Dementia Prevention
Could a Blood Test Help
Protect You From
Dementia?
Nearly half of all dementia cases could be prevented. Many of the risk factors that matter most show up clearly in a standard blood test — years, even decades, before symptoms appear.
The Opportunity
Dementia Isn't Inevitable — and the Science Proves It
Most people think of dementia as something that just happens — an unavoidable consequence of ageing. But that's not what the science says. The 2024 Lancet Commission on Dementia Prevention — one of the most comprehensive reviews ever conducted on the subject — concluded that around 45% of dementia cases worldwide could be prevented or significantly delayed by addressing 14 modifiable risk factors.
That's not a small number. Nearly half. And crucially, many of those risk factors are things a blood test can detect — often decades before any cognitive symptoms appear.
Dementia has a long silent phase. Research shows that in Alzheimer's disease, the most common form, changes in the brain can begin up to 20 years before a person notices any memory or thinking problems. That window — those two decades — is the opportunity. And blood testing is one of the most powerful ways to use it.
Around 45% of dementia cases could be prevented or delayed by addressing modifiable risk factors — many of which show up in routine blood tests.
The 14 Modifiable Risk Factors
The Risks You Can Actually Do Something About
The 2024 Lancet Commission updated its list of modifiable dementia risk factors to 14 — two of which were newly added based on fresh evidence: high LDL cholesterol and untreated vision loss. Together, these 14 factors account for nearly half of all dementia cases.
Detectable via blood test
Additional modifiable factors
Estimated % of dementia cases attributable to key modifiable risk factors
Source: 2024 Lancet Commission on Dementia Prevention, Intervention and Care. Percentages represent population attributable fractions — the proportion of dementia cases linked to each factor.
The Blood Tests That Matter
What to Check — and Why It Matters for Your Brain
Several blood markers have direct, evidence-backed links to dementia risk. Here are the key ones worth tracking — ideally from your 40s, when the window for intervention is widest.
The Homocysteine Story
The Brain Marker Most People Have Never Heard Of
Of all the blood markers linked to dementia risk, homocysteine deserves special attention — because it's one of the strongest, most modifiable, and least discussed.
Homocysteine is an amino acid that naturally occurs in the body. When levels rise — which happens when B12, B6, and folate are low — it becomes toxic to blood vessels and brain cells. High homocysteine is associated with accelerated brain atrophy, white matter damage, and significantly increased Alzheimer's risk.
The remarkable thing is what happens when you lower it. Clinical trials have shown that supplementing with B vitamins (B12, B6, and folate) in people with elevated homocysteine can meaningfully slow brain shrinkage — one of the most direct nutritional interventions for brain health we know of.
The VITACOG Trial — Oxford University
Participants with mild cognitive impairment and elevated homocysteine who took high-dose B vitamins for two years showed up to 53% less brain atrophy than those on placebo. The effect was strongest in those with the highest baseline homocysteine. This is one of the most striking findings in dementia prevention research — and it starts with a simple blood test.
The Emerging Science
Blood Tests That Could Detect Alzheimer's Decades Early
Beyond the modifiable risk markers, a new generation of blood tests is emerging that can detect the biological hallmarks of Alzheimer's disease itself — long before symptoms appear.
The most promising is p-tau217 — a protein that reflects the build-up of both amyloid and tau in the brain, the two key proteins associated with Alzheimer's disease. Research has shown that p-tau217 can detect these brain changes with accuracy comparable to amyloid PET scans and lumbar punctures — which are invasive and expensive — but as a simple blood test.
Blood biomarker accuracy vs current diagnostic methods
Source: Alzheimer's Society Blood Biomarker Challenge / ADAPT trial 2025. The ADAPT trial is currently recruiting across 19+ NHS centres in the UK, aiming to bring p-tau217 into routine NHS care by 2029.
The Alzheimer's Society's Blood Biomarker Challenge — a £5 million programme currently running across 19+ NHS centres — is working to bring these tests into routine NHS care by 2029. It's one of the most exciting developments in dementia medicine in decades. Currently, only around 2% of people diagnosed with Alzheimer's have access to gold-standard diagnostic tests. Blood biomarkers could change that entirely.
What to Do Now
Your Practical Action Plan for Brain Health
You don't need to wait for NHS blood biomarker tests to be widely available to take action. The modifiable risk factors — the ones that account for nearly half of all dementia cases — are measurable right now, with a private blood test.
Get a comprehensive blood test from your 40s
Ideally including: full lipid profile (LDL), HbA1c, homocysteine, B12, folate, vitamin D, hs-CRP, thyroid function, ferritin, and a hormone panel. This gives you a full picture of your modifiable dementia risk factors — all in one go.
Know your homocysteine level
This is the single most overlooked brain health marker. Optimal homocysteine is below 10 µmol/L. If yours is elevated, high-dose B vitamins (B12, B6, folate) can bring it down — with meaningful implications for long-term brain health.
Manage your cholesterol proactively
High LDL in midlife is now the largest newly-identified modifiable risk factor for dementia. Know your numbers — and if they're high, dietary changes, exercise, and medication where appropriate can make a real difference over the long term.
Optimise your vitamin D
In the UK, deficiency is near-universal in winter. Supplementing to maintain levels of 100–150 nmol/L supports immune function, mood, and — based on growing evidence — long-term brain health. You can't know your level without testing.
Test regularly — not just once
Dementia risk is cumulative over decades. Annual or biannual blood testing allows you to track trends, measure the impact of lifestyle changes, and catch shifts early enough to act on them. A single snapshot is useful — a trend is powerful.
The brain changes that lead to dementia often begin 20 years before symptoms. The time to act is now — not when you notice something is wrong.
Start Protecting Your Brain Today
Private blood testing gives you the data to understand and manage your dementia risk factors — decades before they become problems. At Boost & Glow, we can help you find the right path to proactive brain health.
Explore Boost & Glow → Ask Us a Question →This blog is for informational purposes only and does not constitute medical advice. Blood testing for dementia risk markers is not a diagnostic test for dementia. If you have concerns about memory, thinking, or cognitive function, please speak to your GP. Always consult a qualified healthcare professional before making changes to your health routine based on blood test results.
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