Caregiver guide
Is dementia genetic? What a family history of Alzheimer's means for you
Most dementia, including most Alzheimer's disease, is not directly passed down in families. Genes can raise or lower your risk, and having a parent with Alzheimer's raises it somewhat, but it does not mean you will get it. Only a rare early-onset form is caused by a single inherited gene.
If you're caring for a parent and wondering about yourself
It's one of the questions caregivers whisper: "Will this happen to me?" Many adult children watch a parent, and sometimes a grandparent, go through Alzheimer's and start noticing every forgotten name in their own lives.
That fear is normal. Here's what the science actually says, in plain words, so you can worry less about what you can't change and focus on what you can.
Is Alzheimer's genetic?
Yes and no. Genes play a part in almost every case, but in two very different ways:
- Risk genes make the disease more or less likely, but don't decide it. Most people with Alzheimer's fall into this group.
- Cause genes are rare gene changes that almost guarantee the disease. They explain only a small share of cases, mostly people who get sick young.
For most families, Alzheimer's comes from a mix of genes, age, health conditions and lifestyle, built up over many years. Scientists are still learning how these pieces fit together. Read more in What is Alzheimer's disease?
Early-onset vs late-onset: two kinds of genetic link
Late-onset Alzheimer's is by far the most common kind. Symptoms usually start in a person's mid-60s or later. No single gene causes it. Instead, several genes can nudge the risk up or down.
Early-onset Alzheimer's starts between about age 30 and 60. It's rare, affecting fewer than 5 in 100 people with Alzheimer's. Many, though not all, early-onset cases are a type called familial Alzheimer's disease. It's caused by a change in one of three genes, on chromosomes 1, 14 or 21.
With familial Alzheimer's, each child of a parent with the gene change has a 50/50 chance of inheriting it. Someone who inherits it will almost surely develop the disease. If several relatives on one side of the family developed Alzheimer's in their 40s or 50s, talk to a doctor about genetic counseling.
What is APOE e4?
APOE is a gene everyone has. It helps carry cholesterol and other fats in the blood. You get one copy from each parent, and it comes in a few common forms:
- APOE e2 is uncommon and may offer some protection.
- APOE e3 is the most common form and doesn't seem to change risk.
- APOE e4 raises the risk of late-onset Alzheimer's and may make it start earlier. Having two copies (one from each parent) raises risk more than one copy.
But APOE e4 is a risk gene, not a cause. Many people with e4 never get Alzheimer's, and many people with Alzheimer's don't have e4. Researchers have also found other genes that slightly change risk.
Is Alzheimer's inherited from the mother or father?
It can come from either side. You get half your genes from each parent, so risk genes like APOE e4, or a rare familial gene change, can come from your mother or your father equally.
What matters more is the pattern in the family. One parent who developed Alzheimer's in their 80s is very common and raises your risk only modestly. Several close relatives who developed it young, on the same side of the family, is a different picture and worth raising with a doctor.
What are the chances of getting Alzheimer's if a parent has it?
If your parent has the common late-onset type, your risk is higher than someone with no family history, but most of the risk still comes from things like age and health. Many people whose parent had Alzheimer's never develop it.
There's no exact number we can give you for your own chances. Because many families share habits and health conditions, not just genes, some of the family link may also come from things you can change, like blood pressure or activity.
If your parent has rare familial Alzheimer's, the chance of inheriting the gene change is 50/50.
Are other types of dementia genetic?
It depends on the type:
- Frontotemporal dementia: some forms run strongly in families and are linked to known genes.
- Huntington's disease: always inherited. Each child of an affected parent has a 50/50 chance.
- Vascular dementia: usually not inherited directly, but it's linked to stroke, high blood pressure, diabetes and heart disease, which can run in families. A rare inherited form called CADASIL exists.
- Lewy body dementia: not usually considered genetic. Most cases have no known cause. See our Lewy body dementia guide.
People with Down syndrome have an extra copy of chromosome 21, which carries a gene linked to amyloid, and most develop Alzheimer's brain changes, often by middle age.
Learn how these types differ in our guide to the types of dementia.
Should I get genetic testing for Alzheimer's?
For most people, probably not, at least not without talking it through first.
- APOE testing can tell you which forms you carry, and some home DNA kits report it. But it can't tell you whether you'll get Alzheimer's. Experts generally don't recommend it just to predict late-onset risk.
- Testing for familial Alzheimer's genes may make sense if several relatives developed Alzheimer's young. It's usually done with a genetic counselor, who can help you think about what a result would mean for you and your children before you test.
Before any test, ask about cost and insurance coverage, and think about privacy. A federal law called GINA limits how health insurers and employers can use genetic results, but it doesn't cover long-term care, life or disability insurance.
Research studies sometimes offer genetic testing as part of the study. Ask the doctor or a memory clinic.
What you can do about the risks you can control
Look after your heart
What's good for your heart is good for your brain. Keep blood pressure, blood sugar and cholesterol in check, and don't smoke.
Move every day
Walking, dancing, gardening or swimming all count. Physical activity is linked to healthier aging.
Stay connected
Time with friends, volunteering and faith communities keep your mind engaged. Caregiving can be isolating, so this matters for you right now.
Keep learning
Try something new: a class, an instrument, a language or a new hobby.
Sleep, hearing and mood
Get enough sleep, have your hearing checked, and get help if you feel down for weeks at a time.
Questions about Alzheimer's, dementia and genes
Is Alzheimer's hereditary from grandparents?
A grandparent with Alzheimer's is part of your family history, but on its own it doesn't mean much for your risk. Late-onset Alzheimer's in older relatives is common. A pattern of several relatives on one side developing it young is more meaningful.
Who is at highest risk for Alzheimer's?
Age is the biggest risk factor. Other factors include a family history, carrying APOE e4, Down syndrome, and health conditions like high blood pressure, diabetes and heart disease. Having risk factors doesn't mean someone will get Alzheimer's.
At what age does Alzheimer's usually start?
Most people first show symptoms in their mid-60s or later. Early-onset Alzheimer's can begin between about 30 and 60, but it's rare. If you're worried about your own memory, our Alzheimer's and dementia FAQ covers warning signs and screening.
Is Alzheimer's genetic or environmental?
Usually both. Genes, aging, health conditions and lifestyle all play a part. Scientists are also studying how things like diet, activity and exposure to chemicals may switch genes on or off over a lifetime.
Is there a vitamin that prevents dementia?
No vitamin or supplement has been proven to prevent dementia. Low levels of some vitamins, like B12, can cause memory problems, so it's worth asking the doctor to check. Don't start supplements without talking to the doctor, since some can interact with medicines.
I'm scared I'll get Alzheimer's like my parent. What can I do?
You're not alone in that fear, and it's okay to say it out loud. Talk to your own doctor about your family history and your health. Focus on the things you can control, listed above. And take care of yourself while you care for your parent. Our caregiver support groups and free Care Navigation are good places to start.
Can our family learn more about what caused our person's dementia?
Yes. Brain donation through the State of Florida Brain Bank gives families a report of what was found in the brain, which can help answer questions about the type of dementia. ADRC helps Central Florida families enroll. Learn more about how Alzheimer's affects the brain.
Download the free Alzheimer's Disease Genetics Fact Sheet
A short guide from the National Institute on Aging on early- and late-onset Alzheimer's, APOE and genetic testing. Based in part on National Institute on Aging guidance.
Alzheimer's & Dementia Resource Center (ADRC)
Alzheimer's & Dementia Resource Center (ADRC)
1470 Gene Street, Winter Park, FL 32789
Serving Orange and Seminole counties and Central Florida since 1984
(407) 436-7750
info@adrccares.org
Monday to Friday, 8:30 AM to 4:30 PM
The Alzheimer's & Dementia Resource Center (ADRC) in Winter Park, Florida, offers free help for caregivers in Orange and Seminole counties; call (407) 436-7750.