail thereby reducing intelligibility. We investigated the impact of noise-vocoding on recognition of spoken three-digit numbers and used psychometric modelling to ascertain the threshold number of noise-vocoding channels required for 50% intelligibility by each participant. Associations of noise-vocoded speech intelligibility threshold with general demographic, clinical and neuropsychological characteristics and regional grey matter volume (defined by voxel-based morphometry of patients' brain images) were also assessed. Mean noise-vocoded speech intelligibility threshold was significantly higher in all patient groups than healthy controls, and significantly higher in Alzheimer's disease and logopenic variant primary progressive aphasia than semantic variant primary progressive aphasia (all P < 0.05). In a receiver operating characteristic analysis, vocoded intelligibility threshold discriminated Alzheimer's disease, non-fluent variant and logopenic variant primary progressive aphasia patients very well from healthy controls. Further, this central hearing measure correlated with overall disease severity but not with peripheral hearing or clear speech perception. Neuroanatomically, after correcting for multiple voxel-wise comparisons in predefined regions of interest, impaired noise-vocoded speech comprehension across syndromes was significantly associated (P < 0.05) with atrophy of left planum temporale, angular gyrus and anterior cingulate gyrus: a cortical network that has previously been widely implicated in processing degraded speech signals. Our findings suggest that the comprehension of acoustically altered speech captures an auditory brain process relevant to daily hearing and communication in major dementia syndromes, with novel diagnostic and therapeutic implications.

Cognitive Performance, Sociodemographic Factors, Pure-Tone Audiometry, and their Association with Speech Discrimination: A Prospective Population-Based Study of 1,061 Older Adults

OBJECTIVE

Hearing loss is increasingly recognized as a chronic disease state with important health sequelae. Although considered a central component of routine audiometric testing, the degree to which various patient factors influence speech discrimination is poorly characterized to date. The primary objective of the current work was to describe associations of cognitive performance, sociodemographic factors, and pure-tone audiometry with speech discrimination in older adults.

STUDY DESIGN

Prospective study.

SETTING

Olmsted County, Minnesota.

PATIENTS

There were 1,061 study participants 50 years or older at enrollment in the population-based Mayo Clinic Study of Aging between November 2004 and December 2019 who underwent formal audiometric and cognitive testing included in the current investigation.

MAIN OUTCOME MEASURES

The primary outcome measure was word recognition scores (WRSs; measured as <100% vs 100% as well as continuous), with pure-tone averages (PTAs; 0.5, 1, 2, and 3 kHz), age, sex, years of education, state area deprivation index (ADI) quintiles, and global cognition z scores as explanatory features.

RESULTS

The mean (SD) age among the 1,061 participants was 76 (9) years with 528 (50%) males. Participant age [OR (95% CI) for a 10-year increase of 1.8 (1.4-2.3), p < 0.001], male sex [OR = 2.6 (1.9-3.7), p < 0.001], and PTA [OR for a 10-dB hearing loss increase of 2.4 (2.1-2.8), p < 0.001] were all significantly associated with <100% WRSs, with the greatest explanatory ability attributable to the PTA. Years of education ( p = 0.9), state ADI quintile ( p = 0.6), and global cognitive performance ( p = 0.2) were not associated with WRS. The multivariable model demonstrated strong predictive ability for less than perfect WRSs, with a c index of 0.854. Similar results were seen for WRSs analyzed as continuous, with the multivariable model resulting in an R2 value of 0.433.

CONCLUSIONS

Although PTA exhibited the greatest influence on speech discrimination, advancing age and male sex both independently increased the likelihood of having worse speech discrimination among older adults, even after accounting for years of education, neighborhood-level socioeconomic disadvantage, and cognitive function. These findings help identify patient factors that can be instrumental when designing screening programs for adult-onset hearing loss.

Longitudinal trajectories of memory among middle-aged and older people with hearing loss: the influence of cochlear implant use on cognitive functioning

Introduction

Cochlear implants (CI) are the gold standard intervention for severe to profound hearing loss, a known modifiable risk factor for dementia. However, it remains unknown whether CI use might prevent the age-related cognitive decline. Recent studies are encouraging but are limited, mainly by short follow-up periods and, for ethical reasons, lack of appropriate control groups. Further, as age-related cognitive decline is multifaceted and not linear, other statistical approaches have to be evaluated.

Materials and methods

Immediate and delayed recall as measures of cognitive function were assessed in 75 newly implanted CI users (mean age 65.41 years ± 9.19) for up to 5 years (mean 4.5 ± 0.5) of CI use and compared to 8,077 subjects of the same age range from two longitudinal cohort studies, the Health and Retirement Study (HRS) and the English Longitudinal Study of Aging (ELSA). Linear and quadratic changes in cognitive trajectories were analyzed in detail using mixed growth models, considering possible confounders.

Results

For CI users, the linear time slope showed a significant improvement in the specific domains (recall and delayed recall) over time. The quadratic time slope clearly indicated that the predicted change after CI provision followed an inverted U-shape with a predicted decline 2 years after CI provision. In the hearing-impaired group, a significant decline over time was found, with steeper declines early on and the tendency to flatten out in the follow-up.

Conclusion

Cochlear implant use seems to boost cognitive trajectories in the first years after implantation. However, long-term prevention of dementia seems to need far more than restoration of hearing loss.

Is Hearing Loss a Risk Factor for Idiopathic Parkinson's Disease? An English Longitudinal Study of Ageing Analysis

Observations that hearing loss is a substantial risk factor for dementia may be accounted for by a common pathology. Mitochondrial oxidative stress and alterations in α-synuclein pathology may be common pathology candidates. Crucially, these candidate pathologies are implicated in Parkinson's disease (PD). Consequently, hearing loss may be a risk factor for PD. Subsequently, this prospective cohort study of the English Longitudinal Study of Ageing examines whether hearing loss is a risk factor for PD longitudinally. Participants reporting self-reported hearing capabilities and no PD diagnosis prior to entry (n = 14,340) were used. A joint longitudinal and survival model showed that during a median follow up of 10 years (SD = 4.67 years) increased PD risk (p < 0.001), but not self-reported hearing capability (p = 0.402). Additionally, an exploratory binary logistic regression modelling the influence of hearing loss identified using a screening test (n = 4812) on incident PD indicated that neither moderate (p = 0.794), nor moderately severe/severe hearing loss (p = 0.5210), increased PD risk, compared with normal hearing. Whilst discrepancies with prior literature may suggest a neurological link between hearing loss and PD, further large-scale analyses using clinically derived hearing loss are needed.

Cognitive control in age-related hearing loss: A narrative review

Recent evidence suggests links between hearing loss and cognitive impairment in older adults with peripheral age-related hearing loss (ARHL). Earliest cognitive changes have been observed in cognitive control; however, a cohesive account of cognitive control alterations in older adults with peripheral ARHL is lacking. Cognitive control refers to cognitive processes that manage and regulate one's behavior to achieve desired goals. This review summarizes behavioral evidence on alterations in three cognitive control processes, including cognitive flexibility, inhibitory control, and working memory updating, in individuals with ARHL. Of the three processes, cognitive flexibility and working memory updating have been most extensively studied, with relatively fewer studies examining inhibitory control. Most consistent evidence is observed for long-term changes in cognitive flexibility, particularly in individuals with greater severity of ARHL. Equivocal evidence is seen for alterations in inhibitory control and working memory updating, with various factors contributing to inconsistencies across studies. Our review summarizes the emerging body of research on cognitive control in individuals with ARHL to guide future work in this area and considerations related to the management of cognitive issues in this population.

Managing comorbid cognitive impairment and hearing loss in older adults: a UK survey of audiology and memory services

BACKGROUND

midlife hearing loss is a potentially modifiable risk factor for dementia. Addressing comorbid hearing loss and cognitive impairment in services for older adults may offer opportunities to reduce dementia risk.

OBJECTIVE

to explore current practice and views amongst UK professionals regarding hearing assessment and care in memory clinics and cognitive assessment and care in hearing aid clinics.

METHODS

national survey study. Between July 2021 and March 2022, we distributed the online survey link via email and via QR codes at conferences to professionals working in National Health Service (NHS) memory services and audiologists working in NHS and private adult audiology services. We present descriptive statistics.

RESULTS

135 professionals working in NHS memory services and 156 audiologists (68% NHS, 32% private sector) responded. Of those working in memory services, 79% estimate that >25% of their patients have significant hearing difficulties; 98% think it useful to ask about hearing difficulties and 91% do so; 56% think it useful to perform a hearing test in clinic but only 4% do so. Of audiologists, 36% estimate that >25% of their older adult patients have significant memory problems; 90% think it useful to perform cognitive assessments, but only 4% do so. Main barriers cited are lack of training, time and resources.

CONCLUSIONS

although professionals working in memory and audiology services felt addressing this comorbidity would be useful, current practice varies and does not generally address it. These results inform future research into operational solutions to integrating memory and audiology services.

Vision impairment, hearing impairment and functional Limitations of subjective cognitive decline: a population-based study

BACKGROUND

The association between sensory impairment including vision impairment (VI), hearing impairment (HI), dual impairment (DI) and the functional limitations of SCD (SCD-related FL) are still unclear in middle-aged and older people.

METHODS

162,083 participants from BRFSS in 2019 to 2020 was used in this cross-sectional study. After adjusting the weights, multiple logistic regression was used to study the relationship between sensory impairment and SCD or SCD-related FL. In addition, we performed subgroup analysis on the basis of interaction between sensory impairment and covariates.

RESULTS

Participants who reported sensory impairment were more likely to report SCD or SCD-related FL compared to those without sensory impairment (p < 0.001). The association between dual impairment and SCD-related FL was the strongest, the adjusted odds ratios (aORs) and 95% confidence interval (95% CI) were [HI, 2.88 (2.41, 3.43); VI, 3.15(2.61, 3.81); DI, 6.78(5.43, 8.47)] respectively. In addition, subgroup analysis showed that men with sensory impairment were more likely to report SCD-related FL than women, the aORs and 95% CI were [HI, 3.15(2.48, 3.99) vs2.69(2.09, 3.46); VI,3.67(2.79, 4.83) vs. 2.86(2.22, 3.70); DI, 9.07(6.67, 12.35) vs. 5.03(3.72, 6.81)] respectively. The subject of married with dual impairment had a stronger association with SCD-related FL than unmarried subjects the aOR and 95% CI was [9.58(6.69, 13.71) vs. 5.33(4.14, 6.87)].

CONCLUSIONS

Sensory impairment was strongly associated with SCD and SCD-related FL. Individuals with dual impairment had the greatest possibility to reported SCD-related FL, and the association was stronger for men or married subjects than other subjects.

Distinct disease mechanisms may underlie cognitive decline related to hearing loss in different age groups

BACKGROUND

Hearing loss in older adults is associated with increased dementia risk. Underlying mechanisms that connect hearing loss with dementia remain largely unclear.

METHODS

We studied the association of hearing loss and biomarkers for dementia risk in two age groups with normal cognition: 65 participants from the European Medical Information Framework (EMIF)-Alzheimer's disease (AD) 90+ study (oldest-old; mean age 92.7 years, 56.9% female) and 60 participants from the EMIF-AD PreclinAD study (younger-old; mean age 74.4, 43.3% female). Hearing function was tested by the 'digits-in-noise test' and cognition by repeated neuropsychological evaluation. Regressions and generalised estimating equations were used to test the association of hearing function and PET-derived amyloid burden, and linear mixed models were used to test the association of hearing function and cognitive decline. In the oldest-old group, mediation analyses were performed to study whether cognitive decline is mediated through regional brain atrophy.

RESULTS

In oldest-old individuals, hearing function was not associated with amyloid pathology (p=0.7), whereas in the younger-old individuals hearing loss was associated with higher amyloid burden (p=0.0034). In oldest-old individuals, poorer hearing was associated with a steeper decline in memory, global cognition and language, and in the younger-old with steeper decline in language only. The hippocampus and nucleus accumbens mediated the effects of hearing loss on memory and global cognition in the oldest-old individuals.

CONCLUSIONS

Hearing loss was associated with amyloid binding in younger-old individuals only, and with cognitive decline in both age groups. These results suggest that mechanisms linking hearing loss with risk for dementia depends on age.

Investigation of the effect of age-related hearing loss on visual memory

Aim: To investigate the effect of age-related hearing loss on visual memory. Material and Method: 20 participants with normal hearing loss and 38 participants with hearing loss were included in the study. All of the patients were older than 65 years. Pure tone audiometry, speech audiometry and Benton visual retention test were applied to all participants. Results: Mean Benton test score of the hearing-normal and the hearing loss group were 13.10±1.48 and 8.81±3.27 respectively. Patients were divided into three groups as hearing-normal, hearing loss with WRS greater than 80% and hearing loss with WRS lower than 80%. In terms of Benton scores there was statistically significant difference between groups (p

Noise-induced auditory damage affects hippocampus causing memory deficits in a model of early age-related hearing loss

Several studies identified noise-induced hearing loss (NIHL) as a risk factor for sensory aging and cognitive decline processes, including neurodegenerative diseases, such as dementia and age-related hearing loss (ARHL). Although the association between noise- and age-induced hearing impairment has been widely documented by epidemiological and experimental studies, the molecular mechanisms underlying this association are not fully understood as it is not known how these risk factors (aging and noise) can interact, affecting memory processes. We recently found that early noise exposure in an established animal model of ARHL (C57BL/6 mice) accelerates the onset of age-related cochlear dysfunctions. Here, we extended our previous data by investigating what happens in central brain structures (auditory cortex and hippocampus), to assess the relationship between hearing and memory impairment and the possible combined effect of noise and sensory aging on the cognitive domain. To this aim, we exposed juvenile C57BL/6 mice of 2 months of age to repeated noise sessions (60 min/day, pure tone of 100 dB SPL, 10 kHz, 10 consecutive days) and we monitored auditory threshold by measuring auditory brainstem responses (ABR), spatial working memory, by using the Y-maze test, and basal synaptic transmission by using ex vivo electrophysiological recordings, at different time points (1, 4 and 7 months after the onset of noise exposure, corresponding to 3, 6 and 9 months of age). We found that hearing loss, along with accelerated presbycusis onset, can induce persistent synaptic alterations in the auditory cortex. This was associated with decreased memory performance and oxidative-inflammatory injury in the hippocampus, the extra-auditory structure involved in memory processes. Collectively, our data confirm the critical relationship between auditory and memory circuits, suggesting that the combined detrimental effect of noise and sensory aging on hearing function can be considered a high-risk factor for both sensory and cognitive degenerative processes, given that early noise exposure accelerates presbycusis phenotype and induces hippocampal-dependent memory dysfunctions.

The role of care partners in medical visits of older adults with hearing loss and dementia: A national study

BACKGROUND

Dementia and hearing loss (HL) are conditions, which restrict communication ability and amplify the difficulty of implementing effective care coordination and communication with medical providers. We examined how the presence of HL and dementia influence communication with medical providers, and the role of involved care partners during medical visits.

METHODS

Drawing on responses from 7070 community-dwelling older adults who participated in the 2015 National Health and Aging Trends Study, we used logistic regression to quantify care partner accompaniment to medical visits and the role care partners assume during visits by older adult hearing and dementia status.

RESULTS

Nearly 4 in 10 older adults with dementia also reported HL. Eighty-two percent of older adults with both HL and dementia were accompanied to medical visits by a care partner. Those with HL and dementia were six times more likely to be accompanied by a care partner to medical visits than those with neither condition (OR: 6.04; 95% CI:4.06, 8.99). Care partners of older adults with both (vs neither) HL and dementia were more actively engaged in: (1) facilitating understanding between the older adult and doctor (OR: 4.55, 95% CI:2.68, 7.71); (2) asking or telling the doctor information (OR: 6.13, 95% CI:3.44, 10.9); and (3) reminding the older adult of their questions (OR: 2.52, 95% CI: 1.66, 3.83).

CONCLUSIONS

Care partners have an active role during medical visits of older adults with HL and dementia. Efforts to support care partner engagement and teach advocacy skills may close gaps in care quality for the subgroup of older adults who are living with HL and dementia.

Cognitive status in older patients with limited mobility as a predictor of negative outcome

Background. Cognitive impairment (CI) is one of the important disability factors in the elderly. The role of CI in prognosis of the frailest patients with limited mobility is uncertain.The aim. To determine the influence of the initial cognitive status in the group of patronage patients aged 60 years and older on the risk of mortality within one year.Materials and methods. Study group consisted of 450 patients from patronage group with one-year period of observation (from July 2019 till July 2020). Initial physical, functional, neuropsychiatriac and social statuses were evaluated by comprehensive geriatric assessment. Cognitive impairment was screened by Mini-Mental State Examination (MMSE), with dividing patients into dementia group (MMSE ≤ 24) and no-dementia group (MMSE > 24). The mortality rate after one year was assessed.Results. Of the 450 patients included in the study, dementia was present in 44.2 %. Patients with dementia were more prone to greater severity of chronic pain, sleep disturbances, depression, malnutrition and anemia. After one year of observation 34 out of 196 patients (17.3 %) in the group of patients with dementia and 18 out of 248 patients (7.3 %; p = 0.002) in the no-dementia group died. According to multivariate analysis, independent risk factors for death in patients with dementia were anemia, hearing impairment and a history of bone fractures.Conclusion. Thus, the assessment of the cognitive status of frail patients with limited mobility is important for the purpose of identifying the most vulnerable individuals with a high risk of adverse outcomes.

Evaluation of the non-auditory neurocognitive test MoCA-HI for hearing-impaired

Background

Since hearing loss and cognitive decline often co-occur among older adults, a cognitive screening test suitable for hearing-impaired people is of high clinical relevance. We report the first evaluation of a German language version of the Montreal Cognitive Assessment-Hearing Impaired version (MoCA-HI).

Objective

The aim of the present study was to compare cognitively healthy participants with and without hearing loss, to examine the impact of age, sex, educational level and degree of hearing impairment on the German MoCA-HI performance, and to develop normative data.

Material and methods

The German MoCA-HI was tested in 94 participants with normal or mild hearing impairment (group 1: 4PTA ≤ 40 dB on the better hearing ear) and 81 participants with moderate to profound hearing loss (group 2: 4PTA > 40 dB on the better hearing ear). Additionally, all participants performed the standard MoCA (version 8.2).

Results

No significant group difference between group 1 and 2 was found in the MoCA-HI total score (p = 0.05). In contrast, group 1 performed significantly better than group 2 on the standard MoCA (p < 0.001). There was no difference between the MoCA and the MoCA-HI performance in group 1 (p = 0.12), whereas individuals of group 2 performed significantly better on the MoCA-HI than on the standard MoCA (p < 0.001). Test-retest reliability of the MoCA-HI was high (p < 0.001). Higher age (p < 0.001), male sex (p = 0.009) and lower education (p < 0.001) were associated with a lower overall MoCA-HI score. Based on the demographic data normative data were developed by a regression-based approach.

Conclusion

The MoCA-HI is a cognitive screening test which is suitable for people with hearing impairment.

Association between hearing loss and development of dementia using formal behavioural audiometric testing within the Mayo Clinic Study of Aging (MCSA): a prospective population-based study

BACKGROUND

Hearing loss has been identified as a potential major modifiable risk factor for developing dementia. This study examined associations between formal behavioural pure-tone and speech audiometry assessed by an audiologist with development of dementia in the Mayo Clinic Study of Aging (MCSA).

METHODS

The MCSA is a prospective population-based study examining the incidence, prevalence, and risk factors of mild cognitive impairment and dementia in Olmsted County, Minnesota, USA. Participants undergo clinical examinations with neuropsychological testing at enrolment and every 15 months. Participants were 50 years or older at enrolment between Nov 29, 2004, and Dec 23, 2019, who underwent formal behavioural audiometric evaluation by an audiologist due to concerns about hearing loss or as a part of annual comprehensive health assessments. Associations of pure-tone average (PTA) and word recognition scores (WRS) with the development of dementia were evaluated using Cox proportional hazards regression with age as the timescale, and associations with changes in cognitive testing scores over time were evaluated using linear mixed-effects models.

FINDINGS

Among 1200 eligible participants, the mean age at enrolment was 79 years (SD 9), 593 (49%) were men, and 207 developed dementia during a mean of 7·0 years (SD 3·7) of follow-up. After adjusting for sex, years of education, smoking status, diabetes, hypertension, apolipoprotein E ε4 carriership, and hearing rehabilitation (defined as hearing aid or cochlear implant use), neither PTA (hazard ratio [HR] per 10-decibels hearing level increase of 0·99 (95% CI 0·89-1·12; p=0·91) nor WRS (HR per 10% decrease of 0·98, 95% CI 0·89-1 ·07; p=0·65) was significantly associated with the development of dementia. However, both PTA and WRS were significantly associated with poorer performance in cognitive testing over time: participants with a PTA higher than 25 decibels hearing level or a WRS lower than 100% had significantly worse declines in cognitive testing scores. Informant-based hearing difficulties assessed by the participant's study partner were significantly associated with the development of dementia (HR 1·95, 95% CI 1·45-2·62; p<0·0001).

INTERPRETATION

In this prospective population-based study, subjective informant-based hearing difficulties were associated with development of dementia, whereas objective measures on formal behavioural audiometry were predictive of poorer performance on cognitive testing over time but not the development of dementia. Other factors related to central processing might potentiate the effects of peripheral hearing loss detected on behavioural audiometric testing.

FUNDING

National Institute of Health, the Alexander Family Alzheimer's Disease Research Professorship of the Mayo Clinic, the GHR Foundation, the Mayo Foundation for Medical Education and Research, the Liston Award, the Schuler Foundation, the Rochester Epidemiology Project medical records linkage system, and the National Institute on Aging.

Monoallelic loss of the F-actin-binding protein radixin facilitates startle reactivity and pre-pulse inhibition in mice

Hearing impairment is one of the most common disorders with a global burden and increasing prevalence in an ever-aging population. Previous research has largely focused on peripheral sensory perception, while the brain circuits of auditory processing and integration remain poorly understood. Mutations in the rdx gene, encoding the F-actin binding protein radixin (Rdx), can induce hearing loss in human patients and homozygous depletion of Rdx causes deafness in mice. However, the precise physiological function of Rdx in hearing and auditory information processing is still ill-defined. Here, we investigated consequences of rdx monoallelic loss in the mouse. Unlike the homozygous (−/−) rdx knockout, which is characterized by the degeneration of actin-based stereocilia and subsequent hearing loss, our analysis of heterozygous (+/−) mutants has revealed a different phenotype. Specifically, monoallelic loss of rdx potentiated the startle reflex in response to acoustic stimulation of increasing intensities, suggesting a gain of function relative to wildtype littermates. The monoallelic loss of the rdx gene also facilitated pre-pulse inhibition of the acoustic startle reflex induced by weak auditory pre-pulse stimuli, indicating a modification to the circuit underlying sensorimotor gating of auditory input. However, the auditory brainstem response (ABR)-based hearing thresholds revealed a mild impairment in peripheral sound perception in rdx (+/-) mice, suggesting minor aberration of stereocilia structural integrity. Taken together, our data suggest a critical role of Rdx in the top-down processing and/or integration of auditory signals, and therefore a novel perspective to uncover further Rdx-mediated mechanisms in central auditory information processing.

Effect of hearing aids on cognitive functions in middle-aged and older adults with hearing loss: A systematic review and meta-analysis

OBJECTIVE

The study aimed to examine the effects of hearing aids on cognitive function in middle-aged and older adults with hearing loss.

DATA SOURCES AND STUDY SELECTION

PubMed, Cochrane Library, and Embase were searched for studies published before 30 March 2022. Randomized controlled trials (RCTs) and non-randomized studies of interventions (NRSIs) were included in the search. Restriction was set on neither types, severity, or the time of onset of hearing impairment nor cognitive or psychiatric statuses.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers extracted data and assessed the study quality of RCTs. Cognitive function outcomes were descriptively summarized and converted to standardized mean difference (SMD) in the meta-analysis. Meta-analysis was conducted in RCTs. Sub-group analyses were conducted by cognitive statuses, psychiatric disorders, and cognitive domains.

RESULTS

A total of 15 studies met the inclusion criteria, including five RCTs (n = 339) and 10 NRSIs (n = 507). Groups were classified as subjects without dementia or with normal global cognition, subjects with AD or dementia, and subjects with depressive symptoms. For subjects without dementia, improvements were found in global cognition, executive function, and episodic memory. For subjects with depressive symptoms, improvements were found in immediate memory, global cognition, and executive function. No improvement was found in subjects with AD or dementia. In total, four RCTs were included in the meta-analysis. For subjects without dementia (SMD = 0.11, 95% confidence interval [CI]: -0.15-0.37) and those with AD, no significant effect was found (SMD = -0.19, 95% CI: -0.65-0.28). For subjects without dementia, no significant effect was found in language (SMD = 0.14, 95% CI: -0.30-0.59) or general executive function (SMD = -0.04, 95% CI: -0.46-0.38). Further sub-group analysis found no significant effect in executive function (SMD = -0.27, 95% CI: -0.72-0.18) or processing speed (SMD = -0.02, 95% CI: -0.49-0.44).

CONCLUSION

Hearing aids might improve cognitive performance in domains such as executive function in subjects without dementia. The effects on subjects with depressive symptoms remained unclear. No improvement was found in subjects with AD or dementia. Long-term RCTs and well-matched comparison-group studies with large sample sizes are warranted.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022349057.

Can cochlear implantation prevent cognitive decline in the long-term follow-up?

Cognitive function and hearing are known to both decline in older adults. As hearing loss is proposed to be one modifiable risk factor for dementia, the impact of auditory rehabilitation on cognitive decline has been gaining increasing attention. Despite a large number of studies, long-term data are still rare. In a large prospective longitudinal monocentric study, 50 adults (aged ≥ 50 years) with severe postlingual bilateral hearing loss received a cochlear implant (CI). They underwent comprehensive neurocognitive testing prior to implantation (T1), at 12 months (T2) and up to 65 months (T3) after implantation. Various cognitive subdomains such as attention, inhibition, working memory, verbal fluency, mental flexibility and (delayed) recall were assessed by the computer-based non-auditory test battery ALAcog©. The observed trajectories of two exemplary cognitive subdomains (delayed recall and working memory) were then fitted over time using multilevel growth models to adjust for sociodemographic covariates and compared with 5-year longitudinal data from a sample of older adults from the representative Survey of Health, Aging and Retirement in Europe (SHARE) study. Postoperatively, auditory functions improved from 6.98% (SD 12.83) to 57.29% (SD 20.18) in monosyllabic speech understanding. Cognitive functions significantly increased from T1 to T3 in attention (p = 0.001), delayed recall (p = 0.001), working memory (OSPAN; p = 0.001), verbal fluency (p = 0.004), and inhibition (p = 0.002). A closer look at follow-up revealed that cognitive improvement could be detected between T1 and T2 and thereafter remained stable in all subtests (p ≥ 0.06). Additional longitudinal analysis confirmed these findings in a rigorous multilevel approach in two exemplary cognitive subdomains. In contrast to the SHARE data, there was no evidence for age-differential associations over time in CI recipients. This suggests that older adults benefit equally from cochlear implantation. CI users with worse preoperative cognitive skills experienced the most benefit (p < 0.0001). Auditory rehabilitation by cochlear implantation has a stimulating effect on cognitive functions beyond an improvement in speech understanding and an increased well-being. Large multicenter studies using standardized protocols have to be undertaken in the future to find out whether hearing restoration might help to prevent cognitive decline.

Do Not Go Gentle into That Deaf Night: A Holistic Perspective on Cochlear Implant Use as Part of Healthy Aging

Research suggests that cochlear implant (CI) use in elderly people improves speech perception and health-related quality of life (HRQOL). CI provision could also prevent dementia and other comorbidities and support healthy aging. The aim of this study was (1) to prospectively investigate potential changes in HRQOL and speech perception and (2) to identify clinical action points to improve CI treatment. Participants (n = 45) were CI recipients aged 60-90 with postlingual deafness. They were divided into groups, according to age: Group 1 (n = 20) received a CI between the age of 60-70 years; group 2 (n = 25) between the age of 71-90 years. HRQOL and speech perception were assessed preoperatively, and three and twelve months postoperatively. HRQOL and speech perception increased significantly within one year postoperatively in both groups. No difference between groups was found. We conclude that CI treatment improves speech perception and HRQOL in elderly users. Improvement of the referral process for CI treatment and a holistic approach when discussing CI treatment in the elderly population could prevent auditory deprivation and the deterioration of cognitive abilities.

The cognitive hearing science perspective on perceiving, understanding, and remembering language: The ELU model

The review gives an introductory description of the successive development of data patterns based on comparisons between hearing-impaired and normal hearing participants' speech understanding skills, later prompting the formulation of the Ease of Language Understanding (ELU) model. The model builds on the interaction between an input buffer (RAMBPHO, Rapid Automatic Multimodal Binding of PHOnology) and three memory systems: working memory (WM), semantic long-term memory (SLTM), and episodic long-term memory (ELTM). RAMBPHO input may either match or mismatch multimodal SLTM representations. Given a match, lexical access is accomplished rapidly and implicitly within approximately 100-400 ms. Given a mismatch, the prediction is that WM is engaged explicitly to repair the meaning of the input - in interaction with SLTM and ELTM - taking seconds rather than milliseconds. The multimodal and multilevel nature of representations held in WM and LTM are at the center of the review, being integral parts of the prediction and postdiction components of language understanding. Finally, some hypotheses based on a selective use-disuse of memory systems mechanism are described in relation to mild cognitive impairment and dementia. Alternative speech perception and WM models are evaluated, and recent developments and generalisations, ELU model tests, and boundaries are discussed.

Effect of Occupational Noise Exposure on Cognition and Suprathreshold Auditory Skills in Normal-Hearing Individuals

OBJECTIVES

Adverse effects of noise exposure on hearing and cognition are well documented in the literature. Recently, it has becoming increasingly evident that noise exposure deteriorates suprathreshold auditory skills, even though the hearing sensitivity is intact. This condition is termed as cochlear synaptopathy or hidden hearing loss, which is apparent in animal models. However, equivocal findings are reported in humans. This study aimed at assessing the working memory, attention abilities, and suprathreshold hearing abilities in normal-hearing individuals with and without occupational noise exposure. We also explored the relationship between cognitive measures and suprathreshold auditory measures.

DESIGN

The study participants were divided into two groups. All the participants had normal-hearing thresholds. The control group consisted of 25 individuals with no occupational noise exposure, whereas the noise exposure group had 25 individuals exposed to occupational noise of 85 dBA for a minimum period of 1 year. Working memory was assessed using auditory digit span (forward and backward), operation span, and reading span. The Erikson flanker test was used to evaluate attention abilities. The suprathreshold hearing was assessed in terms of gap detection thresholds and sentence identification in noise.

RESULTS

The results showed that the noise exposure group performed poorly compared to the control group on all auditory and cognitive tasks except the reading span.

CONCLUSION

The results of the study suggest that occupational noise exposure may hamper the cognitive skills and suprathreshold hearing abilities of the individual despite having normal peripheral hearing.

Identification of Target Proteins Involved in Cochlear Hair Cell Progenitor Cytotoxicity following Gentamicin Exposure

Given the non-labile, terminal differentiation of inner-ear sensory cells, preserving their function is critical since sensory cell damage results in irreversible hearing loss. Gentamicin-induced cytotoxicity is one of the major causes of sensory cell damage and consequent sensorineural hearing loss. However, the precise molecular mechanisms and target proteins involved in ototoxicity are still unknown. The objective of the present study was to identify target proteins involved in gentamicin-induced cytotoxicity to better characterize the molecular pathways involved in sensory cell damage following ototoxic drug administration using House Ear Institute-Organ of Corti 1 (HEI-OC1) cells and high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). We identified several unique proteins involved in gentamicin-induced cytotoxicity, expression of which were further confirmed using confocal microscopy. Further investigation of these pathways can inform the design and discovery of novel treatment modalities to prevent sensory cell damage and preserve their function.