Childhood hearing is associated with growth rates in infancy and adolescence

Differences Between Self-Reported and Objectively Measured Hearing Loss at Age 61-63 Years: The Newcastle Thousand Families Birth Cohort

PURPOSE

Hearing loss is most prevalent among older adults, yet underestimated by patients, clinicians, and research communities. This study aimed to assess the accuracy of self-reported hearing difficulties among a group of adults aged 61-63 years, against audiometric measures.

METHOD

The analysis used a sample (N = 346) of the Newcastle Thousand Families Study birth cohort. Data from audiological examinations and self-reported hearing difficulties were used to compare subjective and objective hearing. Hearing aid use was also assessed.

RESULTS

Over 40% of the participants had some level of hearing loss (n = 155, 44.8%), and 31% (n = 133) of these reported having hearing problems during subjective assessment. Only 18 (10%) of those with objectively measured hearing loss reported using hearing aids.

CONCLUSIONS

There was an inconsistency between measured and self-perceived hearing loss among adults aged 61-63 years in this cohort. The small number of hearing aid users in the cohort is a concern, in that people in this age group appear not to be getting the help they need. The data also add to the research evidence that people at this age underestimate their hearing loss.

Molecular Basic of Pharmacotherapy of Cytokine Imbalance as a Component of Intervertebral Disc Degeneration Treatment

Intervertebral disc degeneration (IDD) and associated conditions are an important problem in modern medicine. The onset of IDD may be in childhood and adolescence in patients with a genetic predisposition. With age, IDD progresses, leading to spondylosis, spondylarthrosis, herniated disc, spinal canal stenosis. One of the leading mechanisms in the development of IDD and chronic back pain is an imbalance between pro-inflammatory and anti-inflammatory cytokines. However, classical therapeutic strategies for correcting cytokine imbalance in IDD do not give the expected response in more than half of the cases. The purpose of this review is to update knowledge about new and promising therapeutic strategies based on the correction of the molecular mechanisms of cytokine imbalance in patients with IDD. This review demonstrates that knowledge of the molecular mechanisms of the imbalance between pro-inflammatory and anti-inflammatory cytokines may be a new key to finding more effective drugs for the treatment of IDD in the setting of acute and chronic inflammation.

Inflammation, epigenetics, and metabolism converge to cell senescence and ageing: the regulation and intervention

Remarkable progress in ageing research has been achieved over the past decades. General perceptions and experimental evidence pinpoint that the decline of physical function often initiates by cell senescence and organ ageing. Epigenetic dynamics and immunometabolic reprogramming link to the alterations of cellular response to intrinsic and extrinsic stimuli, representing current hotspots as they not only (re-)shape the individual cell identity, but also involve in cell fate decision. This review focuses on the present findings and emerging concepts in epigenetic, inflammatory, and metabolic regulations and the consequences of the ageing process. Potential therapeutic interventions targeting cell senescence and regulatory mechanisms, using state-of-the-art techniques are also discussed.

The genetic architecture of age-related hearing impairment revealed by genome-wide association analysis

Age-related hearing impairment (ARHI) is the most common sensory disorder in older adults. We conducted a genome-wide association meta-analysis of 121,934 ARHI cases and 591,699 controls from Iceland and the UK. We identified 21 novel sequence variants, of which 13 are rare, under either additive or recessive models. Of special interest are a missense variant in LOXHD1 (MAF = 1.96%) and a tandem duplication in FBF1 covering 4 exons (MAF = 0.22%) associating with ARHI (OR = 3.7 for homozygotes, P = 1.7 × 10-22 and OR = 4.2 for heterozygotes, P = 5.7 × 10-27, respectively). We constructed an ARHI genetic risk score (GRS) using common variants and showed that a common variant GRS can identify individuals at risk comparable to carriers of rare high penetrance variants. Furthermore, we found that ARHI and tinnitus share genetic causes. This study sheds a new light on the genetic architecture of ARHI, through several rare variants in both Mendelian deafness genes and genes not previously linked to hearing.

Growth Hormone and the Auditory Pathway: Neuromodulation and Neuroregeneration

Growth hormone (GH) plays an important role in auditory development during the embryonic stage. Exogenous agents such as sound, noise, drugs or trauma, can induce the release of this hormone to perform a protective function and stimulate other mediators that protect the auditory pathway. In addition, GH deficiency conditions hearing loss or central auditory processing disorders. There are promising animal studies that reflect a possible regenerative role when exogenous GH is used in hearing impairments, demonstrated in in vivo and in vitro studies, and also, even a few studies show beneficial effects in humans presented and substantiated in the main text, although they should not exaggerate the main conclusions.

Gender-Based Occupational Segregation and Sex Differences in Sensory, Motor, and Spatial Aptitudes

Research on sex differences in humans documents gender differences in sensory, motor, and spatial aptitudes. These aptitudes, as captured by Dictionary of Occupational Titles (DOT) codes, predict the occupational choices of men and women in the directions indicated by this research. We simulate that eliminating selection on these skills reduces the Duncan index of gender-based occupational segregation by 20 % to 23 % in 1970 and 2012, respectively. Eliminating selection on DOT variables capturing other accounts of this segregation has a smaller impact.

The Role of Insulin-Like Growth Factor 1 in the Progression of Age-Related Hearing Loss

Aging is associated with impairment of sensorial functions and with the onset of neurodegenerative diseases. As pari passu circulating insulin-like growth factor 1 (IGF-1) bioavailability progressively decreases, we see a direct correlation with sensory impairment and cognitive performance in older humans. Age-related sensory loss is typically caused by the irreversible death of highly differentiated neurons and sensory receptor cells. Among sensory deficits, age-related hearing loss (ARHL), also named presbycusis, affects one third of the population over 65 years of age and is a major factor in the progression of cognitive problems in the elderly. The genetic and molecular bases of ARHL are largely unknown and only a few genes related to susceptibility to oxidative stress, excitotoxicity, and cell death have been identified. IGF-1 is known to be a neuroprotective agent that maintains cellular metabolism, activates growth, proliferation and differentiation, and limits cell death. Inborn IGF-1 deficiency leads to profound sensorineural hearing loss both in humans and mice. IGF-1 haploinsufficiency has also been shown to correlate with ARHL. There is not much information available on the effect of IGF-1 deficiency on other human sensory systems, but experimental models show a long-term impact on the retina. A secondary action of IGF-1 is the control of oxidative stress and inflammation, thus helping to resolve damage situations, acute or made chronic by aging. Here we will review the primary actions of IGF-1 in the auditory system and the underlying molecular mechanisms.

Hearing loss in children with growth hormone deficiency

OBJECTIVE

Although insulin-like growth factor 1 (IGF-1) has been shown to be important for inner-ear development in animal models, little is known about the otologic and audiologic findings of children with growth hormone deficiency (GHD). The goal of this study is to evaluate the prevalence, type, and severity of hearing impairment in children with GHD.

METHODS

Audiologic, otologic, and demographic data were recorded for children with a diagnosis of GHD in the AudGen database. Data for each patient were selected based on the first encounter with available complete audiometric data or the first encounter with a type of hearing loss documented. The patients were then stratified by type and severity of hearing loss, and otologic issues were documented. A separate cohort comprised of children with GHD without hearing loss was compared as a control.

RESULTS

209 children with GHD met inclusion criteria. 173 (83%) of these patients had hearing loss. 79% of losses were bilateral and 21% were unilateral (309 total ears with hearing loss). 293 of the 309 ears with hearing loss had audiograms with ear-specific thresholds; 47 had conductive, 24 had sensorineural, 65 had mixed and 157 had undefined hearing loss with incomplete audiograms. Pure-tone averages (PTA) were higher among patients with mixed hearing loss compared to patients with all other loss types.

CONCLUSION

Hearing loss is prevalent in children with GHD with a predisposition to be bilateral. These findings suggest the need for increased awareness and routine hearing screening for patients with GHD. Further studies may elucidate the etiology of the hearing impairment in children with GHD to better aid pediatricians, endocrinologists, otolaryngologists and audiologists when assessing and managing these children.

Clinical Study on 136 Children with Sudden Sensorineural Hearing Loss

Background:

The prevalence of sudden sensorineural hearing loss in children (CSSNHL) is consistently increasing. However, the pathology and prognosis of CSSNHL are still poorly understood. This retrospective study evaluated clinical characteristics and possible associated factors of CSSNHL.

Methods:

One hundred and thirty-six CSSNHL patients treated in Department of Otolaryngology-Head and Neck Surgery and Institute of Otolaryngology at Chinese PLA General Hospital between July 2008 and August 2015 were included in this study. These patients were analyzed for clinical characteristics, audiological characteristics, laboratory examinations, and prognostic factors.

Results:

Among the 136 patients (151 ears), 121 patients (121 ears, 80.1%) were diagnosed with unilaterally CSSNHL, and 15 patients (30 ears, 19.9%) with bilateral CSSNHL. The complete recovery rate of CSSNHL was 9.3%, and the overall recovery rate was 37.7%. We found that initial degree of hearing loss, onset of treatment, tinnitus, the ascending type audiogram, gender, side of hearing loss, the recorded auditory brainstem response (ABR), and distortion product otoacoustic emissions (DPOAEs) had prognostic significance. Age, ear fullness, and vertigo had no significant correlation with recovery. Furthermore, the relevant blood tests showed 30.8% of the children had abnormal white blood cell (WBC) counts, 22.1% had elevated homocysteine levels, 65.8% had high alkaline phosphatase (ALP), 33.8% had high IgE antibody levels, and 86.1% had positive cytomegalovirus (CMV) IgG antibodies.

Conclusions:

CSSNHL commonly occurs unilaterally and results in severe hearing loss. Initial severe hearing loss and bilateral hearing loss are negative prognostic factors for hearing recovery, while positive prognostic factors include tinnitus, gender, the ascending type audiogram, early treatment, identifiable ABR waves, and DPOAEs. Age, vertigo, and ear fullness are not correlated with the recovery. Some serologic indicators, including the level of WBC, platelet, homocysteine, ALP, positive CMV IgG antibody, fibrinogen, and some immunologic indicators, are closely related to CSSNHL.

The effect of childhood infection on hearing function at age 61 to 63 years in the newcastle thousand families study

Objectives:

It is known that childhood hearing function can become impaired after the occurrence of specific infections. However, evidence on the effect of common childhood infections on adult hearing function is limited. The objective of the study was to identify whether associations exist between the occurrence of common childhood infections in a UK birth cohort and hearing function across different frequencies at age 61 to 63 years.

Design:

The Newcastle Thousand Families study is a birth cohort of all individuals born in May and June 1947 to mothers resident in Newcastle upon Tyne, United Kingdom. Of the original cohort members who had an audiometry test at age 61 to 63 years, 333 had data available on infections during their first year of life and 296 on infections up to their fifth year of life. These data were analyzed using linear regression in relation to adult hearing function across differing frequencies in isolation.

Results:

After adjustment for sex, overcrowding in the first year, having had an ear operation, and having worked in a loud environment, significant negative associations were identified between adult hearing and tonsillitis at 250 Hz (p = 0.013), 1 kHz (p = 0.018), 6 kHz (p = 0.012), and 8 kHz (p = 0.033); otorrhea at 4 kHz (p = 0.005), 6 kHz (p = 0.003), and 8 kHz (p = 0.002); bronchitis (two or more episodes) at 2 kHz (p = 0.001), 3 kHz (p = 0.005), 4 kHz (p = 0.009), 6 kHz (p < 0.001), and 8 kHz (p < 0.001); and the total number of severe respiratory infections in the first year at 2 kHz (p = 0.037), 3 kHz (p = 0.049), 4 kHz (p = 0.030), 6 kHz (p < 0.001), and 8 kHz (p = 0.006). That is, individuals who had tonsillitis, bronchitis (twice or more), otorrhea, or a severe respiratory infection (twice or more) in their first year of life were more likely to have impaired adult hearing function than those who did not have any infections in early life.

Conclusion:

The occurrence of some, but not all, childhood infections appears to have an effect on adult hearing function across different frequencies. Reducing the incidence of infectious diseases in early life may reduce subsequent incidence of hearing impairment among adults. However, further research in modern cohorts is needed to clarify the links between infectious childhood diseases and adult hearing function.

Identifying preventable risk factors for adult hearing loss could inform interventions aimed at alleviating the burden of this disease. It is known that specific infections can impair childhood hearing function. However, evidence on common childhood infections, including those known to impair childhood hearing, and their effect on adult hearing is limited. This study found that individuals who had tonsillitis, otorrhea, or bronchitis during their first year, or a severe respiratory infection up to five years of age, were more likely to develop impaired hearing as adults across differing frequencies than individuals who had not.

Analysis of expression patterns of IGF-1, caspase-3 and HSP-70 in developing human tooth germs

AIMS

To analyze expression patterns of IGF-1, caspase-3 and HSP-70 in human incisor and canine tooth germs during the late bud, cap and bell stages of odontogenesis.

MATERIALS AND METHODS

Head areas or parts of jaw containing teeth from 10 human fetuses aged between 9th and 20th developmental weeks were immunohistochemically analyzed using IGF-1, active caspase-3 and HSP-70 markers. Semi-quantitative analysis of each marker's expression pattern was also performed.

RESULTS

During the analyzed period, IGF-1 and HSP-70 were mostly expressed in enamel organ. As development progressed, expression of IGF-1 and HSP-70 became more confined to differentiating tissues in the future cusp tip area, as well as in highly proliferating cervical loops. Few apoptotic bodies highly positive to active caspase-3 were observed in enamel organ and dental papilla from the cap stage onward. However, both enamel epithelia moderately expressed active caspase-3 throughout the investigated period.

CONCLUSIONS

Expression patterns of IGF-1, active caspase-3 and HSP-70 imply importance of these factors for early human tooth development. IGF-1 and HSP-70 have versatile functions in control of proliferation, differentiation and anti-apoptotic protection of epithelial parts of human enamel organ. Active caspase-3 is partially involved in formation and apoptotic removal of primary enamel knot, although present findings might reflect its ability to perform other non-death functions such as differentiation of hard dental tissues secreting cells and guidance of ingrowth of proliferating cervical loops.

Childhood infections, but not early life growth, influence hearing in the Newcastle thousand families birth cohort at age 14 years

Background

While current research priorities include investigations of age-related hearing loss, there are concerns regarding effects on childhood hearing, for example through increased personal headphone use. By utilising historical data, it is possible to assess what factors may have increased hearing problems in children in the past, and this may be used to inform current public health policies to protect children against hearing loss and in turn reduce the long-term burden on individuals and services that may possible evolve. The aim of this study was to investigate which factors in early life significantly impacted on hearing level in childhood using existing data from the Newcastle Thousand Families Study, a 1947 birth cohort.

Methods

Data on early life factors, including growth, socio-economic status and illness, and hearing at age 14 years were collated for a representative subset of individuals from the cohort (n = 147). Factors were assessed using linear regression analysis to identify associations with hearing thresholds.

Results

Males were found to have lower hearing thresholds at 250 Hz, 500 Hz and 1 kHz. Main analyses showed no associations between hearing thresholds and early life growth or socio-economic indicators. An increasing number of ear infections from birth to age 13 years was associated with hearing thresholds at 250Hz (p = 0.04) and 500Hz (p = 0.03), which remained true for females (p = 0.050), but not males (p = 0.213) in sex-specific analysis. Scarlet fever and bronchitis were associated with hearing thresholds at 8 kHz. After adjustment for all significant predictors at each frequency, results remained unchanged.

Conclusions

We found no associations between childhood hearing thresholds and early life growth and socio-economic status. Consistent with other studies, we found associations between childhood infections and hearing thresholds. Current public health strategies aimed at reducing childhood infections may also have a beneficial effect upon childhood hearing.

The role of insulin-like growth factor-I in the physiopathology of hearing

Insulin-like growth factor-I (IGF-I) belongs to the family of polypeptides of insulin, which play a central role in embryonic development and adult nervous system homeostasis by endocrine, autocrine, and paracrine mechanisms. IGF-I is fundamental for the regulation of cochlear development, growth, and differentiation, and its mutations are associated with hearing loss in mice and men. Low levels of IGF-I have been shown to correlate with different human syndromes showing hearing loss and with presbyacusis. Animal models are fundamental to understand the genetic, epigenetic, and environmental factors that contribute to human hearing loss. In the mouse, IGF-I serum levels decrease with aging and there is a concomitant hearing loss and retinal degeneration. In the Igf1(-/-) null mouse, hearing loss is due to neuronal loss, poor innervation of the sensory hair cells, and age-related stria vascularis alterations. In the inner ear, IGF-I actions are mediated by intracellular signaling networks, RAF, AKT, and p38 MAPK protein kinases modulate the expression and activity of transcription factors, as AP1, MEF2, FoxM1, and FoxP3, leading to the regulation of cell cycle and metabolism. Therapy with rhIGF-I has been approved in humans for the treatment of poor linear growth and certain neurodegenerative diseases. This review will discuss these findings and their implications in new IGF-I-based treatments for the protection or repair of hearing loss.

A comparative study of age-related hearing loss in wild type and insulin-like growth factor I deficient mice

Insulin-like growth factor-I (IGF-I) belongs to the family of insulin-related peptides that fulfils a key role during the late development of the nervous system. Human IGF1 mutations cause profound deafness, poor growth and mental retardation. Accordingly, Igf1^−/− null mice are dwarfs that have low survival rates, cochlear alterations and severe sensorineural deafness. Presbycusis (age-related hearing loss) is a common disorder associated with aging that causes social and cognitive problems. Aging is also associated with a decrease in circulating IGF-I levels and this reduction has been related to cognitive and brain alterations, although there is no information as yet regarding the relationship between presbycusis and IGF-I biodisponibility. Here we present a longitudinal study of wild type Igf1^+/+ and null Igf1^−/− mice from 2 to 12 months of age comparing the temporal progression of several parameters: hearing, brain morphology, cochlear cytoarchitecture, insulin-related factors and IGF gene expression and IGF-I serum levels. Complementary invasive and non-invasive techniques were used, including auditory brainstem-evoked response (ABR) recordings and in vivo MRI brain imaging. Igf1^−/− null mice presented profound deafness at all the ages studied, without any obvious worsening of hearing parameters with aging. Igf1^+/+ wild type mice suffered significant age-related hearing loss, their auditory thresholds and peak I latencies augmenting as they aged, in parallel with a decrease in the circulating levels of IGF-I. Accordingly, there was an age-related spiral ganglion degeneration in wild type mice that was not evident in the Igf1 null mice. However, the Igf1^−/− null mice in turn developed a prematurely aged stria vascularis reminiscent of the diabetic strial phenotype. Our data indicate that IGF-I is required for the correct development and maintenance of hearing, supporting the idea that IGF-I-based therapies could contribute to prevent or ameliorate age-related hearing loss.