The most changeable dementia risk isn’t diet or exercise — and almost half of cases may be delayed or prevented

You might start the morning with a crossword, eat more blueberries and walnuts, or even use a brain-training app. Those habits are not useless. But the biggest shift, according to a leading international panel on dementia prevention, may be something many people delay for years: having their hearing checked.

Key Takeaways

• The 2024 Lancet Commission on dementia identified hearing loss as one of the two largest modifiable risk factors for dementia, tied with high LDL (“bad”) cholesterol, with each associated with about 7% of cases.
• The report says addressing 14 modifiable risk factors across the life span could prevent or postpone nearly half of all dementia cases.
• Hearing loss becomes very common with age. About 55% of Americans age 75 and older have disabling hearing loss, yet fewer than 1 in 3 adults age 70 and older who could benefit from hearing aids have ever used them.
• In a major clinical trial, treating hearing loss reduced the pace of thinking and memory decline by 48% over three years in older adults at higher risk of cognitive decline.
• Hearing tests are straightforward, and over-the-counter hearing aids have made treatment easier to access.

What the world’s leading dementia experts found

The Lancet Commission on dementia prevention, intervention, and care is an international group that regularly reviews research on what contributes to dementia risk. In its latest update, presented at the Alzheimer’s Association International Conference, the panel lists 14 modifiable risk factors: less education, hearing loss, high LDL cholesterol, depression, traumatic brain injury, physical inactivity, diabetes, smoking, high blood pressure, obesity, excessive alcohol use, social isolation, air pollution, and untreated vision loss.

Taken together, the Commission estimates these factors account for about 45% of dementia cases worldwide, meaning nearly half could, in theory, be delayed or prevented.

Two factors stand out in particular. Hearing loss and high LDL cholesterol, each measured in midlife, are each linked to about 7% of dementia cases, the largest share among modifiable risks. High LDL was newly added in the 2024 update, alongside untreated vision loss.

What does not appear near the top of the list? Crossword puzzles, special “brain foods,” and supplements. Mental activity over a lifetime still matters, especially through education, but the biggest levers are more medical than many people expect.

Why hearing might affect the brain

Researchers do not yet know exactly how hearing loss increases dementia risk, and several mechanisms may be involved. One theory is that constantly straining to understand speech diverts brain resources away from memory and thinking. Another is that hearing loss can push people to withdraw from conversation and social life, and social isolation is itself a dementia risk factor. Hearing loss may also reduce stimulation to brain regions involved in sound processing.

What scientists are more certain about is the association. Observational studies have linked hearing impairment in older adults to faster cognitive decline and a much higher risk of developing dementia.

What happened when people’s hearing was treated

The strongest evidence comes from ACHIEVE, the largest randomized clinical trial of its kind, published in The Lancet. It followed 977 adults ages 70 to 84 with untreated mild-to-moderate hearing loss for three years. Half received hearing aids and counseling from an audiologist. The other half received a health education program.

In the full group, the hearing intervention did not significantly change the rate of cognitive decline. But among 238 participants at higher risk of cognitive decline — older adults with additional risk factors such as heart disease — the hearing intervention slowed the decline in thinking and memory by 48%.

That suggests the biggest benefit may go to the people who need it most. The Lancet Commission concluded that evidence supporting hearing treatment as a way to lower dementia risk is now stronger than in its earlier report, and that hearing aids may be especially helpful for people with hearing loss plus other risk factors.

Why so many people do not treat it

Hearing loss often develops gradually, so many people do not notice it or assume others are mumbling. According to the National Institute on Deafness and Other Communication Disorders, about 22% of adults ages 65 to 74 and 55% of those 75 and older have disabling hearing loss. Yet among adults 70 and older who could benefit from hearing aids, fewer than 1 in 3 have ever used them.

Cost and stigma have long been barriers. Since 2022, the FDA has allowed over-the-counter hearing aids for adults with perceived mild to moderate hearing loss, which can be purchased without a prescription or exam and usually cost less than traditional devices.

What to do with this information

Get a baseline hearing test, especially if you are over 50, if others have commented on the TV volume, or if you struggle to follow conversations in restaurants. Your primary care doctor can refer you to an audiologist.

If you have hearing loss, treat it. Talk with an audiologist about prescription hearing aids, or consider over-the-counter devices if your hearing loss is mild to moderate. Use them consistently. They only help if they are in.

Protect the hearing you have. Limit exposure to loud noise and use ear protection with loud tools, concerts, or events.

Do not forget the co-leader. Ask your doctor about your LDL cholesterol. It shares the top spot with hearing loss on the Commission’s list.

Keep the other habits too. Physical activity, blood pressure control, not smoking, and staying socially connected are all on the list. Brain games are not harmful. They just are not the whole story.

This article is for general information and is not a substitute for advice from your doctor.

Sources:

• Livingston G, et al. “Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission,” The Lancet, 2024 (report text): https://chronicdisease.org/wp-content/uploads/2024/12/Lancet-2024.pdf
• The Lancet, press release on the 2024 dementia Commission: https://www.eurekalert.org/news-releases/1052982
• Johns Hopkins Cochlear Center, ACHIEVE study results: https://jhucochlearcenter.org/center-news/achieve-study-results-published-presented
• UNC Gillings School of Global Public Health, ACHIEVE results: https://sph.unc.edu/sph-news/hearing-aids-slow-cognitive-decline-in-older-adults-with-hearing-loss-and-at-risk-for-cognitive-decline/
• National Institute on Deafness and Other Communication Disorders, Quick Statistics About Hearing: https://www.nidcd.nih.gov/health/statistics/quick-statistics-hearing