Age-related hearing loss and its association with reactive oxygen species and mitochondrial DNA damage

Abstract

Age-related hearing loss, known as presbyacusis, is characterized by the progressive deterioration of auditory sensitivity associated with the aging process and is the leading cause of adult auditory deficiency in the USA. Presbyacusis is described as a progressive, bilateral, high-frequency hearing loss that is manifested on audiometric assessment by a moderately sloping pure tone audiogram. Approximately 23% of the population between 65 and 75 years of age, and 40% of the population older than 75 years of age are affected by this condition. It was estimated in 1980 that 11% of the population was 76 years or older and this number is expected to almost double by the year 2030. When one considers that the population over 65 years of age is experiencing the most accelerated development of hearing loss, the potential socioeconomic ramifications are staggering. Curiously, the frequency of presbyacusis varies across different societies. This discrepancy has been attributed to many factors including genetics, diet, socioeconomic factors, and environmental variables. The purpose of this article is to review the various molecular mechanisms underlying presbyacusis and to offer insights into potential methods of mitigating the effects of aging on hearing impairment Key words: aging, mitochondrial DNA mutations, presbyacusis, reactive oxygen species.

Cellular Mechanisms of Age-Related Hearing Loss

“…This suggests a key role for mtDNA mutations specifi cally in ARHL (Yamasoba et al 2007 ). In this regard, it has been estimated that nearly 70 % of patients with mitochondrial genomic disorders also display sensorineural hearing loss (Gold and Rapin 1994 ;Seidman et al 2004 ). In an animal model, 9-month-old "mtDNA mutator mice" showed a significantly greater loss of outer hair cells (OHCs) and SGNs in the basal turn of the cochlea, along with increased ABR threshold shifts, compared to age-matched controls (Kujoth et al 2005 ).…”

Comparative study of oxidative stress in individuals with and without age related hearing loss

“…More specifically, these ROS damage mitochondrial DNA (mtDNA), resulting in both the production of specific mtDNA deletions, as well as reducing the mitochondrial membrane potential. 15 However, in this study we tried to exclude the confounding variables and results obtained can be taken as the standard normal in our environment. can be used as a biomarker for the assessment of age related hearing loss.…”

Análise da percepção de um grupo de idosos a respeito de seu handicap auditivo antes e após o uso do aparelho auditivo

“…Esse fato, em geral, compromete seriamente seu processo de comunicação verbal e pode fazer com que apresentem sintomas de depressão e demência, 6 afastando-os do meio social e causando impactos profundos em suas vidas, tendo em vista a implicação direta da perda auditiva com a qualidade de vida dessa população. [7][8][9] A perda auditiva nos idosos significa mais do que diminuição da sensibilidade auditiva; é também a impossibilidade de comunicação mais efetiva, [10][11][12] que acarreta dificuldades para falar ao telefone na presença de ruídos externos, ouvir a televisão e o rádio, participar de reuniões familiares ou profissionais e conversar com mais de uma pessoa ao mesmo tempo. 13,14 Estudos 15,16 demonstram que a implantação de um programa de reabilitação auditiva e o uso de aparelhos auditivos podem minimizar essas reações psicossociais e proporcionar melhora da qualidade de vida dessas pessoas, incluindo a redução da incapacidade auditiva e da desvantagem auditiva (handicap).…”