Age Related Hearing Loss and normal ageing

In our weekly lab meeting an undergraduate gave a presentation about some really interesting work on imaging the cochleae of mice with age related hearing loss (ARHL). He presented some whopping (but true) statistics about how most people by the age of 80 suffer from hearing loss and this instigated an interesting discussion. Doesn’t that make ARHL a part of normal ageing? Needless to say it’s not often discussed in the audiology community because many people know the answer, but after a quick on-line search I realised that it’s a question that isn’t appropriately addressed.

ARHL is a sensorineural hearing loss, meaning it’s a hair cell and neural pathology. Annoyingly, there are about eighteen other pathologies1) that you have to exclude before reaching a differential diagnosis (in theory). If you manage to strip all of these away, there’s additional murkiness: a very large chance of co-morbidities, meaning that you get ARHL combined with other problems like tinnitus. Furthermore, whilst trying to grasp the concept of ARHL, people then find correlations with age *duh* and effects of gender, medication, lifestyle and noise exposure, and begin wondering whether ARHL was simply designed as a vast stew pot of older people with hearing loss.

I can’t hear you so it must be ARHL

 Martin Burton spells it out for us: With advancing age, it is normal for hearing to deteriorate and this is termed ‘presbyacusis’ – it is not a disease, rather the term acknowledges the association between ageing and hearing loss. 2)

So I guess it highlights a distinction that people need to learn to make when working in this field: whether you are working on presbyacusis or ARHL. To answer the initial question, ARHL is not a part of normal ageing – presbyacusis is. ARHL is a further departure from the wear-and-tear of old age. Statistics about the sheer number of people touched by hearing loss are impressive but in this case we needed to look deeper than the ones used for fundraisers and impressive opening sentences. There is an entire spectrum within the large body of people who will have a hearing loss by the age of 80 and those with a larger hearing loss than what is expected with presbyacusis could be the ones with ARHL. It’s these people who may have genetic predispositions, amongst other things, that cause the additional shift from normal hearing.

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1. ototoxic drugs, vestibular schwannoma, neurofibromatosis, otosclerosis, osteogenesis imperfecta, Paget’s disease, chronic otitis media, noise, Meniere’s disease, syphilis, ear injury, head injury, barotrauma, blast injury, perilymph fistula, infections, immunological AND it could always just be idiopathic
2. Burton M (2009). Acquired sensorineural hearing loss. In: Graham J L, Baguley D M (eds). Ballantyne’s Deafness 7th edition. Wiley/Blackwell, Oxford.