Corvallis Hearing Center

Audiology Clinic and Hearing Aids

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Hearing Loss and the Brain

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Frequent readers of this section are well aware that hearing loss changes the brain in ways that foster dementia. Those who have missed this news are referred to the following article (https://corvallishearing.com/hldementia)

Unfortunately, recent information suggests that well before dementia sets in there are a large series of changes that take place that make the brain function in abnormal ways (https://corvallishearing.com/congenital-deafness).

These new findings use radiographic techniques to show the numerous essential inter connections that exist between the primary and secondary auditory areas of the brain and all other parts.

These brain interconnections must be functional for people to completely comprehend spoken or written language or even maintain appropriate social behavior. To quote Dr. Kral and his colleagues, “The experienced adult brain relies on higher-order representations for generating expectations about the environment based on the context and behavioral goals. These expectations are possible since the brain has developed a meaningful representation of the world (sensory information) that is constantly updated and compared with external events. With the mature micro circuitry the auditory (area of the brain) can integrate bottom-up and top-down (sensory and intellectual) information flow. In cases of conflict between the input (from the senses) and these (memory) expectations, error signals drive plastic changes and learning. These processes require experience and a functional interareal (whole brain) and intrinsic (brain) circuitry.”

Stated differently, looking only at the auditory area of the brain is missing the point.

Knowledge of the critical importance of these inter connections brings us to an obvious question: What should we be doing to foster interconnected brain health?

Fortunately, we have research that addresses this intervention question.

First, there must be a foundation that allows for hearing the maximum number of speech sounds in individuals with hearing loss (https://corvallishearing.com/audibility).

Hearing Aid Programming Practices in Oregon: Fitting Errors and Real Ear Measurements

Depending on the level of hearing loss, this first rule mandates use of hearing aids or cochlear implants long before hearing loss becomes chronic.  Again quoting Dr. Kral and colleagues, “changes (due to hearing loss) in columnar microcircuits (deep and superficial brain connections) and interareal couplings (connections within the larger parts of the brain) limit the outcome of sensory restoration (hearing aids and/or cochlear implants) if performed late in life.

Stated differently, there is a point of no return.  The body is a habitual machine and if you let it develop bad physiological habits (untreated hearing loss) for a long period of time, these bad habits cannot be undone.

However simply obtaining timely hearing aids or cochlear implants is not enough.  These devices must be properly programmed and most are not (https://corvallishearing.com/oregon-fitting-errors)

Secondly as noted by Kral and colleagues, the individual must maintain brain stimulating, language-rich social contacts. (Use it or lose it).

To summarize, a healthy brain requires maximum audibility of speech sounds and intellectually stimulating use of those audible words.

For more in-depth discussion of this issue the reader is referred to the following summary (https://corvallishearing.com/entrain-brain).

Hearing Aids for People with Normal Hearing?

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Much research has focused on patients who self-report listening difficulties, but show normal results on the typical pure tone hearing test where you raise your hand, push a button or say “yes” when you hear the tone.

In fact, it is estimated some 26 million people in the U.S. self-report listening difficulties with normal pure tone results (see https://corvallishearing.com/hearing-difficulties for references ).

This 26 million figure would account for nearly 70% of the 37.5 million people in the U.S. who have suspected listening difficulties per the National Institutes of Health estimate.

The literature notes there are a number of auditory disorders that may not produce hearing loss as measured by pure tone testing.  These disorders include Central Auditory Processing Deficit, Auditory Neuropathy Spectrum Disorder, Cochlear Synaptosis, Hyperacusis and tinnitus to name a few.

It is not surprising then that pure tone testing popularized in the early 1940s does not address these more recently-identified auditory maladies.

In a previous article we noted several other tests are often more diagnostically revealing for the disorders listed above.  However, the question for most patients so afflicted with any of these disorders is “What can be done to treat it.”

Unfortunately, the treatment of these disorders is less clear cut than the diagnostic tests used to identify them.

In a recent article Humes (2020) made the case for use of hearing aids with many such patients who show normal pure tone test results (see https://corvallishearing.com/normal-hearing).

In the case of tinnitus (the perception of ringing, buzzing, whooshing sound or music when no sound is actually present) the hearing aid recommendation is often supported. Research has shown oftentimes the brain is essentially turning up the volume looking for sounds that are no longer as loud as they once were before the individual experienced tinnitus.  Thus, hearing aids can amplify these slightly less loud sounds back to their original volume and the perception of tinnitus in as many as 60% of patients is improved.

 

In the case of Hyperacusis (heightened sensitivity to sound, with aversive or pained reactions to normally-loud environmental sounds) this disorder is thought to result from the brain’s loudness mediating function being set at too low a volume.  As such one recommended treatment is gradual introduction of more sound oftentimes from a very low-volume hearing aid combined with counseling to calm an apprehensive patient who is already concerned about too much sound. (see https://corvallishearing.com/tinnitus for discussion).

By contrast in 260 patients with Auditory Neuropathy Spectrum Disorder, 61% of  patients reported little or no hearing aid benefit (see https://corvallishearing.com/auditory-neuropathy).

In short, successful use of hearing aids among patients self-reporting listening difficulties with normal pure tone results depends heavily on the correct diagnosis.  To quote Ghandi “A correct diagnosis is three-fourths the remedy.” It is then imperative that in-depth testing beyond the conventional pure tone examination be completed before any hearing aid recommendation is made for such patients.

Hearing Loss and the Brain: A Story of Evolution

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At times, medical knowledge moves forward in leaps and bounds. At other times such knowledge moves forward in a more gradual fashion. Such has been the case with our knowledge of the effects of hearing loss on the brain.

Seven years ago, Dr. Frank Lin of Johns Hopkins Medical University reported that hearing loss was highly associated with dementia and accelerated brain shrinkage.  At that time, our medical knowledge on this topic took a giant step forward.

Since that report, our understanding of this relationship has been more evolutionary.  For example, Drs. Glick and Sharma showed that untreated and poorly treated hearing loss results in a scrambling of brain resources.

These researchers showed improperly treated hearing loss results in inappropriate use of the frontal and prefrontal areas of the brain. Typically, these two areas of the brain are associated with memory and reasoning. However, in the case of poorly treated hearing loss, these two brain areas are used for understanding speech, lending credence to Dr. Lin’s hypothesis that hearing loss may overwork the memory and reasoning areas of the brain.

On a positive note, Glick and Sharma showed that properly fit hearing aids may reset the brain so that the auditory area is once again used for listening. Now the frontal and prefrontal brain areas can resume their normal functions.

More recently, it was discovered that hearing loss upsets the normal rhythmic pulses and interconnections the brain uses to communicate among its different functional areas.

Within the last few months, two separate reports out of Boston and Northwestern Universities showed reestablishing appropriate pulse rates among these different areas of the brain results in significant memory improvements in older people.

These studies, when considered together, suggest the possibility that properly treated hearing loss with hearing aids, perhaps combined with brain pulse resetting, may combat the devastating effects hearing loss may have on memory.

Currently, several large-scale studies are under way, examining the potential therapeutic benefit of properly fit hearing aids and brain pulse resetting on memory. In the interim, it appears medically prudent to treat hearing loss sooner rather than later, as the average delay between diagnosis of hearing loss and treatment has recently been reported to be nine years. It is no longer appropriate to view hearing loss as an inconvenience that can be ignored.

At our clinic, we are currently reviewing the records of 51 patients who have normal aided scores on the same speech in noise test shown by Glick and Sharma to signal brain resource preservation in hopes of identifying those therapeutic steps that can properly reset the brain.

Those interested in obtaining further information on this topic are invited to the monthly meeting of the Oregon Association for Better Hearing at Corvallis Good Samaritan Hospital, Conference Room B on the second Thursday of every month from 3:30 to 5:00 p.m.

Click Here for the Upcoming Seminar Information

How to Maintain Any Hearing Aid

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This is our presentation we did on August 8th, 2019.

Regardless of hearing aid brand or model there are a number of facts that you should know to maintain the hearing aids’ optimum performance.

Watch the video below to hear us discuss 12 must know items for maintaining optimum hearing aid function.

Researchers Discover Proteins That Could Soon Cure Hearing Loss

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Mouse cochlea with hair cells shown in green and auditory nerves shown in red. Credit: Doetzlhofer lab

Researchers at John Hopkins Medicine have found a pair of proteins that control when hair cells are created in the inner ear. This finding, published on June 12th, may hold the key to curing people with irreversible hearing loss.

Approximately 90% of genetic hearing loss is due to hair cell problems or auditory nerve damage. Hearing loss due to excessive loud noise exposure or viral infections damages these hair cells. Fish, amphibians, reptiles, and birds can regenerate their damaged hair cells. Humans cannot regrow their hair cells. Once our hair cells are damaged hearing loss is permanent.

Click here read more about this incredible new finding!

Corvallis Hearing Center will continue to follow this ongoing research and talk about this new finding at one of our future seminars.

Attend our FREE monthly seminar held at Good Samaritan Regional Medical Center on the second Thursday from 3:30pm – 5:00pm of every month. Click here for this month’s topic and meeting room location.

Passionate for people and community!

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The heart of Corvallis Hearing Center and the passion and purpose of Dr. Ron Leavitt is to serve the people of our community.

One of the ways we strive for this is being a part of Oregon Association for Better Hearing and offering once a month educational seminars at Good Samaritan Regional Medical Center here in Corvallis. Our hope and desire for these meetings is to arm the community with knowledge and power on hearing health and hearing options. [Read more…]

How the Aging Brain Affects Speech Understanding in Noisy Places

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In recent years the focus on hearing health care has shifted from the ears to the brain. One needs to only Google hearing loss and cognition to find dozens of articles in medical and hearing health care journals in the past few years. [Read more…]

Can Hearing Aids Unscramble the Brain?

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A recent publication from Dr. Anu Sharma and colleagues at University Colorado, Boulder showed people who achieve a normal score with their hearing aids on a difficult speech in noise test were spared the brain resource reallocation reported for her subjects who have untreated or poorly treated hearing loss, perhaps explaining the strong relationship between hearing loss and dementia as noted by Dr. Frank Lin and colleagues at Johns Hopkins. [Read more…]

Hearing Loss & Health

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Many view hearing loss as an inconsequential condition that can be ignored without serious implication. Why else would Medicare deny benefits for hearing loss evaluation and rehabilitation to those over 65? Why would people delay seeking hearing help for years? Scientific evidence no long supports this laissez-faire attitude. [Read more…]