Interplay between Nutrition and Hearing Loss: State of Art

Hearing loss has been recently ranked as the fifth leading cause of years lived with disability, ahead of many other chronic diseases such as diabetes, dementia, or chronic obstructive pulmonary disease. Moreover, according to the World Health Organization, moderate-to-profound hearing loss affects about 466 million people worldwide. Its incidence varies in each population segment, affecting approximately 10% of children and increasing to 30% of the population over 65 years. However, hearing loss receives still very limited research funding and public awareness. This sensory impairment is caused by genetic and environmental factors, and among the latter, the nutritional status has acquired relevance due its association to hearing loss detected in recent epidemiological studies. Several experimental models have proved that the onset and progression of hearing loss are closely linked to the availability of nutrients and their metabolism. Here, we have reviewed studies focused on nutrient effects on auditory function. These studies support the potential of nutritional therapy for the protection against hearing loss progression, which is especially relevant to the aging process and related quality of life.

Prevalence, adverse health, and risk factors in association with sensory impairments: data from a prospective cohort study of older Japanese

Sensory impairments, mainly of vision and hearing, are prevalent among the older adults, and are the leading causes of disability in people aged 60 years and above around the world. However, epidemiological data on sensory impairments (prevalence, association with adverse health outcomes, risk and preventive factors, etc.) in community-dwelling older people are sparse in Japan. Using data from the Kurabuchi Study, a community-based prospective cohort study of adults aged 65 years or older, the author and colleagues estimated the prevalence of sensory impairments in this population. Vision and hearing impairments were associated with adverse health outcomes, such as depressive symptoms, dependence in activities of daily living, and early death. In addition, antioxidants, sunlight exposure, hyperglycaemia, and nutritional status were identified as possible risk or preventive factors for vision and/or hearing impairments. Further research is needed into whether the maintenance or improvement of sensory functions contributes to the extension of disability-free life expectancy.

Relationships of Community and Individual Level Social Capital with Activities of Daily Living and Death by Gender

This study determined whether there is an association between social capital and a composite outcome of decline in Activities of Daily Living (ADL) and death by gender. A prospective 3.5 year cohort study was conducted in a rural town in Japan. The study participants were 984 individuals aged 65 years and older with not impaired on ADL at 2010 baseline survey. Social participation and generalized trust were measured as social capital. The individual level responses were dichotomized and aggregated into the community level (eight areas). Multilevel logistic regression adjusting for covariates revealed that social participation at the individual level was significantly associated with higher odds of composite outcome (OR of “not participate” = 1.97, 95% CI = 1.38–2.81). Regarding generalized trust, only in men, there was an inverse association at the community level (OR of “low” = 0.55, 95% CI = 0.32–0.96), and a positive association at the individual level (OR of “tend to be careful” = 2.22, 95% CI = 1.27–3.90). These results suggest that social capital were associated with a decline in ADL and death and that the association may differ by gender.

Markers of Overall Nutritional Status and Incident Hearing Impairment in Community-Dwelling Older Japanese: The Kurabuchi Study

OBJECTIVES

To examine the association between four markers of overall nutritional status (a serum biomarker (albumin) and three anthropometric indices (body mass index (BMI), midarm circumference (MAC), calf circumference (CC))) and incident hearing impairment in older Japanese adults.

DESIGN

Community-based prospective cohort study.

SETTING

Kurabuchi Town, Gunma Prefecture, Japan.

PARTICIPANTS

Individuals aged 65 and older (143 men, 195 women) without hearing impairment at baseline examination (2005-06) who participated in repeated examinations 4 years later (2009-10) (N = 338).

MEASUREMENTS

The three anthropometric indices were measured at baseline, and nephelometry was used to assess serum albumin levels. Hearing impairment was defined as failure to hear a 30-dB hearing level signal at 1 kHz and a 40-dB signal at 4 kHz in the better ear on pure-tone audiometry.

RESULTS

Over the 4-year period, 16.3% of participants developed hearing impairment. Those with lower marker values had greater risk of hearing impairment than those with higher marker values (multivariable adjusted odds ratio (aOR) = 2.18, 95% confidence interval (CI) = 1.05-4.57 for albumin ≤4.0 g/dL; aOR = 2.72, 95% CI = 1.10-6.71 for BMI <19.0 kg/m(2) ). The pattern of association showed a similar tendency for MAC and CC. Excluding obese participants did not changed the results substantially.

CONCLUSION

Further research is needed to determine whether interventions that improve markers of nutritional status may help prevent age-related hearing loss in older adults.

The consequences for human health of stratospheric ozone depletion in association with other environmental factors

Ozone depletion, climate and human health.

Dietary vitamin intake correlates with hearing thresholds in the older population: the Korean National Health and Nutrition Examination Survey

BACKGROUND

Previous animal studies have shown that vitamins may prevent age-related hearing loss. However, no concrete conclusions have been reached about the association between vitamin intake and presbycusis in humans.

OBJECTIVE

We investigated the association between dietary vitamin intake and hearing thresholds in adults between 50 and 80 y of age by using data from a large population-based survey.

DESIGN

We used data from the 2011 Korea National Health and Nutrition Examination Survey. A pure-tone audiogram and physical examination of the ear were performed, and vitamin intake was calculated by using the 24-h recall method. Data from 1910 participants were analyzed through univariate and multivariate linear regression analyses.

RESULTS

After adjustment for age, sex, smoking, and exposure to occupational and explosive noise, intake of vitamin C correlated with better hearing at midfrequency (2000 and 3000 Hz) (coefficient: -0.012; 95% CI: -0.022, -0.002). Dietary supplement use was positively associated with better hearing at all frequencies. The univariate analysis indicated that dietary intakes of retinol, riboflavin, niacin, and vitamin C were positively correlated with better hearing at most frequencies. In contrast, serum concentrations of vitamin D were associated with worse hearing at mid and high (4000 and 6000 Hz) frequencies.

CONCLUSIONS

Dietary intake of vitamin C was associated with better hearing in the older population. Because less than one-half of elderly participants in this study consumed a sufficient amount of vitamins, and vitamin intake decreased with age, we should consider proper diet counseling to prevent hearing decline.

Predictors of hearing acuity: cross-sectional and longitudinal analysis

BACKGROUND

This study aimed to identify predictors of hearing thresholds (best-ear pure-tone average at 1, 2, and 4 kHz) and hearing deterioration in order to define potential target groups for hearing screening.

METHODS

We analyzed data from the Maastricht Aging Study, a Dutch cohort (aged 24-81 years; N = 1,721) that was observed for 12 years. Mixed model analysis was used to calculate each participant's average hearing threshold deterioration rate during the follow-up period. We built ordinary least square linear regression models to predict the baseline threshold and deterioration rate. Potential predictors included in these models were age, gender, type of occupation, educational level, cardiovascular disease, diabetes, systemic inflammatory disease, hypertension, obesity, waist circumference, smoking, and physical activity level. We also examined the relationship between baseline threshold and the deterioration rate.

RESULTS

Poorer baseline thresholds were strongly associated with faster hearing deterioration. Higher age, male gender, manual occupation, and large waist circumference were statistically significantly associated with poorer baseline thresholds and faster deterioration, although the effects of occupation type and waist circumference were small.

CONCLUSIONS

This study indicates that age and gender must be taken into account when determining the target population for adult hearing screening and that the time interval between repeated screenings should be based either on age or on the hearing thresholds at the first screening.

Tinnitus preceded depressive symptoms in community-dwelling older Japanese: a prospective cohort study

OBJECTIVE

Most studies of the association between tinnitus and depression have been cross-sectional, making it difficult to draw any conclusions about the directionality of the association. This study aimed to clarify whether tinnitus precedes the development of depressive symptoms in a general older population.

METHODS

Residents of Kurabuchi Town, Gunma Prefecture, Japan (239 men, 296 women: ≥65years) without depressive symptoms were given health examinations in 2005-2006. Information on tinnitus was obtained via a questionnaire. Depressive symptoms were then assessed in a face-to-face home visit interviews carried out once in 2007 and once in 2008 according to the Geriatric Depression Scale 15-item version (GDS15).

RESULTS

Among the men, the 2.5-year incidence of depressive symptoms (GDS15≥6) was higher in those with tinnitus than in those without (20.5% vs. 9.5%). In the multi-adjusted model, tinnitus was significantly associated with an increased risk of depressive symptoms (relative risk=2.07; 95% confidence interval=1.01-4.25). Among the women, no associations were found.

CONCLUSION

In the present study, tinnitus was independently associated with the risk of depressive symptoms developing in men, but not in women. We believe primary care providers and public health staff should recognize tinnitus as a risk factor for depressive symptoms.