Hearing loss and cognitive decline: What's the connection?Alzheimer's, dementia and hearing loss Learn more about the link between untreated hearing loss and cognitive impairments like dementia, and if hearing aids can help. 2021 1715 Hearing loss and cognitive decline: What's the connection? https://www.healthyhearing.com/report/52904-The-connection-between-hearing-loss-and-cognitive-decline
When my mother hit midlife she sometimes called me “Luna,” the name of my childhood cat. Now that I’m the age she was then, I just as often go looking for my glasses for several minutes before I realize they’re propped on my head.
“Senior moments” frighten me, as I’m still earning my living in a brain-taxing field. It’s even worse if dementia runs in your family.
As we age, connections between cells in the brain are damaged, or some cells are lost—a process that has scarily been called “brain atrophy” or simply “cognitive decline.”
And it’s quite clear that hearing loss, at the very least, puts you at increased risk of cognitive impairment as you get older.
How does dementia affect hearing?
Many studies have found an association between untreated hearing loss, Alzheimer's disease and other types of dementia. Meaning, people with hearing loss are more likely to develop cognitive problems than people who do not have hearing loss. This is an area of intense research with many unanswered questions. For example, we still don’t know yet if hearing loss causes dementia, or vice versa.
Researchers are also not sure if hearing aids can prevent or reverse cognitive decline, though early data looks promising, especially when it comes to delaying the onset of dementia. Clinical trials currently underway on this topic will provide more clarity in the next few years.
Hearing loss can mimic cognitive decline and Alzheimer's
Don’t assume you’re suffering from dementia if you’re having trouble understanding speech, or finding it exhausting to have simple conversations. Hearing loss has some of the same symptoms as cognitive impairment, so it’s vital to have regular hearing checks.
If you do have confirmed hearing loss, though, it’s important to know you are at higher risk of developing dementia. Take as many preventative steps as possible, such as healthy lifestyle choices, wearing hearing aids, taking medications as recommended, and staying active and socially engaged (hearing aids help!).
How hearing loss may change the brain
Hearing loss does seem to shrink some parts of the brain responsible for auditory response. In a study led by Jonathan Peelle, now at Washington University in St. Louis, older adults underwent brain scans while they listened to sentences of varying complexity. They also took tests that measured “gray matter,” the regions of the brain involved in muscle control, and sensory perception such as seeing and hearing, memory, emotions, speech, decision making, and self-control.
It turned out that the neurons (brain cells) in people with hearing loss were less active when they focused on complex sentences. They also had less gray matter in the auditory areas. These effects may accumulate with time or be triggered by age: In other research, Peelle found that older adults with hearing loss do worse on speech comprehension tasks than younger adults with hearing loss.
What research on dementia and hearing loss reveals
Most recently, a study published in July 2021 found that people who struggle to hear speech in noise were more likely to develop dementia than those with normal hearing, as measured over an 11-year period. This was the first time that speech in noise was specifically studied. However, the study wasn't capable of determining if untreated hearing loss caused the dementia, only that they're linked.
In a different study, a team at Johns Hopkins looked at cognitive impairment scores over six years for nearly 2,000 seniors. They concluded that those with hearing loss had a faster decline. The volunteers were all cognitively normal when the research began. But by the study’s end, people with hearing loss were 24 percent more likely to meet the standard of cognitive “impairment” compared to people with normal hearing.
Another approach is to ask people whether they’ve noticed a change. Measures of “subjective” decline can pick up losses before they’ll show up on a test. A large study—using data drawn from more than 10,000 men age 62 and up—ran over eight years. It found that the greater their hearing loss, the more likely men were to express concerns about their memory or thinking over time. With even a mild hearing loss, their chance of reporting cognitive decline was 30 percent higher than among those who did not report any hearing loss. With moderate or severe hearing loss, the risk was 42 and 52 percent higher. (At age 80 or above, moderate hearing loss is more common than mild hearing loss.)
Dr. Sharon Curhan, a doctor and epidemiologist at Brigham and Women’s Hospital in Boston, who led this study, said she plans further research with women and younger populations.
Lastly, a Salt Lake City team found that among nearly 4,500 seniors without dementia, 16.3 percent of those with hearing loss developed dementia compared to 12.1 percent of those with normal hearing. It also tended to occur faster in people with hearing loss. On average, it took a bit over a decade to develop dementia among the group with hearing loss, and 12 years if your hearing was fine.
What about tinnitus and Alzheimer's?
Alzheimer's disease is slightly more common among people who have tinnitus than people who don't, at least one study has indicated. In that study, conducted in Taiwan, 3.1% of tinnitus patients developed Alzheimer's over a 10-year period, compared to 2% of those who did not have tinnitus. However, scientists do not know why this relationship exists, and more research is needed.
Do hearing aids reverse cognitive decline?
Dr. Curhan’s research didn’t get a clear answer to this question. Among volunteers with severe hearing loss, those who wore hearing aids had a slightly lower risk of subsequent subjective cognitive decline than those who didn’t. But the effect was too small to be statistically significant.
She would like to see hearing aids and cognitive decline get a hard look. There isn’t much evidence over long periods of time and what we have isn’t conclusive, she notes. “Several studies have found no relation between hearing aid use and cognitive function decline, while others have been suggestive of a possible association,” she told Healthy Hearing. “This relation merits further study.”
One recent and very large observational study did shed more light on this issue, finding that hearing aids appeared to delay the onset of cognitive impairment and dementia, along with depression and falls that cause injuries. However, it was not a randomized controlled trial, so the results could have been for other reasons (for example, hearing aid wearers have higher incomes and thus more access to good medical care).
As well, one large 2018 study analyzed results from more than 2,000 Americans age 50 and up who took word recall tests every two years for up to 18 years. Among those who acquired hearing aids along the way, the evidence suggested that the aids slowed the rate they lost memory of words.
Personally, I’m grateful I have my hearing aids as they help keep me connected with loved ones and friends. My father, a retired statistician who hasn’t lost a single marble, isn’t fond of wearing his. To nudge him, I go so far as to mention the research. “Dad, I just saw some interesting numbers. Did you know that hearing aids may prevent falls and cognitive loss?”
His answer, “Do they do it from the drawer?”
What are the best hearing aids for dementia?
For patients living with both dementia, hearing loss should never be ignored, as it may exacerbate dementia symptoms, increase their disorientation and make their environment less safe (they can't hear a running faucet, for example).
While there are no hearing products made specifically for dementia patients, there are plenty of devices out there that can still be helpful. They range from the relatively simple, such as a wearable microphone (known as a "pocket talker") to premium hearing aids.
If you are the caretaker of someone with Alzheimer's or a similar disease that affects cognition, you are wise to investigate what hearing devices might work best. A hearing care provider will be your ally in this journey, as they'll know the latest products that may work for your loved one. You'll also be able to discuss your loved one's specific needs, habits and abilities with the hearing care specialist.
For example, hearing aids may not always be the best solution. Most premium hearing aids are designed to be discreet, so they may be too small and too easy to lose for a patient with dementia, especially if they have dexterity problems. Hearing aids also require that a person (or their caretaker) remember to keep the batteries fresh and the device clean and in good working condition. Instead, assistive listening devices may work better.
If you need help with hearing loss
If you're noticing trouble hearing in yourself or a loved one, don't delay—prompt treatment can help you or your loved one stay engaged in the world and avoid social isolation, a common problem for people with untreated hearing loss. Hearing loss is exhausting, but it doesn't have to be. To find a hearing care professional, see our directory of consumer-reviewed hearing clinics to find a hearing specialist or audiologist near you.