Connections Between Decline in Cognitive Abilities and Hearing Impairment

If you have some form of hearing impairment, do you ever notice that listening to people speak is work, and that you have to try hard to understand what people are saying? This is a phenomenon that happens even to those wearing hearing aids, because in order for them to perform well you have to have them fitted and tuned properly, and then get used to using them.

As though that was not bad enough, it might not be just your ability to hear that is affected, but also cognitive functions. Hearing loss greatly raises your risk of developing dementia or Alzheimer’s according to the latest studies.

One such study was conducted by the Johns Hopkins School of Medicine on 639 participants between the ages of 36 and 90 over a period of 16 years. At the end of the research, investigators found that 58 participants (9%) had been diagnosed as suffering from dementia, and that 37 of them (5.8%) had developed Alzheimer’s disease. The degree of hearing loss was positively correlated with the odds of developing either disorder. For every ten decibel further hearing loss, the risk of developing dementia increased 20%.

In a similar study, evaluating 1,984 participants, researchers observed a similar association between hearing loss and dementia, but they also noted that the hearing-impaired experienced noticeable decreases in their cognitive capabilities. Compared to individuals with normal hearing, those with hearing impairment developed memory loss 40% faster. A crucial, but disturbing, finding in each of the two research studies was that the adverse cognitive effects were not lessen by using hearing aids. A number of hypotheses have been put forth to explain this apparent link between hearing loss and loss of cognitive ability. One explanation is related to the question at the beginning of this article, and has been termed cognitive overload. The cognitive overload theory suggests that the hearing-impaired individual expends so much brain power working to hear, that the brain tires itself out and has a reduced capacity to understand and assimilate verbal information. The resulting lack of understanding can cause social isolation, a factor that has been shown in other research studies to lead to dementia. A distinct line of thought, theorizes that dementia and hearing are not causally related to each other at all. Rather the theory states that they are both the result of a third mechanism. This unknown disorder could be genetic, environmental or vascular in nature.

However depressing these study results may seem, there are lessons to be learned from them. For those who wear hearing aids, it is crucial that you have your hearing aids tuned and re-programmed on a consistent basis. You shouldn’t make you brain work harder than it has to work in order to hear. The less energy expended in the mechanics of hearing, the more brain capacity available for comprehension. Also, if the 2 symptoms are connected, early detection of hearing impairment might eventually lead to interventions that could avoid dementia.