Age-related hearing impairment—a risk factor and frailty marker for dementia and AD

Social isolation impairs cognition via Aβ-mediated synaptic dysfunction

Social isolation (SI) is a common phenomenon in the modern world, especially during the coronavirus disease 2019 pandemic, and causes lasting cognitive impairments and mental disorders. However, it is still unclear how SI alters molecules in the brain and induces behavioural dysfunctions. Here, we report that SI impairs cognitive function and induces depressive-like behaviours in C57BL/6 J mice, in addition to impairing synaptic plasticity and increasing the levels of APP cleavage-related enzymes, thereby promoting Aβ production. Moreover, we show that in APP/PS1 transgenic mice, SI accelerates pathological changes and behavioural deficits. Interestingly, downregulation of the expression of the BACE1 attenuates SI-induced Aβ toxicity and synaptic dysfunction. Furthermore, early intervention with BACE1 shRNA blocks SI-induced cognitive impairments. Together, our data strongly suggest that SI-induced upregulation of BACE1 expression mediates Aβ toxicity and induces behavioural deficits. Down-regulation of BACE1 may be a promising strategy for preventing SI-induced cognitive impairments.

Description of a new low-cost and open-source audiometer and its validation with normal-hearing listeners: The Aupiometer

Hearing loss is a major public health problem. In 2050, it could affect 2.5 billion people. It has therefore become necessary to prevent and diagnose them as early and as widely as possible. However, the costs of clinical equipment dedicated to the functional exploration of hearing remain high and hamper their distribution, while the technologies used are relatively basic. For example, the gold-standard pure-tone audiometry (PTA) essentially consists of emitting pure sounds. In addition, clinical audiometers are generally limited to PTA or few audiological tests, while hearing loss induce multiple functional deficits. Here, we present the Aupiometer, a low-cost audiometer implemented on a modular open-source system based on Raspberry Pi, and which integrates the entire technical framework necessary to carry out audiological measurements. Several hearing tests are already implemented (e.g. PTA, speech audiometry, questionnaires), while the clinical validity of the Aupiometer was verified on a panel of participants (N = 16) for an automated test of standard and extended high-frequency PTA, from 0.125 to 16 kHz, in comparison with a clinical audiometer. For this comparison between the two devices and over this wide frequency range, the difference is evaluated as less than ±10 dB for a 90% confidence interval, of the same order of magnitude as on test-retest differences on a single device. The interest of this device also extends to academic research as it should encourage the prototyping of innovative hearing tests by the community, in order to better understand the diversity of hearing problems in the population.

The impact of hearing aids on cognitive function and quality of life in patients with hearing impairment: A cross-sectional study

OBJECTIVE

Age-related cognitive decline involves a complex set of factors. Among these factors, hearing loss is considered to have a significant impact, but the effect of hearing aid use remains unresolved. The purpose of this study was to evaluate the effects of hearing aid use by simultaneously assessing various factors not only cognitive function but also frailty, anxiety, depression, and quality of life (QOL) in patients with hearing loss.

METHODS

The cross-sectional study at the Hearing Aid (HA) Center was conducted between 2020 and 2021. Initially, associations with cognitive function, QOL, frailty, and mental state among patients with hearing loss were examined, irrespective of whether they wore a hearing aid or not. Next, these patients were divided into HA users (using HA for more than 1 year) and non-users (no prior use of HA) with 42 patients in each group. The average age and 6-frequency pure tone audiometry (PTA) was 74.5 ± 6.5 years and 50.6 ± 12.1 dB, respectively. All participants filled out the questionnaire about their life style, medical condition. Mini-Mental State Examination (MMSE) for cognitive function, Hospital Anxiety and Depression Scale for mental state, Short Form 36 version 2 (SF-36v2) for QOL, and Kihon Checklist for frailty were compared between HA users and non-users and correlated with the auditory data (PTA and speech discrimination).

RESULTS

Among 84 patients, 40 had an MMSE score ≦26. All eight scores and three components of SF-36v2 were lower than those of the control group. The patients with hypertension were significantly more in HA user than in non-HA user, whereas there was no difference in diabetes, heart attack, stroke and education. Although HA users were older and showed hypertension more their PTA was worse than that of non-users, MMSE scores were not different between the groups. MMSE scores correlated with both PTA and speech discrimination in non-users but not in HA users. However, a multivariate analysis of the effect of HA use on MMSE scores adjusting for age, hypertension, and hearing loss, could not be revealed. The vitality and mental component summary of the SF-36v2 was better in HA users than in non-users.

CONCLUSION

Elderly patients with hearing loss were cognitively impaired and had low QOL. HA users showed better QOL score than non-HA user, especially about the mental condition. The absence of a correlation between MMSE scores and hearing loss in HA users suggests the potential use of HA in preventing cognitive decline.

Hearing loss is not associated with risk of Parkinson's disease: A Mendelian randomization study

Purpose

A few observational studies have indicated that Parkinson's disease (PD) risk may be higher in those with hearing loss, but the two's causal relationship is yet unknown. Using Mendelian randomization (MR) methods, this study sought to explore the causal link between hearing loss and the risk of PD.

Methods

We identified single nucleotide polymorphisms (SNPs) linked to hearing loss (P-value<5E-08) in a genome-wide association study (GWAS) included 323,978 people from the UK Biobank. The summary data for PD in the discovery group came from a GWAS meta-analysis of 33,647 cases and 449,056 healthy participants of European descent. Using summary data from the aforementioned GWAS of PD (N = 33,647) and hearing loss (N = 323,978), we carried out a two-sample MR study. As validation groups, two separate PD GWAS studies were used. Inverse variance weighting (IVW) was utilized in the principal MR analysis. For our findings to be reliable, further analyses were carried out with the Cochran's Q test, MR-Egger intercept, and leave-one-out analysis. In addition, we assessed the causal link between various forms of hearing loss and PD using the IVW approach.

Results

Twenty-two SNPs with genome-wide significance linked to hearing loss were used as instrumental factors. In the discovery dataset, we failed to detect a causal relationship between hearing loss and PD (OR = 1.297; 95 % CI = 0.420-4.007; P-value = 0.651). The findings of other methods agreed with the IVW method. The results were robust under sensitivity analyses. Furthermore, the above findings were confirmed in two validation PD datasets. Additionally, no causal correlation was found between genetic prediction of four different types of hearing loss and PD (conductive hearing loss, IVW: OR = 1.058, 95%CI = 0.988-1.133, P-value = 0.108; sudden idiopathic hearing loss, IVW: OR = 0.936, 95%CI = 0.863-1.016, P-value = 0.113; mixed conductive and sensorineural hearing loss, IVW: OR = 0.963, 95%CI = 0.878-1.058, P-value = 0.436; sensorineural hearing loss, IVW: OR = 1.050, 95%CI = 0.948-1.161, P-value = 0.354).

Conclusion

In those of European heritage, our investigation revealed no causal link between hearing loss and PD risk.

MicroRNA-7 deficiency ameliorates d-galactose-induced aging in mice by regulating senescence of Kupffer cells

Aging is intricately linked to immune system dysfunction. Recent studies have highlighted the biological function of microRNA-7 (miR-7) as a novel regulator of immune cell function and related diseases. However, the potential role of miR-7 in aging remains unexplored. Here, we investigated the contribution of miR-7 to d-gal-induced aging in mice, focusing on its regulation of senescent Kupffer cells. Our findings revealed that miR-7 deficiency significantly ameliorated the aging process, characterized by enhanced CD4+ T-cell activation. However, the adoptive transfer of miR-7-deficient CD4+T cells failed to improve the age-related phenotype. Further analysis showed that miR-7 deficiency significantly reduced IL-1β production in liver tissue, and inhibiting IL-1β in vivo slowed down the aging process in mice. Notably, IL-1β is mainly produced by senescent Kupffer cells in the liver tissue of aging mice, and miR-7 expression was significantly up-regulated in these cells. Mechanistically, KLF4, a target of miR-7, was down-regulated in senescent Kupffer cells in aging mouse model. Furthermore, miR-7 deficiency also modulated the NF-κB activation and IL-1β production in senescent Kupffer cells through KLF4. In conclusion, our findings unveil the role of miR-7 in d-gal-induced aging in mice, highlighting its regulation of KLF4/NF-κB/IL-1β pathways in senescent Kupffer cells. This research may enhance our understanding of miRNA-based aging immune cells and offer new avenues for new intervention strategies in aging process.

Associations between dietary indices and hearing status among middle-older aged adults - results from the Baltimore Longitudinal Study of Aging

BACKGROUND

Hearing loss, a public health issue in older populations, is closely related to functional decline.

OBJECTIVE

To investigate the longitudinal associations between 4 dietary indices and hearing status.

METHODS

Data from the Baltimore Longitudinal Study of Aging were used and included 882 participants ≥45 y of age. Dietary intake was assessed using a validated food frequency questionnaire, and 4 dietary scores (Mediterranean-Dietary Approaches to Stop Hypertension Intervention for Neurodegenerative Delay diet [MIND], Mediterranean style diet score [MDS], Alternative Healthy Eating Index [AHEI], and Healthy Eating Index [HEI]) were calculated as averages over time. Hearing status was examined using pure-tone audiometry, and pure-tone average (PTA) of hearing thresholds were calculated at speech-level (PTA(500, 1000, 2000, 4000 Hz)), low (PTA(500, 1000 Hz)), and high (PTA(4000, 8000 Hz)) frequencies, with lower thresholds indicating better hearing. Multivariable linear mixed-effect models were used to examine associations between dietary indices and hearing threshold change over time adjusted for confounders.

RESULTS

At baseline, the mean age of participants was 67 y and 55% were female. Over a median of 8 y of follow-up, MDS ≥7 was associated with 3.5 (95% CI: -6.5, -0.4) and 5.0 (95% CI: -9.1, -1.0) dB lower PTA(500, 1000, 2000, 4000 Hz) and PTA(4000, 8000 Hz), respectively, compared with MDS ≤3; the highest tertile of the AHEI was associated with 2.3 (95% CI: -4.6, -0.1) and 5.0 (95% CI: -8.0, -2.0) dB lower PTA(500, 1000, 2000, 4000 Hz) and PTA(4000, 8000 Hz); and each standard deviation increment in HEI was associated with 1.6 dB (95% CI: -2.7, -0.6), 1.1 dB (95% CI: -2.1, -0.1), and 2.1 dB (95% CI: -3.5, -0.6) lower PTA(500, 1000, 2000, 4000 Hz), PTA(500, 1000 Hz), and PTA(4000, 8000 Hz), respectively.

CONCLUSIONS

Adherence to healthy dietary patterns was associated with better hearing status, with stronger associations at high frequencies. Am J Clin Nutr 20xx;x:xx.

Epidemiologic association and shared genetic architecture between cataract and hearing difficulties among middle-aged and older adults

Age-related cataract and hearing difficulties are major sensory disorders that often co-exist in the global-wide elderly and have a tangible influence on the quality of life. However, the epidemiologic association between cataract and hearing difficulties remains unexplored, while little is known about whether the two share their genetic etiology. We first investigated the clinical association between cataract and hearing difficulties using the UK Biobank covering 502,543 individuals. Both unmatched analysis (adjusted for confounders) and a matched analysis (one control matched for each patient with cataract according to confounding factors) were undertaken and confirmed that cataract was associated with hearing difficulties (OR, 2.12; 95% CI, 1.98-2.27; OR, 2.03; 95% CI, 1.86-2.23, respectively). Furthermore, we explored and quantified the shared genetic architecture of these two complex sensory disorders at the common variant level using the bivariate causal mixture model (MiXeR) and conditional/conjunctional false discovery rate method based on the largest available genome-wide association studies of cataract (N = 585,243) and hearing difficulties (N = 323,978). Despite detecting only a negligible genetic correlation, we observe polygenic overlap between cataract and hearing difficulties and identify 6 shared loci with mixed directions of effects. Follow-up analysis of the shared loci implicates candidate genes QKI, STK17A, TYR, NSF, and TCF4 likely contribute to the pathophysiology of cataracts and hearing difficulties. In conclusion, this study demonstrates the presence of epidemiologic association between cataract and hearing difficulties and provides new insights into the shared genetic architecture of these two disorders at the common variant level.

Causal relationship between psychiatric disorders and sensorineural hearing loss: A bidirectional two-sample mendelian randomization analysis

OBJECTIVE

This study employed bidirectional two-sample Mendelian randomization (MR) to investigate the causal links between psychiatric disorders and sensorineural hearing loss (SNHL).

METHODS

Instrumental variables were chosen from genome-wide association studies of schizophrenia (SCH, N = 127,906), bipolar disorder (BD, N = 51,710), major depressive disorder (MDD, N = 500,199), and SNHL (N = 212,544). In the univariable MR analysis, the inverse-variance weighted method (IVW) was conducted as the primary analysis, complemented by various sensitivity analyses to ensure result robustness.

RESULTS

SCH exhibited a decreased the risk of SNHL (OR = 0.949, P = 0.005), whereas BD showed an increased incidence of SNHL (OR = 1.145, P = 0.005). No causal association was found for MDD on SNHL (OR = 1.088, P = 0.246). Multivariable MR validated these results. In the reverse direction, genetically predicted SNHL was linked to a decreased risk of SCH with suggestive significance (OR = 0.912, P = 0.023). No reverse causal relationships were observed for SNHL influencing BD or MDD. These findings remained consistent across various MR methods and sensitivity analyses.

CONCLUSION

This study demonstrated that the causal relationships between diverse psychiatric disorders with SNHL were heterogeneous. Specifically, SCH was inversely associated with SNHL susceptibility, and similarly, a reduced risk of SNHL was observed in schizophrenia patients. In contrast, BD exhibited an increased incidence of SNHL, although SNHL did not influence the prevalence of BD. No causal association between MDD and SNHL was found.

Olfactory decline develops in parallel with frailty in older US adults with obstructive lung diseases

BACKGROUND

Frailty is prevalent among older adults with asthma or chronic obstructive pulmonary disease (obstructive lung diseases [OLDs]). Frailty and OLD's co-occurrence is associated with increased hospitalization/mortality. Chemosensory dysfunction is closely connected to both OLD and frailty. We evaluated the utility of olfactory decline as a biomarker of frailty in the setting of OLD.

METHODS

We performed a prospective, longitudinal, nationally representative study of community-dwelling older US adults in the National Social Life, Health and Aging Project, an omnibus in-home survey. Respondents reported a physician's diagnosis of OLD. Decline in odor identification and sensitivity over 5 years and frailty (adapted fried frailty phenotype criteria) were measured using standard tools. Multivariate logistic regressions evaluated the association between OLD status, olfactory decline, and frailty.

RESULTS

We compared individuals with OLD (n = 98; mean age 71.2 years, 59.2% women) and those without OLD (n = 1036; mean age 69.5 years, 58.9% women). Olfactory identification decline was associated with developing frailty over the 5-year follow-up period in individuals with OLD (odds ratio [OR] = 9.1, 95% confidence interval [CI] = 2.1-38.6, p = 0.003). Olfactory decline predicted incidence of frailty in individuals with OLD (identification: OR = 4.8, 95% CI = 1.3-17.5, P = 0.018; sensitivity: OR = 6.1, 95%CI = 1.2-31.0, p = 0.030) but not in those without OLD adjusting for demographics, heavy alcohol use, current smoking, and comorbidity. Results were robust to different thresholds for olfactory decline and frailty development.

CONCLUSIONS

Older adults with OLD who experience olfactory decline face higher odds of developing frailty. Use of olfactory decline as a biomarker to identify frailty could allow earlier intervention and decrease adverse outcomes for high-risk older adults with OLD.

Hearing and Balance in Healthy Aging Project: Characterization of Hearing, Balance, and Other Associated Disorders in Three Population Groups Aged 55 and Over

INTRODUCTION

Active aging emphasizes optimizing health and participation for a better quality of life as people age. This paper explores the significant impact of hearing loss and balance disorders on the elderly. Age-related hearing loss is thought to contribute to communication breakdown and cognitive dysfunctions. The "hearing and balance in healthy aging" project focuses on early detection, mitigation, and advocacy. Objectives include exploring epidemiological traits, evaluating overall well-being impact, proving positive intervention effects, and advocating societal care for the elderly with hearing loss and balance disorders, aiming to reduce their broader impact on cognition, independence, and sociability.

METHODS

This study is observational, prospective study. Subjects over 55 years old with a follow-up every year or every 2 years were divided into three groups, according to their hearing and balance: within the normal range (group A), detected and not treated (group B), and detected and treated (group C). At each visit, they underwent a series of tests or questionnaires, evaluating different areas: hearing, balance, cognition, depression, dependence, tinnitus, loneliness, health.

RESULTS

A total of 710 patients were included in the study. The distribution of patients was as follows: group A - 210 patients, group B - 302 patients, and group C - 198 patients. Significant differences were found between the three groups related to age, sex, educational level, bilingualism, and work activity. In group C, there was a higher percentage of males, older than in groups A and B, and the percentage of individuals with a university education was lower (28%), as was the rate of bilingualism (23%). In terms of hearing, significant differences were found in the three groups in the mean PTA, speech discrimination in quiet, and the HINT test, with worse results for group C. Only patients in group C presented a perception of hearing impairment, and the handicap caused by hearing impairment worsened from group A to C. Concerning balance, both tests performed (TuGT and DHI) revealed increased difficulty in maintaining autonomous walking from group A to C, which, again, exhibited the worst results, with statistically significant differences across the group. Analysis about cognition revealed significant differences in DSST questionnaires and in TMT scores, where group C had the worst scores. In HUI3 questionnaire scores, the differences between each and every group were statistically significant, with group C showing moderate disability.

CONCLUSION

This extensive analysis, encompassing a considerable number of subjects, reveals significant findings that have important implications for the early prevention of hearing loss and its consequent consequences. At the same time, these data represent an initial exploration, which raises the need for in-depth examinations of additional factors and longer follow-up to continue contributing insights and knowledge for a healthy aging.

Evaluation of glymphatic system activity by diffusion tensor image analysis along the perivascular space in presbycusis

PURPOSE

Previous studies have suggested that presbycusis (age-related hearing loss) is accompanied with cognitive decline and dementia. However, the neural mechanism underlying the cognitive decline in presbycusis remains unclear. This study aimed to evaluate the glymphatic system function in presbycusis patients compared to healthy controls using diffusion tensor imaging (DTI) with the perivascular space (DTI-ALPS) method.

METHODS

DTI scans were obtained from 30 presbycusis patients with cognitive decline (PCD), 30 presbycusis patients with no cognitive decline (PNCD) and 40 age-, gender-, and education-matched healthy controls (HCs). The DTI-ALPS index was calculated for each group. We evaluated the differences in the DTI-ALPS index among PCD, PNCD and HCs. In addition, we conducted a correlation analysis between the DTI-ALPS index and cognitive performance.

RESULTS

There were significant differences of the DTI-ALPS index among three groups. Post-hoc analysis suggested that the DTI-ALPS index in PCD was significantly lower patients in relative to PNCD and HCs (1.49147 vs. 1.57441 vs. 1.62020, p < 0.001). After correcting for age, gender, and education, the DTI-ALPS index is positively correlated with the MoCA scores (rho = 0.426, p = 0.026).

CONCLUSION

Presbycusis patients with cognitive impairment exhibited decreased glymphatic activity than those without cognitive impairment and HCs. The DTI-ALPS index may provide useful disease progression or treatment biomarkers for patients with presbycusis as an indicator of modulation of glymphatic activity.

NADPH Oxidase 3: Beyond the Inner Ear

Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.

Reduced tactile sensitivity is associated with mild cognitive impairment

BACKGROUND

Sensory impairment has been related to age-associated cognitive decline. While these associations were investigated primarily in the auditory and visual domain, other senses such as touch have rarely been studied. Thus, it remains open whether these results are specific for particular sensory domains, or rather point to a fundamental role of sensory deficits in cognitive decline.

METHODS

Data from 31 participants with mild cognitive impairment (MCI), 46 participants with frailty, and 23 non-clinical control participants (NCCs) were included. We assessed sensory function using visual acuity and contrast sensitivity, hearing threshold, and mechanical detection threshold. Cognitive function in participants with MCI was assessed using associative memory performance. Group differences on sensory thresholds were tested using analyses of covariance with age, sex, and years of education as covariates. Associations between measures within participants with MCI were evaluated using Spearman correlations.

FINDINGS

We found a significant difference in mechanical detection threshold between the groups (p < 0.001, η2 = 0.18). Participants with MCI showed significantly reduced tactile sensitivity compared to participants with frailty and NCCs. In participants with MCI, lower associative memory performance was significantly related to reduced tactile sensitivity (rs = 0.39, p = 0.031) and auditory acuity (rs = 0.41, p = 0.022).

INTERPRETATION

Our results indicate that reduced tactile sensitivity is related to cognitive decline. Prospective studies should investigate the age-related alterations of multimodal sensory processes and their contribution to dementia-related processes.

FUNDING

Deutsche Forschungsgemeinschaft (FL 156/41-1) and a grant of the Hector-Stiftung II, Weinheim, Germany.

Evaluation of cognitive functions in the elderly with and without central auditory processing disorder

PURPOSE

Evaluate and compare the performance of cognitive functions between elderly with and without auditory processing disorders.

METHODS

Twenty-eight healthy elderly (14 Control group and 14 Auditory Processing Disorder group - APD group) participated in the study. All elderly were submitted to (central) auditory processing evaluation, P300 event-related potential and brief cognitive battery (BCB). In the comparison between subjects, the Mann-Whitney test was applied and in the intra-subjects comparison, the Wilcoxon signed rank test was used. To verify if there was an association between the performance of the PAC and the cognitive variables, Spearman's correlation was used.

RESULTS

There were no statistically significant differences between the Control and APD groups for the cognitive abilities assessed by BCB, as well as for the P300 cognitive potential variables.

CONCLUSION

Elderly with auditory processing disorders do not seem to show greater cognitive difficulties compared to elderly of the same age group without auditory processing disorders, exception of the clock drawing test, whose task involves multiple cognitive functions, including visuospatial processing, executive function, semantic memory, and planning.

Age-related hearing loss associated with differences in the neural correlates of feature binding in visual working memory

The underlying neural mechanisms underpinning the association between age-related hearing loss (ARHL) and dementia remain unclear. A limitation has been the lack of functional neuroimaging studies in ARHL cohorts to help clarify this relationship. In the present study, we investigated the neural correlates of feature binding in visual working memory with ARHL (controls = 14, mild HL = 21, and moderate or greater HL = 23). Participants completed a visual change detection task assessing feature binding while their neural activity was synchronously recorded via high-density electroencephalography. There was no difference in accuracy scores for ARHL groups compared to controls. There was increased electrophysiological activity in those with ARHL, particularly in components indexing the earlier stages of visual cognitive processing. This activity was more pronounced with more severe ARHL and was associated with maintained feature binding. Source space (sLORETA) analyses indicated greater activity in networks modulated by frontoparietal and temporal regions. Our results demonstrate there may be increased involvement of neurocognitive control networks to maintain lower-order neurocognitive processing disrupted by ARHL.

Cocoa Polyphenols Prevent Age-Related Hearing Loss and Frailty in an In Vivo Model

Age-related hearing loss (ARHL) impairs the quality of life in elderly persons. ARHL is associated with comorbidities, such as depression, falls, or frailty. Frailty syndrome is related to poor health outcomes in old age. ARHL is a potentially modifiable risk factor for frailty. Oxidative stress has been proposed as a key factor underlying the onset and/or development of ARHL and frailty. Cocoa has high levels of polyphenols and provides many health benefits due to its antioxidant properties. Male and female C57Bl/6J mice were randomly assigned to two study groups: animals receiving a cocoa-supplemented diet and the other receiving a standard diet. Then, at the ages of 6, 14, and 22 months, hearing and frailty were measured in all mice. Auditory steady-state responses (ASSR) threshold shifts were measured to different frequencies. The frailty score was based on the "Valencia Score" adapted to the experimental animals. The total antioxidant capacity and total polyphenols in urine samples were also measured. Significant improvements in hearing ability are observed in the cocoa groups at 6, 14, and 22 months compared to the no cocoa group. The cocoa diet significantly retards the development of frailty in mice. Cocoa increases the concentration of polyphenols excreted in the urine, which increases the total antioxidant capacity. In conclusion, cocoa, due to its antioxidant properties, leads to significant protection against ARHL and frailty.

Potential role of Bcl2 in lipid metabolism and synaptic dysfunction of age-related hearing loss

Age-related hearing loss (ARHL) is a prevalent condition affecting millions of individuals globally. This study investigated the role of the cell survival regulator Bcl2 in ARHL through in vitro and in vivo experiments and metabolomics analysis. The results showed that the lack of Bcl2 in the auditory cortex affects lipid metabolism, resulting in reduced synaptic function and neurodegeneration. Immunohistochemical analysis demonstrated enrichment of Bcl2 in specific areas of the auditory cortex, including the secondary auditory cortex, dorsal and ventral areas, and primary somatosensory cortex. In ARHL rats, a significant decrease in Bcl2 expression was observed in these areas. RNAseq analysis showed that the downregulation of Bcl2 altered lipid metabolism pathways within the auditory pathway, which was further confirmed by metabolomics analysis. These results suggest that Bcl2 plays a crucial role in regulating lipid metabolism, synaptic function, and neurodegeneration in ARHL; thereby, it could be a potential therapeutic target. We also revealed that Bcl2 probably has a close connection with lipid peroxidation and reactive oxygen species (ROS) production occurring in cochlear hair cells and cortical neurons in ARHL. The study also identified changes in hair cells, spiral ganglion cells, and nerve fiber density as consequences of Bcl2 deficiency, which could potentially contribute to the inner ear nerve blockage and subsequent hearing loss. Therefore, targeting Bcl2 may be a promising potential therapeutic intervention for ARHL. These findings provide valuable insights into the molecular mechanisms underlying ARHL and may pave the way for novel treatment approaches for this prevalent age-related disorder.

Deafness: from genetic architecture to gene therapy

Progress in deciphering the genetic architecture of human sensorineural hearing impairment (SNHI) or loss, and multidisciplinary studies of mouse models, have led to the elucidation of the molecular mechanisms underlying auditory system function, primarily in the cochlea, the mammalian hearing organ. These studies have provided unparalleled insights into the pathophysiological processes involved in SNHI, paving the way for the development of inner-ear gene therapy based on gene replacement, gene augmentation or gene editing. The application of these approaches in preclinical studies over the past decade has highlighted key translational opportunities and challenges for achieving effective, safe and sustained inner-ear gene therapy to prevent or cure monogenic forms of SNHI and associated balance disorders.

Aging and Speech-in-Noise Perception

The objective was investigating the effect of age on speech-in-noise perception (SINP) using word perception score in white noise (WPS in WN). This cross-sectional study was conducted on 76 participants, including 30 elderly (older than 61 years) and 46 young adults (between 14 and 35 years) with normal levels of stress, night sleep and mini-mental states. Audiological evaluations included acoustic immittance testing, pure tone audiometry, determination of speech reception threshold and WPS in WN. Data analysis were performed using Mann-Whitney and Tukey HSD tests. Based on the results of the tests, the participants were divided into three groups: (1) young adults with normal hearing (n = 30), (2) elderly adults with normal hearing (n = 16), (3) elderly adults with mild to moderate high frequency hearing loss (n = 14). In both groups of old adults, the means WPS in WN differences were significant only in the left ears (Pv = 0.008, 0.033, 0.025 for SNR = 0, +5, +10 dB). In the three groups and in the right ears, there were the significant differences between the means of WPS in WN (Pv = 0.002, 0.000, 0.001 for SNR = 0, +5, +10 dB), and also the left ears (Pv = 0.000, 0.002, 0.002 for SNR = 0,+5, +10 dB).There is a relationship between increasing age and decreasing WPS in WN. The deleterious effects of aging on SINP decline are greater than that of hearing loss.

Cognitive reserve disorder in age-related hearing loss: cognitive cortical compensatory to auditory perceptual processing

The aim of this study is to ascertain the mechanisms of cognitive reserve disorder in age-related hearing loss (ARHL), to study the correlation between ARHL and cognitive decline via EEG, and to reverse the adverse remodeling of auditory-cognitive connectivity with hearing aids (HAs). In this study, 32 participants were enrolled, including 12 with ARHLs, 9 with HAs, and 11 healthy controls (HCs), to undergo EEG, Pure Tone Average (PTA), Montreal Cognitive Assessment (MoCA), and other general cognitive tests. There were the lowest MoCA in the ARHL group (P = 0.001), especially in language and abstraction. In the ARHL group, power spectral density of the gamma in right middle temporal gyrus was significantly higher than HC and HA groups, while functional connectivity between superior frontal gyrus and cingulate gyrus was weaker than HC group (P = 0.036) and HA group (P = 0.021). In the HA group, superior temporal gyrus and cuneus had higher connectivity than in the HC group (P = 0.036). In the ARHL group, DeltaTM_DTA (P = 0.042) and CTB (P = 0.011) were more frequent than in the HC group, while there was less DeltaTM_CTA (P = 0.029). PTA was found to be associated with MoCA (r = -0.580) and language (r = -0.572), DeltaTM_CTB had a likewise correlation with MoCA (r = 0.483) and language (r = 0.493), while DeltaTM_DTA was related to abstraction (r = -0.458). Cognitive cortexes compensate for worse auditory perceptual processing in ARHL, which relates to cognitive decline. The impaired functional connectivity between auditory and cognitive cortexes can be remodeled by HAs. DeltaTM may serve as a biomarker for early cognitive decline and decreased auditory speech perception in ARHL.

Understanding the Association Between Sensory Impairment and Dementia: Toward Informing Future Research and Health Policy

Recent epidemiological research has linked decline in multiple sensory functions with an increased risk of dementia. However, the pathways linking such factors with neurodegenerative disorders remain unclear. Studies that assess this are crucial for guiding the distribution of public health resources and the development of clinical trials aiming to delay or prevent dementia. This commentary examines the contribution of a study by Dintica and colleagues to the field of sensory-cognitive research.

The Relationship between Signs of Medical Conditions and Cognitive Decline in Senior Dogs

Canine cognitive dysfunction syndrome (CCDS) is a progressive age-related neurodegenerative disorder in dogs. Minimal research has been performed to investigate how clinical signs may be impacted by other medical conditions. A cross-sectional study was performed using the Canine Cognitive Assessment Scale (CCAS) to evaluate cognitive impairment as reported by owners. Owner-reported health-related measures included behaviour changes, the body condition score, and veterinary diagnoses of disease. The responses from 804 dogs in the last 25% of their expected lifespan were analysed. Factors were identified in the owner-reported behavioural signs of disease representing pathologies in four body systems: musculoskeletal-neurological, digestive, metabolic, and dermatological, with the items comprising these factors also compiled into a cumulative measure of health. The results showed a strong correlation between the CCAS score and both the musculoskeletal-neurological factor and the overall cumulative measure of health. Moderate correlations between the CCAS score and the digestive factor and metabolic factor were also observed. The correlation between the dermatological factor and the CCAS score was weak. This study highlights the need to screen dogs for concurrent diseases when using scales to assess cognitive impairment and to monitor dogs who have health conditions, particularly those that are painful, for the onset of cognitive impairment.

Cochlear implants: the effects of age on outcomes

INTRODUCTION

Cochlear implants (CIs) provide access to sound for children and adults who do not receive adequate benefit from hearing aids. Age at implantation is known to affect outcomes across the lifespan.

AREAS COVERED

The effects of age on CI outcomes are examined for infants, children, adolescents, and older adults. A variety of outcome measures are considered, including speech perception, language, cognition, and quality of life measures.

EXPERT OPINION/COMMENTARY

For those meeting candidacy criteria, CIs are beneficial at any age. In general, younger age is related to greater benefit when considering pre-lingual deafness. Other factors such as additional disabilities, may mitigate this effect. Post-lingually deafened adults demonstrate similar benefit regardless of age, though the oldest individuals (80+) may see smaller degrees of improvement from preoperative scores. Benefit can be measured in many ways, and the areas of greatest benefit may vary based on age: young children appear to see the greatest effects of age at implantation on language measures, whereas scores on cognitive measures appear to be most impacted for the oldest population. Future research should consider implantation at extreme ages (5-9 months or > 90 years), unconventional measures of CI benefit including qualitative assessments, and longitudinal designs.

Association of Central Auditory Processing Dysfunction With Preclinical Alzheimer's Disease

OBJECTIVE

To investigate whether central auditory processing dysfunction measured by the dichotic digit test-1 digit (DDT1) is present in preclinical Alzheimer's disease (AD) individuals who are cognitively normal (CN) older adults with the cerebral beta-amyloid (Aβ) deposition and to explore the potential of the DDT1 as a screening test for preclinical AD.

STUDY DESIGN

Cross-sectional design.

SETTING

A prospective observational cohort study.

METHODS

CN older adults with a global clinical dementia rating score of 0 were included. The hearing test battery including pure-tone audiometry, speech audiometry, distortion product otoacoustic emission, and DDT1 was administered to participants.

RESULTS

Fifty CN older adults were included. Among them, 38 individuals were included in the Aβ deposition negative (AN) group and 12 were included in the Aβ deposition positive (AP) group. The DDT1 scores of both the better and worse ears were significantly lower in the AP group than in the AN group (p = .008 and p = .015, respectively). No significant differences were observed between the groups in tests of the peripheral auditory pathways. In multivariable logistic regression analysis adjusted for apolipoprotein E4 positivity, the DDT1 better ear score predicted the AP group (p = .036, odds ratio = 0.892, 95% confidence interval: 0.780-0.985) with relatively high diagnostic accuracy.

CONCLUSION

Our findings suggest that Aβ deposition may affect the central auditory pathway even before cognitive decline appears. DDT1, which can easily be applied to the old-age population, may have the potential as a screening tool for preclinical AD.

Correlates of hearing loss among adults with schizophrenia

BACKGROUND

Hearing loss (HL) is associated with adverse cognitive, mental, and physical health outcomes. There is evidence that across age groups HL is more prevalent in people with schizophrenia than the general population. Given that people with schizophrenia may already be vulnerable to cognitive and psychosocial disability, we sought to examine how hearing ability relates to concurrent levels of cognitive, mental and daily functioning.

METHODS

Community-dwelling adults with schizophrenia (N = 84) ages 22-50 completed pure tone audiometry assessments. Hearing threshold (in decibels) was defined as the lowest detectable pure tone at 1000 Hz. Pearson correlation was used to test the hypothesis that higher hearing thresholds (worse hearing) would be significantly associated with poorer performance on the Brief Assessment of Cognition in Schizophrenia (BACS). Additional analyses explored the relationships between audiometric threshold and functional capacity measured with the Virtual Reality Functional Capacity Assessment Tool (VRFCAT) and symptoms severity rated on the Positive and Negative Syndrome Scale (PANSS).

RESULTS

Hearing threshold was inversely and significantly correlated with the BACS composite score (r = -0.27, p = 0.017). This relationship was reduced but remained significant after controlling for age (r = -0.23, p = 0.04). Hearing threshold was not associated with VRFCAT or psychiatric symptom measures.

CONCLUSIONS

While schizophrenia and HL are independently associated with cognitive impairment, the magnitude of impairment in this sample was greater among those with poorer hearing. Findings warrant further mechanistic study of the relationship between hearing impairment and cognition and have implications for addressing modifiable health risk factors for higher morbidity and mortality in this vulnerable population.

Probability Distributions for Associations Between Cognitive Screening and Pure-tone Thresholds in Older Adults

OBJECTIVES

Lower general cognitive function is frequently reported in older adults with elevated pure-tone thresholds. Here, we examined reason(s) for this association, including whether this relationship is dependent on the frequency range or extent of hearing loss and cognitive screening performance.

DESIGN

Linear regression was used to examine associations between better-ear pure-tone thresholds and Mini-Mental Status Exam (MMSE) performance in a cross-sectional sample of relatively healthy older adults (N = 508; 68% women, 60-89+ years; M age = 72). Quantile regression was also used to identify the ranges of 0.5 and 4.0 kHz thresholds and MMSE scores where these variables exhibited significant associations.

RESULTS

MMSE scores and pure-tone thresholds exhibited small but significant associations, particularly for better-ear 0.5 kHz thresholds. This hearing threshold and cognitive screening association was present among participants with better hearing, including the oldest older adults. There was limited evidence for mediating health condition effects on this association. An item analysis of the MMSE revealed that the MMSE and pure-tone threshold associations were largely due to the delayed recall item of the MMSE.

CONCLUSIONS

Together, the small effect results are consistent with the extant literature and suggest that there are multiple reasons for modest pure-tone threshold and cognitive screening performance associations.

Promoting TFEB nuclear localization with curcumin analog C1 attenuates sensory hair cell injury and delays age-related hearing loss in C57BL/6 mice

Sensory hair cell (HC) injuries, especially outer hair cell (OHC) loss, are well-documented to be the primary pathology of age-related hearing loss (AHL). Recent studies have demonstrated that autophagy plays an important role in HC injury in the inner ear. In our previous works, a decline in autophagy levels and HC loss were found to occur simultaneously in the inner ears of aged C57BL/6 mice, and the administration of rapamycin promoted autophagy levels, which reduced OHC loss and delayed AHL, but the underlying mechanism of autophagy in AHL has not been well elucidated. Transcription factor EB (TFEB), an autophagy regulator and the downstream target of mammalian target of rapamycin (mTOR), is involved in the pathological development of neurodegenerative disease. This study would address the link between autophagy and TFEB in aged C57BL/6 mouse cochleae and clarify the effect of the TFEB activator curcumin analog C1 (C1) in aged cochleae. Decreased TFEB nuclear localization (p = 0.0371) and autophagy dysfunction (p = 0.0273) were observed in the cochleae of aged C57BL/6 mice that exhibited AHL, HCs loss and HCs senescence. Treatment with C1 promoted TFEB nuclear localization and restored autophagy, subsequently alleviating HC injury and delaying AHL. The protective effect of C1 on HEI-OC1 cells against autophagy disorder and aging induced by D-galactose was abolished by chloroquine, which is one of the commonly used autophagy inhibitors. Overall, our results demonstrated that the capacity to perform autophagy is mediated by the nuclear localization of TFEB in aged C57BL/6 mouse cochleae. C1 promotes the nuclear localization of TFEB, subsequently alleviating HC injury and delaying AHL by restoring the impaired autophagy function. TFEB may serve as a new therapeutic target for AHL treatment.

Aucubin protects mouse cochlear hair cells from cisplatin-induced ototoxicity via activation of the PI3K/AKT/STAT3 pathway

Cisplatin is commonly used to treat cancers and is associated with a significant risk of irreversible sensorineural hearing loss. However, no effective preventive strategies are available for cisplatin-induced HL. Therefore, significant efforts have been made to discover new drugs protecting cochlear hair cells from cisplatin-induced damage. We found that a new phytochemical, aucubin, attenuated cisplatin-induced apoptosis, the production of reactive oxygen species, and mitochondrial dysfunction in House Ear Institute Organ of Corti 1 cells and cochlear hair cells. Moreover, aucubin attenuated cisplatin-induced sensorineural hearing loss and hair cells loss in vivo. Furthermore, RNA sequencing analysis revealed that the otoprotective effects of aucubin were mainly mediated by increased STAT3 phosphorylation via the PI3K/AKT pathway. Inhibition of the STAT3 signaling pathway with the inhibitor S3I-201 or siRNA disrupted the protective effects of aucubin on cisplatin-induced apoptosis. In conclusion, we identified an otoprotective effect of aucubin. Therefore, aucubin could be used to prevent cisplatin-induced ototoxicity.

Neurochemical and functional reorganization of the cognitive-ear link underlies cognitive impairment in presbycusis

Recent studies suggest that the interaction between presbycusis and cognitive impairment may be partially explained by the cognitive-ear link. However, the underlying neurophysiological mechanisms remain largely unknown. In this study, we combined magnetic resonance spectroscopy (MRS) and resting-state functional magnetic resonance imaging (fMRI) to investigate auditory gamma-aminobutyric acid (GABA) and glutamate (Glu) levels, intra- and inter-network functional connectivity, and their relationships with auditory and cognitive function in 51 presbycusis patients and 51 well-matched healthy controls. Our results confirmed reorganization of the cognitive-ear link in presbycusis, including decreased auditory GABA and Glu levels and aberrant functional connectivity involving auditory networks (AN) and cognitive-related networks, which were associated with reduced speech perception or cognitive impairment. Moreover, mediation analyses revealed that decreased auditory GABA levels and dysconnectivity between the AN and default mode network (DMN) mediated the association between hearing loss and impaired information processing speed in presbycusis. These findings highlight the importance of AN-DMN dysconnectivity in cognitive-ear link reorganization leading to cognitive impairment, and hearing loss may drive reorganization via decreased auditory GABA levels. Modulation of GABA neurotransmission may lead to new treatment strategies for cognitive impairment in presbycusis patients.

Vascular Factors in Patients with Midlife Sensorineural Hearing Loss and the Progression to Mild Cognitive Impairment

Background and Objectives: Midlife hearing loss (HL) has been considered as a major modifiable risk factor for a later-life progression to dementia. Our aim was to detect a link between precocious sensorineural hearing loss (SNHL) and mild cognitive impairment (MCI) and their association to putative risk factors for a common pathology. Materials and methods: In this study, a retrospective case-control study was carried out. A total of 112 patients were enrolled as following: 81 patients with bilateral SNHL and 31 subjects with normal hearing, whose ages ranged from 50 to 65 years. Both groups performed pure tone audiometry, a tinnitus handicap inventory (THI), Mini-Mental State examination (MMSE), and the Montreal Cognitive Assessment (MoCA), Hospital Anxiety and Depression Scale (HADS-A and HADS-D). Results: The mean age was 58 ± 5.2 in SNHL patients and 53.2 ± 4.8 in the control group. The mean pure tone average in the SNHL group was 40.2 ± 18.7 dB HL on the right side and 41.2 ± 17.2 dB HL on the left side, while in the control group it was 12.5 ± 2.8 dB HL on right side and 12.4 ± 3.1 dB HL on left side. About 64% of patients with SNHL exhibited comorbidities, and the most common condition was hypertension. Altered MoCA test scores were significantly related to the pure tone averages in patients with SNHL compared to the control group (p = 0.0004), while the differences in the HADS-A and HADS-D were not significant. Furthermore, a significant correlation was observed in SNHL patients between an altered MoCA test and hypercholesterolemia (p = 0.043). Conclusions: Hearing impairment and screening tests to detect MCI should be considered in the midlife in order to carry out strategies to prevent the progression to dementia. Hypertension and hypercholesterolemia are two risk factors in the development of endothelial dysfunction, oxidative stress, and vascular inflammation, and may represent the common pathology linking the inner ear and brain damage.

Cortical thickness of the left parahippocampal cortex links central hearing and cognitive performance in aging

Hearing impairment is considered a leading modifiable risk factor of cognitive decline and dementia. While most evidence has been established on clinical assessment of peripheral hearing loss, understanding of how central hearing in real-world conditions is associated with cognitive aging is limited. This study analyzed the data of 473 unrelated healthy adults aged 36-100 years old from the Lifespan Human Connectome Project in Aging. Central hearing was evaluated using the Words-in-Noise decibel threshold. Cognitive functions were evaluated by the performance on cognitive tests, and cortical thickness was estimated from magnetic resonance imaging (MRI) data. Here, we show that a higher hearing threshold was associated with a lower performance on immediate and delayed episodic memory retrieval, switching aspect of executive function, working memory, reading decoding, and vocabulary comprehension. Cortical thickness in the left parahippocampal cortex (lPHC) was negatively associated with the hearing threshold and acted as a significant partial mediator in the association of central hearing with immediate recall, switching, reading decoding, and vocabulary comprehension. These findings suggest that cortical thickness in the lPHC, an early target of dementia, partially links central hearing and performance in multiple cognitive domains in aging.

Thwarting Alzheimer's Disease through Healthy Lifestyle Habits: Hope for the Future

Alzheimer's disease (AD) is a neurodegenerative disorder that slowly disintegrates memory and thinking skills. Age is known to be the major risk factor in AD, but there are several nonmodifiable and modifiable causes. The nonmodifiable risk factors such as family history, high cholesterol, head injuries, gender, pollution, and genetic aberrations are reported to expediate disease progression. The modifiable risk factors of AD that may help prevent or delay the onset of AD in liable people, which this review focuses on, includes lifestyle, diet, substance use, lack of physical and mental activity, social life, sleep, among other causes. We also discuss how mitigating underlying conditions such as hearing loss and cardiovascular complications could be beneficial in preventing cognitive decline. As the current medications can only treat the manifestations of AD and not the underlying process, healthy lifestyle choices associated with modifiable factors is the best alternative strategy to combat the disease.

Hearing Impairment and Incident Frailty in Later Life: The Health in Men Study (HIMS)

OBJECTIVES

This study is designed to determine if hearing loss is associated with increased risk of frailty in later life.

DESIGN

A prospective cohort study.

SETTING AND PARTICIPANTS

We retrieved data of a community sample of men aged 70 years and above living in the metropolitan region of Perth, Western Australia. 3,285 participants who were free of frailty at the beginning of the study were followed for up to 17 years. Data were retrieved from the Health in Men Study (HIMS) and the Western Australian Data Linkage System (WADLS).

MEASUREMENTS

Hearing loss was defined by self-report or by diagnosis recorded in the WADLS. Incident frailty was assessed using the Hospital Frailty Risk Score (HFRS).

RESULTS

A total of 2,348 (71.5%) men developed frailty during follow up. The adjusted hazard ratio was 1.03 (95% CI: 0.95-1.12). The majority of the participants became frail by age 90 regardless of hearing condition. The time point where half of the group become frail was delayed by 14.4 months for men without hearing loss compared with hearing impaired men.

CONCLUSIONS

Hearing loss is not associated with incident frailty in men aged 70 years or older when frailty was measured by HFRS. However, this statistically non-significant result could be due to the low sensitivity of study measures. Also, we found a trend that men with hearing loss were more likely to develop frailty compared with their normal-hearing peers, suggesting a potential association between hearing loss and frailty.

No Link Between Speech-in-Noise Perception and Auditory Sensory Memory - Evidence From a Large Cohort of Older and Younger Listeners

A growing literature is demonstrating a link between working memory (WM) and speech-in-noise (SiN) perception. However, the nature of this correlation and which components of WM might underlie it, are being debated. We investigated how SiN reception links with auditory sensory memory (aSM) - the low-level processes that support the short-term maintenance of temporally unfolding sounds. A large sample of old (N = 199, 60-79 yo) and young (N = 149, 20-35 yo) participants was recruited online and performed a coordinate response measure-based speech-in-babble task that taps listeners' ability to track a speech target in background noise. We used two tasks to investigate implicit and explicit aSM. Both were based on tone patterns overlapping in processing time scales with speech (presentation rate of tones 20 Hz; of patterns 2 Hz). We hypothesised that a link between SiN and aSM may be particularly apparent in older listeners due to age-related reduction in both SiN reception and aSM. We confirmed impaired SiN reception in the older cohort and demonstrated reduced aSM performance in those listeners. However, SiN and aSM did not share variability. Across the two age groups, SiN performance was predicted by a binaural processing test and age. The results suggest that previously observed links between WM and SiN may relate to the executive components and other cognitive demands of the used tasks. This finding helps to constrain the search for the perceptual and cognitive factors that explain individual variability in SiN performance.

Improving disease prevention, diagnosis, and treatment using novel bionic technologies

Increased human life expectancy, due in part to improvements in infant and childhood survival, more active lifestyles, in combination with higher patient expectations for better health outcomes, is leading to an extensive change in the number, type and manner in which health conditions are treated. Over the next decades as the global population rapidly progresses toward a super-aging society, meeting the long-term quality of care needs is forecast to present a major healthcare challenge. The goal is to ensure longer periods of good health, a sustained sense of well-being, with extended periods of activity, social engagement, and productivity. To accomplish these goals, multifunctionalized interfaces are an indispensable component of next generation medical technologies. The development of more sophisticated materials and devices as well as an improved understanding of human disease is forecast to revolutionize the diagnosis and treatment of conditions ranging from osteoarthritis to Alzheimer's disease and will impact disease prevention. This review examines emerging cutting-edge bionic materials, devices and technologies developed to advance disease prevention, and medical care and treatment in our elderly population including developments in smart bandages, cochlear implants, and the increasing role of artificial intelligence and nanorobotics in medicine.

Central Auditory Processing Disorder in Patients with Amnestic Mild Cognitive Impairment

Background

This study was conducted to comprehensively examine the central auditory processing (CAP) abilities of patients with amnestic mild cognitive impairment (aMCI) as well as to compare the results with cognitively normal elderly controls.

Methods

A total of 78 participants were screened through pure-tone audiometry and word recognition score in order to exclude peripheral auditory dysfunction. Forty-five people passed screening tests, and 33 people failed. Finally, 25 aMCI (mean age = 71.52 ± 4.8; male : female = 24 : 76) and 20 controls (mean age = 73.45 ± 4.32; male : female = 45 : 55) were enrolled in the study. Seven CAP tests (frequency pattern test, duration pattern test, Gap-In-Noise^© test, dichotic digits test, low-pass filtered word test, speech perception in noise test, and binaural fusion test) were conducted only after the two groups passed the screening. A linear mixed model was applied to analyze CAP tests except for the binaural fusion test. For the binaural fusion test, the independent t-test was used to compare the means of test score between two groups.

Results

The aMCI group had a decrease in the mean score of the frequency pattern test, duration pattern test, Gaps-In-Noise^© test, dichotic digits test, and speech perception in noise test compared with the control group.

Conclusion

The aMCI group's CAP abilities were significantly lower than those of the control group. Thus, if the cognitive assessment and hearing evaluation are conducted in combination, the sensitivity of the diagnostic process for aMCI will be increased.

Auditory-limbic-cerebellum interactions and cognitive impairments in noise-induced hearing loss

AIMS

This study aimed to explore the neural substrate of hearing loss-related central nervous system in rats and its correlation with cognition.

METHODS

We identified the neural mechanism for these debilitating abnormalities by inducing a bilateral hearing loss animal model using intense broadband noise (122 dB of broadband noise for 2 h) and used the Morris water maze test to characterize the behavioral changes at 6 months post-noise exposure. Functional magnetic resonance imaging (fMRI) was conducted to clarify disrupted functional network using bilateral auditory cortex (ACx) as a seed. Structural diffusion tensor imaging (DTI) was applied to illustrate characteristics of fibers in ACx and hippocampus. Pearson correlation was computed behavioral tests and other features.

RESULTS

A deficit in spatial learning/memory, body weight, and negative correlation between them was observed. Functional connectivity revealed weakened coupling within the ACx and inferior colliculus, lateral lemniscus, the primary motor cortex, the olfactory tubercle, hippocampus, and the paraflocculus lobe of the cerebellum. The fiber number and mean length of ACx and different hippocampal subregions were also damaged in hearing loss rats.

CONCLUSION

A new model of auditory-limbic-cerebellum interactions accounting for noise-induced hearing loss and cognitive impairments is proposed.

Development and in vivo validation of small interfering RNAs targeting NOX3 to prevent sensorineural hearing loss

The reactive oxygen species (ROS)-generating enzyme NOX3 has recently been implicated in the pathophysiology of several acquired forms of sensorineural hearing loss, including cisplatin-, noise- and age-related hearing loss. NOX3 is highly and specifically expressed in the inner ear and therefore represents an attractive target for specific intervention aiming at otoprotection. Despite the strong rationale to inhibit NOX3, there is currently no specific pharmacological inhibitor available. Molecular therapy may represent a powerful alternative. In this study, we developed and tested a collection of small interfering (si) RNA constructs to establish a proof of concept of NOX3 inhibition through local delivery in the mouse inner ear. The inhibitory potential of 10 different siRNA constructs was first assessed in three different cells lines expressing the NOX3 complex. Efficacy of the most promising siRNA construct to knock-down NOX3 was then further assessed in vivo, comparing middle ear delivery and direct intracochlear delivery through the posterior semi-circular canal. While hearing was completely preserved through the intervention, a significant downregulation of NOX3 expression in the mouse inner ear and particularly in the spiral ganglion area at clinically relevant levels (>60%) was observed 48 h after treatment. In contrast to successful intracochlear delivery, middle ear administration of siRNA failed to significantly inhibit Nox3 mRNA expression. In conclusion, intracochlear delivery of NOX3-siRNAs induces a robust temporal NOX3 downregulation, which could be of relevance to prevent predictable acute insults such as cisplatin chemotherapy-mediated ototoxicity and other forms of acquired hearing loss, including post-prevention of noise-induced hearing loss immediately after trauma. Successful translation of our concept into an eventual clinical use in humans will depend on the development of atraumatic and efficient delivery routes into the cochlea without a risk to induce hearing loss through the intervention.

Frailty and hearing loss: From association to causation

Background

Observational studies suggest that frailty is associated with hearing loss (HL) but with inconsistent results. This study aims to examine such association and to assess its causality.

Materials and methods

The cross-sectional data from the National Health and Nutrition Examination Survey (NHANES). Multivariate logistic regression models were used to assess the association between HL and frailty index (FI). Genetic variants associated with the FI and HL were obtained from a large genome-wide association study (GWAS) meta-analysis and UK Biobank GWAS. The inverse variance weighting (IVW) method was used to estimate causal effects. Sensitivity analyses were performed to further validate the robustness of results.

Results

In this cross-sectional analysis, results support the possibility that frailty may be associated with a higher risk of developing HL, with self-reported [odds ratio (OR) = 2.813; 95% CI, 2.386, 3.317; p &lt; 0.001], speech frequency HL (OR = 1.975; 95% CI, 1.679–2.323; p &lt; 0.001), and high frequency HL (OR = 1.748; 95% CI, 1.459–2.094; p &lt; 0.001). In the adjusted model, frail participants remained at high risk of HL. Mendelian randomization (MR) studies showed a bidirectional causal association between genetically predicted FI and risk of HL (FI for exposure: OR = 1.051; 95% CI, 1.020–1.083; p = 0.001; HL for exposure: OR = 1.527; 95% CI, 1.227–1.901; p &lt; 0.001).

Conclusion

Our observational study found that inter-individual differences in frailty were associated with the risk of developing HL. Genetic evidence suggests a potential bidirectional causal association between FI and HL. Furthermore, the potential mechanisms of this association require investigation.

Tumor necrosis factor-α mediated inflammation versus apoptosis in age-related hearing loss

An almost universal phenomenon occurring during aging is a state of chronic, low-grade, sterile inflammation. Inflammation is a crucial contributor to various age-related pathologies and natural processes in aging tissues. Tumor necrosis factor-α (TNF-α), a master regulator of the immune system, plays an important role in the propagation of inflammation. Recent research has found correlations between hearing loss and markers such as TNF-α. However, the intrinsic molecular mechanism by which TNF-α influences aging individuals’ increased risk of hearing loss remains unclear. In this study, we found that TNF-α expression gradually increased with age in DBA/2J mice. We then used recombinant TNF-α to upregulate TNF-α levels in House Ear Institute-Organ of Corti 1 (HEI-OC1) cells and found that low concentrations of TNF-α could activate the nuclear factor kappa B (NF-κB) transcriptional response to mediate hair cell survival, while high concentrations of TNF-α could activate the Caspase-3 cascade to mediate hair cell apoptosis, which preliminarily confirmed that a TNF-α mediated signaling pathway plays an important role in the pathogenesis of age-related hearing loss.

Rapid Effects of Vagus Nerve Stimulation on Sensory Processing Through Activation of Neuromodulatory Systems

After sensory information is encoded into neural signals at the periphery, it is processed through multiple brain regions before perception occurs (i.e., sensory processing). Recent work has begun to tease apart how neuromodulatory systems influence sensory processing. Vagus nerve stimulation (VNS) is well-known as an effective and safe method of activating neuromodulatory systems. There is a growing body of studies confirming VNS has immediate effects on sensory processing across multiple sensory modalities. These immediate effects of VNS on sensory processing are distinct from the more well-documented method of inducing lasting neuroplastic changes to the sensory pathways through repeatedly delivering a brief VNS burst paired with a sensory stimulus. Immediate effects occur upon VNS onset, often disappear upon VNS offset, and the modulation is present for all sensory stimuli. Conversely, the neuroplastic effect of pairing sub-second bursts of VNS with a sensory stimulus alters sensory processing only after multiple pairing sessions, this alteration remains after cessation of pairing sessions, and the alteration selectively affects the response properties of neurons encoding the specific paired sensory stimulus. Here, we call attention to the immediate effects VNS has on sensory processing. This review discusses existing studies on this topic, provides an overview of the underlying neuromodulatory systems that likely play a role, and briefly explores the potential translational applications of using VNS to rapidly regulate sensory processing.

Does cognitive impairment precede self-reported poor hearing? Results from the English longitudinal study of ageing

OBJECTIVE

To investigate whether cognitive impairment precedes self-reported poor hearing in adults aged 50 and older over a 14-year period.

DESIGN

Biennial longitudinal study.

STUDY SAMPLE

The data came from the English Longitudinal Study of Ageing carried out in England between 2002 and 2016, with 11,391 individuals aged 50 years and older. For this study, ELSA participants who had a positive perception of hearing at the beginning of the analysis in 2002 (n = 8,895) were eligible. The dependent variable was self-reported poor hearing, and the exposure measure was cognitive impairment. The analyses were performed using Generalised Estimation Equations and adjusted for gender, age, educational level, household wealth, smoking, alcohol consumption, depressive symptoms, ADL/IADL disability, physical activity level, diabetes, and cardiovascular disease.

RESULTS

The results showed 33% increased odds of self-reported poor hearing in individuals with cognitive impairment. In the fully adjusted model, individuals who presented cognitive impairment in the previous wave had, over time, 10% increased odds (95% CI: 1.02; 1.19) of presenting self-reported poor hearing.

CONCLUSIONS

The exposure to cognitive impairment was associated with a subsequent self-reported poor hearing. These data represent important tools for improving cognitive and hearing impairment diagnosis and treatment.

Reorganized Brain Functional Network Topology in Presbycusis

Purpose

Presbycusis is characterized by bilateral sensorineural hearing loss at high frequencies and is often accompanied by cognitive decline. This study aimed to identify the topological reorganization of brain functional network in presbycusis with/without cognitive decline by using graph theory analysis approaches based on resting-state functional magnetic resonance imaging (rs-fMRI).

Methods

Resting-state fMRI scans were obtained from 30 presbycusis patients with cognitive decline, 30 presbycusis patients without cognitive decline, and 50 age-, sex-, and education-matched healthy controls. Graph theory was applied to analyze the topological properties of brain functional networks including global and nodal metrics, modularity, and rich-club organization.

Results

At the global level, the brain functional networks of all participants were found to possess small-world properties. Also, significant group differences in global network metrics were observed among the three groups such as clustering coefficient, characteristic path length, normalized characteristic path length, and small-worldness. At the nodal level, several nodes with abnormal betweenness centrality, degree centrality, nodal efficiency, and nodal local efficiency were detected in presbycusis patients with/without cognitive decline. Changes in intra-modular connections in frontal lobe module and inter-modular connections in prefrontal subcortical lobe module were found in presbycusis patients exposed to modularity analysis. Rich-club nodes were reorganized in presbycusis patients, while the connections among them had no significant group differences.

Conclusion

Presbycusis patients exhibited topological reorganization of the whole-brain functional network, and presbycusis patients with cognitive decline showed more obvious changes in these topological properties than those without cognitive decline. Abnormal changes of these properties in presbycusis patients may compensate for cognitive impairment by mobilizing additional neural resources.

Corticofugal and Brainstem Functions Associated With Medial Olivocochlear Cholinergic Transmission

Cholinergic transmission is essential for survival and reproduction, as it is involved in several physiological responses. In the auditory system, both ascending and descending auditory pathways are modulated by cholinergic transmission, affecting the perception of sounds. The auditory efferent system is a neuronal network comprised of several feedback loops, including corticofugal and brainstem pathways to the cochlear receptor. The auditory efferent system's -final and mandatory synapses that connect the brain with the cochlear receptor- involve medial olivocochlear neurons and outer hair cells. A unique cholinergic transmission mediates these synapses through α9/α10 nicotinic receptors. To study this receptor, it was generated a strain of mice carrying a null mutation of the Chrna9 gene (α9-KO mice), lacking cholinergic transmission between medial olivocochlear neurons and outer hair cells, providing a unique opportunity to study the role of medial olivocochlear cholinergic transmission in auditory and cognitive functions. In this article, we review behavioral and physiological studies carried out to research auditory efferent function in the context of audition, cognition, and hearing impairments. Auditory studies have shown that hearing thresholds in the α9-KO mice are normal, while more complex auditory functions, such as frequency selectivity and sound localization, are altered. The corticofugal pathways have been studied in α9-KO mice using behavioral tasks, evidencing a reduced capacity to suppress auditory distractors during visual selective attention. Finally, we discuss the evolutionary role of the auditory efferent system detecting vocalizations in noise and its role in auditory disorders, such as the prevention of age-related hearing loss.

Mapping cerebral atrophic trajectory from amnestic mild cognitive impairment to Alzheimer's disease

Alzheimer's disease (AD) patients suffer progressive cerebral atrophy before dementia onset. However, the region-specific atrophic processes and the influences of age and apolipoprotein E (APOE) on atrophic trajectory are still unclear. By mapping the region-specific nonlinear atrophic trajectory of whole cerebrum from amnestic mild cognitive impairment (aMCI) to AD based on longitudinal structural magnetic resonance imaging data from Alzheimer's disease Neuroimaging Initiative (ADNI) database, we unraveled a quadratic accelerated atrophic trajectory of 68 cerebral regions from aMCI to AD, especially in the superior temporal pole, caudate, and hippocampus. Besides, interaction analyses demonstrated that APOE ε4 carriers had faster atrophic rates than noncarriers in 8 regions, including the caudate, hippocampus, insula, etc.; younger patients progressed faster than older patients in 32 regions, especially for the superior temporal pole, hippocampus, and superior temporal gyrus; and 15 regions demonstrated complex interaction among age, APOE, and disease progression, including the caudate, hippocampus, etc. (P < 0.05/68, Bonferroni correction). Finally, Cox proportional hazards regression model based on the identified region-specific biomarkers could effectively predict the time to AD conversion within 10 years. In summary, cerebral atrophic trajectory mapping could help a comprehensive understanding of AD development and offer potential biomarkers for predicting AD conversion.

Associations between age-related hearing loss, cognitive decline, and depression in Chinese centenarians and oldest-old adults

Objective:

Age-related hearing loss (ARHL) and age-related cognitive decline (ARCD) are leading causes of disability in older adults. ARHL may increase ARCD risk and cause depression development. This study aimed to explore the associations of ARHL with ARCD and depression in Chinese centenarians and oldest-old adults.

Methods:

A household survey was conducted on 859 centenarians and oldest-old adults residing in 16 cities and counties in China. Basic information was collected using interview questionnaires, physical examinations, and blood tests conducted by systematically trained local doctors and nurses.

Results:

In total, 501 (58.3%), 649 (75.6%), and 211 (24.6%) participants had ARHL, ARCD, and depression, respectively. The prevalence of ARCD and depression was significantly higher in participants with ARHL than in those without ARHL (all p < 0.05). Participants with ARHL had significantly lower Mini-Mental State Examination (MMSE) scores indicative of more cognitive decline, and significantly higher 15-item version of the Geriatric Depression Scale (GDS-15) scores suggesting greater levels of depression, than those without ARHL (all p < 0.05). Multivariate logistic regression analyses (Stepwise) indicated that ARHL was significantly and positively associated with ARCD [odds ratio (OR): 1.594, 95% confidence interval (CI): 1.132, 2.245] and depression (OR: 1.623, 95% CI: 1.139, 2.314; all p < 0.05). Multivariate linear regression analyses (Stepwise) indicated that ARHL was significantly and inversely associated with MMSE scores (B: −2.520, 95% CI: −3.356, −1.684) and significantly and positively associated with GDS-15 scores (B: 0.713, 95% CI: 0.328, 1.098; all p < 0.05).

Conclusion:

ARHL is independently associated with ARCD and depression in Chinese centenarians and oldest-old adults.

Listen Carefully protocol: an exploratory case-control study of the association between listening effort and cognitive function

INTRODUCTION

A growing body of evidence suggests that hearing loss is a significant and potentially modifiable risk factor for cognitive impairment. Although the mechanisms underlying the associations between cognitive decline and hearing loss are unclear, listening effort has been posited as one of the mechanisms involved with cognitive decline in older age. To date, there has been a lack of research investigating this association, particularly among adults with mild cognitive impairment (MCI).

METHODS AND ANALYSIS

15-25 cognitively healthy participants and 15-25 patients with MCI (age 40-85 years) will be recruited to participate in an exploratory study investigating the association between cognitive functioning and listening effort. Both behavioural and objective measures of listening effort will be investigated. The sentence-final word identification and recall (SWIR) test will be administered with single talker non-intelligible speech background noise while monitoring pupil dilation. Evaluation of cognitive function will be carried out in a clinical setting using a battery of neuropsychological tests. This study is considered exploratory and proof of concept, with information taken to help decide the validity of larger-scale trials.

ETHICS AND DISSEMINATION

Written approval exemption was obtained by the Scientific Ethics Committee in the central region of Denmark (De Videnskabsetiske Komiteer i Region Hovedstaden), reference 19042404, and the project is registered pre-results at clinicaltrials.gov, reference NCT04593290, Protocol ID 19042404. Study results will be disseminated in peer-reviewed journals and conferences.