Ageing and the auditory system

L-Ergothioneine slows the progression of age-related hearing loss in CBA/CaJ mice

The naturally occurring amino acid, l-ergothioneine (EGT), has immense potential as a therapeutic, having shown promise in the treatment of other disease models, including neurological disorders. EGT is naturally uptaken into cells via its specific receptor, OCTN1, to be utilized by cells as an antioxidant and anti-inflammatory. In our current study, EGT was administered over a period of 6 months to 25-26-month-old CBA/CaJ mice as a possible treatment for age-related hearing loss (ARHL), since presbycusis has been linked to higher levels of cochlear oxidative stress, apoptosis, and chronic inflammation. Results from the current study indicate that EGT can prevent aging declines of some key features of ARHL. However, we found a distinct sex difference for the response to the treatments, for hearing - Auditory Brainstem Responses (ABRs) and Distortion Product Otoacoustic Emissions (DPOAEs). Males exhibited lower threshold declines in both low dose (LD) and high dose (HD) test groups throughout the testing period and did not display some of the characteristic aging declines in hearing seen in Control animals. In contrast, female mice did not show any therapeutic effects with either treatment dose. Further confirming this sex difference, EGT levels in whole blood sampling throughout the testing period showed greater uptake of EGT in males compared to females. Additionally, RT-PCR results from three tissue types of the inner ear confirmed EGT activity in the cochlea in both males and females. Males and females exhibited significant differences in biomarkers related to apoptosis (Cas-3), inflammation (TNF-a), oxidative stress (SOD2), and mitochondrial health (PGC1a).These changes were more prominent in males as compared to females, especially in stria vascularis tissue. Taken together, these findings suggest that EGT has the potential to be a naturally derived therapeutic for slowing down the progression of ARHL, and possibly other neurodegenerative diseases. EGT, while effective in the treatment of some features of presbycusis in aging males, could also be modified into a general prophylaxis for other age-related disorders where treatment protocols would include eating a larger proportion of EGT-rich foods or supplements. Lastly, the sex difference discovered here, needs further investigation to see if therapeutic conditions can be developed where aging females show better responsiveness to EGT.

Hearing health survey of the population in Bangkok

In this cross-sectional random survey among Thai adults living in Bangkok, we aimed to identify the prevalence of hearing problems and examine their relationship with individual factors. We administered a self-report questionnaire and performed pure-tone air conduction threshold audiometry. A total of 2463 participants (1728 female individuals) aged 15-96 years were included. The hearing loss prevalence was 53.02% and increased with age. The prevalence of a moderate or greater degree of hearing impairment was 2.8%. Participants aged 65 years and over had 8.56 and 6.79 times greater hearing loss and hearing impairment than younger participants, respectively. Male participants were twice as likely to have hearing loss and hearing impairment as female individuals. Participants with higher education levels showed less likelihood of having hearing loss and hearing impairment than those with no or a primary school education. Participants who ever worked under conditions with loud noise for > 8 h per day had 1.56 times greater hearing loss than those without such exposure. An inconsistent correlation was found between hearing loss, hearing impairment and noncommunicable diseases (diabetes, hypertension, and obesity). Although most participants had mild hearing loss, appropriate care and monitoring are necessary to prevent further loss in such individuals. The questionnaire-based survey found only people with hearing problems that affect daily communication.

Ten-year association between change in speech-in-noise recognition and falls due to balance problems: a longitudinal cohort study

BACKGROUND

This study examined the relationship between speech-in-noise recognition and incident/recurrent falls due to balance problems ten years later (RQ-1); 10-year change in speech-in-noise recognition and falls (RQ-2a), as well as the role of dizziness in this relationship (RQ-2b). The association between hearing aid use and falls was also examined (RQ-3).

METHODS

Data was collected from the Netherlands Longitudinal Study on Hearing between 2006 and December 2022. Participants completed an online survey and digits-in-noise test every five years. For this study, data was divided into two 10-year follow-up time intervals: T0 (baseline) to T2 (10-year follow-up), and T1 (5-years) to T3 (15-years). For all RQs, participants aged ≥ 40 years at baseline, without congenital hearing loss, and non-CI users were eligible (n = 592). Additionally, for RQ-3 participants with a speech reception threshold in noise (SRTn) ≥ -5.5 dB signal-to-noise ratio were included (n = 422). Analyses used survey variables on hearing, dizziness, falls due to balance problems, chronic health conditions, and psychosocial health. Logistic regressions using General Estimating Equations were conducted to assess all RQs.

RESULTS

Among individuals with obesity, those with poor baseline SRTn had a higher odds of incident falls ten years later (odds ratio (OR):14.7, 95% confidence interval (CI) [2.12, 103]). A 10-year worsening of SRTn was significantly associated with a higher odds of recurrent (OR: 2.20, 95% CI [1.03, 4.71]) but not incident falls. No interaction was found between dizziness and change in SRTn. Hearing aid use (no use/ < 2 years use vs. ≥ 2 years) was not significantly associated with incident nor recurrent falls. Although there was a significant interaction with sex for this association, the effect of hearing aid use on incident/recurrent falls was not statistically significant among males nor females.

CONCLUSIONS

A longitudinal association between the deterioration in SRTn and recurrent falls due to balance problems after 10 years was confirmed in this study. This result stresses the importance of identifying declines in hearing earlier and justifies including hearing ability assessments within fall risk prevention programs. Mixed results of hearing aid use on fall risk warrant further investigation into the temporality of this association and possible differences between men and women.

Deprivation-Induced Plasticity in the Early Central Circuits of the Rodent Visual, Auditory, and Olfactory Systems

Activity-dependent neuronal plasticity is crucial for animals to adapt to dynamic sensory environments. Traditionally, it has been investigated using deprivation approaches in animal models primarily in sensory cortices. Nevertheless, emerging evidence emphasizes its significance in sensory organs and in subcortical regions where cranial nerves relay information to the brain. Additionally, critical questions started to arise. Do different sensory modalities share common cellular mechanisms for deprivation-induced plasticity at these central entry points? Does the deprivation duration correlate with specific plasticity mechanisms? This study systematically reviews and meta-analyzes research papers that investigated visual, auditory, or olfactory deprivation in rodents of both sexes. It examines the consequences of sensory deprivation in homologous regions at the first central synapse following cranial nerve transmission (vision - lateral geniculate nucleus and superior colliculus; audition - ventral and dorsal cochlear nucleus; olfaction - olfactory bulb). The systematic search yielded 91 papers (39 vision, 22 audition, 30 olfaction), revealing substantial heterogeneity in publication trends, experimental methods, measures of plasticity, and reporting across the sensory modalities. Despite these differences, commonalities emerged when correlating plasticity mechanisms with the duration of sensory deprivation. Short-term deprivation (up to 1 d) reduced activity and increased disinhibition, medium-term deprivation (1 d to a week) involved glial changes and synaptic remodeling, and long-term deprivation (over a week) primarily led to structural alterations. These findings underscore the importance of standardizing methodologies and reporting practices. Additionally, they highlight the value of cross-modal synthesis for understanding how the nervous system, including peripheral, precortical, and cortical areas, respond to and compensate for sensory inputs loss.

Sheep as a large animal model for hearing research: comparison to common laboratory animals and humans

Sensorineural hearing loss (SNHL), caused by pathology in the cochlea, is the most common type of hearing loss in humans. It is generally irreversible with very few effective pharmacological treatments available to prevent the degenerative changes or minimise the impact. Part of this has been attributed to difficulty of translating "proof-of-concept" for novel treatments established in small animal models to human therapies. There is an increasing interest in the use of sheep as a large animal model. In this article, we review the small and large animal models used in pre-clinical hearing research such as mice, rats, chinchilla, guinea pig, rabbit, cat, monkey, dog, pig, and sheep to humans, and compare the physiology, inner ear anatomy, and some of their use as model systems for SNHL, including cochlear implantation surgeries. Sheep have similar cochlear anatomy, auditory threshold, neonatal auditory system development, adult and infant body size, and number of birth as humans. Based on these comparisons, we suggest that sheep are well-suited as a potential translational animal model that bridges the gap between rodent model research to the clinical use in humans. This is especially in areas looking at changes across the life-course or in specific areas of experimental investigation such as cochlear implantation and other surgical procedures, biomedical device development and age-related sensorineural hearing loss research. Combined use of small animals for research that require higher throughput and genetic modification and large animals for medical translation could greatly accelerate the overall translation of basic research in the field of auditory neuroscience from bench to clinic.

Feasibility of a Smartphone-Based Hearing Aid App for Mild-to-Moderate Hearing Loss: Prospective Multicenter Randomized Controlled Trial

Background

Hearing loss is a growing health concern worldwide. Hearing aids (HAs) are the treatment of choice for hearing rehabilitation in most cases of mild-to-moderate hearing loss. However, many patients with hearing loss do not use HAs due to their high cost, stigma, and inaccessibility. Since smartphones are widely used, many apps that mimic the amplification function of HAs have been introduced. Smartphone-based HA apps (SHAAs) are affordable and easy to access. However, the audiological benefit of SHAAs has not been determined.

Objective

We compared the audiological performance between an SHAA and a conventional HA in a prospective, multicenter randomized controlled trial.

Methods

Patients with mild-to-moderate hearing loss were prospectively enrolled from 2 tertiary hospitals and randomly assigned to either an SHAA (Petralex; IT4YOU Corp LLC) or a conventional HA (Siya 1 miniRITE; Oticon A/S). For the cross-over study design, participants used the alternate device and repeated the same 2-month trial. Audiological measurements were obtained using hearing tests, real-ear measurements, and the hearing-in-noise test (HINT). Subjective satisfaction was evaluated using the Abbreviated Profile of Hearing Aid Benefit (APHAB) and International Outcome Inventory for Hearing Aids (IOI-HA).

Results

Overall, 63 participants were screened and 38 completed the study. In sound-field audiometry testing, the SHAA showed a 20- to 60-dB gain in the low-to-high frequencies of the hearing threshold level. The HA provided adequate gain in the middle-to-high frequencies (55, 65, and 75 dB in real-ear measurements), which is the sound level for most speaking volumes. However, the SHAA could not improve word recognition at 50 dB. The HA showed better audiological performance than the SHAA in both quiet and noisy conditions in the HINT. The IOI-HA scores were significantly improved by both the HA and SHAA versus unaided conditions. Among the SHAA users, 37% (14/38), 42% (16/38), 24% (9/38), and 32% (12/38) showed improvement in APHAB scores for ease of communication, reverberation, background noise, and aversiveness of sounds, respectively. There were no differences in adverse events between the 2 study groups.

Conclusions

The HA showed better performance than the SHAA in word recognition and the HINT. However, the SHAA was significantly better than unaided hearing in terms of amplification. The SHAA may be a useful hearing assistance device for patients with mild-to-moderate hearing loss when listening to soft sounds in quiet conditions. The SHAA demonstrated poorer performance than the HA in the mid- to high-frequency sounds that are important for word recognition, sound quality, and hearing in noisy conditions. Further development of the signal technology of SHAAs is needed to improve the sound quality of mid- to high-frequency sounds and overcome noisy environments.

Subclinical hearing loss associated with aging

Objective

Contribute to clarifying the existence of subclinical hearing deficits associated with aging.

Design

In this work, we study and compare the auditory perceptual and electrophysiological performance of normal-hearing young and adult subjects (tonal audiometry, high-frequency tone threshold, a triplet of digits in noise, and click-evoked auditory brainstem response).

Study sample

45 normal hearing volunteers were evaluated and divided into two groups according to age. 27 subjects were included in the "young group" (mean 22.1 years), and 18 subjects (mean 42.22 years) were included in the "adult group."

Results

In the perceptual tests, the adult group presented significantly worse tonal thresholds in the high frequencies (12 and 16 kHz) and worse performance in the digit triplet tests in noise. In the electrophysiological test using the auditory brainstem response technique, the adult group presented significantly lower I and V wave amplitudes and higher V wave latencies at the supra-threshold level. At the threshold level, we observed a significantly higher latency in wave V in the adult group. In addition, in the partial correlation analysis, controlling for the hearing level, we observed a relationship (negative) between age and speech in noise performance and high-frequency thresholds. No significant association was observed between age and the auditory brainstem response.

Conclusion

The results are compatible with subclinical hearing loss associated with aging.

Age-related hearing loss was accelerated by apoptosis of spiral ganglion and stria vascularis cells in ApoE KO mice with hyperglycemia and hyperlipidemia

Age-related hearing loss (ARHL) is associated with diabetes and/or dyslipidemia in humans. However, the detailed mechanism for the development of ARHL by diabetes and/or dyslipidemia has not been elucidated. In this study, we investigated the etiology of ARHL in apolipoprotein E (ApoE)-deficient mice with diabetes and dyslipidemia. The atherosclerotic CD-STZ (mice fed with a control diet and received an STZ injection), WD-con (mice fed with a western diet), and WD-STZ (mice fed with a western diet and received an STZ injection) mice showed a 2.4-, 4.9-, and 6.8-fold larger area, respectively, occupied by lesions throughout the aorta compared with the CD-con mice. A significantly larger area under the curve (AUC) was observed in the STZ-treated groups than in the non-treated groups based on the oral glucose tolerance test (OGTT). At 20 weeks of age, HbA_1c levels were significantly higher in the CD-STZ and WD-STZ mice than in the CD-con and WD-con mice. In all the groups, the auditory brainstem response (ABR) thresholds of the 16-week-old mice were significantly higher compared with those of the 8-week-old mice. In particular, in the WD-STZ mice, the ABR thresholds of the left and right ears reached the maximum decibel peak equivalent sound pressure levels (130 dBpeSPL), which is a sign of deafness. The apoptotic spiral ganglion neurons (SGNs) of the WD-STZ mice were significantly increased compared with those of the other three groups, indicating that SGN apoptosis resulted in hearing loss in STZ-induced diabetic ApoE KO mice fed with a WD. A significant loss of the stria vascularis cells was observed in the WD-STZ group compared with the CD-con mice. In the organ of Corti, few apoptotic hair cells were found in all the groups; however, no significant difference was observed. Therefore, we consider that the reduced hearing ability in the STZ-treated and WD-fed groups was attributed to the damage to the SGN and stria vascularis in the cochlea. Thus, our results indicated that ototoxicity by diabetes and/or dyslipidemia accelerated ARHL in ApoE KO mice, thereby suggesting the importance of appropriate treatment of patients with diabetes and/or dyslipidemia to prevent ARHL.

Age-related Activation of Cyclic GMP-AMP synthase-Stimulator of Interferon Genes Signaling in the Auditory System is Associated with Presbycusis in C57BL/6J Male Mice

Presbycusis, or age-related hearing loss (ARHL), is primarily associated with sensory or transduction nerve cell degeneration in the peripheral and/or central auditory systems. During aging, the auditory system shows mitochondrial dysfunction and increased inflammatory responses. Mitochondrial dysfunction promotes leakage of mitochondrial DNA (mtDNA) into the cytosol, which activates the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway to induce type I interferon and inflammatory responses. However, whether this pathway is involved in the occurrence and development of ARHL is unknown. This study aimed to determine whether there are age-related changes in the levels of cytosolic mtDNA and cGAS-STING pathway activation in the auditory pathway and to explore their relationship with ARHL. The results showed that cGAS-positive immunoreactive cells were observed in the cochlea, inferior colliculus, and auditory cortex. Levels of cytosolic mtDNA, cGAS, STING, phosphorylated interferon regulatory factor 3, and cytokines were significantly increased in the cochlea, inferior colliculus, and auditory cortex of 6-, 9-, and 12-month-old mice compared with 3-month-old mice. These findings suggested that cytosolic mtDNA may play an important role in the pathogenesis of ARHL by activating cGAS-STING-mediated type I interferon and inflammatory responses.

Changes in cortical auditory evoked potentials in response to auditory training in elderly hearing aid users: A pilot study

OBJECTIVE

To compare the cortical auditory evoked potential responses pre-and post-Auditory Musical Training associated with hearing aid adaptation in elderly people with presbycusis.

DESIGN

This is a pilot, prospective, randomized, single-blind study.

STUDY SAMPLE

Eight presbiacusis elderly people between 65 and 80 years, new hearing aid users, divided into two groups participated in the study: Hearing Aid Group: use of hearing aid; and Auditory Training Group: use of hearing aid in addition to musical auditory training for 16 sessions. All participants were submitted to cortical auditory evoked potential tests with verbal stimulation in two different moments: Initial assessment, carried out before hearing aid adaptation and auditory training, and after three months, final assessment at the end of the auditory training sessions. All participants were adapted bilaterally with digital mini hearing aids.

RESULTS

There was a decrease in the P3a latency component for the Auditory Training Group when initial and final assessment were compared.

CONCLUSION

There was a change in the cortical auditory evoked potential in elderly people with presbycusis in response to the Musical Auditory Training associated with the use of hearing aids in elderly people with presbycusis.

Roles of Key Ion Channels and Transport Proteins in Age-Related Hearing Loss

The auditory system is a fascinating sensory organ that overall, converts sound signals to electrical signals of the nervous system. Initially, sound energy is converted to mechanical energy via amplification processes in the middle ear, followed by transduction of mechanical movements of the oval window into electrochemical signals in the cochlear hair cells, and finally, neural signals travel to the central auditory system, via the auditory division of the 8th cranial nerve. The majority of people above 60 years have some form of age-related hearing loss, also known as presbycusis. However, the biological mechanisms of presbycusis are complex and not yet fully delineated. In the present article, we highlight ion channels and transport proteins, which are integral for the proper functioning of the auditory system, facilitating the diffusion of various ions across auditory structures for signal transduction and processing. Like most other physiological systems, hearing abilities decline with age, hence, it is imperative to fully understand inner ear aging changes, so ion channel functions should be further investigated in the aging cochlea. In this review article, we discuss key various ion channels in the auditory system and how their functions change with age. Understanding the roles of ion channels in auditory processing could enhance the development of potential biotherapies for age-related hearing loss.

Baseline audiological profiling of South African females with cervical cancer: an important attribute for assessing cisplatin-associated ototoxicity

BACKGROUND

Cisplatin is a popular antineoplastic agent used to treat cervical cancer in women from low and middle-income countries. Cisplatin treatment is associated with ototoxicity, often resulting in hearing loss. In light of this, it is crucial to conduct baseline audiological assessments prior to treatment initiation in order to evaluate the extent of cisplatin-associated-ototoxicity. Additionally, the identification of inherent risk factors and hearing patterns in specific patient cohorts is needed, especially in South Africa, a middle-income country characterized by the quadruple burden of disease (Human Immunodeficiency Virus (HIV), Tuberculosis (TB), Diabetes and Hypertension).

METHODS

This study aimed to describe a profile of risk factors and hearing in a cohort of females with cervical cancer before cisplatin treatment commenced. A descriptive study design that included 82 cervical cancer patients, who underwent audiological evaluation prescribed for ototoxicity monitoring was conducted.

RESULTS

All participants (n = 82) presented with risk factors (diabetes, hypertension, HIV, and antiretroviral therapy) for cisplatin ototoxicity and/or pre-existing sensorineural hearing loss. High-frequency tinnitus was the most common otological symptom experienced by 25 (31%) participants. Fifty-nine (72%) participants presented with normal hearing, twenty-two (27%) with a sensorineural hearing loss, and 36% were diagnosed with mild hearing loss. Abnormal Distortion Product Otoacoustic Emissions (DPOAE) findings were obtained bilaterally in two participants (2.4%), in the right ear only of another two (2.4%) participants and the left ear of three participants (3.7%). Most participants (94%) had excellent word recognition scores, demonstrating an excellent ability to recognize words within normal conversational levels under optimal listening conditions. Age was significantly associated with hearing loss at all thresholds. Among the co-morbidities, an HIV positive status significantly triggered hearing loss, especially at higher frequencies.

CONCLUSION

This study demonstrated that South African females with cervical cancer present with various co-morbidities, which may predispose them to develop cisplatin-associated -ototoxic hearing loss. Identification of these co-morbidities and hearing loss is essential for the accurate monitoring of cisplatin toxicities. Appropriate management of these patients is pivotal to reduce the adverse effects that hearing impairment can have on an individual's quality of life and to facilitate informed decision-making regarding the commencement of cisplatin chemotherapy.

Noise Damage Accelerates Auditory Aging and Tinnitus: A Canadian Population-Based Study

OBJECTIVE

Age-related hearing loss (ARHL) is the third most challenging disability in older adults. Noise is a known modifiable risk factor of ARHL, which can drive adverse health effects. Few large-scale studies, however, have shown how chronic noise exposure (CNE) impacts the progression of ARHL and tinnitus.

STUDY DESIGN

Retrospective large-scale study.

SETTING

Audiology clinical practice.

PATIENTS

In this study, 928 individuals aged 30-100 years without (n=497) or with the experience of CNE (n=431) were compared in their hearing assessments and tinnitus. In order to only investigate the impact of CNE on ARHL and tinnitus, people with other risk factors of hearing loss were excluded from the study.

INTERVENTION

Diagnostic.

MAIN OUTCOME MEASURES

Noise damage was associated with a greater ARHL per age decades (pure-tone average(PTA)0.5-4kHz alterations 19.6-70.8 dB vs. 8.0-63.2 dB, ≤0.001), an acceleration of developing a significant ARHL at least by two decades (PTA0.5-4kHz 33.4 dB at 50-59yr vs. 28.2 dB at 30-39yr, ≤0.001), and an increased loss of word recognition scores (total average 84.7% vs. 80.0%, ≤0.001). Significant noise-associated growth in the prevalence of tinnitus also was shown, including more than a triple prevalence for constant tinnitus (28.10% vs. 8.85%, ≤0.001) and near to a double prevalence for intermittent tinnitus (19.10% vs. 11.10%, ≤0.001). Noise also resulted in the elevation of the static compliance of the tympanic membrane throughout age (total average 0.61 vs. 0.85 mmho, ≤0.001).

CONCLUSIONS

Our findings emphasize the significant contribution of CNE in auditory aging and the precipitation of both ARHL and tinnitus.

A Narrative Review of Pharmacologic Treatments for COVID-19: Safety Considerations and Ototoxicity

OBJECTIVE/HYPOTHESIS

The purpose of this review is to summarize evidence-based data regarding the ototoxic effects of potential COVID-19 therapeutics to treat patients suffering from SARS-CoV-2.

METHODS

Medications under investigation as novel therapeutics to treat COVID-19 were identified using the search term coronavirus therapeutics, COVID therapeutics, and SARS-CoV-2 therapeutics on ClinicalTrials.gov and the PubMed Database. A literature review was performed using the PubMed Database for each proposed COVID-19 therapeutic to identify relevant articles. Search criteria included Medical Subject Headings (MeSH) and key word search terms for ototoxicity, vestibulotoxicity, hearing disorders, and vertigo.

RESULTS

Six proposed COVID-19 therapeutics were identified as possessing ototoxic side effects including chloroquine and hydroxychloroquine, azithromycin, lopinavir-ritonavir, interferon, ribavirin, and ivermectin.

CONCLUSIONS

Available evidence suggests that ototoxic effects may be improved or mitigated by stopping the offending agent. Recognition of hearing loss, tinnitus, or imbalance/vertigo is therefore crucial to facilitate early intervention and prevent long-term damage. Hospitals should consider the inclusion of audiologic monitoring protocols for patients receiving COVID-19 therapeutics with known ototoxicity, especially in high-risk patient groups such as the elderly and hearing impaired. Laryngoscope, 131:1626-1632, 2021.

Effect of Kv3 channel modulators on auditory temporal resolution in aged Fischer 344 rats

AUT00063 and AUT00202 are novel pharmaceutical modulators of the Kv3 subfamily of voltage-gated K⁺ channels. Kv3.1 channels, which control fast firing of many central auditory neurons, have been shown to decline with age and this may contribute to age-related deficits in central auditory processing. In the present study, the effects of the two novel compounds that specifically modulate Kv3 channels on auditory temporal processing were examined in aged (19-25-month-old) and young-adult (3-5 month-old) Fischer 344 rats (F344) using a behavioral gap-prepulse inhibition (gap-PPI) paradigm. The acoustic startle response (ASR) and its inhibition induced by a gap in noise were measured before and after drug administration. Hearing thresholds in tested rats were evaluated by the auditory brainstem response (ABR). Aged F344 rats had significantly higher ABR thresholds, lower amplitudes of ASR, and weaker gap-PPI compared with young-adult rats. No influence of AUT00063 and AUT00202 administration was observed on ABR hearing thresholds in rats of both age groups. AUT00063 and AUT00202 had suppressive effect on ASR of F344 rats that was more pronounced with AUT00063. The degree of suppression depended on the dose and age of the rats. Both compounds significantly improved the gap-PPI performance in gap detection tests in aged rats. These results indicate that AUT00063 and AUT00202 may influence intrinsic firing properties of neurons in the central auditory system of aged animals and have the potential to treat aged-related hearing disorders.

Protection of Cochlear Ribbon Synapses and Prevention of Hidden Hearing Loss

In the auditory system, ribbon synapses are vesicle-associated structures located between inner hair cells (IHCs) and spiral ganglion neurons that are implicated in the modulation of trafficking and fusion of synaptic vesicles at the presynaptic terminals. Synapse loss may result in hearing loss and difficulties with understanding speech in a noisy environment. This phenomenon happens without permanent hearing loss; that is, the cochlear synaptopathy is "hidden." Recent studies have reported that synapse loss might be critical in the pathogenesis of hidden hearing loss. A better understanding of the molecular mechanisms of the formation, structure, regeneration, and protection of ribbon synapses will assist in the design of potential therapeutic strategies. In this review, we describe and summarize the following aspects of ribbon synapses: (1) functional and structural features, (2) potential mechanisms of damage, (3) therapeutic research on protecting the synapses, and (4) the role of synaptic regeneration in auditory neuropathy and the current options for synapse rehabilitation.

Hearing Impairment in Old Age

BACKGROUND

Hearing impairment associated with old age (presbycusis) is becoming more common because the population is aging.

METHODS

This review is based on publications retrieved by a selective search in Medline and Google Scholar, including individual studies, meta-analyses, guidelines, Cochrane reviews, and other reviews.

RESULTS

The cardinal symptom of presbycusis is impaired communication due to bilateral hearing impairment. Patients may be unaware of the problem for a long time because of its insidious progression. Evidence suggests that untreated hearing impair- ment in old age can have extensive adverse effects on the patient's mental, physical, and social well-being. Early detection is possible with the aid of simple diagnostic tests or suitable questionnaires. In most cases, bilateral hearing aids are an effective treatment. Surgery is rarely indicated. For patients with uni- or bilateral deafness, a cochlear implant is the treatment of choice. These treatments can improve many patients' quality of life.

CONCLUSION

The small amount of evidence that is currently available suggests that presbycusis is underdiagnosed and under- treated in Germany. Early detection by physicians of all specialties, followed in each case by a specialized differential diagnostic evaluation, is a desirable goal.

The Contribution of Ototoxic Medications to Hearing Loss Among Older Adults

BACKGROUND

Ototoxicity may interact with the effects of aging, leading to a more severe hearing loss than that associated with age alone. The purpose of this study was to explore the associations between ototoxic medication use and the incidence and progression of hearing loss in older adults with a population-based longitudinal study.

METHODS

Epidemiology of Hearing Loss Study participants (n = 3,753) were examined. Medication use was assessed using a standardized questionnaire by the examiners at each examination every 5 year. The ototoxic medications include loop diuretics, nonsteroidal anti-inflammatory drugs, antibiotics, chemotherapeutic agents, quinine, and acetaminophen in this study. Generalized estimating equations model was used as a proportional hazard discrete time analysis.

RESULTS

Number of ototoxic medications was associated with the risk of developing hearing loss during the 10-year follow-up period (hazard ratio [HR] = 1.15, 95% confidence interval [CI] = 1.06, 1.25) after adjusting for age, sex, smoking, and body mass index. Loop diuretics (HR = 1.40, 95% CI = 1.05, 1.87) were associated with the 10-year incidence of hearing loss. Nonsteroidal anti-inflammatory drugs (HR = 1.45, 95% CI = 1.22, 1.72) and loop diuretics (HR = 1.33 95% CI = 1.08, 1.63) were associated with risk of progressive hearing loss over 10 years.

CONCLUSION

These ototoxic medications are commonly used in older adults and should be considered as potentially modifiable contributors to the incidence and severity of age-related hearing loss.

Considerations for physical employment standards in the aging workforce

BACKGROUND

If current population and health trends continue, workplace demographics will look significantly different by the turn of the century. Organizations will no longer have a steady pipeline of younger workers and will likely need to rely on older workers to remain competitive in the global marketplace. The future multi-generational workforce will bring with it the challenge of maximizing contributions from each generation whilst at the same time addressing the health, safety and wellbeing needs of all workers.

OBJECTIVE

This review provides an insight into aging and older workers, and presents recommendations to promote worker longevity.

METHODS

This narrative review draws on evidence from 108 published sources.

RESULTS

The relationship between age and work is not simple; factors including the physical nature of the job and worker's health and fitness interact with age to either increase or decrease the potential effect of age. Evidence suggests that the issues arising from an aging workforce can be managed through polices that focus on active aging through: attitude management; flexible working and the provision of occupational health.

CONCLUSION

The integration of such interventions would require company and organizational commitment from the top down with educational programs at all levels to ensure understanding and participation.

Age-related insult of cochlear ribbon synapses: An early-onset contributor to D-galactose-induced aging in mice

Presbycusis results from age-related degeneration of the auditory system. D-galactose (D-gal)-induced aging is an ideal and commonly used animal model in aging research. Previous studies demonstrate that administration of D-gal can activate mitochondria-dependent apoptosis in the cochlear stria vascularis. However, D-gal-induced changes to cochlear inner (IHCs) and outer (OHCs) hair cells, spiral ganglion cells (SGCs), and ribbon synapses connecting IHCs and SGCs have not been systematically reported. The current study investigated changes in the numbers of hair cells, SGCs, and ribbon synapses in the mouse model of aging. We found that in comparison to control mice, the numbers of ribbon synapses and their nerve fibers were significantly decreased in D-gal-treated mice, whereas the numbers of OHCs, IHCs, and SGCs were almost unchanged. Moreover, hair cell stereocilia were also not obviously influenced by D-gal administration. Although D-gal-induced aging did not significantly shift the auditory brainstem response (ABR) thresholds in the 8, 16, and 32 kHz frequency bands, the amplitude and latency of the ABR wave I, reflecting ribbon synapse functions, were abnormal in D-gal-treated mice compared to control mice. We also found that 8-hydroxy-2-deoxyguanosine, a marker of oxidative DNA damage, was significantly increased in mitochondria of cochleae from mice exposed to D-gal-induced aging in comparison to control mice. Moreover, D-gal administration increased the levels of H₂O₂ and mitochondrial 3860-bp common deletion, and decreased superoxide dismutase activity and ATP production in the cochlea. Furthermore, compared with control mice, the protein levels of NADPH oxidase 2 and uncoupling protein 2 were significantly increased in the cochlea of D-gal-treated mice. Taken together, these findings support that the cochlear ribbon synapse is the primary insult site in the early stage of presbycusis, and mitochondrial oxidative damage and subsequent dysfunctions might be responsible for this insult.

Aging Impairs Temporal Sensitivity, but not Perceptual Synchrony, Across Modalities

Encoding the temporal properties of external signals that comprise multimodal events is a major factor guiding everyday experience. However, during the natural aging process, impairments to sensory processing can profoundly affect multimodal temporal perception. Various mechanisms can contribute to temporal perception, and thus it is imperative to understand how each can be affected by age. In the current study, using three different temporal order judgement tasks (unisensory, multisensory, and sensorimotor), we investigated the effects of age on two separate temporal processes: synchronization and integration of multiple signals. These two processes rely on different aspects of temporal information, either the temporal alignment of processed signals or the integration/segregation of signals arising from different modalities, respectively. Results showed that the ability to integrate/segregate multiple signals decreased with age regardless of the task, and that the magnitude of such impairment correlated across tasks, suggesting a widespread mechanism affected by age. In contrast, perceptual synchrony remained stable with age, revealing a distinct intact mechanism. Overall, results from this study suggest that aging has differential effects on temporal processing, and general impairments with aging may impact global temporal sensitivity while context-dependent processes remain unaffected.

Designing Supportive Soundscapes for Nursing Home Residents with Dementia

Sound and its resulting soundscape is a major appraisal component of the living environment. Where environmental sounds (e.g., outdoor traffic sounds) are often perceived as negative, a soundscape (e.g., containing natural sounds) can also have a positive effect on health and well-being. This supportive effect of a soundscape is getting increasing attention for use in practice. This paper addresses the design of a supportive sonic environment for persons with dementia in nursing homes. Starting from a review of key mechanisms related to sonic perception, cognitive deficits and related behavior, a framework is derived for the composition of a sonic environment for persons with dementia. The proposed framework is centered around using acoustic stimuli for influencing mood, stimulating the feeling of safety and triggering a response in a person. These stimuli are intended to be deployed as added sounds in a nursing home to improve the well-being and behavior of the residents.

Age-related hearing loss and tinnitus, dementia risk, and auditory amplification outcomes

Age-related hearing loss (ARHL) or presbycusis, as the third leading cause of chronic disability in older adults, has been shown to be associated with predisposing cognitive impairment and dementia. Tinnitus is also a chronic auditory disorder demonstrating a growth rate with increasing age. Recent evidence stands for the link between bothersome tinnitus and impairments in various aspects of cognitive function. Both ARHL and age-related tinnitus affect mental health and contribute to developing anxiety, stress, and depression. The present review is a comprehensive multidisciplinary study on diverse interactions among ARHL, tinnitus, and cognitive decline in older adults. This review incorporates the latest evidence in prevalence and risk factors of ARHL and tinnitus, the neural substrates of tinnitus-related cognitive impairments, hypothesized mechanisms concerning the association between ARHL and increased risk of dementia, hearing amplification outcomes in cases with ARHL and cognitive decline, and preliminary findings on the link between ARHL and cognitive impairment in animal studies. Given extensive evidence that demonstrates advantages of using auditory amplification in the alleviation of hearing handicap, depression, and tinnitus, and the improvement of cognition, social communication, and quality of life, regular hearing screening programs for identification and management of midlife hearing loss and tinnitus is strongly recommended.

Acoustic Trauma Modulates Cochlear Blood Flow and Vasoactive Factors in a Rodent Model of Noise-Induced Hearing Loss

Noise exposure affects the organ of Corti and the lateral wall of the cochlea, including the stria vascularis and spiral ligament. Although the inner ear vasculature and spiral ligament fibrocytes in the lateral wall consist of a significant proportion of cells in the cochlea, relatively little is known regarding their functional significance. In this study, 6-week-old male C57BL/6 mice were exposed to noise trauma to induce transient hearing threshold shift (TTS) or permanent hearing threshold shift (PTS). Compared to mice with TTS, mice with PTS exhibited lower cochlear blood flow and lower vessel diameter in the stria vascularis, accompanied by reduced expression levels of genes involved in vasodilation and increased expression levels of genes related to vasoconstriction. Ultrastructural analyses by transmission electron microscopy revealed that the stria vascularis and spiral ligament fibrocytes were more damaged by PTS than by TTS. Moreover, mice with PTS expressed significantly higher levels of proinflammatory cytokines in the cochlea (e.g., IL-1β, IL-6, and TNF-α). Overall, our findings suggest that cochlear microcirculation and lateral wall pathologies are differentially modulated by the severity of acoustic trauma and are associated with changes in vasoactive factors and inflammatory responses in the cochlea.

Progressive Dominant Hearing Loss (Autosomal Dominant Deafness-41) and P2RX2 Gene Mutations: A Phenotype-Genotype Study

OBJECTIVES/HYPOTHESIS

P2RX2 encoding P2X purinoreceptor 2 has been identified as the gene responsible for autosomal dominant deafness-41 (DFNA41) as well as mediating vulnerability to noise-induced hearing loss (NIHL). The objective of this study was to investigate the audiological and molecular characteristics of P2RX2-related deafness, with emphasis on its role in NIHL by determining the audiological characteristics of a previously reported six-generation DFNA41 family with a 10-year follow-up. We have also summarized phenotype-genotype correlations of P2RX2-related deafness in human and mouse models.

STUDY DESIGN

We describe clinical longitudinal follow-up in the DFNA41 family with P2RX2 (p.Val60Leu) mutation and perform a systematic literature search in PubMed and poster presentations on meeting/conference websites to identify current insights into P2RX2-mediated NIHL.

METHODS

Clinical and physical examinations of the family members were performed, and audiograms were obtained to assess the hearing thresholds. Clinical follow-up features in this DFNA41 family are presented along with correlation analyses of phenotype-genotype in all reported families with P2RX2-related deafness.

RESULTS

Progressive hearing impairment was confirmed by history and by audiological follow-up testing in all the patients. The onset of hearing loss was between age 25 and 35 years. All affected subjects had bilateral sensorineural hearing loss involving all frequencies with some significant gender differences.

CONCLUSIONS

Our study and the review of the literature suggest that P2RX2 plays a crucial role in predisposition to noise-induced and age-related hearing loss. A better knowledge about the P2RX2-associated genetic variants can help in developing novel therapeutic strategies.

LEVEL OF EVIDENCE

2b Laryngoscope, 130:1657-1663, 2020.

[Presbyacusis]

In the world, the spread of hearing loss due to age is an important socio-medical problem. Age-related hearing loss is the result of the biological process of aging of the tissue elements of the auditory analyzer. Changes in hearing develops by a complex of factors associated with both genetic, environmental and social aspects. Presbycusis is one of the causes of human cognitive disorders. Recent studies on hearing impairment prove a correlation with cognitive processes that increase the risk of dementia in the elderly. Timely rehabilitation of hearing with the use of hearing aids allows you to delay the processes of inhibition of cognitive function, and allows older people to prolong active longevity. Patients require consistent auditory and cognitive training for better socialization.

Hearing Loss in Agricultural Workers Exposed to Pesticides and Noise

Agricultural workers who have concurrent exposure to pesticides and noise are at increased risk of hearing loss. We recruited 163 Thai conventional and 172 organic farmers to answer our questionnaires about personal demographics, agricultural activities, and pesticide and agricultural machinery use. This information was used to calculate the years of conventional (pesticide use) farming and the years of agricultural noise exposure, and to estimate semiquantitative metrics for pesticide exposure (cumulative intensity score-years) and cumulative noise exposure (dB(A)-years) for each conventional farmer. All participants underwent pure tone audiometric testing. The mean hearing threshold in the low-frequency band (0.5-2 kHz) and high-frequency band (3-6 kHz) were used for analysis. Years involved in conventional farming and years using agricultural machinery were associated with an increase in the average hearing threshold for the high-frequency band after controlling for age, ever exposed to industrial noise and cigarette smoking. The highest category of cumulative insecticide exposure (score-years), cumulative organophosphates exposure (score-years) and cumulative noise exposure (dB(A)-years) were also associated with an increased high-frequency band hearing threshold among conventional farmers. Results from the full cohort and the subcohort of conventional farmers support each other and the hypothesis that pesticide and noise have an additive effect on hearing, since no model interactions were significant.

Identification of Neural Stem Cells from Postnatal Mouse Auditory Cortex In Vitro

Auditory signals are processed in multiple central nervous system structures, including the auditory cortex (AC). Development of stem cell biology provides the opportunity to identify neural stem cells (NSCs) in the central nervous system. However, it is unclear whether NSCs exist in the AC. The aim of this study is to determine the existence of NSCs in the postnatal mouse AC. To accomplish this aim, postnatal mouse AC tissues were dissected and dissociated into singular cells and small cell clumps, which were suspended in the culture medium to observe neurosphere formation. The spheres were examined by quantitative real-time polymerase chain reaction and immunofluorescence to determine expression of NSC genes and proteins. In addition, AC-spheres were cultured in the presence or absence of astrocyte-conditioned medium (ACM) to study neural differentiation. The results show that AC-derived cells were able to proliferate to form neurospheres, which expressed multiple NSC genes and proteins, including SOX2 and NESTIN. AC-derived NSCs (AC-NSCs) differentiated into cells expressing neuronal and glial cell markers. However, the neuronal generation rate is low in the culture medium containing nerve growth factor, ∼8%. To stimulate neuronal generation, AC-NSCs were cultured in the culture medium containing ACM. In the presence of ACM, ∼29% AC-NSCs differentiated into cells expressing neuronal marker class III β-tubulin (TUJ1). It was observed that the length of neurites of AC-NSC-derived neurons in the ACM group was significantly longer than that of the control group. In addition, synaptic protein immunostaining showed significantly higher expression of synaptic proteins in the ACM group. These results suggest that ACM is able to stimulate neuronal differentiation, extension of neurites, and expression of synaptic proteins. Identifying AC-NSCs and determining effects of ACM on NSC differentiation will be important for the auditory research and other neural systems.

Age-Related Effects on Cross-Modal Duration Perception

Reliable duration perception of external events is necessary to coordinate perception with action, precisely discriminate speech, and for other daily functions. Visual duration perception can be heavily influenced by concurrent auditory signals; however, age-related effects on this process have received minimal attention. In the present study, we examined the effect of aging on duration perception by quantifying (1) duration discrimination thresholds, (2) auditory temporal dominance, and (3) visual duration expansion/compression percepts induced by an accompanying auditory stimulus of longer/shorter duration. Duration discrimination thresholds were significantly greater for visual than auditory tasks in both age groups, however there was no effect of age. While the auditory modality retained dominance in duration perception with age, older adults still performed worse than young adults when comparing durations of two target stimuli (e.g., visual) in the presence of distractors from the other modality (e.g., auditory). Finally, both age groups perceived similar visual duration compression, whereas older adults exhibited visual duration expansion over a wider range of auditory durations compared to their younger counterparts. Results are discussed in terms of multisensory integration and possible decision strategies that change with age.

The impact of age-related hearing loss and lateralized auditory attention on spatiotemporal parameters of gait during dual-tasking among community dwelling older adults

This investigation assessed the impact of hearing loss and lateralized auditory attention on spatiotemporal parameters of gait during overground dual-tasking by the use of the dichotic listening task. Seventy-eight right-handed, healthy older adults between 60 and 88 years were assigned to a Young-Old (<70 years) or an Old-Old (>71 years) group. Cognitive assessment and pure tone audiometry were conducted. Spatiotemporal parameters of gait quantified by mean (M), and coefficient of variations (CoV) were evaluated with the OptoGait system during 3 dichotic listening conditions: Non-Forced, Forced-Right and Forced-Left. Factorial analyses of variance and covariance were used to assess group differences and the moderating effects of hearing status, respectively. Results demonstrated that three of the gait parameters assessed were affected asymmetrically by the dual-task paradigm after controlling for hearing status. Asymmetries existed on step width, gait speed and variability of stride length. Finally, correlations between gait outcomes and dichotic listening results showed that M and CoVs in gait parameters during right-ear responses were longer compared with left-ear. Left-ear responses were related to increased variability on stride length, which indicates higher difficulty level. Hearing status varying from normal to mild levels of hearing loss modulates spatiotemporal gait outcomes measured during dichotic listening execution. Findings suggest that attending to left side stimuli relates to increased gait variability, while focusing on right-side assures a safe walk. Results demonstrated that attending to right-ear stimuli is an adaptive strategy for older adults that compensates for limited sensorimotor and cognitive resources during walking.

Prevalence of ototoxic medication use among older adults in Beaver Dam, Wisconsin

BACKGROUND AND PURPOSE

Drug-related ototoxicity may exacerbate presbycusis (age-related hearing loss); yet, few data are available on the prevalence of ototoxic medication use by older adults. The purposes of this study were to assess the impact of aging and ototoxicity on hearing loss, the prevalence of ototoxic medication use, and select characteristics associated with ototoxic medication use among older adults.

METHODS

Cross-sectional analyses were conducted using select variables extracted from the baseline and 10-year follow-up assessments of the two population-based epidemiological studies to compare two points in time.

RESULTS

Ninety-one percent of the sample was taking a medication reported to be ototoxic. Nonsteroidal anti-inflammatory drugs were the most commonly used (75.2%), followed by acetaminophen (39.9%) and diuretics (35.6%). Hypertension, diabetes, cardiovascular disease, and history of smoking were associated with ototoxic medication use. Participants with hearing loss were taking a significantly greater number of ototoxic medications than those without hearing loss.

CONCLUSION

Known ototoxic medications are widely used. Any subsequent ototoxicity may interact with age changes and a more severe hearing loss than that associated with only age.

IMPLICATIONS FOR PRACTICE

Nurse practitioners should inform older adults about the possibility of drug-related ototoxicity and monitor hearing acuity of all older adults taking known ototoxic medications.

Age-related changes in auditory processing and speech perception: cross-sectional and longitudinal analyses

Age-related differences in speech perception have been shown in previous cross-sectional studies to be related to auditory temporal processing. We examined this association in both cross-sectional and longitudinal designs, controlling for age-related changes in hearing sensitivity and cognitive ability. Fifty-eight participants were tested in two phases. In phase 1, ages ranged between 22 and 82 years. Phase 2 occurred seven years later. In both phases, participants performed auditory processing tasks, speech perception tests, and cognitive tasks. In both phases, age correlated with hearing level, auditory temporal processing thresholds, word recognition accuracy in noise, and compressed speech. Auditory temporal processing thresholds were correlated with word recognition accuracy in narrowband noise and compressed speech. Longitudinal analysis showed significant decreases in performance from phase 1 to phase 2 in hearing level, dichotic TOJ thresholds, and word recognition accuracy. Steeper slopes were observed in phase 2 than in phase 1 for correlations between age, hearing level, and word recognition accuracy in narrowband noise, but not for age and dichotic TOJ thresholds. Generalized estimating equations revealed an overall decrease in word recognition accuracy from phase 1 to phase 2; this decrease was larger for older participants. Increases in dichotic TOJ and gap detection thresholds were associated with a decrease over time in speech in narrowband and broadband noise, and compressed speech, even when adjusted for age, hearing level, and cognitive ability. These results show that both cross-sectional and longitudinal designs yield similar significant associations between temporal processing and speech perception, even when adjusted for hearing level and cognitive ability.

Judgments of Emotion in Clear and Conversational Speech by Young Adults With Normal Hearing and Older Adults With Hearing Impairment

Purpose

In this study, we investigated the emotion perceived by young listeners with normal hearing (YNH listeners) and older adults with hearing impairment (OHI listeners) when listening to speech produced conversationally or in a clear speaking style.

Method

The first experiment included 18 YNH listeners, and the second included 10 additional YNH listeners along with 20 OHI listeners. Participants heard sentences spoken conversationally and clearly. Participants selected the emotion they heard in the talker's voice using a 6-alternative, forced-choice paradigm.

Results

Clear speech was judged as sounding angry and disgusted more often and happy, fearful, sad, and neutral less often than conversational speech. Talkers whose clear speech was judged to be particularly clear were also judged as sounding angry more often and fearful less often than other talkers. OHI listeners reported hearing anger less often than YNH listeners; however, they still judged clear speech as angry more often than conversational speech.

Conclusions

Speech spoken clearly may sound angry more often than speech spoken conversationally. Although perceived emotion varied between YNH and OHI listeners, judgments of anger were higher for clear speech than conversational speech for both listener groups.

Supplemental Materials

https://doi.org/10.23641/asha.5170717.

Peripheral and central auditory assessment in among the elderly

Abstract Introduction: Presbycusis can affect different portions of the auditory system, causing impacts of varying degrees of seriousness on the daily routine of elderly persons. It is essential that the extent of the deficit as well as the degree of handicap is evaluated, so that the hearing of the elderly can be effectively rehabilitated, improving their quality of life. Purpose: To characterize the peripheral and central hearing of elderly individuals and assess their auditory handicaps. Methods: A cross sectional observational study was performed. We evaluated 83 elderly persons (60-85 years; 33 men, 50 women) with normal hearing or sensorineural hearing loss. Individuals were divided into 3 groups according to the 3 to 6kHz hearing thresholds: G1 - mean of 0 to 39 dBHL (80 ears); G2 - mean of 40 to 59 dBHL (48 ears); G3 - mean of 60 to 120dBHL (38 ears). All individuals responded to the Hearing Handicap Inventory for the Elderly (HHIE), and underwent Pure Tone Audiometry, Auditory Brainstem Response (ABR) and Long Latency Response (P300) evaluation. Results: Men had higher auditory thresholds at frequencies from 500 to 12,000Hz (with a statistical difference between 2-8 kHz) and also significantly greater latencies for ABR components. There was no difference between genders for the P300 evaluation. Comparison between groups showed: a statistically significant difference for age; greater ABR wave latencies and interwave intervals; that questionnaire scores worsened as hearing threshold declined; and similar P300 latencies. Conclusions: Elderly people have impairment throughout the auditory pathway (peripheral and central). The P300 was less accurate at identifying the losses that come with age. The HHIE demonstrated negative effects on the social life of elderly people, agreeing with the hearing thresholds found.

Effect of exercise on the auditory discrimination task in perimenopausal women: a preliminary study

Background The climacteric phase of menopausal transition (perimenopause) is marked by reproductive hormone fluctuations and reduced cognitive capacity. Exercise enhances neurocognitive performance. However, auditory perceptual sensitivity has not been examined. Purpose This study aimed to determine the effect of aerobic exercise on the response speed (reaction time) and error rate during auditory processing among perimenopausal women. Methods Three pitches (500, 1000, and 2000 Hz) were used during a simple auditory discrimination task, which was performed before and after exercise. We included 14 perimenopausal women and 17 right-handed young women (aged 46-54 years and 18-22 years, respectively). To achieve similar exercise intensity in both groups, we proposed two types of physical activities for each group. Mixed models statistics were used to analyze the reaction time and error rate before and after training in the two groups. Results Perimenopausal women exhibited a significantly longer reaction time than young women during the baseline auditory discrimination task (p < 0.05) but not during the second test. The error rate decreased significantly after exercise among perimenopausal women (p < 0.05) but not among young women. Thus, exercise had a stronger beneficial influence on auditory plasticity or sensitivity for perimenopausal women than for young women. Conclusion The ability of aerobic exercise to modulate auditory neurocognitive performance differs between the two groups. Aerobic exercise improves auditory discrimination performance specifically for perimenopausal women. These results provide preliminary evidence concerning the acoustic features of middle-aged women, underscoring the importance of exercise for preventing decline in auditory cognitive function in perimenopausal women.

Long-term omega-3 fatty acid supplementation prevents expression changes in cochlear homocysteine metabolism and ameliorates progressive hearing loss in C57BL/6J mice

Omega-3 polyunsaturated fatty acids (PUFAs) are essential nutrients well known for their beneficial effects, among others on cognitive development and maintenance, inflammation and oxidative stress. Previous studies have shown an inverse association between high plasma levels of PUFAs and age-related hearing loss, and the relationship between low serum folate and elevated plasma homocysteine levels and hearing loss. Therefore, we used C57BL/6J mice and long-term omega-3 supplementation to evaluate the impact on hearing by analyzing their auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAE) thresholds. The omega-3 group showed significantly lower ABR hearing thresholds (~25 dB sound pressure level) and higher DPOAE amplitudes in mid-high frequencies when compared to the control group. These changes did not correlate with alterations between groups in plasma homocysteine or serum folate levels as measured by high-performance liquid chromatography and a microbiological method, respectively. Aging in the control group was associated with imbalanced cytokine expression toward increased proinflammatory cytokines as determined by quantitative reverse transcriptase polymerase chain reaction; these changes were prevented by omega-3 supplementation. Genes involved in homocysteine metabolism showed decreased expression during aging of control animals, and only alterations in Bhmt and Cbs were significantly prevented by omega-3 feeding. Western blotting showed that omega-3 supplementation precluded the CBS protein increase detected in 10-month-old controls but also produced an increase in BHMT protein levels. Altogether, the results obtained suggest a long-term protective role of omega-3 supplementation on cochlear metabolism and progression of hearing loss.

Aging and Speech Understanding

As people age, structural as well as neural degeneration occurs throughout the auditory system. Many older adults experience difficulty in understanding speech especially in adverse listening conditions although they can hear speech sounds. According to a report of the Committee on Hearing and Bioacoustics and Biomechanics of the National Research Council, peripheral, central-auditory, and cognitive systems have long been considered major factors affecting the understanding of speech. The present study aims to review 1) age-related changes in the peripheral, central-auditory, and cognitive systems, 2) the resulting decline in the understanding of speech, and 3) the clinical implication for audiologic rehabilitation of older adults. Once the factors affecting the understanding of speech in older adults are identified and the characteristics of age-related speech understanding difficulties are examined, clinical management could be developed for prevention and treatment. Future research about problems related to the understanding of speech in older adults will help to improve the quality of life in the elderly.

Correlation between the characteristics of resonance and aging of the external ear

PURPOSE

Aging causes changes in the external ear as a collapse of the external auditory canal and tympanic membrane senile. Knowing them is appropriate for the diagnosis of hearing loss and selection of hearing aids. For this reason, the study aimed to verify the influence of the anatomical changes of the external ear resonance in the auditory canal in the elderly.

METHODS

The sample consisted of objective measures of the external ear of elderly with collapse (group A), senile tympanic membrane (group B) and without changing the external auditory canal or tympanic membrane (group C) and adults without changing the external ear (group D). In the retrospective/clinical study were performed comparisons of measures of individuals with and without alteration of the external ear through the gain and response external ear resonant frequency and the primary peak to the right ear.

RESULTS

In groups A, B and C was no statistically significant difference between Real Ear Unaided Response (REUR) and Real Ear Unaided Gain (REUG), but not for the peak frequency. For groups A and B were shown significant differences in REUR and REUG. Between the C and D groups were significant statistics to the REUR and REUG, but not for the frequency of the primary peak.

CONCLUSION

Changes influence the external ear resonance, decreasing its amplitude. However, the frequency of the primary peak is not affected.

D‑galactose‑induced mitochondrial DNA oxidative damage in the auditory cortex of rats

Chronic administration of D-galactose (D-gal) is a useful method for establishing a model of natural aging in the auditory system. Previous studies have demonstrated that NADPH oxidases (NOXs) may be an important source of reactive oxygen species (ROS) in the peripheral auditory system (PAS) and cause an increase in mitochondrial DNA (mtDNA) common deletion (CD) levels in the PAS and central auditory system (CAS) of rats with D-gal-induced aging. However, the source of the ROS in the CAS and the mechanisms of age-related hearing loss (ARHL) have yet to be elucidated. In the present study, male Sprague Dawley rats were administered a daily injection of D-gal (150, 300 and 500 mg/kg, respectively) for eight weeks. All three doses of D-gal caused a significant increase in the expression of NOX2, 8-hydroxy-2-deoxyguanosine, a biomarker of DNA oxidative damage, and uncoupling protein 2, together with a decrease in the mitochondrial total antioxidant capabilities in the auditory cortex, as compared with the control rats (injected daily with the same volume of 0.9% saline for eight weeks). The levels of the mtDNA CD were also increased in the auditory cortex of the D-gal-induced aging rats. These findings suggest that both NOX- and mitochondria-associated ROS generation may contribute to mtDNA oxidative damage in the auditory cortex of the CAS of D-gal-induced aging rats. This study may provide novel insight into the development of ARHL.

Subclinical hearing loss, longer sleep duration, and cardiometabolic risk factors in Japanese general population

Hearing loss leads to impaired social functioning and quality of life. Hearing loss is also associated with sleeping disorders and cardiometabolic risk factors. Here, we determined whether subclinical hearing loss is associated with sleep duration and cardiometabolic risk factors in a cross-sectional and longitudinal study of healthy Japanese general population. 48,091 men and women aged 20–79 years who underwent medical checkups were included in a cross-sectional study, and 6,674 were included in an 8-year longitudinal study. The prevalence of audiometrically determined hearing loss (>25 dB) at 4000 and 1000 Hz increased significantly with increasing sleep duration in any age strata. Logistic regression analysis showed that compared with reference sleep duration (6 h) longer sleep duration (≥8 h) was significantly associated with hearing loss, even after adjusting for potential confounding factors. Simultaneously, hearing loss was significantly associated with male sex, diabetes, and no habitual exercise. In the longitudinal study, the risk of longer sleep duration (≥8 h) after 8 years was significantly greater in subjects with hearing loss at 4000 Hz at baseline. In conclusion, current results suggest a potential association of subclinical hearing loss with longer sleep duration and cardiometabolic risk factors in a Japanese general population.

Effects of ageing on speed and temporal resolution of speech stimuli in older adults

BACKGROUND

According to previous studies, most of the speech recognition disorders in older adults are theresults of deficits in audibility and auditory temporal resolution. In this paper, the effect of ageing on timecompressedspeech and auditory temporal resolution by word recognition in continuous and interrupted noisewas studied.

METHODS

A time-compressed speech test (TCST) was conducted on 30 young and 32 older adults with normalhearing thresholds. Lists of monosyllabic words were used at three time compression ratios. Auditory temporalresolution was determined by measuring the monosyllabic word recognition score (WRS), in the presence ofcontinuous and interrupted noise, at three signal-to-noise ratios (S/Ns).

RESULTS

There was a significant difference in TCST scores at the three compression ratios within and betweenyoung and older adult none (p< 0.001). Similar results were obtained in WRSs at the three S/Ns in the presenceof interrupted and continuous noise (p< 0.001), and in the degree of auditory temporal resolution(p=0.007). A significant correlation was found between the level of test difficulty of TCST with WRSs in bothyoung (r = 0.549, P=0.002) and older adults (r= 0.531, P=0.003).

CONCLUSION

Our results showed that ageing remarkably affects the processing of fast speech stimuli and temporalresolving ability. These results are more supportive of the effect of ageing on speech perception than onloss of hearing.

Hearing loss screening tests for adults

INTRODUCTION

The early detection of hearing loss has been studied widely in newborns due to the emerging technologies for diagnosis and treatment. There are detailed protocols for this goal. Nonetheless, hearing loss screening in adults has become more important lately with the increase of the life expectancy, an expected change in the Mexican population pyramid towards a rectangular shape in the next 50 years (with increased hearing loss prevalence) and the creation of public policies for social security such as the "Seguro Popular". There are no Mexican studies about hearing loss screening in adults. The aim of this work was to assess a tone emission and a questionnaire as screening tools for hearing loss in adults.

METHODS

A sample size of 500 individuals without otology pathology from the outpatient clinics at a general hospital. An otoscopy, 2 screening tests (tone emission and questionnaire) and tonal audiometry were performed on all subjects.

RESULTS

The questionnaire turned out to be a sensitive test but with low specificity, while the tone emission was less sensitive but more specific with a higher rate of precision. In this study, the best result was achieved by a combined strategy using the two tests above, with a precision of 90%.

CONCLUSIONS

The best screening strategy proposed by this study for hearing loss in adults is a questionnaire and tone emission test, which guarantees complete hearing assessment in objective and subjective manners, performed quickly and without special training.