A Look at the Relationships Between Hearing Loss and Decline in Cognitive Function
For those of you who have suffered some type of hearing impairment, do you ever find yourself having to work very hard to understand what’s being said to you or around you? This experience of having to try to understand people is common even among people who use hearing aids, because the aids must be fitted and tuned properly to work right, and you need to become used to wearing them.
As if that was not bad news enough, it may not be just your ability to hear that is affected, but also cognitive abilities. Hearing impairment significantly increases your risk of contracting dementia or Alzheimer’s according to recent studies.
A 16-year study of this connection conducted by the Johns Hopkins School of Medicine included 639 people between the ages of 36 and 90. The researchers found that at the end of the research project, 58 of the participants (9%) had developed dementia, and 37 (5.8 percent) had been diagnosed with Alzheimer’s. The level of hearing loss was positively correlated with the probability of developing either condition. For every ten decibel additional hearing loss, the risk of developing dementia increased 20 percent.
Another 16-year study with 1,984 participants found a very similar association between hearing loss and dementia , but also found noticeable decline in cognitive abilities in the hearing-impaired. They showed loss of thinking capacity and memory 40% faster than those with normal hearing. In both studies, an even more dismal finding was that this association was not reduced by using hearing aids.
The connection between hearing impairment and loss of cognitive functions is an open area of research, but scientists have suggested a few hypotheses to explain the results seen thus far. One hypothesis is associated with the question at the beginning of this article, and has been termed cognitive overload. The theory is that among the hearing-impaired, the brain exhausts itself so much working to hear that it can’t focus on the meaning of the speech that it is hearing. Having a two-way discussion requires understanding. A lack of understanding causes conversations to break down and might bring about social isolation. Another idea is that neither hearing loss nor dementia cause the other, but that they are both linked to an as-yet-undiscovered disease mechanism – possibly vascular, possibly genetic, possibly environmental – that causes both.
While the individual with hearing impairment probably finds these study results dismaying, there is a bright side with important lessons to be derived from them.For those who wear hearing aids, it’s vital that you have your aids re-fitted and re-programmed on a regular basis. You shouldn’t make you brain work harder than it needs to work in order to hear. If you do not have to work as hard to hear, you have greater cognitive capacity to comprehend what is being said, and remember it. Also, if the two conditions are linked, early detection of hearing impairment may at some point lead to interventions that could prevent dementia.