Preventing dementia: what you can and cannot influence

Nobody can promise you will prevent dementia. You can lower the odds. In 2024 the Lancet standing Commission estimated that around 45 percent of cases worldwide is linked to fourteen modifiable factors (Livingston et al., 2024). Those fourteen are not fate. They are a list.

The word prevent is too big for this. Lowering risk is the honest version.

What does preventing dementia actually mean?

Preventing dementia does not mean switching the disease off. It means lowering your chances of getting it, and possibly delaying when it starts. Age remains the strongest risk factor, and nobody can change that. The fourteen factors in the report are about everything else.

That distinction matters. Anyone promising you can stop dementia is selling you something.

The Hersenstichting, the Dutch brain foundation, puts it carefully and correctly: a healthy lifestyle lowers the chance, but offers no guarantee. People who do everything right still get dementia. People who did little about their lifestyle sometimes never do.

How does dementia develop?

Dementia is an umbrella term. In Alzheimer's disease, proteins build up in the brain and nerve cells are slowly lost. In vascular dementia it is the small blood vessels in the brain that get damaged, often after years of high blood pressure. Many people have a mix of both.

That second type matters most here. Damage to your blood vessels is damage to your brain.

Your brain gets its oxygen through a fine network of very small vessels. When those vessels narrow or clog, a tiny piece of tissue dies each time. You do not feel it. After ten or twenty years, it adds up.

That is why the advice for your heart and the advice for your head overlap so heavily. We cover this in our article on preventing a stroke or brain haemorrhage.

Which fourteen risk factors does the Lancet Commission list?

The Commission lists fourteen factors, spread across your life. Two were added in 2024: high LDL cholesterol in midlife, and untreated vision loss in later life. Together those two account for an estimated 9 percent of all cases.

Here is the list. The last column gives you something you will not find elsewhere: whether the factor is visible in a blood test.

Look at that last column again. The honest answer appears fourteen times, and ten of those times it is no.

Which of these factors show up in your blood?

Two of the fourteen sit directly in your blood: your LDL cholesterol and your blood sugar. A third, alcohol use, shows up indirectly through your liver values. The rest of the list is about your hearing, your eyes, your head, your lungs and your social life. Blood says nothing about those.

That is exactly why I wanted to write this article the way it now stands. A blood test is not a brain scan, and pretending otherwise would be dishonest.

What a blood test does do: it makes two of the fourteen factors measurable, at a point when you can still change them. We have explained cholesterol values by age and HbA1c by age separately.

Your blood pressure belongs in this group, but you do not measure it in blood. You measure it with a blood pressure monitor. See blood pressure by age.

Why does one person get dementia and another does not?

Because risk is not a prediction. The fourteen factors explain roughly 45 percent of cases at population level. The other 55 percent is tied to age, inherited susceptibility and factors we do not yet understand. At the level of a single person, a great deal stays uncertain.

Statistics describe groups. You are not a group.

What heredity does and does not mean, and why an affected parent is not a verdict, is covered in our article on preventing Alzheimer's. A large meta-analysis of modifiable factors in Alzheimer's pointed the same way (Xu et al., 2015).

Why are hearing and vision on that list?

Because your brain needs input. If you hear poorly, less language reaches you, and you start avoiding conversations. If you see poorly, you read less and leave the house less. Both lead to less stimulation and more social isolation, and those are all factors from the same list.

In the 2024 report, hearing loss sits among the heaviest-weighing midlife factors. Vision loss was added as a new factor that same year.

The good part is that something can be done about both. A hearing aid and a decent pair of glasses are not medicines, but they keep your world large. Many people put that step off for years, because hearing fades slowly and you get used to it.

If you are wondering whether you still hear well, just have it measured. It takes half an hour, and it sits on a list with very few easy wins on it.

What does exercise do for your brain?

Exercise improves blood flow, including through the small vessels in your brain. It also helps your blood pressure, your blood sugar and your cholesterol, and each of those is a factor from the list of fourteen. So a walk works on several fronts at once.

You do not need to take up a sport for this. Half an hour of brisk walking a day counts.

What strikes me about the report is how often the same advice reappears under different factors. Quitting smoking helps your vessels. Moving more helps your vessels. Treating your blood pressure helps your vessels. And your vessels feed your brain.

Does lowering your blood pressure really help?

Probably, though the evidence is more nuanced than you usually read. In the SPRINT MIND trial, more than 9,000 people with high blood pressure got either a strict or a standard target. Stricter treatment clearly reduced the number of people with mild cognitive problems. For dementia itself, the difference was not statistically significant (SPRINT MIND Investigators, JAMA 2019).

I think that is one of the most honest studies in this whole field. It shows you what it did not prove.

The trial was stopped earlier than planned, which left fewer dementia cases than expected. That makes firm conclusions hard. The direction is favourable, the certainty is limited. That is how it reads, and that is how we pass it on.

What if you already have memory complaints?

Then the question changes. Not: how do I lower my risk over the next twenty years. But: is something going on that can be treated. When you report memory complaints, your GP routinely checks a set of blood values to rule out causes you can actually do something about.

Those causes are not often the explanation, but they are worth ruling out (Muangpaisan et al., 2012).

Which of these your GP requests, and why, is set out in tired and forgetful. We wrote a separate piece on vitamin B12 deficiency in older adults.

Can a blood test detect dementia?

No. A standard blood test cannot detect dementia, cannot rule it out and cannot predict it. What a blood test can do is bring treatable causes of memory complaints into view, and make two of the fourteen risk factors measurable. For the diagnosis itself, your GP is always the one in charge.

Anyone telling you otherwise is overestimating what a tube of blood can do.

What your GP does when dementia is suspected, and which memory tests are involved, is covered in is there a test for dementia.

An example from practice

Picture two men of 64. Both notice they are losing names. One has an LDL cholesterol of 4.1 mmol/l and an HbA1c of 48 mmol/mol, and still smokes a few cigarettes a day. The other sits at an LDL of 2.4 mmol/l, an HbA1c of 36 mmol/mol, and quit twenty years ago.

Of the fourteen factors, three are red for the first man. None are for the second.

That says nothing about which of the two will get dementia. It does say something about who can change something this month. For the first man there is work to do, and that work is plainly visible in his blood.

What can you do this month?

Start with the factors you can measure. You can take your blood pressure at home. Your LDL cholesterol and your HbA1c sit in your blood. You can have your hearing checked at an audiologist and your eyes at an optician, and both of those are factors from the same list of fourteen.

The RIVM, the Dutch national institute for public health, tracks how many people in the Netherlands live with dementia, and those numbers rise mainly because we are getting older. That is not a reason to panic. It is a reason to take the things you can influence and actually act on them.

If you want to know where you stand on the two factors visible in your blood, a lipid screening is a concrete starting point. If you mostly feel tired and forgetful, start with your GP instead.

Frequently asked questions

Is forgetfulness always the start of dementia?

No. Most forgetfulness in later life is just forgetfulness. Names that will not come, or keys you cannot find, come with getting older. It gets more concerning if you lose your way on familiar ground, or if other people notice before you do.

Do vitamin pills help against dementia?

If you have no deficiency, probably not. A meta-analysis of B vitamins found a modest effect on cognitive decline, mainly with long-term use and in people who did not yet have dementia (Wang et al., 2022). In people with dementia it did not help. Topping up a deficiency makes sense. Taking pills without one makes much less.

At what age should I start with this?

Many of the fourteen factors weigh heaviest in midlife, roughly between 45 and 65. That does not mean it stops mattering after 65. Social isolation, hearing loss and vision loss are specifically later-life factors.

References

1. Livingston G, et al. (2024). Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. The Lancet. PMID 39096926.
2. SPRINT MIND Investigators for the SPRINT Research Group (2019). Effect of Intensive vs Standard Blood Pressure Control on Probable Dementia. JAMA. PMID 30688979.
3. Xu W, et al. (2015). Meta-analysis of modifiable risk factors for Alzheimer's disease. J Neurol Neurosurg Psychiatry. PMID 26294005.
4. Muangpaisan W, et al. (2012). Prevalence of potentially reversible conditions in dementia and mild cognitive impairment in a geriatric clinic. Geriatr Gerontol Int. PMID 21794050.
5. Wang Z, et al. (2022). B vitamins and prevention of cognitive decline and incident dementia. Nutrition Reviews. PMID 34432056.
6. Hersenstichting. Dementia: risk factors and a healthy lifestyle. hersenstichting.nl.
7. RIVM. Public Health Foresight Study, figures on dementia in the Netherlands. rivm.nl.

Would you like the two risk factors that are visible in your blood checked at a calm moment, without first booking an appointment with your GP? At Levenswijs Health you can. Every result is reviewed by a doctor registered in the Dutch BIG register. A blood test does not provide a diagnosis and cannot detect dementia. For treatment decisions, always discuss your results with your GP.