Hearing Loss and Dementia Link

Scientists have discovered a possible link between two conditions that become more common as people age: hearing loss and dementia. And, apparently, the greater the hearing loss, the higher the likelihood of having dementia. But what is the exact relationship between these two conditions? Does hearing loss actually cause dementia? The reasons behind the link aren't clear just yet.

The researchers followed 639 men and women between the ages of 36 and 90 for an average of 12 years each, administering cognitive and hearing tests during that time. None of the participants had dementia at the beginning of the study.

  • Over time, 184 participants developed some degree of hearing loss.
  • Fifty-eight participants developed dementia, with about two-thirds of them suffering from Alzheimer's.

The study's authors discovered that patients with only mild hearing loss had a slight increase in dementia risk, but those whose hearing loss was moderate to severe had a much higher risk of developing dementia.

In fact, for every 10 decibels that participants could no longer hear, their risk of dementia went up by 20 percent. Overall, in the case of the study participants aged 60 and older, fully 36 percent of their risk of dementia was connected to hearing loss.

The researchers do not know if reducing hearing loss will cut down on the number of dementia cases or their severity, as the exact nature of the link between the two conditions is still a mystery. But they have several theories as to why there appears to be a connection.

  1. One is that hearing loss is caused by damage to the nerve cells that line the inside of the ear, with similar damage occurring in the nerve cells governing memory and cognitive functioning.
  2. Another is that since hearing loss can cause social isolation, people suffering from it withdraw from others and lose the brain stimulation that relationships offer.
  3. A third possibility is that hearing loss is a biological marker of aging, much as years lived are a chronological marker of aging.

Put another way, a 60-year-old with hearing loss may actually be biologically older than an 80-year-old with perfect hearing. The 60-year-old is aging faster. Since dementia risk increases dramatically with age, the 60-year-old might be expected to develop dementia while the 80-year-old stays healthy.

If you or a loved one have hearing loss, don't panic. But do be on the lookout for signs of mental decline, and certainly speak to your healthcare provider about hearing aids or surgery.

National Institutes of Health