September is World Alzheimer’s Month, a time when medical professionals, lay individuals, and large organizations come together to help spread awareness about the reality of all types of dementia. In a 2019 report by Alzheimer’s Disease International, they reported that many people around the world still wrongly believe that dementia is a normal part of the aging process.
In fact, dementia is a disease. While it cannot always be avoided, there are 12 modifiable risk factors that Lancet has identified. They estimate that almost 40% of dementia cases are caused by the following 12 conditions:
- Midlife hearing loss (8.2%)
- Secondary education not completed (7.1%)
- Smoking in later life (5.2%)
- Depression in later life (3.9%)
- Physical inactivity in later life (1.6%)
- Social isolation in later life (3.5%)
- Hypertension in middle life (1.9%)
- Diabetes in later life (1.1%)
- Obesity in middle life (0.7%)
- Excessive alcohol use in middle life (0.8%)
- Traumatic brain injury (TBI) in middle life (3.4%)
- Air pollution in later life (2.3%)
Of these 12 risk factors, hearing loss is the strongest, accounting for 8.2% of cases.
The Link Between Hearing Loss and Dementia
While it is not yet known exactly why hearing loss seems to increase the risk of dementia so significantly, the research is strong. The risk of dementia tends to increase dramatically with an increase in the severity of hearing loss.
- Mild hearing loss – Double the risk of dementia
- Moderate hearing loss – Triple the risk of dementia
- Severe hearing loss – Quintuple the risk of dementia
While this may look fatalistic, it should also be noted that having even severe hearing loss is by no means a guarantee that a person will develop dementia. If the risk of dementia is already very low, then even multiplying that risk by five could still be a very low risk.
Three Possible Explanations
Scientists are currently studying three possible ways that hearing loss may contribute to dementia.
Those with hearing loss are at a higher risk for social isolation. It may be that the social isolation that tends to accompany untreated hearing loss may contribute to the increased risk of dementia among the hearing impaired population. However, some studies have corrected for the contribution of social isolation and still found that hearing loss is, independently, associated with a higher risk of developing dementia.
Anyone with hearing loss knows that it is exhausting. Having to ask people to repeat themselves, trying to piece together sentences from bits and pieces of heard speech, and straining to catch what one person is saying when background noise is present all take their toll on the frontal cortex. Normally, sound is processed entirely in the auditory cortex and shunted directly into short term memory. But with hearing loss, we have to use more of our brain just to understand what another person is saying, while still doing all the normal work of having a conversation.
It may be that this extra strain on the brain contributes to the development of dementia, over time.
After a while, if the auditory cortex stops receiving information from the ears, it will start to atrophy. It’s not that the brain cells die, exactly, but the gray matter between them begins to dissipate, and the structure collapses. Resources are reallocated to the visual cortex. It may be that the brain’s attempt to reorganize itself in this way contributes to an increased risk of dementia.
Hearing Aids Can Help
While it has not been proven conclusively that hearing aids can help prevent the advent of cognitive decline and/or dementia, contemporary research is pointing in that direction. In one French study, older adults with profound hearing loss who were fitted with cochlear implants saw a reversal of cognitive decline after one year.
Hearing aids are likely able to help prevent dementia because they allow us to keep using our brain the way we always have. By amplifying sound, they give our brain the information it needs from our ears, and that helps keep us healthier in all sorts of ways. Those who wear hearing aids have been shown to get more physical exercise, and feel more confident, independent, and optimistic. All of that positive energy helps us get more out of life, and that translates to better health overall: physically, mentally, and neurologically.
If you or a loved one may be experiencing hearing loss, take action this World Alzheimer’s Month and make an appointment for a hearing test. Find out what hearing aids can do to improve your health, and your life!