Do you have hearing difficulties? If so, do you sometimes find that it feels like work just to understand what the people near you are saying? This is a sensation that happens even to those wearing hearing aids, because for them to work well you need to have them fitted and tuned properly, and then get used to wearing them.
As though that was not bad enough, it may not be just your hearing that is affected, but also cognitive functions. In the latest studies, scientists have found that hearing loss substantially raises your chances of developing Alzheimer’s and dementia.
A 16-year research study of this relationship conducted by the Johns Hopkins School of Medicine included 639 people between the ages of 36 and 90. The data showed that 58 study volunteers – 9 percent of the total – had developed dementia and 37 – 6% – had developed Alzheimer’s disease. The degree of hearing loss was positively correlated with the likelihood of developing either disorder. For every ten decibel additional hearing loss, the risk of developing dementia increased 20%.
A different study of 1,984 people, also 16 years long, demonstrated similar results connecting hearing loss and dementia. In this second research study, investigators also found degradation of cognitive capabilities among the hearing-impaired over the course of the data gathering. The hearing-impaired individuals showed reduced thinking capacity and memory loss 40 percent faster than individuals with normal hearing. A crucial, but disturbing, finding in each of the two studies was that the negative cognitive effects were not diminished by wearing hearing aids. Investigators have offered several hypotheses to explain the connection between loss of hearing and loss of cognitive ability. One of these explanations is related to the question that began this article, about needing to work harder to hear; this has been called cognitive overload. The theory is that among the hearing-impaired, the brain tires itself out so much trying to hear that it can’t concentrate on the meaning of the speech that it is hearing. The resulting lack of comprehension may cause social isolation, a factor that has been shown in other research studies to cause dementia. A second theory is that neither dementia nor hearing loss is the cause of the other, but that both are caused by an unknown mechanism that could be environmental, vascular or genetic.
Although the person with hearing impairment probably finds these study results dismaying, there is a good side with valuable lessons to be extracted from them.For those people who wear hearing aids, these outcomes serve as a reminder to see our hearing specialists regularly to keep the hearing aids properly fitted and programmed, so that we aren’t constantly straining to hear. If you don’t 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 symptoms are linked, early detection of hearing impairment may eventually lead to interventions that could delay dementia.