Why untreated hearing and vision loss are now counted among the biggest modifiable dementia risk factors — and what the evidence does and doesn't show about treating them.
The short version
1Untreated hearing loss is the single largest modifiable dementia risk factor in the 2024 Lancet Commission — linked to about 7% of cases.
2Untreated vision loss was added as a new risk factor in 2024, linked to about 2% of cases.
3The ACHIEVE trial found no overall effect of hearing aids on cognitive decline — but a 48% slower decline in a pre-specified, higher-risk subgroup.
4The practical takeaway is low-risk and concrete: get your hearing and vision checked, and treat what's correctable.
Can treating hearing and vision loss protect your brain? The honest answer is layered: the link is real and strong, the treatment evidence is promising but not yet settled, and getting checked is low-risk enough to be worth doing regardless. The 2024 Lancet Commission identifies untreated hearing loss as the single largest modifiable dementia risk factor on its entire list, and in 2024 it added untreated vision loss as a new one. Sensory health has moved from the margins of dementia prevention toward its center.
Why sensory loss affects the brain
It can seem strange that the ears and eyes would influence the risk of a brain disease. But researchers have proposed several plausible pathways, and the truth is likely a combination of them rather than any single mechanism.
The numbers
The 2024 Lancet Commission expresses each factor as the share of dementia cases that could, in principle, be avoided if it were eliminated across the population. Two sensory factors now appear on that list.
7%
of dementia cases attributable to untreated hearing loss — the largest single modifiable factor
2024 Lancet Commission
What the strongest evidence shows: the ACHIEVE trial
The key trial is ACHIEVE, published in The Lancet in 2023 — the largest randomized controlled trial of hearing aids for slowing cognitive decline. It enrolled 977 adults aged 70–84 with untreated mild-to-moderate hearing loss and no substantial cognitive impairment, and followed them for three years.
48%
slower cognitive decline with hearing intervention — in a pre-specified higher-risk subgroup
ACHIEVE, The Lancet 2023
The 48% figure is real, but it comes with an essential caveat that's easy to lose when the number travels on its own.
What ACHIEVE did and didn't show
In the primary analysis of the full 977-person cohort, the hearing intervention did not slow cognitive decline — the overall result was negative. The 48% slowing came from a pre-specified subgroup of 238 participants recruited from a long-running heart-health study, who were on average older, with lower baseline cognition and more risk factors. Among the larger group of healthy community volunteers, there was no effect. The fair reading: hearing treatment may help most in people already at elevated risk of cognitive decline — but this is a subgroup finding from a three-year trial, and it warrants confirmation before being treated as settled.
Who is likely to benefit most
The ACHIEVE pattern points to a sensible interpretation: treating hearing loss appears most valuable for people whose cognitive risk is already higher. And because hearing loss is classified as a midlife factor, addressing it doesn't have to wait until your 70s.
The practical implication
You don't need the science fully settled to act. Checking and treating hearing and vision is low-risk, often inexpensive, and improves quality of life immediately — with the added possibility of protecting cognition. That's a favorable trade even under uncertainty.
Of all the dementia risk factors, hearing and vision may be the most quietly underrated — and among the most addressable. Untreated hearing loss is the single largest modifiable factor the Lancet Commission has identified, and untreated vision loss now joins it. The evidence that sensory loss is associated with dementia risk is strong; the evidence that treating it prevents dementia is promising but not yet conclusive, resting largely on a subgroup finding from the ACHIEVE trial. But the actions involved — a hearing test, an eye exam, glasses, hearing aids, cataract surgery — are low-risk and life-improving in their own right. This is prevention with very little downside.
Where do you stand across all 14 risk factors?
Take the Brain Health Quiz to get your personalized profile across all five domains — with specific action steps for your highest-priority areas. Takes about 5 minutes.
1. Livingston, G., et al. (2024). Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. The Lancet, 404(10452), 572–628.
2. Lin, F.R., et al. (2023). Hearing intervention versus health education control to reduce cognitive decline in older adults with hearing loss in the USA (ACHIEVE). The Lancet, 402(10404), 786–797.
3. Lin, F.R., et al. (2011). Hearing loss and incident dementia. Archives of Neurology, 68(2), 214–220.
4. Lee, C.S., et al. (2022). Association between cataract extraction and development of dementia. JAMA Internal Medicine. [Confirm exact citation/URL before publishing.]
Medical disclaimer: This content is for educational purposes and is not medical advice. Consult a healthcare professional before making changes to your health routine.
Last reviewed: June 2026
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