Association of inflammatory markers with hearing impairment: The English Longitudinal Study of Ageing

The Hearing Function and Ambulatory Blood Pressure in Older Adults

OBJECTIVE

To examine the association between hearing function, assessed with pure-tone average (PTA) of air conduction thresholds, and 24-hour ambulatory blood pressure (BP) in older adults.

STUDY DESIGN

Cross-sectional study.

SETTING

A total of 1404 community-dwelling individuals aged ≥65 years from the Seniors-ENRICA cohort were examined.

METHODS

Hearing loss was defined as PTA > 40-AudCal hearing loss decibels (dB-aHL) in the better ear for standard frequency (0.5, 1, and 2 kHz), speech frequency (0.5, 1, 2, and 4 kHz), and high frequency (3, 4, and 8 kHz). Circadian BP patterns were calculated as the percentage decline in systolic BP during the night, and participants were classified as dipper, nondipper, and riser. Ambulatory hypertension was defined as BP ≥ 130/80 mm Hg (24 hour), ≥135/85 (daytime), and ≥120/70 (nighttime) or on antihypertensive treatment. Analyses were performed with linear- and logistic-regression models adjusted for the main confounders.

RESULTS

In multivariable analyses, the PTA was associated with higher nighttime systolic BP [β coefficient per 20 dB-aHL increment standard frequency (95% confidence interval, CI): 2.41 mm Hg (0.87, 3.95); β (95% CI) per 20 dB-aHL increment speech frequency 2.17 mm Hg (0.70, 3.64)]. Among hypertensive patients, hearing loss at standard and high-frequency PTA was associated with the riser BP pattern [odds ratio: 2.01 (95% CI, 1.03-3.93) and 1.45 (1.00-2.09), respectively]; also, hearing loss at standard PTA was linked to uncontrolled nighttime BP [1.81 (1.01-3.24)].

CONCLUSION

PTA was associated with higher nighttime BP, and hearing loss with a riser BP pattern and uncontrolled BP in older hypertensives.

The emerging roles and therapeutic implications of immunosenescence-mediated inflammaging in age-related hearing loss

Age-related hearing loss (ARHL) represents one of the most prevalent chronic sensory deficits experienced by the elderly, significantly diminishing their quality of life and correlating with various medical and psychological morbidities. This condition arises from the cumulative effects of aging on the auditory system, implicating intricate interactions between genetic predispositions and environmental factors. Aging entails a progressive decline in immune system functionality, termed immunosenescence, leading to a chronic low-grade inflammation known as inflammaging. This phenomenon potentially serves as a common mechanism underlying ARHL and other age-related pathologies. Recent research suggests that rejuvenating immunosenescence could mitigate inflammaging and ameliorate age-related functional declines, offering promising insights into anti-aging therapies. Consequently, this review endeavors to elucidate the role of immunosenescence-mediated inflammaging in ARHL progression and discuss its therapeutic implications.

Lipid parameters and depression in patients with chronic tinnitus: A cross-sectional observation

BACKGROUND

Pathophysiological theories assume importance of metabolic abnormalities in patients with major depression - and possibly chronic tinnitus. Although chronic tinnitus frequently correlates with depression, links between high-density lipoprotein (HDL) and depression are uninvestigated.

METHODS

Two-hundred patients with chronic tinnitus (Mage = 55; 51% female) were examined. Serum levels of total cholesterol (TC), triglycerides (TGs), HDL, low-density lipoprotein cholesterol (LDL), non-HDL, as well as LDL/HDL and TC/HDL ratios were analysed. Questionnaires included depression subscales of the ICD-10 Symptom Rating, the Hospital Anxiety and Depression Scale (HADS_D), and the Berlin Mood Questionnaire (BSF). Multivariate analyses of covariance and linear regression models - which controlled age, tinnitus-related distress and perceived stress - investigated between-subgroup differences (p < 0.05) and linear associations between HDL indices and depression (p < 0.01).

RESULTS

HDL levels did not differ for tinnitus-symptom durations, smoking and alcohol use levels, statin or antihypertensive drug use, and body-mass indices. Relative to non-to-mildly depressed patients with chronic tinnitus, patients with moderate-to-severe depression (n = 45; 23%) had significantly lower HDL levels (d = -0.35) and higher LDL/HDL (d = 0.39) and TC/HDL ratios (d = 0.40). Across participants, HDL-levels were negatively associated with depression as measured by the HADS_D and BSF_indifference scales.

CONCLUSIONS

In keeping with general depression research, low serum HDL levels correlate with depressive symptomatology in patients with chronic tinnitus. This association may be influenced by proximal (e.g. modulations of HPA-axis activity) or distal factors (e.g. maladaptive coping behaviours) - both of which should be conceptualized within psychological stimulus-processing frameworks.

From biological aging to functional decline: Insights into chronic inflammation and intrinsic capacity

Intrinsic capacity is the sum of an individual's physical and mental capacities, which helps determine functional ability. Intrinsic capacity decline is an important predictor of adverse health outcomes and can identify individuals at higher risk of functional decline. Aging is characterized by a decrease in physiological reserves and functional abilities. Chronic inflammation, a mechanism of aging, is associated with decreased intrinsic capacity, which may mirror the broader relationship between aging and functional ability. Therefore, it is crucial for maintaining functional ability and promoting healthy aging to study the mechanisms of intrinsic capacity decline, identify easily available markers, and make targets for intervention from the perspective of chronic inflammation. We reviewed the current research on chronic inflammation, inflammation-related markers, and intrinsic capacity. To date, there is still no inflammatory markers with high specificity and sensitivity to monitor intrinsic capacity decline. Interleukin-6, C-reactive protein, and tumor necrosis factor-alpha may potentially indicate changes in intrinsic capacity, but their results with intrinsic capacity or each intrinsic capacity domain are inconsistent. Considering the variations in individual responses to changes in inflammatory markers, it may be beneficial to explore the use of multiple analytes instead of relying on a single marker. This approach could be valuable in monitoring the decline of intrinsic capacity in the future.

Association Between Hearing Impairment and Incident Depression: A Nationwide Follow-up Study

BACKGROUND

Accumulating evidence suggests that hearing impairment is associated with the onset of depression. However, large-scale epidemiological studies are required to define this association more clearly. We aimed to investigate the risk of new-onset depression in Korean older adults with and without hearing impairment.

METHODS

From the National Health Insurance Service-Senior Cohort, which is a retrospective-prospective hybrid database, we analyzed data for 254,466 older adults enrolled in the Korea National Health Insurance Service-Senior Cohort who underwent at least one health screening between 2003 and 2019. A Cox proportional hazards regression model was used to evaluate the association between hearing impairment and the risk of incident depression, which was presented as adjusted hazard ratios (aHR) with 95% confidence intervals (CIs). All participants were followed up until the date of incident depression, death, or December 31, 2019.

RESULTS

During 3,417,682 person-years of follow-up investigation, hearing impairment was associated with a higher risk of incident depression (vs. no hearing impairment) in the final adjusted model (aHR, 1.11; 95% CI, 1.01-1.21; p = 0.033). Stratified analyses revealed a significant interaction among age, hearing impairment, and the risk of depression. Participants aged <65 years had a higher risk of depression (aHR, 1.29; 95% CI, 1.12-1.50; p < 0.001) than those aged 65 or above (aHR, 1.15; 95% CI, 1.01-1.30; p = 0.032).

CONCLUSIONS

Hearing impairment is independently associated with a higher risk of depression among older adults. The prevention and treatment of hearing impairment may aid in mitigating the risk of incident depression.

LEVEL OF EVIDENCE

Level 3 Laryngoscope, 133:3144-3151, 2023.

Association of inflammatory markers with hearing loss in young adults

OBJECTIVES

To assess the correlation between inflammatory markers (IM) and hearing loss (HL) in a large cohort of apparently healthy individuals.

DESIGN

A cross sectional study.

SETTING

Tel-Aviv Medical Center (a tertiary referral center) Inflammatory Survey Participants Individuals who attended the Tel-Aviv Medical Center Inflammatory Survey (TAMCIS) for a routine annual health check.

RESULTS

Out of 2,500 individuals included in the final study cohort, 1,170 (47.3%) had some hearing impairment. Those with a hearing loss in 1 or both ears had significantly higher levels of neutrophils, lymphocytes, neutrophil-to-lymphocyte ratio, monocyte-to-lymphocyte ratio, and red blood cell counts. There was a difference between low- and high- frequencies losses associated with the inflammatory status.

CONCLUSIONS

IM levels were associated with the presence of a HL, supporting a link between inflammatory changes and hearing loss.

Analysis of Serum Inflammatory Markers in Infants Under 6 Months of Age with Non-Syndromic Moderate and Severe Hearing Loss Associated with GJB2 Gene Mutations

BACKGROUND The GJB2 gene is reported to be the main hereditary factor responsible for non-syndromic hearing impairment in infants. Several kinds of hearing loss have been linked to elevated inflammatory markers. This study aimed to evaluate serum levels of IL-2, IL-4, IL-6, IL-10, IL-17, alpha-TNF, and γ-IFN and the severity of hearing loss. MATERIAL AND METHODS Ninety newborns were divided into 3 groups: severe hearing impairment (31 infants), moderate hearing impairment (30 infants), and normal hearing (29 infants). Hearing screening was performed using otoacoustic emissions test. Mutations of the GJB2 gene were detected with Sanger sequencing. The patients had DNFB1 mutation. Seven blood inflammatory markers were tested using Cytometric Bead Array. We performed the t test to examine differences in expression of 7 inflammatory markers between sexes in the groups. The correlation between indicators within groups was studied using the Pearson correlation test. Correlation of different indicators among groups was studied using the Spearman correlation test. RESULTS When compared among the 3 groups (severe, moderate hearing impairment, and normal hearing group), we found that IL-10 had a positive correlation with the severity of GJB2-associated hearing loss, which was statistically significant (P<0.05). CONCLUSIONS This research aimed to assess the relationship of 7 serum inflammatory markers with GJB2-associated hearing loss in infants. Inflammatory marker IL-10 had a positive correlation with the severity of GJB2-associated infant hearing loss, and it might have the potential to become a future therapeutic target.

Association of diabetes mellitus with gait and falls in community-dwelling older adults: Serial mediation of vision and cognition

BACKGROUND/OBJECTIVE

Diabetes mellitus (DM) is associated with walking performance, but potential underlying mechanisms of this association remain unclear. The present study aims to disentangle the pathways linking DM to gait and falls through the serial mediation effect of vision and cognition among the older population.

METHODS

Data were taken from wave 9 (2018-2019) of the English Longitudinal Study of Aging (ELSA), including 5496 participants aged 60 years and older. DM was identified based on medical diagnosis and laboratory tests. Vision and falls were self-reported. Cognition was evaluated using questionnaire. Gait speed was measured by the "timed walking test". Serial mediation analysis was performed using Mplus 8.3.

RESULTS

DM was associated with impaired gait speed (c = 0.085, P < 0.05) and falls (c = 0.061, P < 0.05). The serial mediation model revealed that vision and cognition significantly mediated the association of DM with impaired gait speed, with 17.97% and 23.60% of the total effects explained by vision and cognition respectively, and 3.37% explained by the path through vision and then cognition. Similarly, vision and cognition significantly mediated the association of DM with falls, with 14.99% and 6.67% of the total effects explained by vision and cognition respectively, and 1.67% explained by the path through vision and then cognition.

CONCLUSIONS

These findings contribute to deeper understanding of the mechanism underlying the association of DM with walking performance. Evaluation and intervention targeted at vision and the cognition may be beneficial for improving gait or reducing falls in older adults with DM.

Allostatic load and risk of hearing impairment

Background

Methods

Results

Conclusions

•

Allostatic load captures cumulative physiological stress which has consequence for subsequent hearing function.

•

Prolonged high allostatic load was associated with risk of objectively measured hearing impairment.

•

This association is shown in nationally representative longitudinal ageing study.

Age-Related Hearing Loss: The Link between Inflammaging, Immunosenescence, and Gut Dysbiosis

This article provides a theoretical overview of the association between age-related hearing loss (ARHL), immune system ageing (immunosenescence), and chronic inflammation. ARHL, or presbyacusis, is the most common sensory disability that significantly reduces the quality of life and has a high economic impact. This disorder is linked to genetic risk factors but is also influenced by a lifelong cumulative effect of environmental stressors, such as noise, otological diseases, or ototoxic drugs. Age-related hearing loss and other age-related disorders share common mechanisms which often converge on low-grade chronic inflammation known as “inflammaging”. Various stimuli can sustain inflammaging, including pathogens, cell debris, nutrients, and gut microbiota. As a result of ageing, the immune system can become defective, leading to the accumulation of unresolved inflammatory processes in the body. Gut microbiota plays a central role in inflammaging because it can release inflammatory mediators and crosstalk with other organ systems. A proinflammatory gut environment associated with ageing could result in a leaky gut and the translocation of bacterial metabolites and inflammatory mediators to distant organs via the systemic circulation. Here, we postulate that inflammaging, as a result of immunosenescence and gut dysbiosis, accelerates age-related cochlear degeneration, contributing to the development of ARHL. Age-dependent gut dysbiosis was included as a hypothetical link that should receive more attention in future studies.

Subjective Aging and Objectively Assessed Hearing Function: A Prospective Study of Older Adults

OBJECTIVES

Subjective aging is consistently related to a range of health-related outcomes, but little is known about its relationship with sensory functioning. The present prospective study tested whether subjective age and self-perceptions of aging (SPA) are associated with objective hearing function.

METHODS

Participants were 7,085 individuals aged 50-93 years (60% women, mean = 65.15, standard deviation [SD] = 8.71) from the Health and Retirement Study. Measures of subjective age, SPA, and information on demographic factors were obtained in 2008/2010. Objective hearing function was assessed 8 years later in 2016/2018. Furthermore, potential mediating variables (C-reactive protein, body mass index, physical inactivity, and chronic conditions) were assessed in 2012/2014.

RESULTS

In regression analyses that accounted for demographic factors, older subjective age and negative SPA were associated with lower hearing acuity 8 years later. In addition, 1 SD older subjective age and negative SPA were related to a 9% and 7% higher likelihood of hearing impairment. Mediation analyses revealed that physical inactivity and chronic conditions partially mediated subjective age and SPA associations with hearing acuity. There was little evidence that the link between subjective aging and hearing was moderated by hearing aids and partial support for a moderating role of age.

DISCUSSION

This study provides new evidence that subjective aging is prospectively related to hearing function. Individuals with older subjective age or negative SPA have unfavorable behavioral and clinical profiles that explain part of their lower hearing function. Individuals' experience with their aging process is a marker of risk for impaired hearing.

The Link between Gut Dysbiosis Caused by a High-Fat Diet and Hearing Loss

This review aims to provide a conceptual and theoretical overview of the association between gut dysbiosis and hearing loss. Hearing loss is a global health issue; the World Health Organisation (WHO) estimates that 2.5 billion people will be living with some degree of hearing loss by 2050. The aetiology of sensorineural hearing loss (SNHL) is complex and multifactorial, arising from congenital and acquired causes. Recent evidence suggests that impaired gut health may also be a risk factor for SNHL. Inflammatory bowel disease (IBD), type 2 diabetes, diet-induced obesity (DIO), and high-fat diet (HFD) all show links to hearing loss. Previous studies have shown that a HFD can result in microangiopathy, impaired insulin signalling, and oxidative stress in the inner ear. A HFD can also induce pathological shifts in gut microbiota and affect intestinal barrier (IB) integrity, leading to a leaky gut. A leaky gut can result in chronic systemic inflammation, which may affect extraintestinal organs. Here, we postulate that changes in gut microbiota resulting from a chronic HFD and DIO may cause a systemic inflammatory response that can compromise the permeability of the blood-labyrinth barrier (BLB) in the inner ear, thus inducing cochlear inflammation and hearing deficits.

Pathways linking abdominal obesity to poor memory function: Explore the mediating role of hypertension and depressive symptoms

BACKGROUND

The negative effect of abdominal obesity on cognitive function has been widely reported, especially on memory function, however, it is unclear how the effect is mediated. We aim to investigate the mediating role of hypertension and depressive symptoms.

METHODS

Data were collected from wave 6 (2012-2013) of the English Longitudinal Study of Ageing (ELSA). Abdominal obesity was defined as a waist circumference (WC) ≥88cm for women and ≥102cm for men. Hypertension was determined on the basis of objective blood pressure measurement and previous physician diagnosis. Depressive symptoms were assessed with the 8-item version of the Center for Epidemiologic Studies (CESD) scale. Memory function was measured with the 10-word immediate and delayed recall tests. Baron and Kenny's causal steps and Karlson/Holm/Breen (KHB) method were used to examine the mediating effect.

RESULTS

A total of 7,448 participants aged ≥50 years were included in this study. We found a negative effect of abdominal obesity on memory function (β=-0.047, p=0.031). KHB method identified significant mediating effect of hypertension and depressive symptoms on the relationship between abdominal obesity and memory function, they explained 16.92 and 6.32% of the total effect of abdominal obesity on memory function, respectively.

LIMITATIONS

This study was limited by its cross-sectional design and possibility of residual confounding.

CONCLUSIONS

Hypertension and depressive symptoms might be possible pathways linking abdominal obesity and poor memory function, suggesting that collaborative interventions of abdominal obesity, hypertension and depressive symptoms are beneficial in maintaining memory function.

Cochlear Inflammaging in Relation to Ion Channels and Mitochondrial Functions

The slow accumulation of inflammatory biomarker levels in the body-also known as inflammaging-has been linked to a myriad of age-related diseases. Some of these include neurodegenerative conditions such as Parkinson's disease, obesity, type II diabetes, cardiovascular disease, and many others. Though a direct correlation has not been established, research connecting age-related hearing loss (ARHL)-the number one communication disorder and one of the most prevalent neurodegenerative diseases of our aged population-and inflammaging has gained interest. Research, thus far, has found that inflammatory markers, such as IL-6 and white blood cells, are associated with ARHL in humans and animals. Moreover, studies investigating ion channels and mitochondrial involvement have shown promising relationships between their functions and inflammaging in the cochlea. In this review, we summarize key findings in inflammaging within the auditory system, the involvement of ion channels and mitochondrial functions, and lastly discuss potential treatment options focusing on controlling inflammation as we age.

Macrophages in the cochlea; an immunological link between risk factors and progressive hearing loss

Macrophages are abundant in the cochlea; however, their role in hearing loss is not well understood. Insults to the cochlea, such as noise or insertion of a cochlear implant, cause an inflammatory response, which includes activation of tissue-resident macrophages. Activation is characterized by changes in macrophage morphology, mediator expression, and distribution. Evidence from other organs shows activated macrophages can become primed, whereby subsequent insults cause an elevated inflammatory response. Primed macrophages in brain pathologies respond to circulating inflammatory mediators by disproportionate synthesis of inflammatory mediators. This signaling occurs behind an intact blood-brain barrier, similar to the blood-labyrinth barrier in the cochlea. Local tissue damage can occur as the result of mediator release by activated macrophages. Damage is typically localized; however, if it is to structures with limited ability to repair, such as neurons or hair cells within the cochlea, it is feasible that this contributes to the progressive loss of function seen in hearing loss. We propose that macrophages in the cochlea link risk factors and hearing loss. Injury to the cochlea causes local macrophage activation that typically resolves. However, in susceptible individuals, some macrophages enter a primed state. Once primed, these macrophages can be further activated, as a consequence of circulating inflammatory molecules associated with common co-morbidities. Hypothetically, this would lead to further cochlear damage and loss of hearing. We review the evidence for the role of tissue-resident macrophages in the cochlea and propose that cochlear macrophages contribute to the trajectory of hearing loss and warrant further study.

Association Between Central and Peripheral Age-Related Hearing Loss and Different Frailty Phenotypes in an Older Population in Southern Italy

Importance

The association between age-related hearing loss (ARHL) and physical or cognitive frailty has been poorly explored. These associations could define new perspectives for delaying frailty-related processes in older age.

Objective

To examine whether peripheral ARHL and age-related central auditory processing disorder (CAPD) are independently associated with physical or cognitive frailty.

Design, Setting, and Participants

This cross-sectional study analyzed registry data from December 31, 2014, on 1929 older (≥65 years) participants of the Salus in Apulia Study (Southern Italy) who underwent audiologic, physical, and neuropsychological assessment. Data analysis was performed from December 12, 2019, to January 4, 2020.

Main Outcomes and Measures

Prevalence of peripheral ARHL in older individuals with physical and/or cognitive frailty and those without frailty assessed using the Fried criteria (physical) and the Mini-Mental State Examination (cognitive). Multivariable logistic regression models were used to assess associations of audiologic variables with frailty phenotype.

Results

Data from 1929 participants (mean [SD] age, 73.6 [6.3] years; 974 male [50.5%]) were eligible for the analyses. The prevalence of peripheral ARHL was higher in the physical frailty group (96 [26.6%]) than in the nonfrail group (329 [21.0%]) (difference, 5.61 percentage points; 95% CI, 0.63-10.59 percentage points) and in the cognitive frailty group (40 [38.8%]) than in the nonfrail group (385 [21.1%]) (difference, 17.75 percentage points; 95% CI, 8.2-27.3 percentage points). Age-related CAPD was more prevalent in the physical frailty group (62 [17.2%]) than in the nonfrail group (219 [14.0%]) (difference, 3.21 percentage points; 95% CI, -1.04 to 7.46 percentage points) and in the cognitive frailty group (28 [27.2%]) than in the nonfrail group (253 [13.9%]) (difference, 13.33 percentage points; 95% CI, 4.10-22.21 percentage points). In the multivariable models, age-related CAPD was associated with cognitive frailty in the fully adjusted model (odds ratio [OR], 1.889; 95% CI, 1.094-3.311). There was also an inverse association between the unitary increase in Synthetic Sentence Identification With the Ipsilateral Competitive Message scores, indicating a lower likelihood of this disorder, and cognitive frailty (OR, 0.989; 95% CI, 0.988-0.999). Peripheral ARHL was associated with cognitive frailty only in the partially adjusted model (OR, 1.725; 95% CI, 1.008-2.937).

Conclusions and Relevance

In this cross-sectional study of 1929 participants, age-related CAPD was independently associated with cognitive frailty. Whether the management of ARHL may help prevent the development of different frailty phenotypes or improve their clinical consequences should be addressed in longitudinal studies and, eventually, well-designed randomized clinical trials.

Bidirectional Association Between Depression and Hearing Loss: Evidence From the China Health and Retirement Longitudinal Study

The relationship between depression and age-related hearing loss (ARHL) is not fully understood. This study tested the bidirectional associations between clinically significant depressive symptoms (CSDSs) and ARHL in middle-aged and older adults using data from the China Health and Retirement Longitudinal Study. Among 3,418 participants free of baseline ARHL, baseline CSDS was associated with an increased odds of incident ARHL (odds ratio [OR]: 1.51). Cognitive decline, BMI, and arthritis partially mediated the longitudinal CSDS-ARHL association and explained 24% of the variance in the total effect. Among 4,921 participants without baseline CSDS, baseline ARHL was associated with an increased odds of incident CSDS (OR: 1.37). The bidirectional associations remained significant after adjustments for baseline demographic factors, comorbidities, and other health-related covariates. Depression may contribute to the development of ARHL, and vice versa. Interventions in depression, cognitive decline, and arthritis may delay the onset of ARHL and break the vicious circle between them.

Diet Quality and the Risk of Impaired Speech Reception Threshold in Noise: The UK Biobank cohort

OBJECTIVE

Previous studies have examined the association between several diet quality indexes and risk of hearing loss, based on self-reported information or on audiometry test, with inconsistent results. However, the impact of healthy diets on the capacity to listening in noise, a proxy of disability due to hearing loss, is unknown. This research assessed the prospective association between five diet quality indexes and the speech reception threshold in noise in the UK Biobank study.

DESIGN

Prospective cohort with 105,592 participants aged ≥40 years. At baseline, adherence to the Mediterranean Diet Adherence Screener, the alternate Mediterranean Diet score, the Dietary Approaches to Stop Hypertension, the Alternate Healthy Eating Index-2010, and the healthful Plant-Based Diet Index were assessed. Functional auditory capacity was measured with a digit triplet test, and impairment was defined as a speech reception threshold in noise >-3.5 dB in any physical exam during the follow-up.

RESULTS

Over a median follow-up of 3.2 (SD: 2.1) years, 1704 participants showed impaired speech reception threshold in noise. After adjusting for potential confounders, the hazard ratios (95% confidence interval) of impairment per 1-SD increase in the Mediterranean Diet Adherence Screener, alternate Mediterranean Diet score, Dietary Approaches to Stop Hypertension, Alternate Healthy Eating Index-2010 and healthful Plant-Based Diet Index scores were, respectively, 0.98 (0.94 to 1.03), 1.01 (0.96 to 1.06), 1.02 (0.97 to 1.07), 1.01 (0.96 to 1.06), and 1.00 (0.96 to 1.05). Results were similar when analyses were restricted to those >60 years, with British ethnicity, without chronic disease, without tinnitus or with optimal cognitive function.

CONCLUSIONS

Adherence to a healthy diet did not show an association with the speech reception threshold in noise. More research is needed to identify the impact of individual foods or nutrients on this outcome.

The inflammatory potential of the diet is prospectively associated with subjective hearing loss

PURPOSE

We investigated the association between the inflammatory potential of the diet and hearing loss in the context of aging.

METHODS

We studied 3435 French adults enrolled in the SU.VI.MAX 2 (2007-2009) cohort. The inflammatory potential of the diet was estimated by the Dietary Inflammatory Index (DII^®) using ≥ 3 baseline 24-h dietary records. Subjective hearing loss was assessed after a mean of 12.5 ± 0.7 years by 3 individual items (ability to carry a conversation in a noisy setting, frequently asking for repetition, and need to increase the television/radio volume) and by a composite score, dichotomized for analyses. We fit sex-specific multivariable logistic regression models.

RESULTS

Compared with males, females had higher DII scores (i.e., more pro-inflammatory diet) and less subjective hearing loss. Among males, a significant positive association between DII (continuous scale) and inability to carry a conversation in a noisy setting was found (OR = 1.10; 95% CI 1.02, 1.18), while the opposite was seen among females (OR = 0.92; 95% CI 0.87, 0.98). Regarding the need to turn up the television/radio volume, a significant positive association with DII (continuous scale) was found only among males (OR = 1.09; 95% CI 1.01, 1.18). A significant association with the subjective hearing loss composite score was found among females (OR_{Q3 vs Q1} = 0.74; 95% CI 0.57, 0.97).

CONCLUSION

The findings among males supported the hypothesis that a pro-inflammatory diet could increase risk of hearing loss, whereas the findings among females were unexpected. This study could provide impetus for future research in sensory disability and aging.

TRIAL REGISTRATION

www.clinicaltrials.gov # NCT00272428.

Exploring the genetic relationship between hearing impairment and Alzheimer's disease

INTRODUCTION

Hearing loss has been identified as the potentially largest modifiable risk factor for Alzheimer's disease (AD), estimated to account for a similar increase in AD risk as the apolipoprotein E (APOE) gene.

METHODS

We investigated the genetic relationship between hearing loss and AD, and sought evidence for a causal relationship.

RESULTS

We found a significant genetic overlap between hearing impairment and AD and a polygenic risk score for AD was able to significantly predict hearing loss in an independent cohort. Additionally, regions of the genome involved in inflammation were identified to be shared between hearing difficulty and AD. However, causality tests found no significant evidence of a causal relationship between these traits in either direction.

DISCUSSION

Overall, these results show that the relationship between hearing difficulty and AD may, in part, be due to shared genes and immune response pathways between the traits. However, currently available data do not support a causal relationship.