Visceral adipose tissue is significantly associated with hearing thresholds in adult women

Research progress on the correlation between estrogen and estrogen receptor on postmenopausal sarcopenia

Estrogen is a necessary sex steroid and potent neuroprotective hormone. It plays a multifaceted role beyond the reproductive system, extending its influence to the brain, skeletal muscle, and other organs. Estrogen's role in cognition, mood, autonomic regulation, and neuroprotection involves interactions with neurotransmitters, neuromodulators in a distributed manner. Notably, the impact of estrogen on mitochondrial metabolism in skeletal muscle is particularly significant due to a unique modulated bioenergetic profiles, synaptic plasticity, and neuronal health. The deficiency of estrogen in menopause has been linked to changes in brain structure, connectivity, energy metabolism. Therewith, these are crucial factors in cognitive function and the risk of Alzheimer's diseases. Besides, it leads to endocrine and metabolic dysfunction, resulting in osteoporosis, metabolic syndrome, and a tendency toward decreased muscle mass and strength. Estrogen's influence on mitochondrial function is particularly relevant to aging, as it affects the production of ATP and the overall metabolic health of the brain. Estrogen decline in women skeletal muscle mass is usually related to sarcopenia, a prevalent disease observed in vulnerable elderly individuals. Therefore, estrogen is considered to play a crucial role in skeletal muscle homeostasis and motor ability, although the exact mechanism remains unclear. This paper reviews the literature on the impact of estrogen on postmenopausal skeletal muscle diseases and the underlying molecular mechanisms, especially in terms of mitochondrial metabolism. In summary, estrogen plays an important role in the health of skeletal muscle in postmenopausal women, and its impact on mitochondrial function and homeostasis offers potential targets for the development of new strategies to treat sarcopenia.

The Relationship Between Lower Vitamin D Levels and Hearing Loss in Older Adults

BACKGROUND AND OBJECTIVES

Age-related hearing loss (ARHL) is a sensorineural disease that is associated with a number of factors. In addition to age, sex, environment, lifestyle, and comorbidities are all known to be related to ARHL as well. The prevalence of ARHL can be reduced by controlling the adjustable factors that cause it. Vitamin D levels are strongly related to calcium metabolism, which can affect ARHL. This study aimed to investigate the association between vitamin D and ARHL.

SUBJECTS AND METHODS

A total of 1,104 subjects aged >65 years were enrolled from the fifth Korean National Health and Nutrition Examination Survey, which was conducted from 2010-2012. Every participant received both an audiological assessment and a nutritional survey. The association between ARHL and serum vitamin D concentration was analyzed using logistic regression analyses with complex sampling adjusted for confounding factors such as alcohol consumption, smoking status, mobility, and bone mineral density.

RESULTS

Our multivariable analysis revealed that males in the group with lower serum levels of vitamin D (< 20 ng/mL) had a higher prevalence of ARHL (odds ratio, 1.638, 95% confidence interval, 1.058-2.538, p=0.027).

CONCLUSIONS

This finding suggests that lower serum levels of vitamin D are associated with ARHL in the older male population.

Normal Weight Central Obesity is a Poor Prognostic Factor for Sudden Sensorineural Hearing Loss

OBJECTIVES

To investigate the role of normal weight central obesity (NWCO) in the prognosis of sudden sensorineural hearing loss (SSNHL).

METHODS

We retrospectively investigated 807 cases of SSNHL from January of 2008 to August of 2019 from the Department of Otorhinolaryngology at Kaohsiung Medical University Hospital in southern Taiwan. We analyzed the association between overweight and obesity, NWCO, and the prognosis of SSNHL. The demographic and clinical characteristics, audiometry results, and outcomes were also reviewed.

RESULTS

The nonobese (body mass index [BMI] < 24 kg/m2) and overweight and obese groups (BMI ≥ 24 kg/m2) comprised 343 (42.50%) and 464 (57.50%) patients, respectively. The favorable prognosis rates in the nonobese and the overweight and obese groups were 45.48% and 45.91%, respectively, without a significant difference (P = .9048). Multivariate logistic regression revealed that BMI (adjusted odds ratio [aOR] = 1.00, 95% CI = 0.948-1.062, P = .9165) was not significantly associated with SSNHL recovery. The normal weight noncentral obesity (NWNCO) and NWCO groups comprised 266 (77.55%) and 77 (22.45%) patients, respectively, and had favorable prognosis rates of 48.50% and 35.06%, respectively. The difference between the groups was significant (P = .0371). Multivariate logistic regression analysis revealed that NWCO (aOR = 2.51, 95% CI = 1.292-5.019, P = .0075) was significantly associated with SSNHL recovery.

CONCLUSIONS

NWCO may significantly affect the prognosis of SSNHL.

Associations Between Body Composition and Sensorineural Hearing Loss Among Adults Based on the UK Biobank

OBJECTIVE

To explore the association between body composition and sensorineural hearing loss (SNHL).

STUDY DESIGN

Cross-sectional study, prospective study and Mendelian randomization (MR) analyses.

SETTING

UK Biobank.

METHODS

This cross-sectional study included 147,296 adult participants with complete data on body composition and the speech-reception-threshold (SRT) test. We further conducted a prospective study with 129,905 participants without SNHL at baseline and followed up to 15 years to explore the association between body composition and new-onset SNHL. Multivariable logistic regression and Cox regression models were used. Subgroup analyses stratified by age and sex were performed. We further assessed the causal association between body composition and SNHL using two-sample MR analyses.

RESULTS

Our cross-sectional study revealed that fat percentage, especially leg (odds ratio [OR] 1.46, p = .029) and arm (OR 1.43, p = .004), were significant risk factors for SNHL. However, fat-free mass, especially in the arm (OR 0.27, p < .001) and leg (OR 0.58, p < .001) showed significant protective effects against SNHL, which was substantially consistent with the results of the prospective study. In addition, we found that young women with SNHL were more susceptible to body composition indicators. However, MR analyses revealed no evidence of significant causal association.

CONCLUSION

Fat percentage, especially in the leg and arm, was a significant risk factor for SNHL, whereas fat-free mass, especially in the leg and arm, had significant protective effects against SNHL, however, these associations may not be causal.

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

Age-related hearing loss affects a significant proportion of adults aged 60 years and above, with a prevalence of 65%. This condition has a negative impact on both physical and mental well-being, and while hearing interventions can help alleviate the effects of hearing loss, they cannot completely restore normal hearing or halt the progression of age-related hearing loss. Oxidative stress and inflammation have been identified as potential contributors to this condition. By addressing modifiable lifestyle risk factors that exacerbate oxidative stress, there may be an opportunity to prevent hearing loss. Therefore, this narrative review provides an overview of the major modifiable lifestyle risk factors associated with age-related hearing loss, that is, exposure to noise and ototoxic chemicals, smoking, diet, physical activity, and the presence of chronic lifestyle diseases, and offers an overview of the role of oxidative stress in the pathophysiology of this condition.

Impact of Low Skeletal Muscle Mass and Obesity on Hearing Loss in Asymptomatic Individuals: A Population-Based Study

The relationship between low muscle mass (LMM) with obesity and hearing loss has been poorly studied. We aimed to investigate the association of LMM and obesity on hearing loss in the general population. A total of 265,792 adults who underwent a hearing test and body composition analyses were included. Pre-sarcopenia was defined as having an appendicular muscle mass index <5.7 kg/m2 for women and <7.0 kg/m2 for men, and obesity as a body mass index ≥25 kg/m2, while pre-sarcopenic obesity was defined as the co-presence of LMM and obesity. Participants were divided into four groups according to the presence of pre-sarcopenia and/or obesity. The prevalence of hearing loss was 1.8% in the control, 2.5% in the pre-sarcopenia alone, 3.0% in the obesity alone, and 6.2% in the pre-sarcopenic obesity group (p < 0.001). Hearing Thresholds were the highest in the pre-sarcopenic obesity group compared with the other three groups. In multivariable-adjusted models, the risk of hearing loss was the highest in the pre-sarcopenic obesity group (odds ratio: 1.30 [95% confidence interval: 1.10−1.56]), followed by the obesity alone (1.20 [1.12−1.28]) and pre-sarcopenia alone (1.19 [1.06−1.34]) group compared with the control group (p < 0.001). Pre-sarcopenic obesity was independently associated with a higher prevalence of hearing loss, supporting pre-sarcopenic obesity itself as a risk for the decline in hearing function.

Effects of Obesity on the Auditory Function of Children and Adolescents

Introduction Childhood and adolescent obesity is associated with insulin resistance, abnormal glucose metabolism, hypertension, dyslipidemia, inflammation, liver disease, and compromised vascular function.

Objective We aimed to evaluate the effects of obesity on the auditory function and speech audiometry of children and adolescents.

Methods Subjects with a body mass index (BMI) higher than +2 standard deviation (SD) were classified as obese, and subjects with normal BMI SD were classified as the control group. Blood samples were taken for glucose, insulin, and lipid profiles following an 8-hour fasting period, and a hepatobiliary ultrasound was performed. The homeostatic model assessment for insulin resistance (HOMA-IR) was calculated. The audiological evaluation included pure-tone audiometry (PTA), speech reception threshold (SRT), and speech discrimination score (SDS).

Results The study included 100 children (50 girls) with obesity, with a mean age of 11.4 ± 2.9 years and 30 children with normal body weight, with a mean age of 11.9 ± 3.3 years. Of the children with obesity, 55% (n = 55) were found to have hyperlipidemia, 68% (n = 68) insulin resistance, and 21% (n = 21) hepatosteatosis. There were no statistically significant differences between children with obesity and the control group in terms of SDS or PTA, while SRT was found to be higher in children with obesity. There was no difference between obese children with or without hyperlipidemia, between obese children with or without insulin resistance, and between obese children with or without hepatosteatosis, according to hearing tests.

Conclusion The result of the present study indicates that children with obesity are more prone to having auditory problems than the normal population. We recommend more frequent audiological evaluations, including speech audiometry, in children and adolescents with obesity problems

Antioxidant Therapy against Oxidative Damage of the Inner Ear: Protection and Preconditioning

Oxidative stress is an important mechanism underlying cellular damage of the inner ear, resulting in hearing loss. In order to prevent hearing loss, several types of antioxidants have been investigated; several experiments have shown their ability to effectively prevent noise-induced hearing loss, age-related hearing loss, and ototoxicity in animal models. Exogenous antioxidants has been used as single therapeutic agents or in combination. Antioxidant therapy is generally administered before the production of reactive oxygen species. However, post-exposure treatment could also be effective. Preconditioning refers to the phenomenon of pre-inducing a preventative pathway by subtle stimuli that do not cause permanent damage in the inner ear. This renders the inner ear more resistant to actual stimuli that cause permanent hearing damage. The preconditioning mechanism is also related to the induction of antioxidant enzymes. In this review, we discuss the mechanisms underlying antioxidant-associated therapeutic effects and preconditioning in the inner ear.

Role of Obesity in Otorhinolaryngologic Diseases

PURPOSE OF REVIEW

Obesity is a major public health problem associated with various diseases. Improving obesity control and achieving greater patient satisfaction are critical unmet needs. Various otorhinolaryngologic diseases can have negative effects on quality of life or actual health status depending on their type. Over the past decade, the relationship between obesity and otorhinolaryngologic conditions has been investigated. The purpose of this review was to discuss the relationship between obesity and otorhinolaryngological diseases.

RECENT FINDINGS

This is a narrative review on the current state of incidence, effects, and associated mechanisms between obesity and otorhinolaryngologic diseases. In various otologic diseases, otitis media (OM) and hearing loss (HL) are associated with obesity. In rhinologic parts, chronic rhinosinusitis (CRS) and obstructive sleep apnea (OSA) were significantly associated with obesity. Most of these diseases are reported to have higher susceptibility and severity as body mass index (BMI) increases. However, the incidence of head and neck cancer (HNC) was inversely associated with obesity, especially central adiposity. The relevance of obesity in laryngopharyngeal reflux disease (LPR) and allergic rhinitis (AR) has yet to be clarified, and this remains controversial. This review provides a comprehensive overview of the current state of incidence, effects, and associated mechanisms between obesity and otorhinolaryngologic diseases. Various otorhinolaryngological diseases are related to obesity. As obesity can be a negative risk factor in these otorhinolaryngologic diseases, early diagnosis and treatment of these diseases in obese patients will be critical.

Association of Nutritional Factors with Hearing Loss

Hearing loss (HL) is a major public health problem. Nutritional factors can affect a variety of diseases, such as HL, in humans. Thus far, several studies have evaluated the association between nutrition and hearing. These studies found that the incidence of HL was increased with the lack of single micro-nutrients such as vitamins A, B, C, D and E, and zinc, magnesium, selenium, iron and iodine. Higher carbohydrate, fat, and cholesterol intake, or lower protein intake, by individuals corresponded to poorer hearing status. However, higher consumption of polyunsaturated fatty acids corresponded to better hearing status of studied subjects. In addition to malnutrition, obesity was reported as a risk factor for HL. In studies of the relationship between middle ear infection and nutrition in children, it was reported that lack of vitamins A, C and E, and zinc and iron, resulted in poorer healing status due to vulnerability to infection. These studies indicate that various nutritional factors can affect hearing. Therefore, considering that multifactorial nutritional causes are responsible, in part, for HL, provision of proper guidelines for maintaining a proper nutritional status is expected to prevent some of the causes and burden of HL.

The association between obesity, diet quality and hearing loss in older adults

BACKGROUND

With the aging population, the prevalence of age-related hearing loss will increase substantially. Prevention requires more knowledge on modifiable risk factors. Obesity and diet quality have been suggested to play a role in the etiology of age-related hearing loss. We aimed to investigate independent associations of body composition and diet quality with age-related hearing loss.

METHODS

We performed cross-sectional and longitudinal analyses (follow-up: 4.4 years) in the population-based Rotterdam Study. At baseline (2006-2014), 2,906 participants underwent assessment of body composition, diet, and hearing. Of these 2,906 participants, 636 had hearing assessment at follow-up (2014-2016). Association of body composition and of diet quality with hearing loss were examined using multivariable linear regression models.

RESULTS

Cross-sectionally, higher body mass index and fat mass index were associated with increased hearing thresholds. These associations did not remain statistically significant at follow-up. We found no associations between overall diet quality and hearing thresholds.

CONCLUSIONS

This study shows that a higher body mass index, and in particular a higher fat mass index, is related to age-related hearing loss. However, whether maintaining a healthy body composition may actually reduce the effects of age-related hearing loss in the aging population requires further longitudinal population-based research.

Evaluation of Hearing in Children with Metabolic Syndrome

Objective

The frequency of metabolic syndrome is increasing in both children and adults. In addition to metabolic complications such as obesity, hypertension, cardiovascular diseases, insulin resistance, and type 2 diabetes, metabolic syndrome may affect all systems of the body. The aim of the present study was to investigate the effect of metabolic syndrome on hearing in childhood.

Methods

A prospective, controlled study was performed on 38 obese children diagnosed with metabolic syndrome and 34 healthy children. Anthropometric measurements and biochemical studies were performed. All individuals underwent pure-tone audiometry, tympanogram, and transient evoked otoacoustic emission (TEOAE) tests. The hearing thresholds of the patients were compared with healthy volunteers.

Results

There was no significant difference in terms of age and gender between the groups (p>0.05). There was no significant difference in mean hearing levels between the groups. When frequencies were compared, significantly increased hearing threshold levels were determined at low frequencies in children with metabolic syndrome. Analysis of the TEOAE results elicited no statistically significant variation in terms of signal-to-noise ratio values, signal amplitudes, or test reproducibility values between the study groups.

Conclusion

Identification of the potential hearing losses early by means of detailed hearing examinations in children with metabolic syndrome is important. To the best of our knowledge, this is the first study to examine the effect of metabolic syndrome on hearing in this age group.

Cross-sectional epidemiology of hearing loss in Australian children aged 11-12 years old and 25-year secular trends

OBJECTIVE

In a national study of Australian children aged 11-12 years old, we examined the (1) prevalence and characteristics of hearing loss, (2) its demographic risk factors and (3) evidence for secular increases since 1990.

METHODS

This is a cross-sectional CheckPoint wave within the Longitudinal Study of Australian Children. 1485 children (49.8% retention; 49.7% boys) underwent air-conduction audiometry. Aim 1: hearing loss (≥16 decibels hearing level (dB HL)) was defined in four ways to enable prior/future comparisons: high Fletcher Index (mean of 1, 2 and 4 kHz; primary outcome relevant to speech perception), four-frequency (1, 2, 4 and 8 kHz), lower frequency (1 and 2 kHz) and higher frequency (4 and 8 kHz); aim 2: logistic regression of hearing loss by age, gender and disadvantage index; and aim 3: P for trend examining CheckPoint and reported prevalence in studies arranged by date since 1990.

RESULTS

For high Fletcher Index, the prevalence of bilateral and unilateral hearing loss ≥16 dB HL was 9.3% and 13.3%, respectively. Slight losses (16-25 dB HL) were more prevalent than mild or greater (≥26 dB HL) losses (bilateral 8.5% vs 0.8%; unilateral 12.5% vs 0.9%), and lower frequency more prevalent than higher frequency losses (bilateral 11.0% vs 6.9%; unilateral 15.4% vs 11.5%). Demographic characteristics did not convincingly predict hearing loss. Prevalence of bilateral/unilateral lower and higher frequency losses ≥16 dB HL has risen since 1990 (all P for trend <0.001).

CONCLUSIONS AND RELEVANCE

Childhood hearing loss is prevalent and has risen since 1990. Future research should investigate the causes, course and impact of these changes.

Relationships Among Factors Relevant to Abdominal Fat and Age-Related Hearing Loss

Objectives

Metabolic syndrome is related with abdominal fat and with age-related hearing loss (ARHL). In this study, we evaluated the association between a variety of factors relevant to abdominal fat (FRAs) and hearing thresholds.

Methods

We reviewed retrospectively the medical records of 2,602 subjects aged over 40 years with symmetrical sensorineural hearing loss who underwent abdominal fat computed tomography (CT) scans. Univariate and multivariate linear regression analyses were used to demonstrate the association between each FRA and hearing thresholds at low and high frequencies.

Results

Four of 5 FRAs were associated with hearing thresholds at high frequencies in males. All FRAs examined showed a relationship with hearing thresholds at low frequencies in females. Diabetes mellitus (DM) among clinical factors and visceral adipose tissue (VAT) among the 5 FRAs were the most reflective of hearing thresholds in both males and females.

Conclusion

We found that FRAs were associated with hearing loss with frequency specific characteristics according to sex and reinforced that DM and VAT is particularly an important role for hearing.

The Association Between Age-Related Hearing Impairment and Metabolic Syndrome in Korean Women: 5-Year Follow-Up Observational Study

BACKGROUND

Although several observational studies showed a relationship between various conditions of metabolic syndrome (MetS) and hearing threshold, there are no studies about longitudinal audiometric results related MetS. The aim of this study was to investigate the association between MetS and age-related hearing impairment (ARHI) through a large, average 5-year longitudinal follow-up, clinical comparative analysis.

MATERIALS AND METHODS

We recruited 1381 women older than 50 years who were enrolled in 2007 and reevaluated in 2012. They had normal or symmetrical sensorineural hearing loss. For the evaluation of the independent impact of MetS on hearing, multivariate analysis was used.

RESULTS

The average follow-up period was 5.0 ± 0.2 years. Subjects with MetS had higher hearing thresholds than subjects without MetS. The loss in high-frequency hearing (≥2000 Hz) progressed more rapidly in women with MetS over a 5-year period.

CONCLUSION

Our analysis using longitudinal and large data revealed that MetS is associated with ARHI in women 50 years and older. High-frequency hearing loss tended to be greater in women with MetS than in those without MetS at the 5-year follow-up. Therefore, older women with MetS should be followed up closely for hearing evaluation.

A narrative review of obesity and hearing loss

The comorbidities related to obesity are already extensive, but as the prevalence of obesity increases globally, so do the number of its associated conditions. The relationship between hearing impairment and obesity is a relatively recent research interest, but is significant as both conditions have the ability to substantially reduce an individual's quality of life both physically and psychologically. Obesity has a significant effect on vascular function, and this may have an impact on highly vascular organs such as the auditory system. This review aims to provide an overview of the existing literature surrounding the association between hearing loss and obesity, in order to emphasise these two highly prevalent conditions, and to identify areas of further investigation. Our literature search identified a total of 298 articles with 11 articles of relevance to the review. The existing literature in this area is sparse, with interest ranging from obesity and its links to age-related hearing impairment (ARHI) and sudden sensorineural hearing loss (SSNHL), to animal models and genetic syndromes that incorporate both disorders. A key hypothesis for the underlying mechanism for the relationship between obesity and hearing loss is that of vasoconstriction in the inner ear, whereby strain on the capillary walls due to excess adipose tissue causes damage to the delicate inner ear system. The identified articles in this review have not established a causal relationship between obesity and hearing impairment. Further research is required to examine the emerging association between obesity and hearing impairment, and identify its potential underlying mechanisms.

Secondhand Smoke is Associated with Hearing Threshold Shifts in Obese Adults

Hearing loss resulted from multiple intrinsic and extrinsic factors. Secondhand smoke (SHS) and obesity had been reported to be related to hearing loss. This study explored the possible associations of SHS and obesity with the hearing threshold. The relations between SHS and the hearing threshold in subjects from three different body mass index classes were analyzed. Our study included data from 1,961 subjects aged 20–69 years that were obtained from the National Health and Nutrition Examination Survey for the years 1999–2004. After adjusting for potential confounding factors, the subjects with the higher tertiles of serum cotinine levels tended to have higher hearing thresholds than those with the lowest tertile of serum cotinine levels (for both trends, p < 0.05). Notably, the obese subjects with the higher tertiles of serum cotinine levels had significantly higher hearing thresholds for high frequencies and low frequencies than those with the lowest tertile of serum cotinine levels (for both trends, p < 0.05). Our study showed a significant positive association between SHS exposure and hearing thresholds in the adult population, especially in obese individuals. Based on our findings, avoiding exposure to SHS, especially in obese adults, may decrease the risk of hearing loss.

Is Body Mass Index Associated With the Development of Age-Related Hearing Impairment in Koreans? The Korean National Health and Nutrition Examination Survey 2009-2012

Objectives

The aim of this study was to evaluate whether body mass index (BMI) is associated with age-related hearing loss (ARHL) in the Asian elderly population.

Methods

Data from the Korean National Health and Nutrition Examination Survey 2009–2012 were used for the analyses. The pure tones at 0.5 and 1 kHz of both ears of each subject were averaged to obtain the low-frequency, those at 2 and 3 kHz were averaged to obtain the mid-frequency, and those at 4 and 6 kHz were averaged to obtain the high-frequency. The average hearing threshold (AHT) was calculated as pure tone average at 4 frequencies in the better ear. ARHL was defined as the AHT >25 dB.

Results

Univariate analyses revealed an increase in the BMI tertile in men was associated with a decreased low-frequency threshold, while an increase in the BMI tertile in women was associated with decreased mid- and high-frequency thresholds. Multivariate analyses adjusted for confounders show no significant differences in low-, mid-, or high-frequency. There was no significant difference in the prevalence of ARHL by BMI tertiles. Linear regression analyses show no association between BMI and low-, mid-, and high-frequency or AHTs. The area under the receiver operating characteristic curve values for AHT was 0.515 in men and 0.522 in women. The logistic regression analyses showed no association between BMI and ARHL in either sex.

Conclusion

BMI is not advantageous for the prediction of ARHL. In future epidemiological studies, BMI as a covariate of obesity may be replaced by other active metabolic parameters that have better predictive ability of ARHL than BMI.

The association of obesity with hearing thresholds in women aged 18-40 years

An elevation in hearing thresholds and decrease in hearing sensitivity in adults, particularly due to aging, are quite common. Recent studies have shown that, apart from aging, various other factors also play a role in auditory changes. Studies on the association of hearing loss (HL) with obesity are limited in advanced age cases and present contradictions. In this study, the association between obesity and hearing thresholds in women aged 18-40 years has been assessed. Forty women diagnosed with obesity (mean age, 31.8 years) and 40 healthy non-obese female controls (mean age, 30.5 years) were included in this prospective study. Each subject was tested with low (250, 500, 1000 and 2000 Hz) and high (4000, 6000 and 8000 Hz) frequency audiometry. In the case and control groups, the average hearing thresholds at low frequencies were 16.03 ± 4.72 and 16.15 ± 2.72 (p = 0.885) for the right ear, respectively, and 16.15 ± 5.92 and 14.71 ± 3.18 (p = 0.180) for the left ear, respectively. The average hearing threshold levels at high frequencies were 20.70 ± 10.23 and 15.33 ± 3.87 (p = 0.003), respectively, for the right ear, and 22.91 ± 15.54 and 15.87 ± 4.35 (p = 0.007), respectively, for the left ear with statistical significance. This is the first report on the association of obesity with hearing threshold in women aged 18-40 years. We have demonstrated that obesity may affect hearing function, particularly that related to high frequencies. Hearing loss can be prevented by avoidance or control of obesity and its risk factors. Moreover, an auditory screening of obese cases at an early stage may provide early diagnosis of HL and may also contribute to their awareness in the fight against obesity.

Sarcopenia and Hearing Loss in Older Koreans: Findings from the Korea National Health and Nutrition Examination Survey (KNHANES) 2010

Age-related hearing impairment (ARHI) is becoming a more significant issue as geriatric population increases. Sarcopenia in older people is known to have a diverse health problem in various circumstances in recent studies. We assessed whether the decrease in muscle mass is related to ARHI. We used the 2010 data of the Korea National Health and Nutrition Examination Survey (KNHANES) to examine the associations between sarcopenia and ARHI. A total number of participants was 1,622 including 746 males and 876 females aged 60 years or older. Muscle mass was assessed as an appendicular skeletal muscle mass, and hearing loss was defined as the pure-tone averages (PTA) of test frequencies 0.5, 1, 2, 4 kHz at a threshold of 40 dB or higher in worse hearing side of the ear. Among 1,622 participants, 298 men and 256 women had hearing loss. Appendicular muscle mass (ASM), expressed as kg, was categorized in tertiles. In female population, after adjusting for age, smoking, drinking, amount of exercise, total body fat, education level, income level, and tinnitus, the odds ratio (OR) for hearing loss was 1.57 (95% confidence interval (CI) = 0.92–2.68) in the middle tertile and 1.79 (1.03–3.08) in the lowest tertile, compared with the highest tertile. P for trend in this model was 0.036. Controlling further for hypertension, diabetes mellitus, chronic kidney disease, and three types of noise exposure did not change the association. Larger muscle mass is associated with lower prevalence of hearing loss in elderly Korean females.

Metabolic Syndrome Is not an Independent Risk Factor for Hearing Impairment

OBJECTIVE

We aimed to investigate the association between metabolic syndrome (MS) and hearing impairment (HI) using nationally representative data from Korean adults.

DESIGN, SETTING AND PARTICIPANTS

A total of 16,799 subjects (≥19 years old; 7,170 men and 9,629 women) who underwent pure tone audiometry testing were included in the analysis. Data were obtained from the fifth Korea National Health and Nutrition Examination Survey (2010-2012). Subjects were divided into two groups according to the presence of MS.

RESULTS

Among the subjects with MS, 47% had HI. Logistic regression analysis revealed that MS was not an independent risk factor for HI, although increased fasting plasma glucose (OR 1·4, 95% CI: 1·1-1·8) was independently associated with HI. In addition, older age, male sex, very low body mass index (≤17·5 kg/m2), lower education level, smoking history, and occupational noise exposure were independently associated with HI. For low-frequency HI, independent risk factors included older age, lower educational level, lower economic status, and very low BMI (≤17·5 kg/m2). For high-frequency HI, independent risk factors included older age, male sex, lower educational level, lower economic status, increased blood pressure, lower high-density lipoprotein cholesterol, and smoking history.

CONCLUSIONS

MS itself was not an independent risk factor for HI, and, among the individual metabolic components, only increased fasting plasma glucose was independently associated with HI.

Soybean β-Conglycinin Prevents Age-Related Hearing Impairment

Obesity-related complications are associated with the development of age-related hearing impairment. β-Conglycinin (β-CG), one of the main storage proteins in soy, offers multiple health benefits, including anti-obesity and anti-atherosclerotic effects. Here, to elucidate the potential therapeutic application of β-CG, we investigated the effect of β-CG on age-related hearing impairment. Male wild-type mice (age 6 months) were randomly divided into β-CG-fed and control groups. Six months later, the body weight was significantly lower in β-CG-fed mice than in the controls. Consumption of β-CG rescued the hearing impairment observed in control mice. Cochlear blood flow also increased in β-CG-fed mice, as did the expression of eNOS in the stria vascularis (SV), which protects vasculature. β-CG consumption also ameliorated oxidative status as assessed by 4-HNE staining. In the SV, lipofuscin granules of marginal cells and vacuolar degeneration of microvascular pericytes were decreased in β-CG-fed mice, as shown by transmission electron microscopy. β-CG consumption prevented loss of spiral ganglion cells and reduced the frequencies of lipofuscin granules, nuclear invaginations, and myelin vacuolation. Our observations indicate that β-CG ameliorates age-related hearing impairment by preserving cochlear blood flow and suppressing oxidative stress.

Components of Metabolic Syndrome as Risk Factors for Hearing Threshold Shifts

Background

Hearing loss was a common, chronically disabling condition in the general population and had been associated with several inflammatory diseases. Metabolic syndrome, which was associated with insulin resistance and visceral obesity, was considered a chronic inflammatory disease. To date, few attempts had been made to establish a direct relationship between hearing loss and metabolic syndrome. The aim of the present study was to investigate the relationship between metabolic syndrome and hearing loss by analyzing the data in the reports of the National Health and Nutrition Examination Survey 1999–2004.

Methods

This study included 2100 participants aged ≤ 65 years who enrolled in the National Health and Nutrition Examination Survey (1999–2004). We examined the relationship between the presence of different features of metabolic syndrome in the participants and their pure-tone air-conduction hearing thresholds, including low-frequency and high-frequency thresholds.

Results

After adjusting for potential confounders, such as age, medical conditions, and smoking status, the participants with more components of metabolic syndrome were found to have higher hearing thresholds than those with fewer components of metabolic syndrome (p < 0.05 for a trend). The low-frequency hearing threshold was associated with individual components of metabolic syndrome, such as abdominal obesity, high blood pressure, elevated triglycerides, and a low level of high-density lipoprotein cholesterol (HDL-C) (p < 0.05 for all parameters).

Conclusions

The results indicated that the presence of a greater number of components of metabolic syndrome was significantly associated with the hearing threshold in the US adult population. Among the components of metabolic syndrome, the most apparent association was observed between low HDL and hearing loss.

Visceral Fat Area Determined Using Bioimpedance Analysis Is Associated with Hearing Loss

BACKGROUND

Visceral fat area (VFA) using bioimpedance analysis (BIA) as a simple analyzer can be used to assess VFA, which may be associated with HL. The aim of the present study was to evaluate the clinical relevance and usefulness of VFA using BIA as a predictor of HL.

PATIENTS AND METHODS

In total, 18,415 patients were recruited into our study. VFAs were measured using multi-frequency BIA. VFAs were normalized by body mass index (BMI). Participants were divided into 3 tertiles based on their VFA/BMI for both sexes. For both ears of each participant, the low-frequency (Low-Freq), mid-frequency (Mid-Freq), and high-frequency (High-Freq) values were obtained calculating the pure tone averages at 0.5 and 1 kHz, 2 and 3 kHz, and 4 and 6 kHz, respectively. The average hearing threshold (AHT) was calculated as the pure tone average at the 4 frequencies (i.e., 0.5, 1, 2, and 3 kHz). HL was defined as AHT >40 dB.

RESULTS

The VFA/BMI had the greatest AUROC among VFA, BMI, and VFA/BMI in both sexes in this study. In both univariate and multivariate analyses, VFA/BMI tertiles were associated with all 4 hearing thresholds (i.e., Low-Freq, Mid-Freq, High-Freq, and AHT). The 4 hearing thresholds were positively correlated with VFA/BMI as a continuous variable. The odds ratio for HL increased as the VFA/BMI tertile increased.

CONCLUSION

VFA/BMI was associated with hearing impairment in the Asian population. The participants with high VFA/BMI should be closely monitored for hearing impairment.

Adiponectin deficiency exacerbates age-related hearing impairment

Obesity-related disorders are closely associated with the development of age-related hearing impairment (ARHI). Adiponectin (APN) exerts protective effects against obesity-related conditions including endothelial dysfunction and atherosclerosis. Here, we investigated the impact of APN on ARHI. APN-knockout (APN-KO) mice developed exacerbation of hearing impairment, particularly in the high frequency range, compared with wild-type (WT) mice. Supplementation with APN prevented the hearing impairment in APN-KO mice. At 2 months of age, the cochlear blood flow and capillary density of the stria vascularis (SV) were significantly reduced in APN-KO mice as compared with WT mice. APN-KO mice also showed a significant increase in terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive apoptotic cells in the organ of Corti in the cochlea at 2 months of age. At the age of 6 months, hair cells were lost at the organ of Corti in APN-KO mice. In cultured auditory HEI-OC1 cells, APN reduced apoptotic activity under hypoxic conditions. Clinically, plasma APN levels were significantly lower in humans with ARHI. Multiple logistic regression analysis identified APN as a significant and independent predictor of ARHI. Our observations indicate that APN has an important role in preventing ARHI.