Researchers have long known about the connection between hearing loss and cognitive issues. But new research suggests hearing loss may play a bigger role in dementia than previously suspected—and treating it might help preserve cognition in older people.
The study, published in JAMA Otolaryngology—Head & Neck Surgery in April, looked at a group of nearly 3,000 seniors, and found that about one-third of dementia cases could be tied to hearing loss. This is “quite a lot higher than previous research” has estimated, explained study author Jason Smith, MS, a doctoral student at the Johns Hopkins Bloomberg School of Public Health.
However, the researchers also noted that there was a “modest association” between using hearing aids and a lower dementia risk.
“Because of how widespread hearing loss is in the older adult population, the potential benefits of treating it for delaying or preventing dementia at the population level could be significant,” Smith told Health.
For now, experts agreed it’s too soon to say that interventions such as hearing aids can definitively prevent dementia. But the findings pinpoint just how crucial these devices can be for both auditory and overall health.
In the U.S., about 33% of people between age 65 and 74 have hearing loss—that number climbs to almost 50% among people over 75. It’s also a well-documented risk factor for dementia, a neurological condition which affects more than 6 million Americans. That burden is expected to grow as more Americans get older.
With this in mind, Smith and his colleagues wanted to further investigate how the two might be related. They used data on 2,946 older adults ranging in age from 66 to 90, all of whom lived near study centers in Mississippi, North Carolina, Minnesota, and Maryland.
Based on audiometric testing, a type of sound intensity and frequency assessment, researchers discovered that 66% of the participants had hearing loss. About 37% self-reported having hearing loss. Of those participants with hearing loss, 30% used hearing aids.
After an average follow-up of about 6.5 years, 239 study participants (about 8%) developed dementia.
Smith and his team used an epidemiological method called population attributable fraction to determine how this variable—hearing loss—might impact dementia incidence in a population. They found that 32% of these dementia cases might be attributable to hearing issues.
Interestingly, self-reported hearing loss was not associated with a higher dementia risk, the data showed.
The results of this study do complement existing research, Willa Brenowitz, PhD, MPH, Alzheimer’s disease investigator with the Kaiser Permanente Center for Health Research, told Health.
Brenowitz published a study back in 2020, which found that older adults who still had a strong sense of hearing, touch, and vision had half the risk of developing dementia as compared to their peers with sensory impairments.
Importantly, most research out there “only demonstrates associations” between hearing loss and cognitive decline, she explained.
But there are some theories as to why auditory impairments might affect your brain function:
- Cognitive demands. People with hearing loss have to pay closer attention and use more cognitive energy every day, which may impair their cognition over time, Brenowitz said. “Think of the strain from constantly trying to understand speech around you while performing tasks of daily living,” Smith added.
- Social isolation concerns. Hearing loss could cause someone to spend less time with others or spend less time moving or exercising, which could fuel mental health issues, David Reuben, MD, director of the Multicampus Program in Geriatrics Medicine and Gerontology and chief of geriatrics at the UCLA Center for Health Sciences, told Health. Social isolation, depression, and lack of physical activity are each risk factors for dementia.
- Underlying biological connections. According to Smith, hearing loss causes “decreased neural activation” in the brain. This could make it harder for different parts of the brain to communicate, leading to atrophy of brain cells. Or, he said, hearing loss might otherwise impact brain structure, acting “like an additional hit” for people facing other dementia risk factors.
In the new study, Smith and his colleagues said they spotted a “modest association” between a lower dementia risk and treating auditory impairment, warranting further investigation into whether hearing aids could be a way to protect against cognitive decline.
It’s possible that hearing aids might help delay dementia if the hearing issues are the true culprit behind a person’s cognitive concerns, said Brenowitz.
Even if that’s not the case, getting diagnosed and treated for auditory impairment can parse out whether someone is actually experiencing cognition issues, or whether they were simply having trouble hearing, she added.
Beyond this, though, research doesn’t necessarily support the idea that hearing aids can protect against cognitive decline. The link between hearing loss and dementia is more established, Reuben said, but “the case for [interventions like hearing aids] being able to prevent [dementia] is not as compelling.”
“Only one large, multi-center, randomized trial that would provide that high level of evidence has been conducted—the ACHIEVE trial—and the primary results were null,” Smith said. However, that 2023 trial did find that treating hearing loss could lead to positive cognitive changes in people with a higher-than-average baseline risk for dementia.
In general, the issue is that there could be a wide range of risk factors at play that might explain why a person with hearing loss is developing dementia (outside of the hearing loss itself), Reuben explained. Researchers just don’t have the full picture yet.
This was a limitation of Smith’s study too, he said. He and his colleagues couldn’t account for the “cumulative impacts of hearing loss on dementia,” he explained.
Though the study’s findings are promising, more research needs to be done to better understand the true connection between hearing and brain health, experts said.
“We still don’t know whether treating hearing loss—primarily through hearing aids and associated rehabilitative services—reduces the risk of cognitive decline and dementia,” Smith stressed.
But that being said, treating auditory issues is always a good idea, even if it doesn’t end up boosting your brain health.
“Treating hearing loss—like getting fit with hearing aids—improves communication and improves quality of life,” Smith said. “There are no risks or harms.”
This is why screening for hearing loss is so important for aging adults, Brenowitz said. It allows healthcare providers to “catch and treat or mitigate hearing loss at earlier stages,” when hearing aids are more effective, she said. That is, as long as they’re being worn properly, Reuben added.
