Hearing Loss Could Pose Greater Risk to Dementia

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People who experience hearing loss could be at greater risk of memory and thinking problems later in life than those without auditory issues, research suggests.

The study focused on people who were at risk of Alzheimer’s disease, revealing that those who were diagnosed with hearing loss had a higher risk of “mild cognitive impairment” four years later.

“It’s really not mild,” said Clive Ballard, professor of age-related disease at the University of Exeter. “They are in the lowest 5 percent of cognitive performance and about 50 percent of those individuals will go on to develop dementia.”

Presented at the Alzheimer’s Association International Conference in London, researchers from the US looked at the memory and thinking skills of 783 cognitively healthy participants in late middle age, more than two-thirds of whom had at least one parent who had been diagnosed with Alzheimer’s disease.

The team carried out a range of cognitive tests on the participants over a four-year period, aimed at probing memory and mental processing, revealing that those who had hearing loss at the start of the study were more than twice as likely to be found to have mild cognitive impairment four years later than those with no auditory problems, once a variety of other risk factors were taken into account.

Taylor Fields, a PhD student at the University of Wisconsin who led the research, said that the findings suggest hearing loss could be an early warning sign that an individual might be at greater risk of future cognitive impairment – but added more research was necessary to unpick the link.

“There is something here and it should be looked into,” she said.

It is not the first study to suggest a link between hearing loss and cognitive troubles – previous research has found that the more severe hearing loss is, the greater the risk of dementia.

But it is not yet clear whether hearing loss is the result of changes linked to dementia, or whether hearing loss itself could contribute to cognitive decline. As a result, it is unclear whether treating hearing loss could mitigate against increased risk.

“Potentially it is something you can do something about, which I think makes it really important to understand better,” said Ballard.

In a separate study, researchers from Wisconsin found a link between thinking and memory difficulties, and changes to the fluency of speech. In 219 late-middle aged participants were assessed at the beginning and end of a two year period. The team found that those with early signs of mild cognitive impairment at the start of the study showed a steeper decline in fluency over the two years than those without.

A further series of studies presented at the conference focused on the link between diet and prowess at memory and thinking tasks. While all differed in the range of participants and the type of diet applied, overall the results suggest that eating healthily was linked to a lower risk of cognitive difficulties, and even a lower risk of dementia.

In one study, carried out by researchers in the US with almost 6,000 participants, scientists found that after taking into account a host of factors including smoking, physical activity, health and socioeconomic status, those who stuck best to a Mediterranean or similar diet over the course of a year were about 35 percent less likely to have low scores on cognitive tests than those who did not stick to the regime.

While the study does not show that eating badly triggers cognitive problems, and further work is needed to monitor the impact of the diet over time, Claire McEvoy – co-author of the research from the University of California San Francisco – noted that benefits of healthy eating seem to exist on a sliding scale.

“Even moderate adherence to these high-quality dietary patterns showed a protective association with cognitive function,” she said.

New Test Detects Hidden Hearing Loss

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Two researchers at UConn School of Medicine have developed a new hearing test that can identify hearing loss or deficits in some individuals considered to have normal or near-normal hearing in traditional tests.

Many adults report difficulties hearing in everyday situations, despite having their physicians or audiologists tell them that the results of their hearing tests are normal or near-normal.

“We now have a validated technique to identify ‘hidden’ hearing deficits that would likely go undetected with traditional audiograms,” says Leslie R. Bernstein, professor of neuroscience and surgery at UConn, who conducted the study with Constantine Trahiotis, emeritus professor of neuroscience and surgery.

Their newly developed hearing test measures a person’s ability to detect across-ears (binaural) changes in sounds presented at levels of loudness that are close to those experienced in normal conversations.

The binaural system plays a fundamental and predominant role in the ability to localize sounds, to understand conversation in places such as busy restaurants, and to attend to one of multiple, simultaneous sounds.

The researchers studied 31 adults ages 30 to 67 with normal or near-normal audiograms. They found that listeners who have essentially normal clinical hearing test results may exhibit substantial deficits in binaural processing. The results of the study have been published in the Journal of the Acoustic Society of America.

“Our study shows that our novel binaural hearing test can help early identify vulnerable populations of listeners, and perhaps help determine when critical interventions are warranted,” says Trahiotis.

Bernstein and Trahiotis, who have been colleagues for nearly 40 years, including 29 at UConn School of Medicine, are widely considered to be at the forefront of binaural auditory research.

Bernstein notes that acquired hearing loss from excessive noise exposure has long been known to produce significant, and sometimes debilitating, hearing deficits. The new research suggests that hearing loss may be even more widespread than was once thought.

He says experts in the field, for example, used to think that post-concert hearing loss or ear ringing was only a temporary injury that went away. But this new, mounting evidence may change expert opinion.

Hearing problems pose substantial societal and economic problems for the approximately 15 percent of American adults who report some kind of trouble hearing. Worldwide, 360 million people have disabling hearing loss, with the World Health Organization projecting that 1.1 billion teenagers and young adults are at risk of hearing loss due to the lingering effects of excessive noise from personal audio devices and loud concerts.

“Our research team has been working hard to define what normal human hearing really is,” says Trahiotis. “Greater understanding of normal hearing and the early detection of any underlying slight hearing deficits in supposed ‘normal’ listeners could help practitioners have a better chance of identifying ways to slow the progression of debilitating hearing loss in one’s lifetime, and even possibly finding future ways to restore it.”

The team’s research is funded through a $1.5 million grant by the Office of Naval Research. The U.S. Navy has a keen interest in finding new ways to protect its workforce, some of whom are known to be at high risk of noise-induced hearing loss caused by exposure to excessively loud sounds.

Study Shows Impact of Long-Term Noise Exposure

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Prolonged exposure to loud noise alters how the brain processes speech, potentially increasing the difficulty in distinguishing speech sounds, according to neuroscientists at The University of Texas at Dallas.

In a paper published in Ear and Hearing, researchers demonstrated for the first time how noise-induced hearing loss affects the brain’s recognition of speech sounds.

Noise-induced hearing loss (NIHL) reaches all corners of the population, affecting an estimated 15 percent of Americans between the ages of 20 and 69, according to the National Institute of Deafness and Other Communication Disorders (NIDCD).

Exposure to intensely loud sounds leads to permanent damage of the hair cells, which act as sound receivers in the ear. Once damaged, the hair cells do not grow back, leading to NIHL.

“As we have made machines and electronic devices more powerful, the potential to cause permanent damage has grown tremendously,” said Dr. Michael Kilgard, co-author and Margaret Fonde Jonsson Professor in the School of Behavioral and Brain Sciences. “Even the smaller MP3 players can reach volume levels that are highly damaging to the ear in a matter of minutes.”

Before the study, scientists had not clearly understood the direct effects of NIHL on how the brain responds to speech.

To simulate two types of noise trauma that clinical populations face, UT Dallas scientists exposed rats to moderate or intense levels of noise for an hour. One group heard a high-frequency noise at 115 decibels inducing moderate hearing loss, and a second group heard a low-frequency noise at 124 decibels causing severe hearing loss.

For comparison, the American Speech-Language-Hearing Association lists the maximum output of an MP3 player or the sound of a chain saw at about 110 decibels and the siren on an emergency vehicle at 120 decibels. Regular exposure to sounds greater than 100 decibels for more than a minute at a time may lead to permanent hearing loss, according to the NIDCD.

Researchers observed how the two types of hearing loss affected speech sound processing in the rats by recording the neuronal response in the auditory cortex a month after the noise exposure. The auditory cortex, one of the main areas that processes sounds in the brain, is organized on a scale, like a piano. Neurons at one end of the cortex respond to low-frequency sounds, while other neurons at the opposite end react to higher frequencies.

In the group with severe hearing loss, less than one-third of the tested auditory cortex sites that normally respond to sound reacted to stimulation. In the sites that did respond, there were unusual patterns of activity. The neurons reacted slower, the sounds had to be louder and the neurons responded to frequency ranges narrower than normal. Additionally, the rats could not tell the speech sounds apart in a behavioral task they could successfully complete before the hearing loss.

In the group with moderate hearing loss, the area of the cortex responding to sounds didn’t change, but the neurons’ reaction did. A larger area of the auditory cortex responded to low-frequency sounds. Neurons reacting to high frequencies needed more intense sound stimulation and responded slower than those in normal hearing animals. Despite these changes, the rats were still able to discriminate the speech sounds in a behavioral task.

“Although the ear is critical to hearing, it is just the first step of many processing stages needed to hold a conversation,” Kilgard said. “We are beginning to understand how hearing damage alters the brain and makes it hard to process speech, especially in noisy environments.”

Oticon Opn Offers Rechargeable Hearing Aid with Tinnitus Relief

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Hearing aids just got much more convenient. Oticon, Inc. today introduced the advantages of a rechargeable battery and on-demand tinnitus management to its Internet-connected Oticon Opn™ hearing aid. These features, among others, allow wearers to hear better all day—even in the noisiest environments—while relieving the annoyance of tinnitus and enjoying all the benefits of Internet connectivity.

Powered by Oticon’s exclusive BrainHearing™ technology, the award-winning Opn hearing aids deliver an open sound experience that improves the wearer’s ability to hear and manage multiple speakers in the most challenging environments, including restaurants, social gatherings, and public venues.

Wearers can now easily charge Opn hearing aids overnight, gaining the convenience and confidence of all-day power so they can hear better and stay connected throughout the day. All previously purchased Opn miniRITE devices can get retrofitted to be rechargeable. These hearing aids also are compatible with disposable batteries for instances when charging overnight is not possible.

New soothing tinnitus relief sounds, including popular ocean and nature sounds, provide relief for the discomfort experienced by the estimated 50 million Americans with tinnitus, or ringing in the ears. Oticon’s Tinnitus SoundSupport™ will come preloaded on all new Opn devices, and current Opn wearers can obtain it through a simple update by their local hearing care professional.

“Oticon Opn Internet-connected hearing aids have unlocked an entirely new experience for wearers who want the power of the Internet while hearing better in their daily lives,” said Sheena Oliver, Vice President of Marketing for Oticon. “Our new rechargeable solution extends that experience by providing a degree of confidence hearing aid wearers deserve. They’re also environmentally friendly. One pair of rechargeable batteries used in Opn hearing aids can save an estimated 150 to 200 disposable batteries per year. Add to this our Tinnitus SoundSupport, and we can now provide greater comfort to more hearing-impaired people than ever before.”

Oticon Opn hearing aid wearers strain less to listen, understand, and remember information. In fact, Opn hearing aids have been shown to boost speech understanding by 30 percent, while reducing listening effort by 20 percent and improving memory capacity by 20 percent.*

Understanding Age-Related Hearing Loss

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As people grow older, their ability to hear gradually decreases. This biological process leads to a sensorineural hearing disorder known as Age-Related Hearing Loss (ARHL) or Presbycusis.

Presbycusis is the third most common chronic health condition among the elderly and it usually affects both ears equally. While men develop a high-frequency hearing loss, women mostly show a low-frequency hearing loss.

Presbycusis – Causes and Effects

Tiny hair cells that line the bottom of the cochlea in our inner ear aid us in hearing. As we get older, these hair cells get damaged and gradually die, leading to presbycusis. This is a permanent disorder as the damaged hair cells do not regrow.

Additionally, some changes occur in the central auditory system due to the effects of aging. The neurons in the auditory system may reduce slowly. They also begin to age and hence accumulate an aging pigment, lipofuscin. The volume of the auditory structure becomes less compared with to that of younger, which is due to the loss of neuropil.

Although aging is the biggest factor that causes presbycusis, other factors such as high blood pressure, diabetes, medicines that are toxic to the sensory cells, smoking, long exposure to loud noise, family continuum also contribute to this condition.

Sometimes abnormalities of the outer ear or the middle ear such as the reduced function of the tympanic membrane or the three tiny bones in the middle ear can also cause ARSL.

Most of the elderly who are affected with hearing loss have a combination of both age-related hearing loss and noise-induced hearing loss.

Signs and Symptoms

As presbycusis happens very gradually, it cannot be easily recognized.

The different signs and symptoms that are associated with ARHL are as follows:

  • The sound of other people’s talk seems mumbled.
  • People start repeating dialogues for you to hear.
  • Difficulty in understanding in a noisy background.
  • Difficulty in keeping pace with group conversations.
  • Feeling a need for applying more concentration while hearing.
  • Your TV/music volume seems too loud for others.
  • Difficulty in telephone communication.
  • Difficulty in distinguishing high-pitched sounds like “s” or “th.”
  • A masculine voice seems more audible than feminine.
  • A Few sounds seem too loud and irritating.
  • Tinnitus inside the ear (a ringing/roaring/hissing sound).

Types of Presbycusis

Depending upon the part of the auditory system that gets damaged or the source of damage, presbycusis can be divided into four types, as follows:

  • Sensory Presbycusis: When individuals suddenly lose hearing in the frequency range of 4 kHz, they are diagnosed with sensory presbycusis. The organ of Corti is flattened due to the loss of sensory and supporting cells. Typically, the sensory cell degeneration happens at the basal end of the cochlea. Outer hair cells are affected first. Its damage is often associated with some amount of loss in the neural spiral ganglion cells and inner hair cell damage can lose ganglion cells. The hearing loss is progressive as the hair cell will start losing stereocilia. The neurosensorial epithelium will be modified as undifferentiated epithelium as the pillar cells are affected.
  • Neural Presbycusis: The ratio of hearing loss, in this case, is proportional to the increasing sound frequency. The damage will be caused to the first-order sensory neurons; this includes lipofuscin accumulation, and spiral ganglion neuron cell body degeneration. Abnormal transmission is possible if the myelin sheath in the auditory nerve fiber is disrupted. Speech discrimination is severely reduced due to the loss of 50% or more of cochlear neurons, affecting the quality of life of the individuals. Patients may find it difficult to hear in a noisy location and this may lead them to social isolation.
  • Metabolic Presbycusis: Hearing loss may begin at the age of 30 years and progresses gradually. The degeneration of the vascular stria may disturb the function of the ear, causing metabolic presbycusis. The hearing threshold is related to the reduced potential of the endocochlea. Women are prone to this type of hearing loss and genetics also add to this cause. There is a limited influence on speech audiometry. There will be a hearing loss of about 30–40 dB in this case.
  • Mechanical Presbycusis: This type of presbycusis happens due to the changes in the mechanical properties of the cochlea’s basilar membrane, such as thickening, especially at the basal cochlea, and showing of calcified, hyaline, or fatty deposits. Changes in the hair cells or sensory neurons do not occur here.

Mixed presbycusis and intermediate presbycusis are the other two types of ARHL. If a combination of all four main types of presbycusis happens together, it is mixed. Additionally, if the damage is microstructural in the tip links of stereocilia and mechanoelectrical transduction channels it is intermediate.

Diagnosis and treatment/rehabilitation of ARHL are the same as that of any other sensorineural hearing loss. Use of hearing aids and implants are widely used to help patients with ARHL.

U.S. Army Accepts New Hearing Protection

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The U.S. Army has accepted two 3M™ products to equip soldiers with hearing protection and auditory situational awareness. The 3M Personal Safety Division has received initial orders for more than 6,500 devices that include 3M™ PELTOR™ TEP-100 Tactical Earplug Kits and 3M™ PELTOR™ COMTAC™ III ACH Communications headsets, plus spare parts and accessories totaling more than $1.6 million. Deployment of these Tactical Communications and Protective Systems (TCAPS) is managed by PEO Soldier.

“3M supports PEO Soldier’s objective to maintain hearing protection and prevent hearing loss. These products will help soldiers be more effective in combat, and will help allow them to return home with their hearing intact,” said Shawn Gregg, U.S. Business Director, 3M Personal Safety Division.

“Our history with U.S. Special Forces, collaboration with the U.S. Army, and relationships with U.S. Military Audiologists all helped contribute to the hearing solutions we have been asked to supply,” said Doug Moses, U.S. Product Marketer for Protective Communications at 3M Personal Safety Division.

The patented 3M PELTOR TEP-100 earplugs were introduced to the market in 2014 when demand for ruggedized, stand-alone electronic “in-the-ear” hearing protection devices surfaced. 3M’s research and development team responded by designing and developing a low-cost, easy-to-use, system that could be utilized in a wide range of applications, and in remote locations. A key application was for military service members and tactical law enforcement teams requiring auditory situational awareness, as well as hearing protectors to protect against the effects of hazardous noise.

The 3M PELTOR COMTAC III ACH was originally introduced to U.S. Military forces and law enforcement tactical teams in the early 2000s. The COMTAC Headset was the first tactical communications headset to offer an environmental listening function, sometimes referred to as “Talk-Through,” which enhances the ability to locate and identify opposing forces, by allowing safe audio sounds through. The headset reduces harmful noises, which promotes increased mission effectiveness, safety and survivability. The headset utilizes a proprietary digital audio circuit to sense noise levels above the desired threshold and compress them to a safe decibel level. Additionally, weak sounds can be amplified to an audible level, to better serve team members with existing hearing loss. Now in its fourth generation, over 600,000 systems have been delivered to military forces worldwide.