Early on in our journey, Mom’s PCP suggested we see an audiologist to rule out hearing loss. As it turned out, she passed the hearing test with flying colors, but that isn’t always the case. Consider how hearing problems can result in social withdrawal, which may, in turn, exacerbate cognitive decline. I’m pleased to share this guest post by Melanie Lewis of Hearing Direct.
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There are various causes that contribute to hearing loss. Many people are aware of the corollary links between noise exposure and hearing damage. Both the intensity level (noise above 85dB(A) is considered ‘harmful’) and the length of exposure time can put one’s hearing at risk.

Factors affecting the transmission of sound through the outer or middle ear are also common causes of conductive (and often temporary) hearing loss – this is largely seen in blockages of the ear canal due to wax or other foreign bodies, susceptibility to outer or middle ear infections, Eustachian tube dysfunction or previous ear surgery. Notwithstanding these examples however the most common type of hearing loss and perhaps surprisingly so, is in fact sensorineural in nature and due to natural deterioration brought about by age.

According to the Hearing Loss Association of America, 20% of adults in the USA report some degree of hearing impairment. Perhaps the most obvious sign of the extent of age related hearing loss is the statistic by John Hopkins Medicine that one in three over the age of 65 has hearing loss. Hearing loss amongst the older population does not only contribute to a reduced quality of life but may have far more sinister results with links to cognitive decline and dementia.

How We Hear

The ability to hear combines two corresponding processes, the capture and transfer of sound. When sound waves reach the end of the ear canal, it causes the eardrum to vibrate and in turn passes these vibrations through three tiny bones of the ossicular chain in the middle ear. These three bones (malleus, incus and stapes) form a bridge to transfer the energy of the sound waves from the outer section of the ear through to the fluid section of the inner ear.

A critical part of the inner ear is the cochlea, which has thousands of hair cells (cilia) that act as sensory receptors. From there and by means of the auditory nerve, the information is sent to the brain where it is translated into sound. As the body matures the number of hair cells and their quality is significantly reduced, leading to hearing loss. The body is unable to regenerate new hair cells, so resultant hearing loss is permanent. Coincidently, exposure to harmful noise, which we mentioned earlier, also damages the hair cells and leads to the same, irreversible hearing loss.

Unmanaged Hearing Loss and Dementia

Unmanaged hearing loss is likely to compromise an individual’s role in social exchange.  The dual effects of auditory fatigue, the physical exertion of trying to ‘hear’ alongside the associated embarrassment of not being able to, is often enough to cause complete withdrawal from conversation altogether. Such social exclusion often leads to cognitive decline and may, in fact have an impact on the speed at which dementia progresses. Links between hearing loss and the development of dementia have been posited from as early as 2011 and continue to do so in present studies.

Management of Hearing Loss

Whilst regeneration of the inner ear hair cells holds exciting possibilities for ‘curing’ hearing loss in the future, research is still in its infancy, and solutions for hearing loss today are still bent towards managing, rather than curing the condition.  The latest aids for hearing are designed to restore normal loudness growth by compartmentalizing the sound environment into different sound intensities and altering the gain levels accordingly.

The aim is to create sound fidelity, which is as close to ‘normal’ hearing as possible. By stimulating the residual hair cells in the cochlea of the inner ear and promoting auditory activity, it is possible that hearing aids may help to inhibit further cognitive decline and delay dementia.

Signs Of Hearing Loss

Signs of hearing loss may present symptoms from as early as 40 years, but manifest largely in the over-65 age group. There is no exact measurement for the rate of hair cell deterioration and the threshold response can vary markedly between people of the same age bracket. Common signs, indicating possible hearing impairment and which should be investigated, include:

• Difficulty hearing people around you
• Frequently asking people to repeat themselves
• Perception that people are ‘mumbling’ or speaking indistinctly
• Certain sounds seeming overly loud
• Problems hearing in noisy areas
• Problems telling apart certain sounds such as “s” or “th”
• More difficulty understanding people with higher-pitched voices
• Ringing in the ears.

As with any health concern, it is essential that you access referral from the appropriate medical healthcare provider. A simple hearing test can help to shed light on any hearing concerns you might have as well as offer the necessary rehabilitation tools to manage its effect.

Melanie Lewis is a trained hearing aid audiologist. She works for Hearing Direct, a UK-based vendor of deaf and hard of hearing assistive listening devices.