How important are genetics when it comes to dementia?
Last Updated: Jan 12 2025
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While age and lifestyle factors are the most significant contributors to dementia risk, your genes may also have an influence.
In this article, we’ll break down how genetics impacts dementia, whether you should consider genetic testing, and what you can do to reduce your overall risk.
How important are genes when it comes to dementia?
How do genetics influence dementia risk?
Dementia, including Alzheimer’s disease, can sometimes run in families, which suggests that genes can play a role.
However, most cases of dementia are not purely genetic.
In fact, only an estimated 1% of dementia cases are caused by genetic mutations that lead to early onset disease before the age of 65.
Lifestyle factors play a MUCH BIGGER role than genetics in 90% of people who go on to develop the disease.
Two types of genetic risks
Despite being relatively rare, there are two ways in which your genes can impact your risk of future dementia.
1) Genetic risks for dementia before age 65
Early-onset dementia can be caused by mutations in specific genes, such as APP, PSEN1, or PSEN2.
These genetic mutations are inherited in an autosomal dominant pattern, meaning if you inherit the mutation from one parent, you are very likely to develop dementia, typically before the age of 65.
This form of dementia is rare, accounting for less than 1% of all cases. We talk about what to do in this scenario in this article.
In the majority of early-onset cases, people do not have one of these genetic mutations – and their disease is what we call “sporadic”, meaning randomly arising, not due to genes.
Another potential reason for early-onset dementia is having several big lifestyle habits that are highly linked to dementia such as: heavy alcohol use, significant head trauma, uncontrolled heart-health risk factors such as high blood pressure, diabetes, and smoking (which then cause small or large strokes) or other drug use.
The key takeaway is that early-onset dementia is rare, and even then, many cases could be prevented with lifestyle changes. Late onset dementia is much more common, and even more in our control.
Early onset dementia due to genetic risk is very rare - only 1% of all cases.
2) Genetic risks for dementia after age 65
For the vast majority of people, dementia develops later in life and is primarily due to lifestyle and environmental factors, outlined in this article.
However, one of the most well-known genetic risk factors for late-onset Alzheimer’s disease is the APOE gene, particularly the APOE-e4 variant, which accounts for roughly 7% of all dementia cases (Lancet, 2017).
Carrying one or two copies of the APOE-e4 gene can increase your risk of developing Alzheimer’s, but it doesn’t guarantee you will get the disease.
Most people who carry this gene do not develop dementia, and many without the gene still do. Therefore, it’s just one piece of the puzzle.
How we lead our lives is the biggest determinant for whether we develop dementia later in life (responsible for 45% of world-wide dementia cases), much more than our genetics (about 10% of dementia cases).
Should you consider genetic testing?
Genetic testing for dementia risk is available, particularly for the APOE-e4 gene. But before rushing to get tested, there are some key points to consider:
It’s not a definitive answer: Carrying a risk gene like APOE-e4 doesn’t mean you will definitely get dementia, and not having it doesn’t mean you won’t. Your overall risk depends on many factors, including your lifestyle and other health conditions.
Emotional and practical impacts: Learning you have a genetic risk factor can be emotionally challenging, and it doesn’t always provide clear guidance on what to do next. If you’re considering genetic testing, it’s a good idea to speak with a doctor who can help you understand the implications of the results.
For most people, focusing on prevention through lifestyle changes is more useful than undergoing genetic testing, unless there is a history of early-onset dementia in your family.
In people with a strong family history of dementia before the age of 65, it may be worth discussing genetic testing for the rare but significant genes (APP, PSEN1, or PSEN2) with your healthcare provider.
Can you reduce your risk, even with genetic factors?
Yes!
The good news is that genetic risk is only one part of the picture.
Research shows that lifestyle factors play a major role in determining whether or not someone will develop dementia, even in those with a genetic predisposition (except in those with APP, PSEN1, or PSEN2 genes, in which case genetics is the major determinate of future disease).
For 99% of us, learning how to prevent dementia through simple daily lifestyle habits can increase your odds of overcoming any genetic predisposition you might have.
We’d encourage you to explore all topics at Aldora to reduce your risk as much as possible, but 6 big impact lifestyle tips include:
Do not drink excessive alcohol (keep it to less than 7 a week for most of your life, and ideally less than 2).
Do not partake in activities that lead to significant head trauma (such as contact sports); wear a helmet; and prevent falls
Get sleep apnea treated early by wearing CPAP if you need it
Manage your heart-health with diet and exercise, or medications (including high blood pressure, diabetes, smoking cessation, weight, and cholesterol)
Wear hearing aids all the time, if you need them.
Stay socially engaged – build a friend group, go to events, and make sure if you live alone you’re talking to people at least 3-4 times a week.
In Closing
While genetics can play a role in your dementia risk, they are only one small part of a much larger picture in 90-99% of people.
Most people who develop dementia do so because of a combination of lifestyle factors (learn about this balance here).
Even if you carry a genetic risk, making healthy choices can significantly lower your chances of cognitive decline.
Focus on what you can control - your lifestyle - and consider talking with a healthcare professional about your concerns if you have a strong family history of dementia.
By staying proactive, you can take steps to protect your brain health for years to come.
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