Can Dementia Be Prevented? Yes, Up to 45% of the Risk

Yes, in part. The 2024 report of the Lancet standing Commission on dementia attributed 45% of dementia worldwide to fourteen risk factors that could in principle be changed, and called its own finding a hopeful picture. It is a population estimate rather than a promise that any one person can cut their own risk by 45%.

The largest contributors are not the ones most often talked about: hearing loss and high LDL cholesterol at 7% each head the list, ahead of social isolation, less education, air pollution and untreated vision loss. The World Health Organization's July 2026 guidelines set out which changes the evidence supports, and most of it is the same advice that protects your heart.

Just as useful is what is not recommended. Vitamin B, vitamin E, multivitamins and fish oil are not endorsed for reducing dementia risk in people without a diagnosed deficiency, because the trials do not support them. Knowing what not to spend your money on is part of the advice.

In part, yes. Up to 45% of dementia risk is attached to things that can be changed. The figure comes from the 2024 report of the Lancet standing Commission on dementia, which put it at 45% across fourteen risk factors, and the World Health Organization adopted it in the risk-reduction guidelines it published on 15 July 2026.

That number deserves care in both directions. It does not mean 45% of dementia is preventable in any individual, and it does not mean anyone is to blame for developing it.

What it means is that across a whole population, a substantial share of risk is attached to things that can change, and the list of those things is now specific enough to act on.

Which risk factors carry the most weight

The Lancet Commission did not stop at a total. It modelled fourteen risk factors and published the share of dementia worldwide attached to each one, which is the part worth reading, because the largest contributors are not the ones most often talked about. The Commission calls its own result a “hopeful picture”.

Hearing loss, 7% of dementia worldwide
High LDL cholesterol, 7%
Social isolation, 5%
Less education, 5%
Air pollution, 3%
Untreated vision loss, 2%

Depression, traumatic brain injury, physical inactivity, smoking, diabetes, high blood pressure, obesity and excessive drinking account for the rest, each between about 1% and 3%. All fourteen together come to 45%, and these are the report’s own rounded figures.

Two things are worth knowing about those shares. They are already adjusted for the fact that these problems travel together: the Commission found five underlying components explaining 54% of the variation across the fourteen factors, so the numbers cannot simply be added up or treated as independent. And several of them are not individual choices at all. Air pollution is a matter of where you live, and social isolation is often a consequence of bereavement, mobility or income rather than preference.

That is worth saying plainly, because risk-reduction advice can otherwise read as an accusation. Hearing loss heading the list is the clearest example of the opposite: it is treatable, and treating it is not a matter of willpower.

Source: Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. The Lancet, published online 31 July 2024. doi:10.1016/S0140-6736(24)01296-0

How you can take charge

Increase physical activity
Stop tobacco use
Reduce alcohol intake
Eat a healthy diet
Reduce exposure to air pollution
Managing cardiometabolic conditions, including hypertension, diabetes and high cholesterol
Consider hearing aids as part of risk reduction
Stimulate your brain by learning new things or train your brain to more
Engage socially with other people

these are things you are in complete control of, and most of them are the same things that protect your heart. That overlap is not a coincidence.

Common supplements are not recommended

this is the part worth reading twice.

The guidelines do not recommend vitamin B or vitamin E supplementation, omega-3 polyunsaturated fatty acids, or multivitamin and mineral supplements for reducing dementia risk in people without a diagnosed deficiency.

That runs against a great deal of popular advice, including some you will find on brain-health websites.

If you are taking a supplement specifically to protect your memory, and you do not have a diagnosed deficiency, the current guidance does not support it. Talk to your doctor before changing anything you take.

We have written about omega-3 and brain health ourselves. We are reviewing that article against these guidelines, and we would rather say so than quietly leave it.

Where testing fits

One thing to be clear about: these guidelines are about risk reduction. They do not make recommendations about cognitive screening or early detection, and nothing here should be read as an endorsement of any particular test, ours included.

What they do establish is that changes you make can matter. Which raises a practical question the guidelines do not answer: how would you know whether anything you are doing is working?

That is the argument for having a baseline. A single memory score tells you where you sit against people of your age and education.

A score you can compare against your own result from a year ago tells you about direction, which is the thing risk reduction is trying to influence. If you want to read more, we have written about tracking memory over time.

The Memory Exam is a screening test, not a diagnosis, and it cannot tell you why anything has changed. That conversation belongs with your doctor.

Read the sources

the announcement is available on the World Health Organization website, and the research behind the 45% figure is in the Lancet Commission’s 2024 report (doi:10.1016/S0140-6736(24)01296-0).

If you have noticed changes in your own memory or someone else's, our early warning signs checklist may help you describe them, and our page for caregivers is written for people worried about a parent.