A Narrative Review of Lifestyle Risk Factors and the Role of Oxidative Stress in Age-Related Hearing Loss

Preliminary Analysis of Drug-Induced Ototoxicity in South Korea: Trends From a National Sample Dataset

BACKGROUND AND OBJECTIVES

Certain medications are associated with ototoxicity. This study assesses drug-induced ototoxicity in South Korea by analyzing the Korean national health data.

SUBJECTS AND METHODS

Hospital records of National Health Insurance members from 2009 to 2016 were reviewed. Data were compared between patients with and without hearing loss (HL). Individuals with HL were identified as having a primary diagnosis code for sensorineural HL or another type of HL in at least one outpatient or inpatient record according to the International Classification of Diseases-10.

RESULTS

The members in the HL group increased slightly from 0.8% to 1.0% relative to the total sample, compared with 99.2% to 99.0% among the controls. The proportion of males in the HL group ranged from 45.6% to 47.6%, compared with 48.4% to 48.8% among the controls. The proportion of those aged ≥65 years in the HL group increased from 34.1% to 41.4%, compared with 10.6% to 13.3% among the controls. Hypertension prevalence (24.7%-25.7%) in the HL group was higher than that in the control group (12%-12.6%). Diabetes prevalence in the HL group was 10.6%-12.3%, compared with 4.4%-5.9% among the controls. The use of proton pump inhibitor components increased, particularly esomeprazole magnesium trihydrate and rabeprazole sodium, whereas the usage of pantoprazole sodium sesquihydrate and revaprazan was high initially but declined subsequently. The usage of painkillers such as acetaminophen, loxoprofen sodium, and ibuprofen remained high, and antibiotics such as cephalosporins indicated the highest usage. However, the use of penicillin antibiotics such as amoxicillin decreased significantly. Anticancer agents showed relatively low usage compared with other drug categories, whereas antihistamines showed extremely high usage across all years, with a continual increase.

CONCLUSIONS

These correlations and the underlying mechanisms necessitate further investigation, as several medicines have been linked to an increased risk of HL.

Nutritional Supplements for Healthy Aging: A Critical Analysis Review

Background: Healthy aging is defined as survival to advanced age while retaining autonomy in activities of daily living, high societal participation, and good quality of life. Sarcopenia, insomnia, cognitive impairment, and changes in sensation can be key hinderances to healthy aging, but nutritional supplements may abate their impact. As research advances, an updated review on their efficacy on age-related conditions is warranted. Results: Sarcopenia can be mitigated through proper protein intake, supplements like creatine, and in certain situations Branched-Chain Amino Acids and Vitamin D, in adults over 65. Melatonin supplementation has moderate evidence for improving sleep, while valerian root lacks evidence. Magnesium, tart cherry, and kiwifruits have shown promising impacts on sleep in limited articles. Magnesium, Vitamin D, and B vitamin supplementation have been shown to improve cognition in those with mild cognitive impairment and Alzheimer's disease but require further study prior to recommendation. The Age-Related Eye Disease Study supplement combination is routinely recommended to reduce risk of progression to advance stages of age-related macular degeneration. Alpha-Lipoic Acid and Folate have been investigated for their roles in mitigating age-related hearing losses. Conclusions: Nutritional supplements and lifestyle changes may mitigate disabilities across multiple domains of age-related illnesses and promote healthy aging.

Patients' satisfaction and efficacy of modern conventional hearing aids: A comprehensive analysis of the self-reported user experiences in adult people

OBJECTIVE

Hearing loss is a widespread condition that impacts the quality of life, affecting communication, social interactions, and cognitive functions. This study aimed to evaluate the subjective benefit and satisfaction of using hearing aids among patients since the adoption rate of hearing aids remains low.

METHODS

The study retrospectively analysed data from 133 patients with hearing aids, using the Abbreviated Profile of Hearing Aid Benefit (APHAB) and the Satisfaction with Amplification in Daily Life (SADL) questionnaires. Patients were divided into two groups based on this median age and sex for comparative analysis. The Mann Whitney test was applied with references to numerical parameters (APHAB and SADL) to assess differences between male vs female subjects and adults vs elderly. The Spearman correlation test was applied to assess the possible correlation between APHAB and SADL. A p-value lower than 0.05 was considered statistically significant.

RESULTS

Results indicated no significant gender differences in most APHAB and SADL subscales, except for the SADL "personal image" subscale, which showed lower scores for women (p =  0.023). Age-based comparison revealed no significant differences in APHAB scores; the SADL scores showed significant differences in the "positive effect" (p = 0.013), "negative features" (p = 0.005), and overall scores (p = 0.039), with lower satisfaction in older patients. Correlation analysis identified a positive relationship between the SADL "negative features" and APHAB "aversiveness" subscales (p = 0.042, correlation coefficient ρ = 0.176).

CONCLUSIONS

The study highlights the importance of addressing subjective perceptions and aesthetic concerns in hearing aid adoption, emphasizing the need for personalized rehabilitation strategies to improve patient outcomes and satisfaction.

LEVEL OF EVIDENCE

Level 3.

Establishment of reference audiometric norms for the elderly population: A community-based study on mean and median hearing thresholds

Background

This investigation quantifies the mean and median hearing thresholds and assesses the prevalence of age-related hearing loss within the senior population of Taipei.

Methods

In a substantive geriatric assessment supported by government initiative, 1696 individuals from a community hospital partook in this cross-sectional study (2016-2018). Detailed audiometric evaluations logged pure-tone thresholds across critical frequencies (0.5k, 1k, 2k, 4k Hz), in conjunction with participant ages, genders, and HHIE-S questionnaire results.

Results

The findings indicated mean and median pure tone averages (PTA) of 25.3 ± 15.6 dB HL and 22.5 dB HL, respectively. Gender-based analysis showcased higher PTAs for males than females. The study illuminated a progressive increase in hearing thresholds with age and higher frequencies. A 41 % prevalence of hearing impairment was recorded, with a notable 15.2 % deemed disabling, and a potential candidacy for cochlear implantation in 1.5 % of the study group.

Conclusions

Hearing loss was prevalent in 41 % of the non-hospitalized elderly demographic, chiefly characterized as mild. However, older age groups, particularly those over 85, presented an elevated occurrence of moderate hearing loss.

Effect of Antioxidants on the Gut Microbiome Profile and Brain Functions: A Review of Randomized Controlled Trial Studies

BACKGROUND

Antioxidants are widely recognized for their potential health benefits, including their impact on cognitive function and gut microbiome modulation. Understanding these effects is essential for exploring their broader clinical applications.

OBJECTIVES

This review aims to evaluate the effects of antioxidants on the gut microbiome and cognitive function, with a focus on findings from randomized controlled trials (RCTs).

METHODS

The studies involved human participants across a range of age groups, with interventions encompassing natural antioxidant sources, such as berries, as well as specific antioxidant vitamins. An extensive search across PubMed, SCOPUS, and Web of Science databases identified six relevant RCTs, each evaluated for potential bias.

RESULTS

These studies focused on a variety of antioxidant-rich products, including both naturally derived sources and supplemental forms. Antioxidants, including vitamins C, B2, and D, along with polyphenols such as xanthohumol, fermented papaya, peanuts, and berry extracts, demonstrate the potential to support cognitive function and promote gut health through mechanisms that modulate microbiome diversity and reduce inflammation. However, observed changes in microbiome diversity were modest and inconsistent across the studies.

CONCLUSIONS

While preliminary evidence suggests that antioxidants may benefit gut health and cognitive function, the heterogeneity of existing studies limits their immediate clinical applicability. Additionally, more robust RCTs are needed to substantiate these findings and guide future interventions.

Joint Association of Combined Healthy Lifestyle Factors and Hearing Loss With Cognitive Impairment in China

BACKGROUND

Hearing loss and lifestyle factors have been associated with cognitive impairment. We aimed to explore the joint association of combined healthy lifestyle factors and hearing loss with cognitive impairment, which has been scarcely studied.

METHODS

This baseline study used data from the CHOICE-Cohort study (Chinese Hearing Solution for Improvement of Cognition in Elders). Hearing loss was assessed by the better-ear pure-tone average. A composite healthy lifestyle score was built based on never smoking, never drinking, regular physical activity, and a balanced diet. Cognitive impairment was diagnosed by the Mini-Mental State Examination score of less than 24.

RESULTS

We included 17 057 participants aged 60 years or older in China (mean age 69.8 [standard deviation 6.2] years, 55.7% female). Among the participants, 48.3% (n = 8 234) had mild hearing loss, and 25.8% (n = 4 395) had moderate or greater hearing loss. The proportion of participants with healthy lifestyle scores of 0-1, 2, 3, and 4 was 14.9% (n = 2 539), 29.3% (n = 5 000), 37.4% (n = 6 386), and 18.4% (n = 3 132), respectively. About 29.6% (n = 5 057) participants had cognitive impairment. When compared to those with normal hearing and healthy lifestyle (scores of 3-4), participants with hearing loss plus unhealthy lifestyle (scores of 0-2) exhibited approximately twofold increased risk of cognitive impairment (odds ratio [OR] = 1.92, 95% confidence interval [CI] 1.70-2.18). Conversely, the risk was greatly attenuated by adherence to healthy lifestyle in individuals with hearing loss (OR = 1.57, 95% CI 1.40-1.76).

CONCLUSIONS

Our findings demonstrated adherence to a broad range of healthy lifestyle factors was associated with a significantly lower risk of cognitive impairment among participants with hearing loss.

Research trends and hotspot analysis of age-related hearing loss: A bibliometric analysis from 2019 to 2023

BACKGROUND

Age-related hearing loss (ARHL) - also termed presbycusis - is prevalent among older adults, leading to a range of issues. Although considerable progress in the understanding of ARHL over the decades, available reports lack data from recent years and do not comprehensively reflect the latest advancements and trends. Therefore, our study sought to assess research hotspots and trends in ARHL over the past 5 years to provide the basis for future research.

MATERIALS AND METHODS

The Web of Science Core Collection database was searched and screened from January 1, 2019 to October 21, 2023, according to the inclusion criteria. CiteSpace (5.8.R3), VOSviewer (1.6.19), and Microsoft Excel 2019 were employed for bibliometric analysis and visualization.

RESULTS

3084 articles from 92 countries led by the United States and China were included. There has been a steady upward trend in the number of publications from 2019 to 2023. The most productive institutions, authors, and journals are Johns Hopkins University (n = 113), Lin FR (n = 66), and Ear and Hearing (n = 135), respectively. Trend topic analyses revealed that "cochlear synaptopathy" and "dementia" were the predominant foci. Keywords, including "individuals" and "national health", began to appear.

CONCLUSION

Over the past 5 years, the annual number of publications has increased significantly and will continue to do so. Research on the mechanism of ARHL, represented by "oxidative stress", is a continuing focus. Emerging topics such as "individual differences" and "national health" may be potential future hotspots in this field.

Polygenic Risk Score-Based Association Analysis Identifies Genetic Comorbidities Associated with Age-Related Hearing Difficulty in Two Independent Samples

PURPOSE

Age-related hearing loss is the most common form of permanent hearing loss that is associated with various health traits, including Alzheimer's disease, cognitive decline, and depression. The present study aims to identify genetic comorbidities of age-related hearing loss. Past genome-wide association studies identified multiple genomic loci involved in common adult-onset health traits. Polygenic risk scores (PRS) could summarize the polygenic inheritance and quantify the genetic susceptibility of complex traits independent of trait expression. The present study conducted a PRS-based association analysis of age-related hearing difficulty in the UK Biobank sample (N = 425,240), followed by a replication analysis using hearing thresholds (HTs) and distortion-product otoacoustic emissions (DPOAEs) in 242 young adults with self-reported normal hearing. We hypothesized that young adults with genetic comorbidities associated with age-related hearing difficulty would exhibit subclinical decline in HTs and DPOAEs in both ears.

METHODS

A total of 111,243 participants reported age-related hearing difficulty in the UK Biobank sample (> 40 years). The PRS models were derived from the polygenic risk score catalog to obtain 2627 PRS predictors across the health spectrum. HTs (0.25-16 kHz) and DPOAEs (1-16 kHz, L1/L2 = 65/55 dB SPL, F2/F1 = 1.22) were measured on 242 young adults. Saliva-derived DNA samples were subjected to low-pass whole genome sequencing, followed by genome-wide imputation and PRS calculation. The logistic regression analyses were performed to identify PRS predictors of age-related hearing difficulty in the UK Biobank cohort. The linear mixed model analyses were performed to identify PRS predictors of HTs and DPOAEs.

RESULTS

The PRS-based association analysis identified 977 PRS predictors across the health spectrum associated with age-related hearing difficulty. Hearing difficulty and hearing aid use PRS predictors revealed the strongest association with the age-related hearing difficulty phenotype. Youth with a higher genetic predisposition to hearing difficulty revealed a subclinical elevation in HTs and a decline in DPOAEs in both ears. PRS predictors associated with age-related hearing difficulty were enriched for mental health, lifestyle, metabolic, sleep, reproductive, digestive, respiratory, hematopoietic, and immune traits. Fifty PRS predictors belonging to various trait categories were replicated for HTs and DPOAEs in both ears.

CONCLUSION

The study identified genetic comorbidities associated with age-related hearing loss across the health spectrum. Youth with a high genetic predisposition to age-related hearing difficulty and other related complex traits could exhibit sub-clinical decline in HTs and DPOAEs decades before clinically meaningful age-related hearing loss is observed. We posit that effective communication of genetic risk, promoting a healthy lifestyle, and reducing exposure to environmental risk factors at younger ages could help prevent or delay the onset of age-related hearing difficulty at older ages.

Environmental Risk Factors, Protective Factors, and Biomarkers for Hearing Loss: An Umbrella Review

OBJECTIVE

We aimed to investigate the potential environmental risk factors, protective factors, and biomarkers of hearing loss (HL), and establish a hierarchy of evidence.

DATA SOURCES

Embase, PubMed, Cochrane Library, and Web of Science electronic database from inception to June 1, 2023.

REVIEW METHODS

We included meta-analyses of observational studies of associations between HL and environmental risk factors, protective factors, or biomarkers. We calculated summary effect estimates, 95% confidence interval, heterogeneity I2 statistic, 95% prediction interval, small study effects, and excess significance biases.

RESULTS

Of the 9211 articles retrieved, 60 eligible articles were included. The 60 eligible articles identified 47 potential environmental risk and protective factors (N = 4,123,803) and 46 potential biomarkers (N = 173,701). Evidence of association was convincing (class I) for rheumatoid arthritis (RA) and every 1 cm increase in height. Evidence of association was highly suggestive (class II) for human immunodeficiency virus (HIV), diabetes, cumulative noise exposure (CNE), smoking, congenital cytomegalovirus (CMV) infection, combined exposure to organic solvents and noise, non-Gaussian noise exposure, each 1 kg increase in birth weight, noise exposure, and alopecia areata (AA).

CONCLUSION

In this umbrella review, RA, every 1 cm increase in height, HIV, diabetes, CNE, smoking, congenital CMV infection, combined exposure to organic solvents and noise, non-Gaussian noise exposure, each 1 kg increase in birth weight, noise exposure, and AA were strongly associated with HL.

Association of vision and hearing impairment and dietary diversity among the oldest old in China: findings from the Chinese longitudinal healthy longevity survey

BACKGROUND

The presence of sensory impairment among older age cohorts exerts a significant impact on both individuals and society generally. Although the impact of dietary patterns on health is vital across all stages of life, there still a paucity of comprehensive research on the association between dietary variety and sensory impairments.

OBJECTIVE

To investigate the potential relationship between dietary diversity and the prevalence of visual and hearing impairment or dual sensory impairments (visual and hearing impairment) among the oldest old population.

METHODS

This is a cross-sectional study relied on data obtained from the 2018 survey conducted by the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Subjects aged 80 and older with complete vision and hearing data were included in the study. Multivariate logistic regression models were developed to examine the association between dietary components and visual and hearing impairment while controlling for age, gender, socioeconomic demographic factors, living habits, other food habits, and general health status.

RESULTS

The study included 10,093 participants, with an average age of 92.29 ± 7.75 years. Vision and hearing function were assessed based on the ability to distinguish the direction of the break in the circle and the requirement for hearing aids, respectively. Upon controlling for confounding variables, individuals with a greater Dietary Diversity Score (DDS, the number of food groups, range: 1-11) had a reduced likelihood of experiencing visual impairment (odds ratio [OR] = 0.944, 95% confidence interval [CI], 0.915-0.974) and dual sensory impairment (OR = 0.930, 95% CI, 0.905-0.955). In comparison to the low dietary variety group (insufficient dietary diversity, DDS < 4), the high dietary diversity group (sufficient dietary diversity, DDS ≥ 4) exhibited a decreased risk of visual impairment (OR = 0.820, 95% CI, 0.713-0.944) and dual sensory impairment (OR = 0.751, 95% CI, 0.667-0.846). However, no statistically significant correlation was observed between dietary diversity and the presence of only hearing impairment (OR = 0.924, 95% CI, 0.815-1.047) (P < 0.05). CONCLUSIONS AND IMPLICATIONS: The synthesis of research findings suggests that following diverse dietary patterns and healthy nutritional practices may be an effective and affordable way to prevent age-related decline in visual impairment and dual sensory impairment.

Serum Prealbumin as a Potential Predictive Factor for Age-Related Hearing Loss: A Retrospective Study

Objectives: Age-related hearing loss (ARHL) is a complex disease associated with the interaction of multiple factors. Furthermore, indicators of liver function represent the body's metabolic, immune, and repair abilities. This study investigated correlations between liver function and ARHL. Methods: A total of 107 patients with ARHL and 107 age- and sex-matched healthy volunteers were included. Linear correlations, logistic regression, and receiving operator characteristic curves were used to assess the associations between liver function and ARHL. Results: Serum prealbumin (PAB) levels were significantly lower in the ARHL group compared to the control group. Logistic regression analysis indicated that low PAB levels may be an independent risk factor for ARHL. The ARHL was divided into 2 groups according to the degree of hearing loss (moderately severe-to-profound and mild-to-moderate); the median ages in the 2 groups were 70.48 and 66.85 years, respectively, with the difference being significant. Age was an independent risk factor for moderately severe-to-profound ARHL, as shown by the logistic regression analysis. Conclusions: Lower PAB levels in patients with ARHL suggested that PAB may be a risk factor for ARHL. Furthermore, higher age in patients with ARHL was associated with a greater degree of hearing loss.

Association of oxidative balance score with hearing loss and tinnitus: NHANES 1999-2018

Background

Oxidative stress is associated with the occurrence of hearing loss and tinnitus. The oxidative balance score (OBS), a composite indicator evaluating the balance between antioxidant and pro-oxidative components across various dietary and lifestyle factors, indicates the overall oxidative balance status. However, the association of OBS with hearing loss and tinnitus has not been reported previously.

Methods

Cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) 1999-2018 were analyzed. Weighted multivariable logistic regression, weighted multivariable linear regression, and restricted cubic spline curve (RCS) regression were employed to explore the relationship between OBS and hearing loss at speech, low, and high frequencies, along with tinnitus. Subgroup analysis and sensitivity analysis were used to ascertain the consistency across subgroups and stability of the results.

Results

We included 13,715 and 21,644 individuals to investigate the association between OBS and hearing loss, as well as between OBS and tinnitus, respectively. The second, third, and fourth quartiles of OBS were significantly associated with a lower risk of hearing loss at speech, low, and high frequencies, as well as tinnitus, compared to the lowest quartile. The RCS regression analysis indicated a negative linear association of OBS with hearing loss and tinnitus. Most associations were maintained in subgroup analysis and sensitivity analysis. Additionally, the dietary and lifestyle OBS independently contribute to the protection against hearing loss and tinnitus.

Conclusion

OBS is negatively correlated with the risk of hearing loss and tinnitus. The findings suggest that combined antioxidant diet and lifestyle hold promise as potential strategies for reducing the prevalence of hearing loss and tinnitus.

Association between oxidative balance score and hearing loss: a cross-sectional study from the NHANES database

Aim

The oxidative balance score (OBS), a composite score of dietary nutrients and lifestyles, reflects an individual's oxidative and antioxidant status. Evidence showed that oxidative stress levels were related to hearing loss. The relationship between OBS and hearing loss remains unclear. This study was to explore the association between OBS and hearing loss in adults.

Methods

In this cross-sectional study, data of participants aged 20-69 years who received hearing tests were extracted from the National Health and Nutrition Examination Survey (NHANES) database (2011-2012, 2015-2016). Hearing loss was defined as hearing threshold >25 dB in either ear. The OBS was composed of 16 dietary nutrients and 4 lifestyles. The covariates were screened using the backward stepwise regression analysis. The association of OBS and hearing loss was assessed with odds ratios (ORs) and 95% confidence intervals (CIs). Subgroups of age, gender, occupational noise exposure, recreational noise exposure, firearm noise exposure, and veteran status were further evaluated the associations. The importance ranking of OBS components was analyzed by the weighted random forest model.

Results

Of the total 3,557 adults, 338 (9.5%) suffered from hearing loss. High OBS levels were associated with lower odds of hearing loss (OR = 0.58, 95%CI: 0.41-0.82), after adjusting age, gender, race, hypertension, tinnitus, recreational noise exposure, and occupational noise exposure. Similar results were discovered in individuals aged50-59 years old (OR = 0.47, 95%CI: 0.24-0.93), aged 60-69 years old (OR = 0.31, 95%CI: 0.16-0.61), with female (OR = 0.44, 95%CI: 0.20-0.96), without occupational noise exposure (OR = 0.31, 95%CI: 0.16-0.62), recreational noise exposure (OR = 0.48, 95%CI: 0.30-0.76), firearm noise exposure (OR = 0.38, 95%CI: 0.19-0.77), and veteran status (OR = 0.57, 95%CI: 0.39-0.82). In OBS components, vitamin B12, total fat and physical activity were important for hearing loss.

Conclusion

Elevated OBS may be associated with hearing health in adults. Appropriate vitamin B12 supplementation, reduction of total fat intake, and increased physical activity may be beneficial to the prevention of hearing loss.

Association between Chronic Obstructive Pulmonary Disease and Hearing Loss with Impaired Speech Recognition: A Cross-Sectional Study

INTRODUCTION

Studies have identified a greater risk of sensory neural hearing loss in individuals with chronic obstructive pulmonary disease (COPD) compared to healthy individuals, but it is unclear whether they are at increased risk of hearing loss with impaired speech recognition. The aim of this study was to assess whether COPD is associated with hearing loss that affects speech recognition.

METHODS

This is a case-control study. We screened individuals from health facilities in the municipality of Jundiai. We enrolled a test group of individuals with COPD and an age-matched control group composed of individuals with asthma. The selected individuals attended an appointment with a chest physician, responded to questionnaires, and underwent tonal and speech audiometry. Adjusted binary logistic regression analysis evaluated whether COPD was associated with reduced speech recognition.

RESULTS

We enrolled 36 individuals with COPD and 72 with asthma. Individuals with COPD were more likely to have a reduced speech recognition compared to asthmatic individuals (reduced recognition of three-syllable words: adjusted OR 3.72, 95 CI [1.38-10.02]) (reduced recognition of monosyllable words: adjusted OR 4.74, 95 CI [1.52-14.76]).

CONCLUSION

We conclude that individuals with COPD from primary and secondary healthcare facilities have at least 38% greater risk of hearing loss with reduced speech recognition compared to an age-matched control group of individuals with asthma recruited from the same facilities. We recommend that longitudinal studies evaluate whether regular screening could contribute to the prevention or early treatment of hearing loss in individuals with moderate-severe COPD.

Age-related hearing loss and its potential drug candidates: a systematic review

BACKGROUND

Age-related hearing loss (ARHL) is one of the main illnesses afflicting the aged population and has a significant negative impact on society, economy, and health. However, there is presently no appropriate therapeutic treatment of ARHL due to the absence of comprehensive trials.

OBJECTIVES

The goal of this review is to systematically evaluate and analyze recent statistics on the pathologic classifications, risk factors, treatment strategies, and drug candidates of ARHL, including that from traditional Chinese medicine (TCM), to provide potential new approaches for preventing and treating ARHL.

METHODS

Literature related to ARHL was conducted in databases such as PubMed, WOS, China National Knowledge Infrastructure (CNKI), and Wanfang from the establishment of the database to Jan, 2023. The pathology, causal factor, pathophysiological mechanism, treatment strategy, and the drug candidate of ARHL were extracted and pooled for synthesis.

RESULTS

Many hypotheses about the etiology of ARHL are based on genetic and environmental elements. Most of the current research on the pathology of ARHL focuses on oxidative damage, mitochondrial dysfunction, inflammation, cochlear blood flow, ion homeostasis, etc. In TCM, herbs belonging to the kidney, lung, and liver meridians exhibit good hearing protection. Seven herbs belonging to the kidney meridian, 9 belonging to the lung meridian, and 4 belonging to the liver meridian were ultimately retrieved in this review, such as Polygonum multiflorum Thunb., Panax ginseng C.A. Mey, and Pueraria lobata (Willd.) Ohwi. Their active compounds, 2,3,4',5-Tetrahydroxystilbene-2-O-D-glucoside, ginsenoside Rb1, and puerarin, may act as the molecular substance for their anti-ARHL efficacy, and show anti-oxidative, neuroprotective, anti-inflammatory, anti-apoptotic, or mitochondrial protective effects.

CONCLUSION

Anti-oxidants, modulators of mitochondrial function, anti-inflammation agents, vasodilators, K+ channel openers, Ca2+ channel blockers, JNK inhibitors, and nerve growth factors/neurotrophic factors all contribute to hearing protection, and herbs are an important source of potential anti-ARHL drugs.