I Have a Family History of Dementia. What Should I Do to Assess My Risk

You watched your mother struggle to find words that used to come easily. You sat with your father as he forgot the name of the street he had lived on for 40 years. And now, in your 40s or 50s, the quiet question follows you around. Will the same thing happen to me?

If someone in your family has had dementia or Alzheimer's disease, that question is not irrational. Family history is a recognised risk factor. But a risk factor is not the same thing as certainty. And knowing how much of your risk is genetic versus how much is within your control changes everything about how you respond.

Here is what the science says, what you can do, and how to turn worry into a plan.

Key Takeaways

• Having a first-degree relative (parent or sibling) with dementia does increase your statistical risk, but it does not mean you will develop the condition.
• The APOE-e4 gene variant is the strongest known genetic risk factor for late-onset Alzheimer's, but carrying it is neither necessary nor sufficient for developing the disease.
• The 2024 Lancet Commission found that up to 45% of dementia cases globally may be attributable to 14 modifiable risk factors, meaning a significant portion of risk is within your control regardless of genetics.
• A 2026 study found that a favourable lifestyle reduced dementia risk dramatically even among people with the highest genetic risk, from an 18-fold increase down to a near-normal level.
• Establishing a cognitive baseline now, while you are healthy, gives you and your doctor the best possible reference point for detecting any future changes early.

What Family History Actually Means for Your Risk

Family history increases your statistical probability of developing dementia, but it does not determine your outcome. For late-onset Alzheimer's, which accounts for the vast majority of cases and typically appears after age 65, having one first-degree relative with the condition roughly doubles your lifetime risk compared to the general population. Having two or more affected relatives increases it further.

But "doubled risk" needs context. The baseline lifetime risk for someone over 65 is roughly 10 to 15%. Doubling that takes you to 20 to 30%, which means even with family history, the probability is still that you will not develop the condition.

For a broader understanding of how dementia develops and what distinguishes different types, a separate guide covers the full picture.

Genetics vs. What You Can Actually Control

The genetic and modifiable sides of dementia risk are not separate stories. They interact. And the research on that interaction is genuinely encouraging.

The Genetic Side

The most well-studied genetic risk factor for late-onset Alzheimer's is the APOE-e4 variant. Carrying one copy of APOE-e4 increases risk by roughly two to three times. Carrying two copies increases it by about eight to twelve times. But APOE-e4 is not destiny. Many people who carry the variant never develop dementia, and many people who develop Alzheimer's do not carry it at all.

A small number of families carry rare mutations in genes called APP, PSEN1, or PSEN2 that cause early-onset familial Alzheimer's, typically appearing before age 65. These account for less than 1% of all Alzheimer's cases and follow a much more predictable genetic pattern. If your family member was diagnosed before 65, genetic counselling may be appropriate.

The Modifiable Side

The ​2024 Lancet Commission identified 14 modifiable risk factors that, if fully addressed, could potentially prevent up to 45% of dementia cases globally. These include physical inactivity, untreated hearing loss, social isolation, high blood pressure, diabetes, smoking, excessive alcohol, depression, obesity, high LDL cholesterol, traumatic brain injury, air pollution, lower education, and untreated vision loss.

A ​2026 study from the University of Kansas Medical Center examined how modifiable risk factors interact with genetic risk. Among individuals in the highest polygenic risk group, those who maintained a favourable lifestyle (addressing multiple modifiable factors) saw their dementia risk drop from an 18-fold increase down to a near-normal level. The study concluded that dementia risk is driven more by modifiable factors and APOE genotype than by broader polygenic risk, meaning lifestyle choices matter enormously even when the genetic deck is not in your favour.

What You Can Do Right Now

If you have a family history of dementia, the most empowering thing you can do is shift from worry to action. While no single step can guarantee how to prevent dementia entirely, the research points to a clear set of actions that meaningfully reduce risk.

• Get a cognitive baseline: A structured Cognitive Assessment while you are healthy gives you a documented reference point. Without a baseline, there is nothing to compare against if subtle changes appear later.
• Manage cardiovascular risk factors: Blood pressure, blood sugar, and cholesterol all affect the brain directly. Getting these checked and managed is one of the highest-impact steps you can take.
• Stay physically active: Aerobic exercise increases BDNF, supports hippocampal volume, and is one of the most consistently supported strategies for brain health.
• Protect your hearing: Untreated hearing loss in midlife is the single largest modifiable risk factor for dementia. A baseline audiogram in your 40s is a simple, practical step.
• Stay socially connected: Social isolation is a recognised risk factor. Regular, meaningful interaction with others supports both emotional and cognitive resilience.
• Keep your brain engaged: Mental stimulation through varied, challenging activities helps build cognitive reserve. Consistency matters more than intensity.

For a practical breakdown of simple habits that reduce dementia risk, a separate guide covers each one in detail.

When and How to Get Assessed

A cognitive baseline is most valuable when it is established before any symptoms appear. If you are in your 40s or 50s with a family history, now is the right time, not because something is likely wrong, but because a baseline set while you are healthy gives you the longest possible window for early detection.

If you are noticing changes, even subtle ones like increased word-finding difficulty, trouble concentrating, or mental fatigue that does not improve with rest, those observations deserve a structured evaluation, not reassurance from a five-question online quiz. The guide on when to be concerned about memory loss can help you assess what you are noticing.

Turning Worry Into a Plan This September

September is both World Alzheimer's Month and Healthy Ageing Month. The 2026 campaign from Alzheimer's Disease International, "The Earlier You Know, The More You Can Do," speaks directly to people carrying the weight of family history. You already know the risk exists. The next step is knowing where you stand.

The ​Ivory Brain Function Test measures 22 cognitive skills across 17 gamified tasks and produces a Cognitive Profile report in about 20 minutes, all from home. For daily tracking, the ​Ivory app measures Reasoning, Memory, Attention, Coordination, and Perception through personalised tasks that take about 8 to 10 minutes. Together, they replace the anxiety of not knowing with data you can act on. The question you have been carrying does not need to stay unanswered.

Note: The information in this blog is for educational and informational purposes only. Nothing here should be taken as medical or genetic advice. If you have concerns about your genetic risk for dementia, please speak with a qualified healthcare provider or a genetic counsellor.

Frequently Asked Questions

Is Dementia Hereditary?

Dementia has both genetic and non-genetic components. Having a first-degree relative with the condition increases your statistical risk, but most cases of late-onset Alzheimer's are not caused by a single inherited gene. The APOE-e4 variant is the strongest known genetic risk factor, but carrying it does not guarantee developing the condition, and many people with Alzheimer's do not carry it.

If My Parent Had Dementia, What Are My Chances of Getting It?

Having one parent with late-onset Alzheimer's roughly doubles your lifetime risk compared to the general population, from about 10-15% to about 20-30%. That means even with a family history, the probability is still that you will not develop the condition. Lifestyle factors play a significant role in modifying that risk.

Should I Get Genetic Testing for Alzheimer's Risk?

Genetic testing for APOE status is available but not universally recommended. Knowing your APOE status can inform lifestyle decisions and motivate risk-reduction behaviours, but it cannot predict with certainty whether you will develop Alzheimer's. If your family member was diagnosed before age 65, genetic counselling is worth considering to assess whether rare early-onset mutations may be involved.

Can I Prevent Dementia Even With a Family History?

No single action guarantees prevention. However, a 2026 study found that people with the highest genetic risk who maintained a favourable lifestyle saw their dementia risk drop dramatically compared to those with unfavourable lifestyles. The 2024 Lancet Commission identified 14 modifiable risk factors that may collectively account for up to 45% of dementia cases, suggesting that a significant portion of risk is within your control.

What is the Single Most Important Step I Can Take?

Establishing a cognitive baseline while you are still healthy. A structured Cognitive Assessment gives you a documented reference point that you and your doctor can compare against in the future. Without that baseline, subtle changes may go undetected until they become more advanced. Combining a baseline with lifestyle interventions gives you the strongest possible position.

At What Age Should I Start Getting My Brain Checked if I Have a Family History?

Research suggests that Alzheimer's pathology can begin accumulating 10 to 30 years before symptoms appear. If you have a family history, starting a cognitive baseline in your 40s gives you the longest window for early detection. Annual or biannual repeat assessments, combined with routine blood work and cardiovascular screening, create a comprehensive picture of how your brain health is tracking over time.

Sources

1. The Lancet Commission on Dementia Prevention, Intervention, and Care, 2024 update. ​The Lancet
2. Burns J.M. et al. (2026). "A Favorable Modifiable Risk Factor Profile Mitigates Polygenic Risk for Alzheimer's Disease and Related Dementia." medRxiv. ​medRxiv
3. Williams V.J. et al. (2025). "Life Course Modifiable Risk Factors for Dementia Stratified by ApoE-4 Status." Innovation in Aging. ​PMC
4. Alzheimer's Disease International (2026). "World Alzheimer's Month. The Earlier You Know, The More You Can Do." ​ADI