Hearing Loss and Dementia: What the Research Says

In 2020, The Lancet Commission on dementia prevention identified untreated hearing loss as the single largest modifiable risk factor for dementia, ahead of smoking, high blood pressure, obesity, and physical inactivity. That finding got a lot of attention in the medical community, and the research published since then has only strengthened the connection.

If you or someone you care about has untreated hearing loss, this is worth understanding.

What the research actually shows

The link between hearing loss and cognitive decline has been studied extensively over the past two decades. Here are the key findings:

The Lancet Commission (2020, updated 2024) estimated that addressing hearing loss could prevent or delay up to 8 percent of all dementia cases worldwide. That makes it the single largest modifiable risk factor on the list.

The ACHIEVE trial (2023), published in The Lancet, was the first large randomized controlled trial to directly test whether treating hearing loss slows cognitive decline. Among adults at higher risk for cognitive decline, hearing aid use was associated with a 48 percent reduction in the rate of cognitive decline over three years.

Johns Hopkins longitudinal studies followed adults for over a decade and found that people with mild hearing loss were twice as likely to develop dementia as those with normal hearing. For moderate hearing loss, the risk tripled. For severe, it was five times higher.

These are not small effects, and they come from some of the most respected research institutions in the world.

Why hearing loss affects the brain

There are three main theories for why untreated hearing loss accelerates cognitive decline, and they are not mutually exclusive. All three likely play a role:

Cognitive overload. When hearing is impaired, the brain has to work much harder to decode sounds and piece together incomplete speech signals. This redirects cognitive resources away from other functions like memory and comprehension. Over time, this constant extra effort takes a toll.

Brain atrophy. The auditory cortex, the part of the brain that processes sound, begins to lose volume when it is not receiving adequate stimulation. Brain imaging studies have shown accelerated shrinkage in the temporal lobe among people with untreated hearing loss. Use it or lose it applies to the brain just as it does to muscles.

Social isolation. People with untreated hearing loss tend to withdraw from conversations, social gatherings, and activities they once enjoyed. Social engagement is one of the most powerful protectors against cognitive decline. When hearing loss makes socializing exhausting or embarrassing, people pull back, and the brain pays the price.

Hearing aids as a protective factor

The ACHIEVE trial was significant because it moved the conversation from correlation to causation. Previous studies showed that hearing loss and dementia tend to occur together, but the ACHIEVE trial demonstrated that intervening with hearing aids actually slows the rate of cognitive decline.

This does not mean hearing aids prevent dementia. But the evidence strongly suggests that treating hearing loss reduces one of the most significant modifiable risk factors. In practical terms, that means keeping the brain engaged, reducing cognitive load, and maintaining the social connections that protect cognitive health.

The benefits appear to be greatest when hearing loss is treated earlier rather than later. The longer hearing loss goes unaddressed, the more the brain adapts to reduced input, and the harder it is to retrain those pathways.

What this means for you

If you have noticed changes in your hearing, or if someone close to you has been pointing out that your hearing has changed, getting tested is a straightforward step with potentially significant benefits.

A hearing test does not commit you to anything. It gives you information. And that information, combined with what the research now shows about the link between hearing and brain health, puts you in a much better position to make decisions about your care.

If hearing aids are recommended, wearing them consistently is what matters most. The brain needs regular, adequate sound input to stay active. Wearing hearing aids only occasionally does not provide the same protective effect as consistent daily use.

The seven-year gap

On average, people wait seven to ten years between first noticing hearing loss and actually getting hearing aids. During those years, the brain is adapting to less and less sound input. Social connections are gradually thinning. Cognitive resources are being diverted to the simple act of trying to hear.

Every year of that gap is a year the brain is not getting the stimulation it needs. The research is now clear enough that waiting is no longer a neutral choice. It carries a real cost.

Getting tested in Edmonton

At Medicine Place Hearing Care, we offer comprehensive hearing assessments at both of our Edmonton locations. The test is quick, painless, and does not require a referral. If your hearing is fine, you leave with peace of mind and a baseline for the future. If there is a concern, you leave with a clear explanation and your options.

Your brain health is connected to your hearing health. The science says so. And the first step is knowing where you stand.

Book a hearing test at Medicine Place Hearing Care in Edmonton. No referral needed.