Hearing Loss and the Connection to Alzheimer’s Disease, Dementia

Sound has the power to stimulate the brain, which is why hearing loss has the potential to have a profound effect on health – especially among older adults.

About 1 in 3 people in the United States between the ages of 65 and 74 has hearing loss, according to the National Institutes of Health. A 2016 study in the American Journal of Public Health found about two-thirds of adults ages 70 or older suffer from hearing impairment that may affect daily communication.

Hearing loss is associated with cognitive decline, though more research is needed to determine the degree of the connection, said Dr. Costantino Iadecola, director of the Feil Family Brain and Mind Research Institute at Weill Cornell Medical College in New York City.

A 2011 study in Archives of Neurology, now named JAMA Neurology, found those with mild hearing loss had nearly twice the risk of developing dementia compared to people with normal hearing. Those with moderate loss had three times the risk, while those with severe loss had five times the risk.

“All we know is that people who tend to have hearing loss tend to have more dementia,” Iadecola said. “It doesn’t mean that the hearing loss is causing the dementia, it doesn’t mean that the dementia is causing the hearing loss.”

There were about 5 million people in the United States living with Alzheimer’s disease and related dementias in 2014, about 1.6% of the U.S. population, according to the Centers for Disease Control and Prevention. The number is expected to grow to 13.9 million, or roughly 3.3% of the population, by 2060.

Dementia can develop for a variety of reasons, including vascular, neurogenerative and neuroimmune conditions, Iadecola said. “Each has a different impact on the brain.”

One theory behind the connection between dementia and hearing loss is that dementia creates certain conditions that may affect the ability to hear, Iadecola said. Or, he added, it could be the reverse, with hearing loss somehow impairing the brain’s ability to function.

“If you break down what hearing is, it is a major component in our ability to connect with the rest of the world,” said Nicholas Reed, an audiologist and core faculty member at the Cochlear Center for Hearing and Public Health at Johns Hopkins Bloomberg School of Public Health in Baltimore.

Hearing loss is “highly related to social isolation and loneliness,” he said, “and we’ve known for a long time that social isolation and loneliness are related to important age-related health outcomes like dementia and cognitive decline.”

Reed is part of a Johns Hopkins team leading a federally funded study looking at the potential of hearing treatments to reduce cognitive decline in older adults. It’s the kind of research that could make a difference in the quality of life of older populations for generations to come.

Results aren’t expected for a few years. For now, Reed said, while existing research hasn’t definitively concluded whether hearing aids can help, “I think many of us believe that most likely, hearing care does help.”

But not everyone with mild hearing loss needs a hearing aid right away, he said. “You very much may be able to get by adjusting the way you live your life. Making sure you face sounds you want to hear, making sure you’re avoiding background noise for important conversations, and use simple amplifiers to help in more difficult situations.”

He advises people to start getting their hearing checked regularly in their 60s, and to use earplugs at loud sporting events or concerts, regardless of age.

Reed points to a 2017 report from The Lancet International Commission on Dementia Prevention, Intervention and Care as proof of the importance of prevention. The report identified hearing loss as one of nine potentially modifiable risk factors that contributed to about 35% of dementia cases, with hearing loss the biggest contributor at 9%.

“What that means is 9% of dementia cases could be eliminated theoretically if all hearing loss were eliminated,” Reed said. That assumes, however, there were no other contributing factors, he said.

Staying healthy overall, like getting enough exercise and preventing high blood pressure, also may affect hearing health.

“In terms of health, the primary concern as we go through aging, is to maintain our ability to function independently as much as possible,” Iadecola said, “and hearing is one of the central elements of this.”

Source: American Heart Association


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Healthful Diet Tied to Lower Risk of Hearing Loss

Investigators from Brigham and Women’s Hospital have found that eating a healthy diet may reduce the risk of acquired hearing loss. Using longitudinal data collected in the Nurses’ Health Study II Conservation of Hearing Study (CHEARS), researchers examined three-year changes in hearing sensitivities and found that women whose eating patterns more closely adhered to commonly recommended healthful dietary patterns, such as the Dietary Approaches to Stop Hypertension (DASH) diet, the Alternate Mediterranean (AMED) diet, and the Alternate Healthy Index-2010 (AHEI-2010), had substantially lower risk of decline in hearing sensitivity. The team’s findings are published in the American Journal of Epidemiology

“A common perception is that hearing loss is an inevitable part of the aging process. However, our research focuses on identifying potentially modifiable risk factors — that is, things that we can change in our diet and lifestyle to prevent hearing loss or delay its progression,” said lead author Sharon Curhan, MD, a physician and epidemiologist in the Brigham’s Channing Division of Network Medicine. “The benefits of adherence to healthful dietary patterns have been associated with numerous positive health outcomes and eating a healthy diet may also help reduce the risk of hearing loss.”

Previous studies have suggested that higher intake of specific nutrients and certain foods, such as the carotenoids beta-carotene and beta-cryptoxanthin (found in squash, carrots, oranges and other fruits and vegetables), folate (found in legumes, leafy greens, and other foods), long-chain omega-3 fatty acids (found in seafood and fish), were associated with lower risk of self-reported hearing loss. These findings revealed that dietary intake could influence the risk of developing hearing loss, but investigators sought to further understand the connection between diet and hearing loss by capturing overall dietary patterns and objectively measuring longitudinal changes in hearing sensitivities.

To do so, the researchers established 19 geographically diverse testing sites across the U.S. and trained teams of licensed audiologists to follow standardized CHEARS methods. The audiologists measured changes in pure-tone hearing thresholds, the lowest volume that a pitch can be detected by the participant in a given ear, over the course of 3 years. An audiologist presented tones of different frequencies (0.5, 1 and 2 kHz as low-frequencies; at 3 kHz and 4 kHz as mid-frequencies; and at 6 kHz and 8 kHz as higher frequencies) at variable “loudness” levels and participants were asked to indicate when they could just barely hear the tone.

Using over 20 years of dietary intake information that was collected every four years beginning in 1991, the researchers investigated how closely participants’ long-term diets resembled some well-established and currently recommended dietary patterns, such as the DASH diet, the Mediterranean diet, and Alternate Healthy Index-2010 (AHEI-2010). Greater adherence to these dietary patterns has been associated with a number of important health outcomes, including lower risk of heart disease, hypertension, diabetes, stroke and death as well as healthy aging.

The team found that the odds of a decline in mid-frequency hearing sensitivities were almost 30 percent lower among those whose diets most closely resembled these healthful dietary patterns, compared with women whose diets least resembled the healthful dietary patterns. In the higher frequencies, the odds were up to 25 percent lower.

“The association between diet and hearing sensitivity decline encompassed frequencies that are critical for speech understanding,” said Curhan. “We were surprised that so many women demonstrated hearing decline over such a relatively short period of time. The mean age of the women in our study was 59 years; most of our participants were in their 50s and early 60s. This is a younger age than when many people think about having their hearing checked. After only three years, 19 percent had hearing loss in the low frequencies, 38 percent had hearing loss in the mid-frequencies, and almost half had hearing loss in the higher frequencies. Despite this considerable worsening in their hearing sensitivities, hearing loss among many of these participants would not typically be detected or addressed.”

The study included female health care professionals, which enhanced the validity of the health information collected and reduced the variability in educational achievement and socioeconomic status, but the study population was limited to predominantly middle-aged, non-Hispanic white women. The authors note that further research in additional populations is warranted. The team hopes to continue to longitudinally follow the participants in this study with repeated hearing tests over time and is investigating ways to collect research-quality information on tens of thousands of participants for future studies across diverse populations.

Source: Brigham and Women’s Hospital


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Link Between Hearing and Cognition Begins Earlier Than Once Thought

Research has shown that adults with age-related hearing loss have higher rates of cognitive decline.

Now, a study from researchers at Columbia University Vagelos College of Physicians and Surgeons has found that even the earliest stage of hearing loss—when hearing is still considered normal—is linked to cognitive decline.

The study was published online today in JAMA Otolaryngology-Head and Neck Surgery.

Link Between Hearing Loss and Cognitive Impairment

Age-related hearing loss is one of the most common health disorders of aging, affecting two-thirds of those over age 70. However, few adults are tested for hearing loss, and even fewer are treated. Only 14% of adults with hearing loss in the United States wear hearing aids, the standard treatment.

Because studies show people with age-related hearing loss are more likely to have impaired cognition, it is thought that hearing loss may trigger cognitive decline. But these studies have only examined people diagnosed with hearing loss, which is defined as the inability to hear sounds under 25 decibels (dB).

“Physicians in this field have used 25 dB—about the loudness of a whisper—to define the border between normal hearing and mild hearing loss in adults, but this level is arbitrary,” says Justin S. Golub, MD, MS, assistant professor of otolaryngology-head & neck surgery at Columbia University Vagelos College of Physicians and Surgeons and a hearing specialist at Columbia University Irving Medical Center and NewYork-Presbyterian.

“It has been assumed that cognitive impairment wouldn’t begin until people passed this threshold. But no one actually looked at whether this was true.”

Any Hearing Loss May Be Cause for Concern

The researchers looked at data from 6,451 adults (average age 59) who were enrolled in two ethnically diverse epidemiologic studies. Participants underwent hearing and cognitive testing as part of the studies.

Golub and his colleagues found that for every 10 dB decrease in hearing, there was a significant decrease in cognitive ability, a pattern seen across the entire spectrum of hearing.

Surprisingly, the largest decrease in cognitive ability occurred in those whose hearing was just starting to become impaired, just 10 dB off the perfect mark.

“Most people with hearing loss believe they can go about their lives just fine without treatment, and maybe some can,” says Golub. “But hearing loss is not benign. It has been linked to social isolation, depression, cognitive decline, and dementia. Hearing loss should be treated. This study suggests the earlier, the better.”

Can Hearing Aids Prevent Cognitive Loss?

The current study did not address whether hearing loss causes cognitive impairment. It is possible that early declines in both hearing and cognitive performance are related to common aging-related processes, the researchers noted.

“But it’s also possible that people who don’t hear well tend to socialize less and, as a result, they have fewer stimulating conversations. Over many years, this could have a negative impact on cognition,” says Golub. “If that’s the case, preventing or treating hearing loss could reduce dementia incidence by more than 9%, according to a recent analysis published in The Lancet.”

A new study, funded by the National Institutes of Health, is now testing the possibility that hearing aids can slow cognitive decline in older people with age-related hearing loss.

More studies are needed before recommending changes in hearing loss categories. “One possibility is to formally introduce a new category, such as borderline hearing loss, ranging from 16 to 25 dB of hearing ability,” says Golub.

Source: Columbia University


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With Age Comes Hearing Loss and a Greater Risk of Cognitive Decline

Scott LaFee wrote . . . . . . . . .

Hearing impairment is a common consequence of advancing age. Almost three-quarters of U.S. adults age 70 and older suffer from some degree of hearing loss. One unanswered question has been to what degree hearing impairment intersects with and influences age-related cognitive decline.

In a new study, researchers at University of California San Diego School of Medicine report that hearing impairment is associated with accelerated cognitive decline with age, though the impact of mild hearing loss may be lessened by higher education.

The findings are published in the Journal of Gerontology: Series A Medical Sciences.

A team of scientists, led by senior author Linda K. McEvoy, PhD, professor in the departments of Radiology and Family Medicine and Public Health, tracked 1,164 participants (mean age 73.5 years, 64 percent women) in the longitudinal Rancho Bernardo Study of Healthy Aging for up to 24 years. All had undergone assessments for hearing acuity and cognitive function between the years 1992 to 1996 and had up to five subsequent cognitive assessments at approximately four-year intervals. None used a hearing aid.

The researchers found that almost half of the participants had mild hearing impairment, with 16.8 percent suffering moderate-to-severe hearing loss. Those with more serious hearing impairment showed worse performance at the initial visit on a pair of commonly used cognitive assessment tests: the Mini-Mental State Exam (MMSE) and the Trail-Making Test, Part B. Hearing impairment was associated with greater decline in performance on these tests over time, both for those with mild hearing impairment and those with more severe hearing impairment.

However, the association of mild hearing impairment with rate of cognitive decline was modified by education. Mild hearing impairment was associated with steeper decline among study participants without a college education, but not among those with higher education. Moderate-to-severe hearing impairment was associated with steeper MMSE decline regardless of education level.

“We surmise that higher education may provide sufficient cognitive reserve to counter the effects of mild hearing loss, but not enough to overcome effects of more severe hearing impairment,” said McEvoy.

Degree of social engagement did not affect the association of hearing impairment with cognitive decline. “This was a somewhat unexpected finding” said first author Ali Alattar. “Others have postulated that cognitive deficits related to hearing impairment may arise from social isolation, but in our study, participants who had hearing impairment were as socially engaged as those without hearing loss.”

The findings, said the authors, emphasize the need for physicians to be aware that older patients with hearing impairments are at greater risk for cognitive decline. They also emphasized the importance of preventing hearing loss at all ages, since hearing impairment is rarely reversible. One important way to protect hearing, they said, is to minimize loud noise exposure since this is the largest modifiable risk factor for hearing impairment.

Source: UC San Diego


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Exploring the Connection between Hearing Loss and Cognitive Decline

Hearing loss affects tens of millions of Americans and its global prevalence is expected to grow as the world’s population ages. A new study led by investigators at Brigham and Women’s Hospital adds to a growing body of evidence that hearing loss is associated with higher risk of cognitive decline. These findings suggest that hearing loss may help identify individuals at greater risk of cognitive decline and could provide insights for earlier intervention and prevention.

“Dementia is a substantial public health challenge that continues to grow. There is no cure, and effective treatments to prevent progression or reverse the course of dementia are lacking,” said lead author Sharon Curhan, MD, MSc, a physician and epidemiologist in the Channing Division for Network Medicine at the Brigham. “Our findings show that hearing loss is associated with new onset of subjective cognitive concerns which may be indicative of early stage changes in cognition. These findings may help identify individuals at greater risk of cognitive decline.”

Curhan and colleagues conducted an eight-year longitudinal study among 10,107 men aged ?62 years in the Health Professionals Follow-up Study (HFPS). They assessed subjective cognitive function (SCF) scores based on responses to a six-item questionnaire administered in 2008, 2012 and 2016. SCF decline was defined as a new report of at least one SCF concern during follow-up.

The team found that hearing loss was associated with higher risk of subjective cognitive decline. Compared with men with no hearing loss, the relative risk of cognitive decline was 30 percent higher among men with mild hearing loss, 42 percent higher among men with moderate hearing loss, and 54 percent higher among men with severe hearing loss but who did not use hearing aids.

Researchers were interested to see if hearing aids might modify risk. Although the found that among men with severe hearing loss who used hearing aids, the risk of cognitive decline was somewhat less (37 percent higher), it was not statistically significantly different from the risk among those who did not use hearing aids. The authors note that this may have been due to limited power or could suggest that if a difference truly exists, the magnitude of the effect may be modest.

The authors also note that the study was limited to predominantly older white male health professionals. This allowed for greater control of variability but further studies in additional populations would be helpful. In addition, the study relies on self-reported hearing loss and subjective measures of cognitive function. In the future, the team plans to investigate the relationships between self-reported hearing loss, change in audiometric hearing thresholds, and changes in cognition in women using several different assessment measures.

“Whether there is a temporal association between hearing loss and cognitive decline and whether this relation is causal remains unclear,” said Curhan. “We plan to conduct further longitudinal studies of the relation of hearing loss and cognition in women and in younger populations, which will be informative.”

Source : Science Daily