Wendy Haaf answers your questions about health, nutrition, and well-being
Can hearing aids help reduce the risk for dementia?
It’s been clear for some time that hearing loss is linked with an increased likelihood of developing dementia. In fact, a 2020 report by The Lancet Commission named hearing loss as a leading potentially modifiable risk factor for dementia. Yet although observational studies of people with hearing loss have found lower rates of dementia among those who wear hearing aids, this research couldn’t establish cause and effect.
“We didn’t know if the benefit was due to wearing hear- ing aids or some other factor,” says Marilyn Reed, an audiologist and clinical researcher at Baycrest Health Sciences in Toronto. “For example, people who get hearing aids may be more outgoing and social or they might have fewer medical issues”—both traits that are linked with lower dementia risk. Consequently, “we were waiting for the first randomized controlled trial,” she adds.
The first such study, the ACHIEVE trial, was published in The Lancet in June 2024. Participants aged 70 to 84 with untreated hearing loss were randomly assigned to receive either hearing aids plus counselling from an audiologist or a control intervention—education on successful aging. Some of these people were healthy community members recruited via ads; the rest were already enrolled in a long-running study investigating cardiovascular risk factors. At the three-year follow-up, participants in the latter group had 2.7 times more cognitive decline than the former. However, in this high-risk subset of participants, those who received the hearing-aid intervention saw their rate of cogni- tive decline cut by nearly half—48 per cent. The researchers will continue tracking participants to see whether those at lower risk benefit similarly over a longer time frame.
So we now have stronger evidence that a combination of hearing education and hearing aids protects against dementia—but we still don’t entirely understand why. One possibility is the “cognitive-load hypothesis.” Essentially, hearing loss demands that you focus much harder on what you want to hear and ignore irrelevant sounds. “You’re using cognitive resources that you would normally use for things like processing information and storing it into memory,” Reed says. “So you’re changing what the brain is doing when you’re making more effort, and it’s possible that that alters pathways in the brain.”
Hearing loss also cuts down on stimulation to the nerves responsible for sensing, transmitting, and decoding sound signals. “When you’re not stimulating those pathways, it leads to shrinkage in certain areas of the brain,” Reed explains, adding that it’s brain imaging that allows us to see this.
Then there’s the fact that people often avoid social situations when they don’t hear well, and social isolation is linked with a greater likelihood of both dementia and depression, which is itself a risk factor for dementia. Finally, Reed says, “it’s possible that there are age-related pathological changes that affect both hearing and cognition.”
Whatever the protective mechanisms might be, the World Health Organization advocates regular screening for hearing loss starting at age 50, Reed says, “so that we can identify and treat it sooner and hopefully reduce any risk it poses for brain health and healthy aging.”
