Hearing Aids Can Halve the Risk for Cognitive Decline and Dementia; ACHIEVE Study Highlighted at ADA Conference

For more than a decade, research has shown that hearing loss is associated with cognitive decline and dementia. However, only now has concrete evidence emerged demonstrating that the use of hearing aids can effectively reduce the risk for rapid mental decline for some people. The Aging and Cognitive Health Evaluation in Elders (ACHIEVE) study—a relatively short 3-year randomized trial—does just that: in fact, it showed hearing aids that were professionally fit using best practices cut in half cognitive decline for a group of people who were at greater risk for dementia.

ACHIEVE is a landmark study for both doctors and the broader community of aging adults concerned with the onset of cognitive decline and dementia. It also has huge implications for worldwide healthcare. According to the World Health Organization (WHO), $1.3 trillion is spent annually on dementia-related care, with approximately 50% of the total spent by family members and close friends who also provide about 5 hours of care and supervision per day.

The study provides powerful, high-level evidence that hearing aids and treatment can reduce the risk of dementia for at-risk populations. It should prove extremely useful for general practitioners, as well as for decision-makers involved in medicine, health insurance, economic policies, and legislation globally. In fact, The Lancet —one of the world's most respected medical journals—did something fairly unusual: it highlighted the ACHIEVE study’s findings on the front cover of its September 2, 2023 edition.

This article features the viewpoints of three ACHIEVE study authors who presented their findings to approximately 450 audiologists and hearing care experts attending the 2023 Academy of Doctors of Audiology (ADA) AuDacity General Session on November 2-4 in Bonita Springs, Fla.

A deeper dive into the ACHIEVE study

The keynote ADA General Session featured ACHIEVE study lead-researcher Frank Lin, MD, PhD of the Cochlear Center for Hearing and Public Health at Johns Hopkins, followed by a more in-depth look at the research methods, findings, and its implications presented by study co-authors Nicholas Reed, AuD, of Johns Hopkins and Victoria Sanchez, AuD, PhD, of the University of South Florida.

Dr. Lin began by explaining that, in 2050, about 1 in 30 people will be living with dementia. Although this represents a vast patient population, it also suggests that dementia isn't an extremely common consequence of aging. Not everyone experiences rapid cognitive decline, and various mediating factors have been shown to buffer the risk of developing dementia.

Why are hearing loss and dementia linked?

Although Lin says the exact reason(s) why hearing loss may contribute to cognitive decline are still unknown, there are at least four general hypotheses that have been proposed:

1. Multi-hit theory: Microvascular disease, plaques in the brain associated with Alzheimer’s disease, or other medical conditions—when not buffered by the ability to hear well—may lead to accelerated neurodegeneration and cognitive decline
2. Cognitive load theory: Continually straining to understand speech might create undue stress or "cognitive load” on the brain, causing mental resources to be diverted toward the act of processing sounds instead of normal functions like memory retention and other brain activities that may help buffer against dementia
3. Auditory deprivation theory: Hearing loss may cause structural changes as the brain shuffles its sensory processing centers (via neuroplasticity) in response to auditory deprivation, possibly resulting in cascading cognitive deficits
4. Social isolation theory: Hearing loss can cause social disengagement, loneliness, and depression, accelerating brain atrophy and leading to poorer health and cognitive function

Any or all of these factors could help explain why hearing loss is associated with dementia.

Lin reviewed three previous epidemiological studies from the past decade that link hearing loss with reduced cognitive wellness, starting with his own research in 2011 that found mild hearing loss doubles your risk for cognitive decline, while moderate and severe hearing loss triples and quintuples your risk, respectively. A year later, John Gallacher and a team of UK researchers reported similar findings using a different method and study population. Epidemiologist Jennifer Deal and a US team of researchers in 2017 found that moderate-to-severe hearing loss increases the risk of developing dementia in older adults.

Yet, data has been lacking about whether hearing care and treatment with hearing devices can reduce the risk of cognitive decline. Some studies, including a 2022 meta-analysis published in JAMA Neurology, have indicated hearing aids and cochlear implants are associated with a decreased chance of cognitive decline. But other studies were less supportive of this idea. A large-scale randomized trial was sorely needed to show if there was an actual causative relationship.

ACHIEVE study set-up for 3-year randomized trial

In the 3-year ACHIEVE study, close to a thousand older adults ages 70-84 with untreated mild-to-moderate hearing loss and normal cognitive function participated. Importantly, these subjects were assembled from two distinct groups: 739 community volunteers were recruited by ads and online—meaning these people were mentally active, health-conscious, and motivated enough to volunteer and commit to a long-term clinical trial focused on ways to promote healthy aging. Lin likened them to people concerned enough about their health to worry themselves into wellness ("worried well"), and they are known in the study as the De Novo group.

A second group of 238 people were already enrolled in the Atherosclerosis Risk in Communities (ARIC) study. These individuals had been monitored for their cardiovascular problems since 1987 and were at greater risk for cognitive decline and dementia. They had distinctly different health metrics and attitudes, as well as baseline cognitive scores, than the "worried-well" De Novo group.

All participants were told the trial involved two types of interventions: 1) general health education and 2) treatment using hearing aids and audiological care at regular intervals from an audiologist who used a well-defined “best practices” protocol. They would be randomly assigned to one intervention type and offered the other after 3 years.

Lin emphasized the study was conducted by a research consortium involving 8 universities and clinics, more than 60 staff researchers, with nearly $40 million in funding over 10 years from the National Institutes of Health (NIH). Support from Sonova in the form of Phonak hearing aids and accessories, which NIH did not fund, was also crucial to the study.

Implications for people concerned about cognitive decline and dementia

After 3 years (which included the 2020 pandemic), an impressive 90% of the study participants returned for follow-up testing. People undergoing hearing intervention in both groups had high adherence to and satisfaction with the treatment program, with an average of 7 hours of hearing aid use per day.

Incredibly, the ARIC group participants receiving hearing aids and treatment showed a large (48%) reduction in global cognitive decline after only 3 years. For this group who were at greater risk for cognitive decline, the intervention program made a huge difference in their rate of cognitive decline. However, in the healthy De Novo (“worried well”) group, there was no difference in cognitive scores between those who received hearing intervention or the health education program.

So, why didn't the larger De Novo group benefit from hearing aids and hearing care services? The data showed the De Novo individuals had a very slow rate of cognitive change; their mental functioning was very similar at the beginning and end of the study. Lin noted, “It becomes clear, when we take a closer look at the data, the rate of cognitive change—or the baseline cognitive change among the controls in the De Nova group versus ARIC—was three times slower…Over 3 years, they had very little cognitive change, and if you have very little cognitive change, a hearing intervention can’t slow down something that isn’t changing to begin with.”

In other words, there wasn't much to slow down for this larger “worried well” health-conscious group relative to dementia. However, in the more at-risk, less healthy ARIC group, hearing intervention with hearing aids made a big difference. This is why, overall, the study found hearing treatment did not significantly change cognitive outcomes for the group as a whole; the the overall results were biased by the lack of cognitive change (with or without hearing aids) within the much larger De Novo group.

However, it’s important to note that in both participant groups, hearing intervention was found to improve communication abilities and social functioning while reducing loneliness.

Lin says the results from the ACHIEVE study support the findings of the landmark Lancet Commission study that found hearing loss to be the number-one modifiable factor for mid- and late-life adults, accounting for 8% of dementia cases. He notes that hearing care is underused, does not pose any adverse risks, has been shown to improve self-perceived communication and lessen loneliness, and may substantially reduce cognitive decline in people who are at increased risk for dementia.

Along with his research, Lin has been advocating for more public awareness of hearing treatment and the adoption of the Hearing Number—an easy-to-understand and monitor measurement of your hearing ability—the same way blood pressure numbers can be used to inform people about their cardiovascular health. Lin has also been a strong advocate for over-the-counter (OTC) hearing aid legislation and insurance coverage for hearing aids and related services and accessories.

Implications for Medicare and policy-makers

Dr. Lin’s presentation was followed up with more specifics about the study from Drs. Reed and Sanchez, ending in a roundtable discussion facilitated by Shannon Basham, AuD, senior director of audiology and education at Sonova, the company that donated the Phonak hearing aids and accessories used in the study.

The key takeaway from the ACHIEVE study is that people who have hearing loss and whose health history may place them at greater risk for developing dementia may greatly reduce (by 48%) their chances of experiencing it. The other important point is that both participant groups in the study were satisfied with and benefitted in other important ways from hearing treatment, including a reduction in loneliness and social isolation.

The 2020 Lancet Commission study shows that many of the modifiable factors for stacking your odds against developing dementia are things you need to do during early or midlife, like attaining sufficient education or avoiding obesity and cardiovascular disease. Reed pointed out that hearing intervention is particularly attractive for policy-makers targeting cognitive wellness because it is a mid- and late-life modifiable factor. “This is not something that has to happen in your 20s and 30s when it comes to cognition or dementia,” he said.

He also noted the incredible costs involved in Medicare’s potential coverage of drugs to slow the advance of Alzheimer's disease. By some estimates, the new FDA-approved Lecanemab (Leqembi™) might cost Medicare $82,500 per patient per year—or $2-5 billion annually for the entire program—and risks of brain swelling and bleeding may outweigh the drug's practical benefits. Hearing treatment with hearing aids, in contrast, is a fraction of that cost with no real risks, and it comes with proven side-benefits like reduced chances for loneliness and depression.

“The estimate for hearing care provision under Medicare using the Build Back Better framework was $89 million over 10 years,” noted Reed. “So, when someone puts the appraisal that way, hearing care is actually probably the most cost-effective dementia prevention intervention that exists.”

Implications for clinicians and “precision audiology”

Reed and Sanchez say the ACHIEVE study poses as many questions as it provides answers. Data about other facets of hearing treatment, including MRI brain structural changes, health-related quality of life, depression, hospitalizations, physical activity and functioning, and associated healthcare costs, is still being gleaned from the study—so stay tuned for more to come.

It's also unclear how lengthy a study of this type needs to be. Symptoms of dementia can emerge over many years. Is a more extended timeframe than 3 years required to fully understand the effects of hearing intervention? The potential impact of waiting to adopt a hearing treatment is also interesting. Does a 3+ year wait to obtain hearing aids have a negative effect on subsequent health benefits compared to earlier intervention? The ACHIEVE study has now been funded and extended into a 6-year investigation.

Also, how might over-the-counter (OTC) hearing aids influence cognitive decline and dementia compared to the prescriptive hearing aid model used in the study? With the advent of OTC hearing devices, a three-tiered system appears to be emerging: 1) self-directed care using OTC hearing aids, 2) a hybrid approach of self-directed care with professional assistance via telecare or office visits when needed, and 3) the traditional "gold standard" prescriptive hearing aid with treatment from an audiologist or hearing aid specialist. How might each of these affect the trajectory of the disease?

It's important to note that ACHIEVE used a very detailed patient care program using audiology best-practice protocols. Dr. Sanchez presented specifics on this intervention program detailed in a 305-page electronic searchable manual with step-by-step instructions and scripted language to be used by audiologists throughout the treatment. The intervention included comprehensive hearing assessment and service delivery while targeting specific person-centered goals. She emphasizes there is no “one-size-fits-all” approach to audiological care. The program also resulted in the Toolkit for Self-Management, which assists in educating adult hearing aid users about their hearing loss and customizing the intervention to the individual’s specific goals and health literacy.

So, what can clinicians, like audiologists, do with information from the ACHIEVE study? It’s agreed that the research shouldn’t be weaponized into scare tactics to drive people toward hearing care; however, the data is important and must be responsibly disseminated to the public. Doubtlessly, this will be a central task in the future, with white papers, recommendations, and guidelines to come. In fact, Phonak and ADA assisted in convening a daylong meeting of experts in numerous areas, including researchers and clinicians like Reed and Sanchez, as well as neurologists, psychologists, gerontologists, economists, and others.

“Dementia is scary. Dementia is complex. Most people don't really understand dementia,” said Reed. “We talk about dementia as a cognitive condition. But the real definition of dementia is not just the cognitive component; it's functional, it’s about people in their daily living…You're no longer able to live independently, you're no longer able to bathe or dress yourself. It's about real, functional, daily life, not just cognition.

“So people are fearful of it. And I think this is one of those conversations in which it's important that a clinician understands the literature. It’s important that we explain broadly how hearing care fits into [the picture], and I don't think that's easy to do.” For example, he noted that amplification may not just improve communication, but could also decrease cognitive load or increase social engagement—concepts not always easy to explain to a patient during a short consultation.

Sanchez emphasized that it all comes down to patient-centered care. “Our patients come to the clinic for different reasons, right? Not everyone's coming into the clinic saying, ‘I'm afraid of dementia.’ And not everyone's coming into the clinic [only wanting] to hear better. There are so many different reasons, and I think we need to meet patients where they are. If we tell every patient about the connection between hearing loss, cognition, and the ACHIEVE trial, that's probably not the right approach if the patient isn’t looking for that information…Patient conversations differ. If you do have a patient who is worried about cognitive health and resilience, then it's very appropriate to have that conversation. What does the research tell us? What do we know? What don't we know? Don't over-interpret and don't under-interpret. But each patient probably needs a little bit different messaging, depending on why they're in your clinic and how you can help them the most.”

All of the above hints at a future where hearing intervention might evolve into more specific and individualized treatments based on a person’s history, communication goals, current cognitive status, risk factors, etc. Precision medicine is used to optimize efficiency or therapeutic benefit for particular groups of patients. “I really don't want to discount the fact that we can move toward a model of precision audiology,” said Reed. “And maybe there is a study in the future where specific cognitive measures change the way we fit and literally change the [hearing aid] settings or aural rehabilitation planning.”

While emphasizing that much more work is needed, given the complexity of dementia and the relatively early stages of their work, Lin, Reed and Sanchez think the future is bright for more revealing findings in the coming years from the ACHIEVE research.