Age Related Hearing Loss and the Link to Dementia

Age related hearing loss (or presbyacusis) shows a link between one’s age and the rate of hair cell death that occurs in the inner ear. Research has linked memory problems and unmanaged hearing loss. They have found there is a link to the progression of dementias, such as Alzheimer’s disease. This article investigates the issue in a little more depth. It also shows how the two might be linked.

How We Hear?

The process of ‘hearing’ may be described as a series of mechanical processes. The system ensures the efficient transfer of sound through the air filled outer and middle ear chambers. The sound then travels into the fluid filled inner ear.

On a very basic level the outer ear captures and funnels sound vibration. The eardrum vibrates. Which in turn enables the effective transfer of sound across the ossicular chain. This is located in the middle ear. The cochlea is located in the inner ear. It is responsible for receiving sound vibration. It converts sound into a nerve impulse. This is then transferred via the auditory nerve to the brain for re-interpretation. The receptors (tiny hair cells) enable this final process. There are thousands of these tiny hair cells, or stereocilia.

Interference in the transmission of sound will affect one’s hearing capability. The transmission can be impeded in the outer, the middle or the inner ear. When conductive losses occur this happens in the outer or middle ear. The most common cause is due to hair cell decline in the inner ear.

As the body ages, the hair cells decrease in both quantity and quality. The inability of the body to regenerate replacement cells results in permanent hearing loss. The rate of hair cell decline varies for people within the same social generation. This may be due, in part to other factors such as:

• Hereditary links
• Degrees of noise exposure
• Even use of certain ototoxic medication

It is a widely accepted reality that by the age of 70, three in every four people are affected. Loss of hearing, without intervention, is a possible cause for the progression of dementia.

Hearing Loss and Cognitive Decline

Age related hearing loss rarely leads to subtotal hearing loss. For most individuals the volume of sound is maintained . But the level of intelligibility, or clarity, is compromised. For many, this manifests in the perception that people mumble or speak indistinctly.

In cases where intervention to improve hearing is not sought, it is common to see social isolation and memory problems.

The amount of energy used to hear is both physically and psychologically challenging. A person struggles to understand the pace and tenet of speech must not be underestimated. The potential for misunderstanding what is being said leads to avoidance. People with hearing difficulty fear being mocked by others . Avoiding people is easier for many, than to consider wearing a hearing aid.

Reduced auditory stimulus and patterns of social isolation are causing concern. This is thought to contribute to the development of dementia. An article, in The Journal of the American Medical Association, recently highlighted that… untreated hearing loss contributes to dementia progressing faster.

Johns Hopkins University studies have determined that social isolation contributes to developing dementia. The study has 639 participants. Researchers found those that had hearing loss at the beginning of the study were more likely to develop dementia. In fact, the risk of developing dementia over time was believed to increase by as much as fivefold.

Managing Hearing Loss

It is important that any hearing deficit is investigated by a health professional. An initial consultation will rule out temporary causes: such as earwax blockage. It will also help to establish the general health and condition of the outer ear. Then, the hearing threshold level is assessed against a normative value. The hearing test, which is normally conducted at a private hearing center, is vital. It determines the correct means of intervention. Depending upon the extent of hearing loss, treatment maybe through hearing aid amplification. A person may also need to use of situation-specific devices. These are amplified telephones or basic lifestyle changes. While there is no cure for hearing loss there are ways of managing the condition. This enables effective communication. Techniques such as:

Facing the speaker

Being aware of the room acoustics

Limiting background noise can all help. Whether used alone or in conjunction with amplification devices.

More on Hearing Loss and Dementia

The 90 Plus Study- What we have Learned about Developing Dementia