Researchers Find Potential Link Between Hearing Aid Users And Reduced Dementia Risk
In a large and significant study published on April 13 in The Lancet Public Health, it was discovered that there is a potential link between hearing aid use and reduced dementia risk for people with hearing loss.
Researchers found that people with untreated hearing loss were more likely to develop dementia than those with normal hearing. However, this increased risk was not observed in individuals who used hearing aids.
The study’s corresponding author, Dr. Dongshan Zhu, who also happens to be a postdoctoral researcher at Shandong University in Jinan, China, explains that hearing loss is increasingly recognized as a crucial modifiable risk factor in dementia during midlife. But, the real-world impact of hearing aid use on reducing dementia risk has remained unclear.
Dr. Zhu says, “Our study provides the best evidence to date to suggest that hearing aids could be a minimally invasive, cost-effective treatment to mitigate the potential impact of hearing loss on dementia.”
The Link Between Dementia and Hearing Loss
According to the National Institute on Deafness and Other Communication Disorders (NIDCD), approximately one in three people aged 65 to 74 in the United States has some degree of hearing loss and nearly half of those older than 75 experience hearing difficulties.
“We do see consistent evidence across population-based studies for a strong association between hearing loss, accelerated cognitive decline, and dementia, which impacts millions of Americans,” says epidemiology researchers at the Johns Hopkins Bloomberg School of Public Health in Baltimore, Alison R. Huang, PhD, MPH. Dr. Huang, who was not involved in the study, also studies the impact of sensory loss on cognitive and mental health in older adults.
Dr. Huang also explains that there are three main mechanisms that could possibly explain why hearing loss could be linked with dementia.
“First, with hearing loss, speech and sound are heard as garbled by the time they reach the brain, which requires the brain to use extra effort for processing and deciphering this speech and sound,” she says.
As a result, the brain has fewer resources for activities such as memory and executive function. Dr. Huang explains that this can eventually lead to cognitive impairment.
She continues by sharing that when someone suffers from hearing loss, the portions of the brain that are usually stimulated by speech and sound end up under stimulated, leading to atrophy and changes within the brain structure and function.
“Finally, hearing loss can make communicating with others more difficult, which can lead to social isolation, another risk factor for dementia,” says Dr. Huang.
Those with Hearing Loss Who Don’t Use Hearing Aids More Likely to Have Dementia
The researchers gathered data from the U. Biobank database, which included information from over 430,000 participants. Hearing loss and hearing aid usage were determined through self-reported questionnaires, and dementia diagnoses were identified using hospital records and death registers.
At the start of the study, participants’ average age was 56 years, and they were followed for an average of 12 years. Around 75 percent of the participants had no hearing loss, while the remaining 25 percent had some level of hearing impairment. Among those with hearing loss, only about 1 in 8 individuals used hearing aids. The researchers accounted for various factors that could influence dementia risk, such as education, ethnicity, income levels, alcohol use, depression, social isolation, and other chronic conditions.
The results showed that compared to individuals with normal hearing, those with untreated hearing loss had a 42 percent higher risk of all-cause-dementia. In contrast, no increased risk of dementia was observed in people with hearing loss who used hearing aids.
Although the overall risk of developing dementia was relatively low, with a 1.7 percent absolute risk among those with untreated hearing loss, compared to 1.2 percent absolute risk among those without hearing loss or those using hearing aids, the findings still underline the potential benefits of hearing aid use in reducing dementia risk.
People Who Use Hearing Aids May Have Other Healthy Behaviors
Dr. Huang shares that the strengths of the study include ‘the large sample size and longitudinal design (looking at a particular variable, in this case, dementia, over a period of several years).
“While the authors’ findings regarding hearing aid use and dementia risk are encouraging, it is still difficult to disentangle whether what we’re seeing is due to the hearing aid itself or other factors,” she says.
The study’s authors noted that hearing aid use among participants with self-reported hearing loss was relatively low (12 percent), and this could be related to other health-promoting factors and access to healthcare resources that may also contribute to lower dementia risk.
While Dr. Zhu agrees that while the study controlled for many factors, there are still some unmeasured areas. Moreover, they note that those using hearing aids could also possibly take better care of their health than those who did not.According to the Hearing Loss Association of America, ‘about 1 in 5 (20 percent) of Americans who would benefit from a hearing aid uses one.’
More Randomized Controlled Trials Are Needed
While the findings are very encouraging and consistent with results from a recent meta-analysis published in late 2022 in JAMA Neurology which ‘observed lower risk of cognitive decline among older adults with hearing loss that use hearing aids,’ Dr. Huang says “but more research is needed, particularly from randomized controlled trials.”
The study authors also agree that those kinds of trails are needed to confirm the observed association seen between hearing aid use and dementia risk.
“This study is observational, the association between hearing loss and dementia might be due to reverse causation through neurodegeneration or other shared mechanisms,” says Dr. Zhu.
Moreover, the findings are also limited by a lack of diversity, explain the authors. The UK Biobank participants are 95 percent white, explains the journal article. While very few of the participants were born deaf, or have experienced hearing loss, before acquiring spoken language. This also limits the generalization of the findings to other ethnicities and those with limited hearing that use sign language.
Will Hearing Aids Help Prevent Dementia? Expert Advice Given on Hearing Tests and Hearing Aids
“Changes to our hearing happen very gradually over time so many individuals may not even be aware of hearing problems if they haven’t had a hearing test. Getting a hearing test every 1 to 2 years is certainly reasonable, and this is something that a person could get by seeing an audiologist,” says Huang. Depending on your insurance coverage, you may or may not need a physician’s referral to see an audiologist, she adds.
Alternatively, individuals can also self-test their hearing with a compatible smartphone. “A website that we created at the Johns Hopkins Cochlear Center for Hearing and Public Health takes people through how to do this,” she says.
According to Dr. Huang, the question of whether people with hearing loss should get hearing aids in an effort to reduce dementia risk, more work is needed using randomized trials in order to definitely determine whether hearing aid use may actually reduce the risk of dementia and cognitive impairment.
Currently, that work is underway with the ACHIEVE (Aging and Cognitive Health Evaluation in Elders) study, being funded by the National Institute on Aging, says Dr. Huang. The trial recruited almost 1,000 older adults in their seventies and early eighties with mild-to-moderate hearing loss, while randomly assigning them to receive either hearing intervention or a healthy aging education control intervention and followed them for three years.
“This trial will give us a clearer sense of whether treating hearing loss can actually slow cognitive decline. Results from this trial are expected later this year,” says Huang.