Menopause and postmenopausal hormone therapy and risk of hearing loss

Establishing multifactorial risk factors for adult-onset hearing loss: A systematic review with topic modelling and synthesis of epidemiological evidence

BACKGROUND

This systematic review explores the multifaceted nature of risk factors contributing to adult-onset HL. The objective was to synthesise the most recent epidemiological evidence to generate pooled proportional incidences for the identified risk factors.

METHODS

We conducted an extensive search of electronic databases (MEDLINE, EMBASE, and psychINFO) for studies providing epidemiological evidence of risk factors associated with hearing loss. Topic modelling using Latent Dirichlet Allocation (LDA) was first conducted to determine how many risk factor themes were available from the papers. Data were analysed by calculating the pooled proportional incidence using a meta-analysis of proportions.

RESULTS

From the 72 studies reviewed, six key risk factor themes emerged through LDA topic modelling. The review identified ototoxicity, primarily caused by cancer treatments and antibiotics, infectious diseases like COVID-19, occupational noise exposure, lifestyle factors, health conditions, biological responses, and age progression as significant risk factors for HL. The highest proportional incidence was found with cancer-related ototoxicity at 55.4% (95%CI: 39.0-70.7), followed closely by ototoxicity from infectious diseases at 50.0% (95%CI: 28.5-71.5). This high proportional incidence suggests the need to explore less destructive therapies and proactively monitor hearing function during treatments.

CONCLUSIONS

The findings of this review, combined with the synthesis of epidemiological evidence, enhance our understanding of hearing loss (HL) pathogenesis and highlight potential areas for intervention, thereby paving the way for more effective prevention and management of adult-onset hearing loss in our ageing global population.

An Observational Study of Hearing Loss Among Menopausal Women

Senile deafness and hearing loss in adults over 50 are major public health issues as a result of the population's ageing demographic. Menopausal women tend to develop hearing loss, while no clear link has been found between the two. The purpose of this study was to determine how menopause and diabetes mellitus affects hearing loss. We assessed 158 menopausal women in total. Pure Tone Audiometry and HbA1c levels was measured, along with appropriate clinical history and examination. The association between those levels and hearing was researched by chi-square test. There were 158 study participants. Mean age of the study population was 50.5 (± 2.49) years. Onset and duration of hard of hearing was assessed in 41 patients (25.9%). 33% (N = 53) of the patients had history of Diabetes mellitus, of which 52.8% offered history of the disease for more than or equal to five years. On audiological assessment, 74.1% had no hearing loss (N = 117), 4.4% had unilateral sensorineural hearing loss (N = 7) and 21.5% had bilateral sensorineural hearing loss (N = 34). Statistics show that hearing loss is statistically connected with ageing and poor glycemic management. With chi square values of 9.629 and P value 0.002 found a significant correlation between ageing and hearing loss. Poor glycemic control is significantly associated with hearing loss with a chi-square value of 4.304 and P value 0.038. Poor glycemic control and menopause is found to be strongly associated with sensorineural hearing loss. Further prospective, hormonal studies including larger population is recommended.

Age-related hearing loss: An updated and comprehensive review of the interventions

Aging causes progressive degenerative changes in many organs, particularly the auditory system. Several attempts have been conducted to investigate preventive and therapeutic strategy/strategies for age-related auditory dysfunction, such as maintaining a healthy lifestyle through good nutrition, lower anxiety levels, and noise exposure, different pharmacological approaches, gene and cell therapy, and other strategies. However, it is not clear which approach is the best to slow down these dysfunctions because several different underlying mechanistic pathways are associated with presbycusis which eventually leads to different types of this disease. A combination of several methods is probably required, whereas the effectiveness for some people needs to be monitored. The effectiveness of treatments will not be the same for all; therefore, we may need to have a unique and personalized approach to the prevention and treatment of ARHL for each person. In addition, each method needs to specify what type of presbycusis can prevent or treat and provide complete information about the extent, duration of treatment, persistency of treatment, side effects, and whether the approach is for treatment or prevention or even both. This paper reviews the updated literature, which targets current interventions for age-related hearing loss.

The impact of menopausal status on auditory brainstem responses

OBJECTIVE

To determine the effect of decreased estrogen levels due to menopause on auditory brainstem response measurements (ABR).

STUDY DESIGN

Retrospective chart review.

SETTING

Academic.

PATIENTS

Pre- and post-menopausal females (pre-M, post-M) and age-matched males.

METHODS

ABR measurements of wave I, III, and V latencies, and interpeak latencies; amplitudes of waves I, III, V, and V/I ratio.

OUTCOME MEASURE

Differences in ABR measurements between pre-M and post-M.

RESULTS

164 subjects (101 female and 64 male) were included. Post-M had significantly greater latencies (msec) than pre-M of wave V. Post-M had a significantly smaller wave I amplitude (uV) than pre-M. Post-M had a significantly higher wave V/I amplitude ratio than pre-M. Pre-M had significantly shorter latencies than young males for wave III, and wave V. Post-M had significantly shorter latencies than older males at wave III, and wave V. A two-way ANOVA revealed a significant interaction between the effects of age category and gender on V/I amplitude.

CONCLUSION

Post-M group showed a significant drop in wave I amplitude compared with pre-M group, even in the absence of hearing loss, suggesting that the gender differences in hearing are related to estrogen signaling along the auditory pathway. If wave I amplitude changes between older and younger groups resulted from decreased peripheral hearing sensitivity, we would expect larger drops in amplitude in males since rates of presbycusis are higher. We observed much larger drops in wave I amplitude in females, which cannot be attributed to peripheral hearing loss. These results may assist in understanding gender differences in presbycusis and a possible protective effect of estrogen on the auditory system. Knowledge of gender differences in wave I may be important when ABR is used to assess possible synaptopathy.

Sex differences in the pleiotropy of hearing difficulty with imaging-derived phenotypes: a brain-wide investigation

Background

Hearing difficulty (HD) is one of the major health burdens in older adults. While aging-related changes in the peripheral auditory system play an important role, genetic variation associated with brain structure and function could also be involved in HD predisposition.

Methods

We analyzed a large-scale HD genome-wide association study (GWAS; N total = 501,825, 56% females) and GWAS data related to 3,935 brain imaging-derived phenotypes (IDPs) assessed in up to 33,224 individuals (52% females) using multiple magnetic resonance imaging (MRI) modalities. To investigate HD pleiotropy with brain structure and function, we conducted genetic correlation, latent causal variable (LCV), Mendelian randomization (MR), and multivariable generalized linear regression analyses. Additionally, we performed local genetic correlation and multi-trait colocalization analyses to identify genomic regions and loci implicated in the pleiotropic mechanisms shared between HD and brain IDPs.

Results

We observed a widespread genetic correlation of HD with 120 IDPs in females, 89 IDPs in males, and 171 IDPs in the sex-combined analysis. The LCV analyses showed that some of these genetic correlations could be due to cause-effect relationships. For seven correlations, the causal effects were also confirmed by the MR approach: vessel volume→HD in the sex-combined analysis; hippocampus volume→HD, cerebellum grey matter volume→HD, primary visual cortex volume→HD, and HD→rfMRI-ICA100 node 46 in females; global mean thickness→HD and HD→mean orientation dispersion index in superior corona radiata in males. The local genetic correlation analyses identified 13 pleiotropic regions between HD and these seven IDPs. We also observed a colocalization signal for the rs13026575 variant between HD, primary visual cortex volume, and SPTBN1 transcriptomic regulation in females.

Conclusion

Brain structure and function may have a role in the sex differences in HD predisposition via possible cause-effect relationships and shared regulatory mechanisms.

Correlation between hearing impairment and the Triglyceride Glucose Index: based on a national cross-sectional study

Objective

Data from the National Health and Nutrition Examination Survey (NHANES) were used to assess the association between the triglyceride-glucose (TyG) index and hearing impairment (HI).

Methods

We used eight survey cycles from NHANES 2001-2012 and 2015-2018 to conduct this cross-sectional study. HI was designed as an dependent variable, and the TyG index was selected as an exposure factor (independent variable). The correlation between the two variables was assessed using multiple logistic regression. In order to assess whether there was a non-linear relationship between the TyG index and HI, the TyG index was distributed and a test for trend was conducted (P for trend), followed by smooth curve fitting (penalized spline) and generalized additive model (GAM) regression. We also performed a subgroup analysis to identify sensitive groups whose responses were clearly associated with independent variables.

Results

10,906 participants were finally included in the study, and those with a higher TyG index had a higher frequency of hearing impairment. There was a linear positive correlation between the TyG index and HI. For the low-frequency HI, however, this positive correlation was not statistically significant (OR = 1.05, 95% CI: 0.98, 1.14); however, it was more stable for the high-frequency HI (OR = 1.12, 95% CI: 1.03, 1.22). Additionally, as the TyG index increased, this positive association increased as well (P for trend = 0.05). The HPTA test showed a positive association with more severe HI (simultaneous) as the independent variable increased (OR = 1.14, 95% CI: 1.05-1.24), and this association was even more significant with increasing severity (P for trend 0.05). According to the subgroup analysis, the positive association between TyG index and high-frequency HI was more significant in females, 40-69 years old, without hypertension or diabetes, and when strict high-frequency HI was significant in males, females, 40-69 years old, with hypertension and diabetes.

Conclusion

Participants with a higher TyG index may have a higher risk of HI. TyG index and HI risk showed a linear relationship, which became even more significant when HPTA was included.

Sex-Linked Biology and Gender-Related Research Is Essential to Advancing Hearing Health

There is robust evidence that sex (biological) and gender (behavioral/social) differences influence hearing loss risk and outcomes. These differences are noted for animals and humans-in the occurrence of hearing loss, hearing loss progression, and response to interventions. Nevertheless, many studies have not reported or disaggregated data by sex or gender. This article describes the influence of sex-linked biology (specifically sex-linked hormones) and gender on hearing and hearing interventions, including the role of sex-linked biology and gender in modifying the association between risk factors and hearing loss, and the effects of hearing loss on quality of life and functioning. Most prevalence studies indicate that hearing loss begins earlier and is more common and severe among men than women. Intrinsic sex-linked biological differences in the auditory system may account, in part, for the predominance of hearing loss in males. Sex- and gender-related differences in the effects of noise exposure or cardiovascular disease on the auditory system may help explain some of these differences in the prevalence of hearing loss. Further still, differences in hearing aid use and uptake, and the effects of hearing loss on health may also vary by sex and gender. Recognizing that sex-linked biology and gender are key determinants of hearing health, the present review concludes by emphasizing the importance of a well-developed research platform that proactively measures and assesses sex- and gender-related differences in hearing, including in understudied populations. Such research focus is necessary to advance the field of hearing science and benefit all members of society.

Sex-Specific Interactions Between Hearing and Memory in Older Adults With Mild Cognitive Impairment: Findings From the COMPASS-ND Study

OBJECTIVES

Hearing loss (HL) in older adults is associated with a decline in performance on cognitive tasks and the risk of developing dementia. However, very few studies have investigated sex-related effects on these associations. A previous study of cognitively healthy older adults showed an association between HL and lower cognitive performance in females only. In the present study, we examined the effects of sex and hearing on cognition in individuals with mild cognitive impairment (MCI). We predicted that females with HL would be more likely to show poorer performance on the cognitive measures compared to females with normal hearing (NH), while cognitive performance in males would not depend on hearing. We further predicted that these auditory-cognitive associations would not depend on test modality, and would thus be observed in females for both auditory and visual tests.

DESIGN

Participants were 101 older adults with amnestic MCI (M = 71 years, 45% females) in the Canadian Consortium on Neurodegeneration in Aging (CCNA) COMPASS-ND study. Performance on the Montreal Cognitive Assessment (MoCA), Rey Auditory Verbal Learning (RAVLT), and Brief Visuospatial Memory Test-Revised (BVMT-R) was analyzed to investigate sex-related differences and/or hearing-related differences. Participants were categorized as having NH or HL using two different measures: pure-tone hearing screening results (normal based on a pure-tone threshold < 25 dB HL at 2000 Hz in the worse ear) and speech-in-noise speech reception thresholds (SRTs; normal < -10 dB SNR on the Canadian Digit Triplet Test [CDTT]).

RESULTS

Males and female groups did not differ in age, years of education, or other relevant covariates. Yet, females with better hearing on either pure-tone or speech-in-noise measures outperformed their worse hearing counterparts on the MoCA total score. Additionally, females with better hearing were more likely to recall several words on the MoCA delayed recall trial relative to those with worse hearing. Females with NH showed significant correlations between CDTT SRTs and both MoCA and RAVLT scores, while no correlations were observed in males. In contrast, males but not females showed an effect of hearing group on BVMT-R test status.

CONCLUSIONS

There were sex-specific differences in auditory-cognitive associations in individuals with MCI. These associations were mostly observed in females and on auditory tests. Potential mechanisms and implications are discussed.

Objective and Subjective Hearing Difficulties Are Associated With Lower Inhibitory Control

OBJECTIVE

Evidence suggests that hearing loss increases the risk of cognitive impairment. However, the relationship between hearing loss and cognition can vary considerably across studies, which may be partially explained by demographic and health factors that are not systematically accounted for in statistical models.

DESIGN

Middle-aged to older adult participants (N = 149) completed a web-based assessment that included speech-in-noise (SiN) and self-report measures of hearing, as well as auditory and visual cognitive interference (Stroop) tasks. Correlations between hearing and cognitive interference measures were performed with and without controlling for age, sex, education, depression, anxiety, and self-rated health.

RESULTS

The risk of having objective SiN difficulties differed between males and females. All demographic and health variables, except education, influenced the likelihood of reporting hearing difficulties. Small but significant relationships between objective and reported hearing difficulties and the measures of cognitive interference were observed when analyses were controlled for demographic and health factors. Furthermore, when stratifying analyses for males and females, different relationships between hearing and cognitive interference measures were found. Self-reported difficulty with spatial hearing and objective SiN performance were better predictors of inhibitory control in females, whereas self-reported difficulty with speech was a better predictor of inhibitory control in males. This suggests that inhibitory control is associated with different listening abilities in males and females.

CONCLUSIONS

The results highlight the importance of controlling for participant characteristics when assessing the relationship between hearing and cognitive interference, which may also be the case for other cognitive functions, but this requires further investigations. Furthermore, this study is the first to show that the relationship between hearing and cognitive interference can be captured using web-based tasks that are simple to implement and administer at home without any assistance, paving the way for future online screening tests assessing the effects of hearing loss on cognition.

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

Although a causal association remains to be determined, epidemiologic evidence suggests an association between hearing loss and increased risk of dementia. If we determine the association is causal, opportunity for targeted intervention for hearing loss may play a fundamental role in dementia prevention. In this discussion, we summarize current research on the association between hearing loss and dementia and review potential casual mechanisms behind the association (e.g., sensory-deprivation hypothesis, information-degradation hypothesis, common cause). We emphasize key areas of research which might best inform our investigation of this potential casual association. These selected research priorities include examination of the causal mechanism, measurement of co-existing hearing loss and cognitive impairment and determination of any bias in testing, potential for managing hearing loss for prevention of dementia and cognitive decline, or the potential to reduce dementia-related symptoms through the management of hearing loss. Addressing these research gaps and how results are then translated for clinical use may prove paramount for dementia prevention, management, and overall health of older adults.

The impact of cardiovascular diseases on hearing deterioration: a 13-year follow-up study

OBJECTIVE

To study the impact of cardiovascular diseases (CVDs) on hearing deterioration among ageing adults in a longitudinal setting. Furthermore, to describe the pure tone threshold changes at the 0.125-8 kHz frequency range over 13 years.

DESIGN

A population-based follow-up study.

STUDY SAMPLE

A random sample of 850 adults, of whom 559 participated in the follow-up study. Otological examination, a structured interview, and pure tone audiometry were conducted. Multivariate regression models were used to estimate the effect of CVD (participants had at least one cardiovascular condition) on hearing deterioration of the better ear hearing level (BEHL), defined as a change in the pure-tone average (PTA) of the frequencies 0.5, 1, 2, and 4 kHz and separately at the lower (0.125, 0.25, and 0.5 kHz) and higher (4, 6, and 8 kHz) frequencies.

RESULTS

In the multivariable-adjusted analysis, the BEHL change at 13 years was 0.7 dB greater among participants with CVD (p = 0.3). The mean BEHL change during the 13-year follow-up was 12.0 dB (95% CI 11.4-12.6) among all participants.

CONCLUSIONS

No significant association between CVD and hearing threshold changes was found.

Sex Differences in Otolaryngology: Focus on the Emerging Role of Estrogens in Inflammatory and Pro-Resolving Responses

Otolaryngology (also known as ear, nose, and throat (ENT)) diseases can be significantly affected by the level of sex hormones, which indicates that sex differences affect the manifestation, pathophysiology, and outcomes of these diseases. Recently, increasing evidence has suggested that proinflammatory responses in ENT diseases are linked to the level of sex hormones. The sex hormone receptors are present on a wide variety of immune cells; therefore, it is evident that they play crucial roles in regulating the immune system and hence affect the disease progression of ENT diseases. In this review, we focus on how sex hormones, particularly estrogens, regulate ENT diseases, such as chronic rhinosinusitis, vocal fold polyps, thyroid cancer, Sjögren’s syndrome, and head and neck cancers, from the perspectives of inflammatory responses and specialized proresolving mediator-driven resolution. This paper aims to clarify why considering sex differences in the field of basic and medical research on otolaryngology is a key component to successful therapy for both males and females in the future.

Sex Differences in the Triad of Acquired Sensorineural Hearing Loss

The triad of noise-generated, drug-induced, and age-related hearing loss is the major cause of acquired sensorineural hearing loss (ASNHL) in modern society. Although these three forms of hearing loss display similar underlying mechanisms, detailed studies have revealed the presence of sex differences in the auditory system both in human and animal models of ASNHL. However, the sexual dimorphism of hearing varies among noise-induced hearing loss (NIHL), ototoxicity, and age-related hearing loss (ARHL). Importantly, estrogen may play an essential role in modulating the pathophysiological mechanisms in the cochlea and several reports have shown that the effects of hormone replacement therapy on hearing loss are complex. This review will summarize the clinical features of sex differences in ASNHL, compare the animal investigations of cochlear sexual dimorphism in response to the three insults, and address how estrogen affects the auditory organ at molecular levels.

Birth Weight and Adult-Onset Hearing Loss

OBJECTIVES

Among low-birth-weight infants, exposure to stress or undernutrition in utero may adversely affect cochlear development. As cochlear reserve declines, the risk of hearing loss may increase with age. While low birth weight is associated with a higher risk of neonatal hearing loss, our objective was to examine whether birth weight was associated with adult-onset, self-reported hearing loss in the Nurses' Health Studies (NHS) I and II (n = 113,130).

DESIGN

We used Cox proportional hazards regression to prospectively examine whether birth weight, as well as gestational age at birth, is associated with adult-onset hearing loss. Participants reported their birth weight in 1992 in NHS I and 1991 in NHS II. Mothers of NHS II participants reported gestational age at birth in a substudy (n = 28,590). The primary outcome was adult-onset, self-reported moderate or greater hearing loss, based on questionnaires administered in 2012/2016 in NHS I and 2009/2013 in NHS II.

RESULTS

Our results suggested a higher risk of hearing loss among those with birth weight <5.5 lbs compared with birth weight 7 to <8.5 lbs (pooled multivariable-adjusted hazard ratio 1.14, 95% confidence interval = 1.04-1.23; p trend = 0.01). Additionally, participants with gestational age at birth ≥42 weeks had a higher risk of hearing loss, compared with gestational age 38 to <42 weeks (multivariable-adjusted hazard ratio 1.33, 95% confidence interval = 1.06-1.65).

CONCLUSIONS

Birth weight <5.5 lbs was independently associated with higher risk of self-reported, adult-onset hearing loss. In addition, gestational age at birth ≥42 weeks was also associated with higher risk.

Age-related hearing loss pertaining to potassium ion channels in the cochlea and auditory pathway

Age-related hearing loss (ARHL) is the most prevalent sensory deficit in the elderly and constitutes the third highest risk factor for dementia. Lifetime noise exposure, genetic predispositions for degeneration, and metabolic stress are assumed to be the major causes of ARHL. Both noise-induced and hereditary progressive hearing have been linked to decreased cell surface expression and impaired conductance of the potassium ion channel K_V7.4 (KCNQ4) in outer hair cells, inspiring future therapies to maintain or prevent the decline of potassium ion channel surface expression to reduce ARHL. In concert with K_V7.4 in outer hair cells, K_V7.1 (KCNQ1) in the stria vascularis, calcium-activated potassium channels BK (KCNMA1) and SK2 (KCNN2) in hair cells and efferent fiber synapses, and K_V3.1 (KCNC1) in the spiral ganglia and ascending auditory circuits share an upregulated expression or subcellular targeting during final differentiation at hearing onset. They also share a distinctive fragility for noise exposure and age-dependent shortfalls in energy supply required for sustained surface expression. Here, we review and discuss the possible contribution of select potassium ion channels in the cochlea and auditory pathway to ARHL. We postulate genes, proteins, or modulators that contribute to sustained ion currents or proper surface expressions of potassium channels under challenging conditions as key for future therapies of ARHL.

Effects of endogenous and exogenous oestrogen exposure on hearing level in postmenopausal women: A cross-sectional study

OBJECTIVE

To investigate the effect of endogenous and exogenous oestrogen exposure on hearing levels in postmenopausal women.

STUDY DESIGN

Retrospective cross-sectional study.

SETTING

Population-based survey data collected by the Korean National Health and Nutrition Survey between 1 January 2010 and 31 December 2012.

SUBJECTS AND METHODS

Participants comprised 3653 postmenopausal women. Detailed histories for reproductive factors and data on the use of hormone replacement therapy were obtained through health questionnaires and otologic examinations, including pure-tone audiogram and otoscopic findings. Complex-sample linear regression models controlling for confounding factors were generated to determine whether hormone-related factors were associated with hearing loss.

RESULTS

Women who experienced a longer duration of oestrogen exposure had better hearing compared to those who do not in multivariate model adjusting for confounding factors with a lower adjusted beta coefficient of hearing threshold (β = -0.18, 95% confidence interval = -0.3 to -0.07, P = .002). The results also suggested that hormone replacement therapy may be beneficial for attenuating hearing loss (β = -1.22, 95% confidence interval = -2.19 to -0.25, P = .014), particularly in the high-frequency range from 3 to 6 KHz.

CONCLUSION

A longer duration of lifetime oestrogen exposure (LEE) and the use of hormone replacement therapy are likely to attenuate hearing loss. These epidemiologic data provide evidence that oestrogen may be beneficial for attenuating age-related hearing decline.

Translational implications of the interactions between hormones and age-related hearing loss

Provocative research has revealed both positive and negative effects of hormones on hearing as we age; with in some cases, mis-regulation of hormonal levels in instances of medical comorbidities linked to aging, lying at the heart of the problem. Animal model studies have discovered that hormonal fluctuations can sharpen hearing for improved communication and processing of mating calls during reproductive seasons. Sex hormones sometimes have positive effects on auditory processing, as is often the case with estrogen, whereas combinations of estrogen and progesterone, and testosterone, can have negative effects on hearing abilities, particularly in aging subjects. Too much or too little of some hormones can be detrimental, as is the case for aldosterone and thyroid hormones, which generally decline in older individuals. Too little insulin, as in Type 1 diabetics, or poor regulation of insulin, as in Type 2 diabetics, is also harmful to hearing in our aged population. In terms of clinical translational possibilities, hormone therapies can be problematic due to systemic side effects, as has happened for estrogen/progestin combination hormone replacement therapy (HRT) in older women, where the HRT induces a hearing loss. As hormone therapy approaches are further developed, it may be possible to lower needed doses of hormones by combining them with supplements, such as antioxidants. Another option will be to take advantage of emerging technologies for local drug delivery to the inner ear, including biodegradeable, sustained-release hydrogels and micro-pumps which can be implanted in the middle ear near the round window. In closing, exciting research completed to date, summarized in the present report bodes well for emerging biomedical therapies to prevent or treat age-related hearing loss utilizing hormonal strategies.

Cigarette Smoking, Smoking Cessation, and Risk of Hearing Loss in Women

BACKGROUND

Previous studies demonstrated higher risk of hearing loss among cigarette smokers, but longitudinal data on whether the risk is influenced by smoking cessation are limited. We prospectively investigated relations between smoking, smoking cessation, and risk of self-reported moderate or worse hearing loss among 81,505 women in the Nurses' Health Study II (1991-2013).

METHODS

Information on smoking and hearing status was obtained from validated biennial questionnaires. Cox proportional hazards regression was used to estimate multivariable-adjusted relative risks (MVRR, 95% confidence interval).

RESULTS

During 1,533,214 person-years of follow-up, 2760 cases of hearing loss were reported. Smoking was associated with higher risk of hearing loss and the risk tended to be higher with greater number of pack-years smoked. Compared with never smokers, the MVRR (95% confidence interval) among past smokers with 20+ pack-years of smoking was 1.30 (1.09-1.55) and 1.21 (1.02-1.43) for current smokers. The magnitude of elevated risk diminished with greater time since smoking cessation. Compared with never smokers, the MVRR among smokers who quit <5 years prior was 1.43 (1.17-1.75); 5-9 years prior was 1.27 (1.03-1.56); 10-14 years prior was 1.17 (0.96-1.41); and plateaued thereafter. Additional adjustment for pack-years smoking attenuated the results.

CONCLUSIONS

The higher risk of hearing loss associated with smoking may diminish over time after quitting.

Associations of Hearing Loss and Menopausal Hormone Therapy With Change in Global Cognition and Incident Cognitive Impairment Among Postmenopausal Women

BACKGROUND

Hearing loss (HL) and menopausal hormone therapy (conjugated equine estrogens [CEE] and/or medroxyprogesterone acetate [MPA]) are separately associated with cognitive decline and increased risk of incident cognitive impairment. Joint effects of HL and HT could be associated with additive or synergistic decline in global cognition and risk of incident cognitive impairment among postmenopausal women.

METHODS

Using the Women's Health Initiative (WHI) Memory Study, 7,220 postmenopausal women with measures of HL, global cognition (Modified Mini-Mental State Examination score), and cognitive impairment (centrally adjudicated diagnoses of mild cognitive impairment and dementia) from 1996 to 2009. Multivariable linear mixed-effects models were used to analyze rate of change in global cognition. Accelerated failure time models were used to evaluate time to incident cognitive impairment, stratified by HT.

RESULTS

Within the CEE-Alone trial, observed adverse effects of CEE-Alone on change in global cognition did not differ by HL, and estimated joint effects of HL and CEE-Alone were not associated with incident cognitive impairment. Within the CEE+MPA trial, while HL did not independently accelerate time to cognitive impairment, the adverse effect of CEE+MPA on global cognition was heightened in older women with HL. Older women on CEE+MPA either with HL (time ratio [TR] = 0.82, 95% confidence interval [CI]: 0.71, 0.94) or with normal hearing (TR = 0.86, 95% CI: 0.76, 0.97) had faster time to cognitive impairment than those with normal hearing and placebo.

CONCLUSIONS

HL may accentuate the adverse effect of CEE+MPA, not CEE-Alone, on global cognitive decline, not incident cognitive impairment, among postmenopausal women on HT.

Understanding hormone and hormone therapies' impact on the auditory system

Hormones such as estrogen, progesterone, and aldosterone all demonstrate vital roles in sustaining auditory function through either the maintenance of cochlear neurons, up/down regulation of critical molecules (i.e., IGF-1, BDNF, etc.), or generation of the endocochlear potential. With disease and/or age, hormone expression begins to decline drastically, which ultimately affects cochlear structures and the integrity of cochlear cells. The following review explores the latest findings as well as realistic outcomes for hormone therapy treatment in the auditory system. This information could serve as a potential guide for patients considering hormone therapy as a medicinal choice to alleviate the signs of onset of presbycusis-age-related hearing loss. Additional scientific investigations could also be carried out to further enhance recent findings.

Auditory function and dysfunction: estrogen makes a difference

Estrogen is the major female hormone involved in reproductive functions, but it also exerts a variety of additional roles in non-reproductive organs. In this review, we highlight the preclinical and clinical studies that have pointed out sex differences and estrogenic influence on audition. We also describe the experimental evidences supporting a protective role of estrogen towards acquired forms of hearing loss. Although a high level of endogenous estrogen is associated with a better hearing function, hormonal treatments at menopause have provided contradictory outcomes. The various factors that are likely to explain these discrepancies include the treatment regimen as well as the hormonal status and responsiveness of the patients. The complexity of estrogen signaling is being untangled and many downstream effectors of its genomic and non-genomic actions have been identified in other systems. Based on these advances and on the common physio-pathological events that underlie age-related, drug or noise-induced hearing loss, we discuss potential mechanisms for their protective actions in the cochlea.

Biomarkers of Systemic Inflammation and Risk of Incident Hearing Loss

BACKGROUND

Chronic inflammation may lead to cochlear damage, and the only longitudinal study that examined biomarkers of systemic inflammation and risk of hearing loss found an association with a single biomarker in individuals <60 years of age. The purpose of our study was to determine whether plasma inflammatory markers are associated with incident hearing loss in two large prospective cohorts, Nurses' Health Studies (NHS) I and II.

METHODS

We examined the independent associations between plasma levels of markers of systemic inflammation (C-reactive protein [CRP], interleukin-6 [IL-6], and soluble tumor necrosis factor receptor 2 [TNFR-2]) and self-reported hearing loss. The participants in NHS I (n = 6194 women) were 42 to 69 years of age at the start of the analysis in 1990, while the participants in NHS II (n = 2885 women) were 32 to 53 years in 1995. After excluding women with self-reported hearing loss before the time of blood-draw, incident cases of hearing loss were defined as those women who reported hearing loss on questionnaires administered in 2012 in NHS I and 2009 or 2013 in NHS II. The primary outcome was hearing loss that was reported as moderate or worse in severity, pooled across the NHS I and NHS II cohorts. We also examined the pooled multivariable-adjusted hazard ratios for mild or worse hearing loss. Cox proportional hazards regression was used to adjust for potential confounders.

RESULTS

At baseline, women ranged from 42 to 69 years of age in NHS I and 32 to 53 years of age in NHS II. Among the NHS I and II women with measured plasma CRP, there were 628 incident cases of moderate or worse hearing loss during 100,277 person-years of follow-up. There was no significant association between the plasma levels of any of the three inflammatory markers and incident moderate or worse hearing loss (multivariable-adjusted pooled p trend for CRP = 0.33; p trend IL-6 = 0.54; p trend TNFR-2 = 0.70). There was also no significant relation between inflammatory marker levels and mild or worse hearing loss. While there was no significant effect modification by age for CRP or IL-6 in NHS I, there was a statistically significant higher risk of moderate or worse hearing loss (p interaction = 0.02) as well as mild or worse hearing loss (p interaction = 0.004) in women ≥60 years of age who had higher plasma TNFR-2 levels.

CONCLUSIONS

Overall, there was no significant association between plasma markers of inflammation and risk of hearing loss.

Sex differences in hearing: Probing the role of estrogen signaling

Hearing loss is the most common form of sensory impairment in humans, with an anticipated rise in incidence as the result of recreational noise exposures. Hearing loss is also the second most common health issue afflicting military veterans. Currently, there are no approved therapeutics to treat sensorineural hearing loss in humans. While hearing loss affects both men and women, sexual dimorphism is documented with respect to peripheral and central auditory physiology, as well as susceptibility to age-related and noise-induced hearing loss. Physiological differences between the sexes are often hormone-driven, and an increasing body of literature demonstrates that the hormone estrogen and its related signaling pathways may in part, modulate the aforementioned differences in hearing. From a mechanistic perspective, understanding the underpinnings of the hormonal modulation of hearing may lead to the development of therapeutics for age related and noise induced hearing loss. Here the authors review a number of studies that range from human populations to animal models, which have begun to provide a framework for understanding the functional role of estrogen signaling in hearing, particularly in normal and aberrant peripheral auditory physiology.

Hormone replacement therapy attenuates hearing loss: Mechanisms involving estrogen and the IGF-1 pathway

Estradiol (E) is a multitasking hormone that plays a prominent role in the reproductive system, and also contributes to physiological and growth mechanisms throughout the body. Frisina and colleagues have previously demonstrated the beneficial effects of this hormone, with E‐treated subjects maintaining low auditory brainstem response (ABR) thresholds relative to control subjects (Proceedings of the National Academy of Sciences of the United States of America, 2006;103:14246; Hearing Research, 2009;252:29). In the present study, we evaluated the functionality of the peripheral and central auditory systems in female CBA/CaJ middle‐aged mice during and after long‐term hormone replacement therapy (HRT) via electrophysiological and molecular techniques. Surprisingly, there are very few investigations about the side effects of HRT in the auditory system after it has been discontinued. Our results show that the long‐term effects of HRT are permanent on ABR thresholds and ABR gap‐in‐noise (GIN) amplitude levels. E‐treated animals had lower thresholds and higher amplitude values compared to other hormone treatment subject groups. Interestingly, progesterone (P)‐treated animals had ABR thresholds that increased but amplitude levels that remained relatively the same throughout treatment. These results were consistent with qPCR experiments that displayed high levels of IGF‐1R in the stria vascularis (SV) of both E and P animal groups compared to combination treatment (E + P) animals. IGF‐1R plays a vital role in mediating anti‐apoptotic responses via the PI3K/AKT pathway. Overall, our findings gain insights into the neuro‐protective properties of E hormone treatments as well as expand the scientific knowledge base to help women decide whether HRT is the right choice for them.

Hormone therapy is not associated with the risk of sudden sensorineural hearing loss in postmenopausal women: a 10-year nationwide population-based study

OBJECTIVE

The association between hormone therapy (HT) and the risk for sudden sensorineural hearing loss (SSNHL) in postmenopausal women has been described only in case reports. No large study has further evaluated the association between HT and the risk of SSNHL in postmenopausal women. The objective of our study was to investigate whether postmenopausal women with HT exhibit a risk of SSNHL.

METHODS

This matched cohort study enrolled 13,112 postmenopausal women 45 to 79 years of age who used HT between 2000 and 2010; they were selected from the National Health Insurance Research Database of Taiwan, and 39,336 participants without HT use were enrolled as controls matched by age and index year at a 1:3 ratio.

RESULTS

We used a Cox proportional hazards regression model to identify the risk of SSNHL during 10 years of follow-up, and the results indicated no significant increase in the proportion of postmenopausal women with HT use (P = 0.814) who developed SSNHL compared with those without HT use (1.14%, 150/13, 112 vs 1.12%, 439/39, 336). After adjustment for age and other variables, the adjusted hazard ratio was 0.78 (95% CI, 0.308-1.025, P = 0.762) and showed no association between HT use and SSNHL development in postmenopausal women.

CONCLUSIONS

Our results showed that HT was not associated with the risk of SSNHL in postmenopausal women over a 10-year follow-up study.

Hearing Performance in the Follicular-Luteal Phase of the Menstrual Cycle

Introduction

Estrogen has a protective role on auditory function. It may have an excitatory action on auditory nerve fibers and can have a neuroprotective effect. Progesterone has a mainly inhibitory action on the central nervous system, which may balance the mainly excitatory action of estrogen.

Objective

To determine changes in hearing performance with pure tone audiometry (PTA), tympanometry, distortion product otoacoustic emissions (DPOAEs), and auditory brainstem responses (ABR) as hormonal changes occur from follicular to luteal phase.

Materials and Methods

Twenty healthy female volunteers (age 19 ± 30 years) with normal menstrual cycle and without any hearing problems are included in this case-control study. Hearing evaluation was performed on the 13th day of the menstrual cycle (follicular phase) and then on the 22nd day (luteal phase).

Results

All of the participants had normal results in follicular phase. In luteal phase, four cases showed abnormalities as follows: reduced hearing thresholds 250 Hz (mean= 15 dBHL), increased amplitudes of DPOAE (mean= 3 dBspl), decreased middle ear pressure (mean= -110 dapa), and delayed ABR interpeak latencies (mean of IPLs I-III= 0.4 and mean of IPLs III-V= 0.6 ms).

Conclusions

In some women, changing of ovarian hormones may induce fluctuating hearing and increased progesterone in luteal phase can lead to abnormal outcomes in auditory function. However, elevated estrogen modifies its consequences in follicular phase.

Hormone replacement therapy decreases the risk of tinnitus in menopausal women: a nationwide study

The incidence and risk of tinnitus associated with hormone replacement therapy (HRT) in menopausal women have not yet been fully examined. We examined the medical records of menopausal women aged between 45 and 79 years from Taiwan's National Health Insurance Research Database of records between 1 January 2000 and 31 December 2010 to establish matched cohorts (13,920 HRT users and 41,760 nonusers). The incidence of tinnitus in HRT users and nonusers were matched 1:3 based on propensity-score matching over this ten year period. The Cox regression hazard model was used to identify risk factors of tinnitus, and results indicate that a significantly lower percentage of HRT users (P = 0.017) developed tinnitus in comparison with nonusers (0.43%, 60/13, 920 vs. 0.59%, 246/41, 760). Using Cox regressions analysis after adjustments for age and other variables (adjusted hazard ratio: 0.505 (95% confidence interval, 0.342–0.756)), we were also able to show that HRT users appeared to have a reduced risk of developing tinnitus in comparison with nonusers. Based on our observation of the lower incidence of tinnitus among HRT users in this cohort, we speculate that HRT may have provided potential benefits on the management and prevention of tinnitus among menopausal women.

Herbal medicine (Danggui Liuhuang decoction) for managing menopausal symptoms: A protocol of systematic review of randomized clinical trials

BACKGROUND

Danggui Liuhuang (DLH) decoction is a traditional herbal medicine that is widely used in East Asia to treat menopausal symptoms. Most of the available clinical trials that investigated DLH decoction have been included in this review. The objectives of this protocol are to provide the information of how to evaluate the effectiveness and safety of DLH decoction for the treatment of menopausal symptoms.

METHODS AND ANALYSIS

Fourteen databases will be searched from inception until February 2018. We will include randomized controlled trials (RCTs) testing any type of DLH decoction. All RCTs investigating DLH decoction or modified DLH decoction will be included. The methodological quality of the RCTs will be evaluated using the Cochrane's risk of bias assessment tool.

ETHICS AND DISSEMINATION

The full systematic review will be published in a peer-reviewed journal. The review will also be disseminated electronically and in print. Updates of the review will be conducted to inform and guide healthcare practice and policy.

TRIAL REGISTRATION NUMBER

PROSPERO 2017 CRD42017079189.