How is Hearing Impairment Connected to Reduction of Cognitive Function?

Do you have hearing loss? If yes, do you sometimes find that it feels like work just to understand what the people around you are saying? This is a sensation that happens even to those wearing hearing aids, because in order for them to perform well you have to have them tuned and adjusted correctly, and then become accustomed to using them.

This common phenomenon may impact more than your hearing; it might also influence your memory and your cognitive abilities. The latest studies have indicated that there is a solid relationship between hearing loss and your chance of contracting Alzheimer’s and dementia.

One of these research studies, conducted at Johns Hopkins School of Medicine, followed 639 people ages 36 to 90, for a period of sixteen years. The data showed that 58 study participants – 9 percent – had developed dementia and 37 – 6% of the total – had developed Alzheimer’s disease. Moreover, the more significant their degree of hearing impairment, the higher was the likelihood of developing dementia; for every 10 decibels of hearing loss, the odds of dementia went up 20 percent.

In a similar study, surveying 1,984 participants, scientists found a similar association between hearing loss and dementia, but they also noted that the hearing-impaired suffered measurable decreases in their cognitive capabilities. The hearing-impaired individuals showed memory loss and reduced thinking capacity 40 percent faster than individuals with normal hearing. An even more startling finding in each of the two research studies was that the connection between hearing loss and dementia held true even if the participants used hearing aids.

Several hypotheses have been put forth to explain this seeming relationship between hearing loss and loss of cognitive performance. Researchers have coined the term cognitive overload in association with one particular hypothesis. The cognitive overload hypothesis states that the hearing-impaired person expends so much brain energy working to hear, that the brain is tired and has a diminished capacity to comprehend and absorb verbal information. This can lead to social isolation, which has been linked to dementia risk in other studies. 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 individual with hearing loss probably finds these study results dismaying, there is a good side with important lessons to be extracted from them.For people who wear hearing aids, it is important to have your aids tuned and re-programmed on a consistent basis. You shouldn’t make you brain work harder than it needs to work in order to hear. The less you strain to hear, the more cognitive power your brain has in reserve to understand what is said, and remember it. Also, if the 2 conditions are linked, early detection of hearing impairment may eventually lead to interventions that could prevent dementia.

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