Tag: hearing loss

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Chemo Drug may Cause Significant Hearing Loss in Longtime Cancer Survivors   

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Photo by Brett Sayles

An interdisciplinary study led by researchers at the University of South Florida and Indiana University has uncovered significant findings on the long-term effects of one of the most common forms of chemotherapy on cancer survivors.

Published in JAMA Oncology, the study tracked a cohort of testicular cancer survivors who received cisplatin-based chemotherapy. The team followed the patients for an average of 14 years, revealing that 78% experience significant difficulties in everyday listening situations, negatively impacting their quality of life. This collaborative research is the first to measure real-world listening challenges and hearing loss progression in cancer survivors over a long period of time.

“It’s important that we understand the real-world effects of patients’ sensory problems and if we can understand that, then we can develop better therapeutic strategies and preventive measures to improve the long-term quality of life for cancer survivors,” said Robert Frisina, distinguished university professor and chair of the USF Department of Medical Engineering.

Cisplatin is commonly used in chemotherapy treatments for a variety of cancers, including bladder, lung, neck and testicular. It is administered intravenously and affects various parts of the body. However, the ears are particularly vulnerable as they have little ability to filter out the drug, causing it to become trapped. This leads to inflammation and the destruction of sensory cells that are critical for coding sound, causing permanent hearing loss that can progressively get worse well after cisplatin treatments are completed.

Lead author Victoria Sanchez, associate professor in the USF Health Department of Otolaryngology Head & Neck Surgery, said that despite the known risks, there’s a nationwide lack of routine hearing assessments for patients undergoing chemotherapy. “Most patients still do not get their hearing tested prior to, during or after chemotherapy. Our study highlights the need for regular auditory evaluations to manage and mitigate long-term hearing damage.”

The research team found higher doses of cisplatin led to more severe and progressing hearing loss, especially in patients with risk factors, such as high blood pressure and poor cardiovascular health. They also experienced increased difficulty hearing in common environments, such as a loud restaurant.

“It will be critically important to follow these patients for life. Their current median age is only 48 years, and eventually they will enter the years at which age-related hearing loss also begins to develop,” said Dr. Lois B. Travis, Lawrence H. Einhorn Professor of Cancer Research at Indiana University School of Medicine and a researcher at the IU Melvin and Bren Simon Comprehensive Cancer Center. This research is part of The Platinum Study, an ongoing research effort led by Dr. Travis and funded by the National Cancer Institute to study cisplatin-treated testicular cancer survivors.

The hope is that this study will inspire further investigation into alternative chemotherapeutic protocols and preventive measures, such as FDA-approved drugs to prevent or reduce hearing loss.

“This research gives oncologists the information they need to explore alternative treatment plans that could reduce the long-term side effects, such as altering the dosages and timing of the cisplatin in the treatment, when that could be an appropriate option,” Frisina said.

Innovative solutions, such as Pedmark, a new FDA-approved injection that mitigates cisplatin-induced hearing loss in children, represent promising steps forward, according to Frisina.

“We want to protect our hearing or treat a hearing loss if hearing damage occurs,” Sanchez said. “Hearing allows us to connect to the world we love. Staying connected through conversations with family and friends, enjoyment of music and entertainment, staying safe and finding pleasure in our vibrant surroundings. Promoting optimal hearing for overall wellness is essential for healthy living.”

According to the American Cancer Society, in addition to cisplatin, other platinum chemotherapy drugs, such as carboplatin, cause damage to the cochlea in the inner ear and lead to hearing loss. The risk of damage is greater with higher doses of chemotherapy.

Source: University of San Francisco

Categories : ENT PaediatricsTags :

Earbuds and Headphone Exposure Creating Noise Health Risks for Children

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Photo by Emily Wade on Unsplash

While it’s not surprising to spot teens wearing headphones and earbuds, it’s also becoming a widespread trend among younger children, a national poll suggests. Two in three parents say their child ages five to 12 uses personal audio devices, with half of parents of children ages five to eight reporting elementary-aged kids use a device.

Among parents whose children use headphones and earbuds, half say kids spend at least an hour a day using them. One in six say their child typically uses them for at least two hours, according to University of Michigan’s C.S. Mott Children’s Hospital National Poll on Children’s Health.

“Over recent years we’ve mostly been concerned about teens overusing audio devices. But earbuds have become increasingly popular and prevalent among younger kids, exposing them to more intense noise on a regular basis,” said Susan Woolford, MD, MPH, Mott paediatrician and co-director of the poll.

“Noise exposure risks to young children have historically involved loud singular events like concerts or fireworks, but parents may underestimate the potential harm from excessive use of listening devices. It may be difficult to know whether their child’s exposure to noise is healthy.”

Children are most likely to use these devices at home, school and in the car, report findings show. About a fourth of parents also say children occasionally use audio devices on airplanes while less than 10% say kids use them on the bus, outside or in bed.

Half of parents agree that headphones or earbuds help keep their child entertained.

The American Academy of Pediatrics released a statement in 2023 on the need to reduce noise risks to children, with increasing evidence that children and teens may be more exposed through personal listening devices.

Prolonged or extreme exposure to high volumes of noise can result in long term health issues, including hearing loss or tinnitus, Woolford says.

“Young children are more vulnerable to potential harm from noise exposure because their auditory systems are still developing. Their ear canals are also smaller than adults, intensifying perceived sound levels,” Woolford said.

Noise exposure among children can also affect their sleep, academic learning, language, stress levels and even blood pressure, she adds.

More parents of children aged 9–12 years than 5–8 years report their child uses headphones or earbuds and daily use was also more likely to be higher among the older age group, the poll suggests.

But only half of parents share they’ve tried to limit their child’s audio device usage, citing strategies such as asking the child to take a break, having set hours for use and using a timer.

Parents whose child uses headphones for more than two hours a day are also less likely to set time or volume limits, compared to parents who report less headphone use for their child.

Woolford offers four tips to reduce risks of noise exposure to children through headphones and earbuds:

Monitor volume levels

Parents can minimise the negative impact of audio device usage by monitoring and adjusting the child’s volume and time on devices, Woolford says. She recommends parents follow the 60/60 rule – children should be limited to no more than 60 minutes of audio devices a day at no more than 60% of the maximum volume.

The sound level on listening devices that are less than 70 dBA (relative loudness of decibels heard) are very unlikely to cause noise-related damage.

“A good way to tell if an audio device is too loud is if a child wearing headphones can’t hear you when you’re an arm’s length away,” she said.

Parents can also limit their child’s risk by setting specific hours for audio device use or using a timer to keep track.

Use noise cancelling or volume limiting headphones

Parents should consider the risk of noise exposure when purchasing audio devices for their child by checking the information on device packages to identify products that limit the volume.

But some products marketed as “kid safe,” Woolford warns, do not limit the volume to 70 decibels.

However, children should avoid using noise-cancelling listening devices in situations when perception of sounds is crucial for safety.

“Noise-cancelling devices may help prevent children from increasing the volume to levels that are too high,” Woolford said. “But these devices shouldn’t be used when a child is engaged in activities where it’s important to hear their surroundings for their safety, such as walking or bike riding.”

Ensure kids take breaks from personal listening devices

Parents should help children intentionally have daily ‘device-free’ time, Woolford says. This may involve putting away or locking the child’s audio devices when time limits are up.

They may also encourage kids to enjoy things like music on a low volume in their rooms instead of using earbuds to reduce noise intensity.

Personal audio devices should also be avoided when children are sleeping or at bedtime, Woolford says.

Be mindful of early signs of hearing loss

If parents feel their child may be at risk of hearing loss due to using audio devices, Woolford recommends checking with a paediatrician, an audiologist, or an ENT specialist.

“Early signs of hearing loss may include asking for repetition, hearing ringing noises often, speaking loudly to people nearby, delayed speech, or lack of reaction to loud noises,” Woolford says.

“Healthcare providers may be of assistance to parents by offering a simple explanation about hearing loss to help the child understand the reasons for limiting their use of audio devices.”

Source: Michigan Medicine – University of Michigan

Categories : Genetics UncategorizedTags :

Dual Testosterone Blockers More Effective in Treating Prostate Cancer

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Credit: Darryl Leja National Human Genome Research Institute National Institutes Of Health

Combining testosterone-blocking drugs in patients with prostate cancer relapse prevents the spread of cancer better than treatment with a single drug, a multi-institution, Phase 3 clinical trial led by UC San Francisco researchers has found.

The approach can extend the time between debilitating drug treatments without prolonging the time it takes to recover from each treatment.

Prostate cancer affects 1 in 8 men, and is usually treated with one of several testosterone-lowering drugs for a set period of time.

“This adds to a growing body of evidence in favour of more intensive testosterone-blocking therapy in patients with higher-risk prostate cancer,” said Rahul Aggarwal, MD, professor in the UCSF School of Medicine and lead author of the paper.

The researchers’ findings were published in the Journal of Clinical Oncology. They were first announced in September 2022 at the annual meeting of the European Society for Medical Oncology.

A case for intensifying prostate cancer treatment

The new study focused on patients who had surgery for prostate cancer, and yet the cancer relapsed and was detected through a sudden jump in the blood levels of a protein called prostate-specific antigen (PSA).

“We looked at patients who had a fast rise in their PSA – an indicator of a higher-risk form of relapsed prostate cancer,” Aggarwal said.

“Our goal was to test several different hormone therapy strategies to find the best approach in terms of delaying the cancer’s progression.”

Between 2017 and 2022, 503 patients were randomly assigned to take a single testosterone-lowering therapy chosen by their oncologist, or to combine it with one or two other testosterone-lowering drugs.

The additional drugs were already FDA-approved for other cancers but hadn’t been tested in this way with prostate cancer.

The patients stayed on the assigned therapy for a year. Whether given singly or in combination, the drugs caused their testosterone to plummet.

That put the brakes on their cancer but also caused fatigue, hot flashes, decreased libido and other problems for patients, according to Aggarwal.

Compared to the prostate cancer patients who only received a single drug therapy during their year of treatment, patients who received either one or two additional drugs stayed cancer-free, with low PSA levels, for longer.

Once off the treatment, patients who took the combination therapies saw their testosterone levels recover just as fast as others who took the single drug.

The researchers are following up with a more detailed analysis of how patients fared on the different treatments – which side effects they experienced and for how long, and how they felt overall as they recovered.

“New cancer therapies must clear a high bar to make their way to patients,” Aggarwal said. “With the evidence in this study and others, combination hormone therapy should be considered a standard of care in prostate cancer patients with high-risk relapse after prior treatment.”

Source: University of California – San Francisco

Categories : Ageing NeurologyTags : Leave a comment

In Hearing Loss, How Hair Cells Lose Their ‘Hair’

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In some cases of hearing loss, a cochlear implant is required. Photo by Brett Sayles

With age, many people will eventually need hearing aids. In some cases, the reason for this may be a signalling pathway that controls auditory sensory cell function and is downregulated with age. In the journal iScience, researchers at the University of Basel report the clues they have uncovered about this process, which may yield potential therapies to slow its progression.

Nearly everyone eventually experiences hearing loss: loud noises or simple aging gradually cause the auditory sensory cells and their synapses in the inner ear to degenerate and die off. The only treatment option is a hearing aid or, in extreme cases, a cochlear implant.

“In order to develop new therapies, we need to better understand what the auditory sensory cells need for proper function,” explains Dr Maurizio Cortada from the Department of Biomedicine at the University of Basel and University Hospital Basel. In collaboration researchers at the Biozentrum, Cortada investigated which signalling pathways influence the sensory hair cells in the inner ear. In the process, the researchers discovered a central regulator.

This signaling pathway, known by researchers as the mTORC2-signaling pathway, plays an important role, among other things, for cell growth and the cytoskeleton. The role it plays for the hair cells in the inner ear has not previously been studied.

When the researchers removed a central gene of this signalling pathway in the hair cells of the inner ear of mice, the animals gradually lost their hearing. By the age of twelve weeks, they were completely deaf, the authors report in the study.

Shortening ‘hair’ and fewer synapses

Closer examination indicated that the sensory hair cells in the inner ear lost their sensors without the mTORC2 signalling pathway: the distinctive fibre bundles known as stereocilia. Through electron microscopes, the researchers observed the shortening of stereocilia. The number of synapses that transmit the signals to the auditory nerve was also reduced.

“From other studies, we know that the production of key proteins in this signaling pathway decreases with age,” Cortada explains. There may be a connection to the loss of synapses and the reduced function of the auditory sensory cells in the inner ear that leads to hearing loss with increasing age.

“If this is confirmed, it would be a possible starting point for future therapies,” says the researcher. The middle and inner ear, for example, would be readily accessible for locally-administered medications or gene therapies. The results could pave the way for the development of such treatment options.

Source: University of Basel

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A New Way to Map the Human Auditory Pathway

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Photo by Brett Sayles

Researchers have developed a non-invasive method for mapping the human auditory pathway, which could potentially be used as a tool to help clinicians decide the best surgical strategy for patients with profound hearing loss. The findings, published online in the journal eLife, highlight the importance of early interventions to give patients the ability to hear and understand speech, so that their auditory-language network can develop properly and their long-term outcomes are improved.

Sensorineural hearing loss (SNHL) occurs when the sensitive hair cells inside the cochlea are damaged, or when there is damage to the auditory nerve which transmits sound to the brain. A person with profound hearing loss is typically unable to hear any sounds, or at best, only very loud sounds. Congenital SNHL has increased in prevalence over the past two decades, from 1.09 to 1.7 cases per 1000 live births.

The sound of speech is carried through the brain by nerve fibres in regions known as the auditory pathway, and are processed in a region called the language network. In cases of congenital SNHL, the lack of speech inputs reaching the language network may hinder its proper development, leading to poorer spoken language skills.

Currently, the primary treatments for profound SNHL are cochlear and auditory brainstem implantation, where a device is used to stimulate the peripheral cochlea or the central cochlear nucleus, respectively. Both techniques can partially restore hearing in patients, but their language development outcomes can vary. This is especially true for patients with inner ear malformations (IEM) or cochlear nerve deficiencies (CND), which contribute to 15-39% of congenital SNHL cases.

“Where SNHL is caused by CNDs and/or IEMs, there is a great deal of uncertainty around the best method of treatment. This is due to the difficulty of assessing the condition of the cochlear nerve and distinguishing between certain types of IEM, both of which impact surgical decision making,” says senior authors Hao Wu, a professor and Chief Physician specialising in Otolaryngology at Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, China. Wu also serves as the Hospital Administrator and the Clinical and Academic Lead for the department. “We therefore need a more effective method for mapping the auditory pathway and diving deeper into how IEMs and CNDs affect the development of the auditory-language network.”

In their study, professor Wu’s team investigated the auditory and language pathways in 23 children under the age of six. They included 10 children with normal hearing, and 13 with profound SNHL. In the latter group, seven children had received cochlear implantations, two had received auditory brainstem implantations, and four were candidates for auditory brainstem implantations.

The human auditory pathway is difficult to investigate non-invasively due to its delicate and intricate subcortical structures located deep within the brain. To navigate this, the team developed a new methodology to reconstruct the pathway. First, they segmented the subcortical auditory structures using track density imaging, which are reconstructed from a specific type of MRI scan and provide much greater detail and information on the structural connectivity of the brain. This allowed them to delineate the cochlear nucleus and the superior olivary complex of the auditory pathway. They then tracked the auditory and language pathways using a neuroimaging technique called probabilistic tractography, which uses the information from an MRI scan to provide the most likely view of structural brain connectivity. Next, the team assessed the density and cross-section of the nerve fibres in the auditory and language pathways.

This combined methodology allowed them to investigate three key areas to inform surgical decision making: the condition of the nerve fibres in the auditory-language network of children with profound SNHL; the potential impact of IEMs and CNDs on the development of the network before surgical intervention; and the relationship between the pre-implant structural development of the network and the auditory-language outcomes following implantation.

The team’s observations revealed a lower nerve fibre density in children with profound SNHL, in comparison to those with normal hearing. This reduction was most pronounced in two regions of the inferior central auditory pathway, as well as the left language pathway.

In addition, the findings revealed that the language pathway is more sensitive than the central auditory system to IEMs and/or CNDs, implying that the structural development of the language pathway is more negatively impacted by the condition of the peripheral auditory structure. However, the authors caution that further study is required to validate this finding. As it is more difficult to image the central auditory pathway than the language pathway, this difference could have arisen due to the limitations of current neuroimaging technologies.

The authors say the study is also limited by a relatively small cohort of patients and an incomplete genetic dataset, so more studies with a more diverse patient population will also be needed. But with further validation, they add that the methodology could be used more widely for informing decisions in treating profound SNHL.

Source: eLife

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A Natural Repair Process for Damaged Auditory Hair Cells

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Auditory researchers have discovered how hair cells can repair themselves after being damaged, an important insight could benefit efforts to develop new and better ways to treat and prevent hearing loss. Their findings are published in the free online journal eLife.

Found in the inner ear, hair cells derive their name from the hair-like structures that cover them and serve as mechanical antennas for sound detection. The prevailing belief is that when auditory hair cells are killed, they are gone for good. But this new research from University of Virginia School of Medicine shows that these delicate cells have the ability to repair themselves from damage caused by loud noises or other forms of stress.

“For many years, auditory research has placed considerable emphasis on the regeneration of sensory hair cells. Although these efforts continue, it is equally important to enhance our comprehension of the intrinsic mechanisms that govern the repair and maintenance of these cells. By gaining a deeper understanding of these inherent repair processes, we can uncover strategies to fortify them effectively. One such approach in the future might involve the utilisation of drugs that stimulate repair programs,” said researcher Jung-Bum Shin, PhD, of UVA’s Department of Neuroscience. “In essence, when replacement of hair cells proves challenging, the focus shifts towards repairing them instead. This dual strategy of regeneration and repair holds strong potential in advancing treatments for hearing loss and associated conditions.”

Repairing the damaged cells

In order to sense sound, hair cells are naturally fragile, but they also must withstand the continuous mechanical stress inherent in their jobs.

Prolonged exposure to loud noise harms hair cells in a variety of ways, and one of those is by damaging the cores of the “hairs” themselves. These hair-like structures are known as stereocilia, and Shin’s new research shows a process they use to repair themselves.

The hair cells do this by deploying a protein called XIRP2, which has the ability to sense damage to the cores, which are made of a substance called actin. Shin and his team found that XIRP2 first senses damage, then migrates to the damage site and repairs the cores by filling in new actin.

“We are especially excited to have identified a novel mechanism by which XIRP2 can sense damage-associated distortions of the actin backbone,” Shin said. “This is of relevance not only for hair cell research, but the broader cell biology discipline.”

The pioneering work has netted a grant to fund additional research into how the cores are repaired. By understanding this, scientists will be better positioned to develop new ways to battle hearing loss – even the kind that comes from aging, the researchers say.

“Age-related hearing loss affects at least a third of all older adults,” Shin said. “Understanding and harnessing internal mechanisms by which hair cells counteract wear and tear will be crucial in identifying ways to prevent age-related hearing loss. Furthermore, this knowledge holds potential implications for associated conditions such as Alzheimer’s disease and other dementia conditions.”

Source: University of Virginia Health System

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Backdoor to the Inner Ear Allows Delivery of Gene Therapy

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An international team of researchers has developed a new method to deliver drugs into the inner ear, according to a new study in Science Translational Medicine. The discovery was possible by harnessing the natural flow of fluids in the brain and employing a little-understood backdoor into the cochlea. When combined to deliver a gene therapy that repairs inner ear hair cells, the researchers were able to restore hearing in deaf mice.

“These findings demonstrate that cerebrospinal fluid transport comprises an accessible route for gene delivery to the adult inner ear and may represent an important step towards using gene therapy to restore hearing in humans,” says lead author Barbara Canlon, professor at Karolinska Institutet.

The number of people worldwide predicted to have mild to complete hearing loss is expected to grow to around 2.5 billion by mid-century.  The primary cause is the death or loss of function of hair cells found in the cochlea – which relay sounds to the brain – due to mutations of critical genes, aging, noise exposure, and other factors. 

While hair cells do not naturally regenerate in humans and other mammals, gene therapies have shown promise and in separate studies have successfully repaired the function of hair cells in neo-natal and very young mice.

“However, as both mice and humans age, the cochlea, already a delicate structure, becomes enclosed in the temporal bone. At this point, any effort to reach the cochlea and deliver gene therapy via surgery risks damaging this sensitive area and altering hearing,” says Barbara Canlon.

In the new study, the researchers describe a little-understood passage into the cochlea called the cochlear aqueduct. The cochlear aqueduct is a thin boney channel no larger than several strands of hair. 

Channel for spinal fluid

A new study shows that the cochlear aqueduct acts as a conduit between the cerebrospinal fluid found in the inner ear and the rest of the brain. 

Scientists are developing a clearer picture of the mechanics of the glymphatic system, the brain’s unique process of removing waste. Because the glymphatic system pumps cerebrospinal fluid deep into brain tissue to wash away toxic proteins, researchers have been eyeing it as a potential new way to deliver drugs into the brain, a major challenge in developing drugs for neurological disorders. 

The new study represented an opportunity to put the drug delivery potential of the glymphatic system to the test, while at the same time targeting a previously unreachable part of the auditory system.   

Employing several imagining and modeling technologies, the researchers were able to develop a detailed portrait of how fluid from other parts of the brain flows through the cochlear aqueduct and into the inner ear.

The team then injected an adeno-associated virus into the cisterna magna, a large reservoir of cerebrospinal fluid found at the base of the skull. 

The virus found its way into the inner ear via the cochlear aqueduct and delivered a gene therapy that expresses a protein called vesicular glutamate transporter-3, which enables the hair cells to transmit signals and rescue hearing in adult deaf mice. 

“This new delivery route into the ear may not only serve the advancement of auditory research but also prove useful when translated to humans with progressive genetic-mediated hearing loss,” says Barbara Canlon.

Source: Karolinska Institutet

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Possible Explanation for Why More Men Develop Hearing Loss in Old Age

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A new study led by Yale School of Medicine scientists and published in BMC has pinpointed why some adults – by some estimates, at least 50% of the population after 75 years of age – develop hearing problems.

While congenital hearing impairment – usually presenting in childhood – result from rare mutations, hearing problems in adults are likely due to the cumulative effect of polygenic risk and environmental factors.

Recent genome-wide association studies have uncovered several risk genes that are implicated in hearing problems in adults, however some factors still have not adequately been investigated by large-scale genetic studies.

For instance, there is limited information about why hearing problems among older adults are more common, more severe, and with earlier onset in men than in women. It is uncertain how hearing-related polygenic risk translates among people of diverse ancestral backgrounds.

While environmental risk factors such as noise exposure and tobacco smoking are known to increase the risk of hearing problems, the molecular mechanisms underlying these associations are unclear.

Researchers sampled nearly 750 000 adults and identified 54 risk variants – including 12 novel variants – that could contribute to hearing problems. They also highlighted how hormonal regulation may play a role in the differences between hearing problems in men and women.

Analysing multiple ancestry groups, the researchers demonstrated that polygenic risk in hearing problems is shared across human populations. They also determined genes involved in brain development interact with sex, noise pollution, and tobacco smoking in relation to their associations with hearing problems.

“Our results support that large-scale genetic studies are useful instruments to understand the biology and the epidemiology of hearing problems in adults,” said Renato Polimanti, PhD, associate professor of psychiatry at Yale School of Medicine and senior author of the study.

Overall, the findings contribute to identifying possible molecular targets for drug development and define novel strategies to identify older adults at risk of losing their hearing.

The study could lead to changes in how older adults with hearing problems are assessed and treated. Hearing loss can impair communications, and that can result in social isolation with major health, psychosocial, and economic consequences, reducing the quality of life of those affected.

Source: Yale University

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Can Progressive Hearing Loss be Reversed?

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In humans, hearing loss from exposure to loud noises is progressive because the primary cells which detect sound, cochlear hair cells, cannot regenerate if damaged or lost. People who have repeated exposure to loud noises, like military personnel, construction workers, and musicians, are most at risk for this type of hearing loss, though it can happen to anyone over time.

On the other hand, birds and fish can regenerate these hair cells, and now researchers report their advances in promoting this effect in mammals. Their work is published in Frontiers in Cellular Neuroscience.

“We know from our previous work that expression of an active growth gene, called ERBB2, was able to activate the growth of new hair cells (in mammals), but we didn’t fully understand why,” said Patricia White, PhD, professor of Neuroscience and Otolaryngology at the University of Rochester Medical Center. The 2018 study led by Jingyuan Zhang, PhD, a postdoctoral fellow in the White lab at the time, found that activating the growth gene ERBB2 pathway triggered a cascading series of cellular events by which cochlear support cells began to multiply and activate other neighbouring stem cells to become new sensory hair cells.

“This new study tells us how that activation is happening – a significant advance toward the ultimate goal of generating new cochlear hair cells in mammals,” said White.

Using single-cell RNA sequencing in mice, researchers compared cells with an overactive growth gene (ERBB2 signalling) with similar cells that lacked such signalling. They found the growth gene, ERBB2, promoted stem cell-like development by initiating the expression of multiple proteins – including SPP1, a protein that signals through the CD44 receptor. The CD44 receptor is known to be present in cochlear-supporting cells. This increase in cellular response promoted mitosis in the supporting cells, a key event for regeneration.

“When we checked this process in adult mice, we were able to show that ERBB2 expression drove the protein expression of SPP1 that is necessary to activate CD44 and grow new hair cells,” said Dorota Piekna-Przybylska, PhD, a staff scientist in the White Lab and first author of the study. “This discovery has made it clear that regeneration is not only restricted to the early stages of development. We believe we can use these findings to drive regeneration in adults.”

“We plan to further investigation of this phenomenon from a mechanistic perspective to determine whether it can improve auditory function after damage in mammals. That is the ultimate goal,” said White.

Source: University of Rochester Medical Center

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Hearing Loss Linked to Dementia Risk

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A nationally representative study published in JAMA found that older adults with greater severity of hearing loss were more likely to have dementia, but the likelihood of dementia was lower among hearing aid users compared to non-users.

The findings are consistent with prior studies showing that hearing loss might be a contributing factor to dementia risk over time, and that treating hearing loss may lower dementia risk.

“This study refines what we’ve observed about the link between hearing loss and dementia, and builds support for public health action to improve hearing care access,” says lead author Alison Huang, PhD, MPH, a senior research associate in the Bloomberg School’s Department of Epidemiology and at the Cochlear Center for Hearing and Public Health, also at the Bloomberg School.

Hearing loss is a critical public health issue affecting two-thirds of Americans over 70. The growing understanding that hearing loss might be linked to the risk of dementia, which impacts millions, and other adverse outcomes has called attention to implementing possible strategies to treat hearing loss.

For the new study, Huang and colleagues analysed a nationally representative dataset from the National Health and Aging Trends Study (NHATS). Funded by the National Institute on Aging, the NHATS has been ongoing since 2011, and uses a nationwide sample of Medicare beneficiaries over age 65, with a focus on the 90-and-over group as well as Black individuals.

The analysis covered 2413 individuals, about half of whom were over 80 and showed a clear association between severity of hearing loss and dementia. Prevalence of dementia among the participants with moderate/severe hearing loss was 61% higher than prevalence among participants who had normal hearing. Hearing aid use was associated with a 32% lower prevalence of dementia in the 853 participants who had moderate/severe hearing loss.

The authors note that many past studies were limited in that they relied on in-clinic data collection, leaving out vulnerable populations that did not have the means or capacity to get to a clinic. For their study, the researchers collected data from participants through in-home testing and interviews.

How hearing loss is linked to dementia isn’t yet clear, and studies point to several possible mechanisms. Huang’s research adds to a body of work by the Cochlear Center for Hearing and Public Health examining the relationship between hearing loss and dementia.

Source: Johns Hopkins Bloomberg School of Public Health