Is there a connection between hearing loss and cognitive decline?

Several studies have indicated that there is a connection between hearing loss, brain function decline, and loss of brain tissue. Brain “shrinkage” occurs as a natural part of aging, but older adults with hearing loss appear to lose brain mass at a faster rate than individuals with normal hearing.

The first study, conducted and published by researchers from Johns Hopkins and the National Institute on Aging, “adds to a growing list of health consequences associated with hearing loss, including increased risk of dementia, falls, hospitalizations, and diminished physical and mental health overall.”

A related study by the same team found that older adults with hearing loss were far more likely to experience problems with thinking and memory than individuals with normal hearing, and indicated that “hearing loss should not be considered an inconsequential part of aging. It may come with some long-term consequences to healthy brain functioning.”

Essentially, the human brain can only do so much. When forced to struggle to make sense of the world, be that reading a book or understanding the myriad sounds we hear through the course of a day, other important tasks suffer.


What We Know

While a direct one-to-one relationship has not yet been established between use of hearing aids and cognitive improvement, here is what we do know:

A prospective study of 1,984 older adults directed by Dr. Frank R. Lin of Johns Hopkins University found that those who initially had hearing loss were 24 percent more likely than their age-mates with normal hearing to experience cognitive decline within six years.

Their cognitive abilities declined up to 40 percent faster than others with normal hearing. They had greater problems with brain functions like thinking and memory, developing them on average three years earlier than people their age with normal hearing. And the more severe their hearing loss at the start of the study, the greater their cognitive loss over time.

“Older adults with hearing loss face an increased risk of dementia even when you control for diseases like diabetes and high blood pressure,” Dr. Lin said in an interview. “So we think they’re causally related.”

He suggested three ways that may explain how poor hearing and dementia are linked. One involves “cognitive load” — when you can’t hear well, the brain receives garbled signals, forcing it to work harder to derive meaning from the message.

Another mechanism may be that people who can’t hear well tend to become socially isolated, which results in diminished cognitive stimulation and cognitive loss.

Perhaps most important is a third possible explanation involving brain structure; hearing loss results in a faster rate of brain atrophy mostly over the hearing portion of the brain, which is also involved in functions like memory, learning and thinking.

At Washington University in St. Louis, Jonathan Peelle and colleagues have shown through functional M.R.I. studies that even people with mild hearing loss “recruit more of their frontal cortex,” which means that the part of the brain needed for thinking and decision-making is overworked when trying to understand speech.

“Even in young adults with clinically normal hearing,” Dr. Peelle said, “just a small decline in how well they hear engages more of their frontal cortex.” When hearing loss is advanced, studies have shown that the auditory cortex shrinks, which may diminish the brain’s ability to perform tasks other than hearing, he said.

If you are concerned that hearing loss may be having even the smallest affect on your mental sharpness – or that of someone you’re concerned about or caring for – contact Elkhart Audiology Rehab and Sharon at (574) 262-3277. Why wait?

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