Hearing Loss Leads to Brain Tissue Loss in Older Adults

Hearing loss isn’t just an inconvenience—it could be harmful for your brain, too.

A new study from Johns Hopkins University and the National Institute on Aging shows that people with hearing loss have accelerated brain tissue loss. This is in addition to a higher risk of poor physical and mental health, dementia, falls, and hospitalizations.Lin

Frank Lin, Ph.D., an assistant professor at Johns Hopkins, evaluated data from the ongoing Baltimore Longitudinal Study of Aging to compare brain alterations that occurred over time in adults with normal hearing and those with an impaired sense. His research was published in Neuroimage.

According to the American Speech-Language-Hearing Association, more than 30 percent of people over the age of 65 have some type of hearing loss, and 14 percent of people between 45 and 64 do as well. Close to 8 million people between the ages of 18 and 44 have hearing loss.

How Does Hearing Loss Change the Brain?

Studies in the past have linked hearing loss to structural differences in human and animal brains. They’ve found that brains are sometimes smaller in people and animals with poor hearing.

In the Baltimore Longitudinal Study of Aging, 126 participants had yearly magnetic resonance imaging (MRI) to track brain changes for up to a decade. They also had physical exams and hearing tests.

When the study period began in 1994, 75 participants had normal hearing, and 51 had impaired hearing that included at least a 25-decibel loss. Lin found that people with hearing loss at the start of the study had quicker rates of brain atrophy than those with normal hearing.

The scientists say that people with diminished hearing lost more than an additional cubic centimeter of brain tissue each year compared to those with normal hearing. People with hearing loss also experienced more shrinkage in the superior, middle, and inferior temporal gyri—parts of the brain that process sound and speech.

Lin wasn’t surprised by that; in fact, he said it may be a result of an “impoverished” auditory cortex, which could shrink due to lack of stimulation. But those parts don’t work alone; they also play roles in memory and sensory integration. And they have been shown to be linked with the early phases of dementia and Alzheimer’s disease.

“Our results suggest that hearing loss could be another ‘hit’ on the brain in many ways,” Lin said. He urges people not to ignore possible hearing loss. If hearing loss is contributing to the differences the scientists saw on the MRI scans, it should be treated before structural brain changes occur.

Eric Smouha, M.D., an associate professor of otolaryngology at the Icahn School of Medicine at Mount Sinai in New York City, said that the new study offers more evidence that hearing loss contributes to dementia.

Time for a Hearing Test?

The American Speech-Language-Hearing Association recommends that adults be screened for hearing loss at least every decade through age 50 and at three-year intervals thereafter. A hearing test takes about 30 minutes and measures hearing sensitivity to pure tones and speech.

A first visit to an audiologist will include questions about your medical history and an ear exam with an instrument called an otoscope. The doctor will then put you through various tests that involve listening and signaling when the audiologist says to.

If you suspect hearing loss, Smouha says, you should go for audiometric testing right away and get a hearing aid if significant loss is detected.  “The study makes a good case for the concept of disuse atrophy…use it or lose it,” Smouha said.

Eric W. Healy, Ph.D., a professor of speech and hearing at Ohio State University, thinks it’s a good idea to have a screening if you think you might have some hearing loss—even the tiniest bit. “It’s not uncommon to believe that you have a ‘problem’ with your hearing,” Healy said. “It’s simple to test, and many people who believe that they have an issue actually don’t.”  If you are routinely exposed to loud noises or music, go in for a hearing screening, he said.  “A test done early can serve as a baseline for future comparison,” Healy said. “There’s little reason not to.”

#hearingloss, #dementia

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Hearing Loss Video Simulation

Below is a good YouTube video demonstrating how the progressive high frequency hearing loss can affect a person’s ability to understand speech. Notice how speech intelligibility deteriorates further and further as a person loses more and more of the high frequencies. High frequency hearing loss related to noise exposure and/or aging often progresses so slowly that the person with the impairment is not aware. Their family and friends usually notice the problem before the person with the loss. People with high frequency hearing loss will respond inappropriately because they misunderstand what is said. These people sometimes begin to withdraw from various social situations because they cannot hear properly. Significant others often think that their family member or friend may be suffering from dementia because they sometimes give a very unexpected response.

Click the link below:

YouTube Hearing Loss Simulation


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More on Hearing Loss and Dementia

The 2011 study of 639 people at Johns Hopkins found the following disturbing and direct relationship:  For each 10 decibel loss in hearing, the risk of dementia rose about 20 percent among the participants in the study. This study was conducted by otolaryngologist Frank Lin and his colleagues.

It has been estimated that more than 75% of adults with significant hearing loss do not seek professional help.Those people who do seek help have waited approximately seven years before doing anything about their hearing impairment.

It is very important to seek help as soon as the problem is detected.  Quite often, family members and friends may notice the problem first.  Hearing loss usually develops gradually and the person with the loss is unaware.  A “significant other” needs to step up and talk with the person with the impairment.  The sooner the problem is detected and dealt with the better the changes of reducing dementia.

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Hearing Loss and Dementia

According to a recent study published in the medical journal Archives of Neurology, adults with hearing loss are significantly more likely than adults with normal hearing to develop dementia. The study was conducted by researchers at Johns Hopkins and the National Institute on Aging. The study found that the greater the hearing loss the higher the risk of dementia and may open a new avenue of research into dementia and Alzheimer’s disease. Men and women in the study who experienced severe hearing loss were five times more likely to develop dementia than those with normal hearing. But even mild hearing loss doubled the risk of dementia.

The study followed 639 people ages 36 to 90 who initially did not have dementia, logic and language that interferes with daily living. The volunteers were tested for hearing loss and dementia every two years for nearly two decades.Researchers found that those with hearing loss at the beginning of the study were much more likely to develop dementia by the end, even after taking into account age and other risk factors. The risk of dementia only began to rise once hearing loss began to interfere with the ability to communicate. The study also found that hearing loss increased the risk of Alzheimer’s disease, but the two were not as strongly linked as hearing loss and dementia.

The social isolation often caused by hearing loss can aid in the development of dementia. Also, it is quite possible that auditory deprivation may be related to the increase in dementia. Auditory deprivation occurs because of inadequate stimulation of the auditory system. With auditory deprivation, a person gradually loses their ability to comprehend speech making communication even more frustrating. This is why it is important to wear hearing aids at the early onset of hearing loss to continue stimulation of the entire auditory system.

“The brain might have to reallocate resources to help with hearing at the expense of cognition,” says the lead researcher, Frank R. Lin, M.D., an ear surgeon at Johns Hopkins Hospital in Baltimore. That may explain in part why straining to hear conversations over background noise in a loud restaurant can be mentally exhausting for anyone, hard of hearing or not, he adds.

The findings suggest that poor hearing is a “harbinger of impending dementia,” says George Gates, M.D., a hearing expert at the University of Washington in Seattle, who was not involved in the new study but whose own research has demonstrated a link between the two conditions.”We listen with our ears but hear with our brains,” Gates says. “It is simply not possible to separate audition and cognition.

“Lin says that hearing loss has an enormous impact on the lives of his patients and their family members. “Yet because it is such a slow and insidious process, it is often left ignored and untreated.

“There is no cure for dementia, and there are no surefire ways of preventing it. Gates isn’t optimistic that restoring hearing can affect the course of dementia. However, if treatments and prevention strategies for dementia do become available in the future, he says, hearing loss could play an important role in early detection.

Lin and his colleagues have begun researching the effect of hearing aids on the risk of dementia. “Whether or not it can help dementia, we don’t know yet,” he says. “But in the meantime, there’s no reason not to take your hearing loss seriously and pursue some type of treatment.”

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