Frequently asked questions on how to find out your risk of Alzheimer's disease from an APOE4 gene test.
The APOE test checks the apolipoprotein E genes.
These genes make APOE protein that helps in clearing cholesterol plaque in the nerves cells of our brains.
The plaque forms when damaged cholesterol particles called amyloid-β stick together and are not efficiently cleared away.
Presence of amyloid-β is one of the key signs of Alzheimer's disease. Therefore, APOE is an excellent marker of Alzheimer's.
There are three different forms: APOE2, APOE3, APOE4. And we carry two copies of them (one from each parent).
APOE4/APOE4 combination increases the risk of Alzheimer's disease by almost 10 years.
Symptoms of the disease, onset of dementia, and death—all occur about a decade earlier compared to those without APOE4 genes.
Even one copy of APOE4 increases the risk by about five years.
APOE4 also increases the risk of heart disease due to it's contribution to higher cholesterol, LDL, and triglyceride levels.
The odds of getting Alzheimer's depend on whether you have one or two copies of APOE4 gene.
A new study concludes that almost everyone carrying two copies of APOE4 is at risk of Alzheimer's disease by the age of 65 years.
With APOE4/APOE4, the symptoms of early onset of Alzheimer's, and signs of plaque build up in the brain from lab test results, might be visible as early as 55.
Those carrying one copy of APOE4 are also at risk, albit lower. But it's still not as low as APOE3/APOE3.
The APOE2 genes have opposite effect and reduce the risk of Alzheimer's and dementia. That's because Apolipoprotein E2 is more efficient at clearing the amyloid-β plaque.
However, in rare cases, APOE2/APOE2 carriers may high cholesterol levels from a genetic condition called hyperlipoproteinemia (III HLP).
Either parent can pass the Alzheimer's gene.
All of us have two copies of the APOE gene, one from mother and one from father.
It may not always be possible know which parent passed on the gene even if we test both the parents.
The strongest genetic predictor of Alzheimer's disease is the APOE4 gene. Two copies have the highest risk but even one copy carries some risk.
Other predictors are lab tests to check amyloid-β plaque, tau residue, and neuropathological change scores (which are markers of damage to the brain).
Many of these markers are tested with brain imaging, brain tissue stains, and other advanced techniques.
Abnormal signs of cognitive decline such as repeat unexplained forgetfulness and mood changes are early indicator of potential risk of Alzheimer's.
Another important but rare predictor of Alzheimer's is a variant of PSEN1 gene that makes presenilin 1 protein.
The E280A variant in blood relatives of a Columbian town has shown near 100% certainty of dementia and cognitive decline by their forties.
Another rare form of APOE3, called the APOE-Christchurch, has positive effect, and can postpone the symptoms by almost 30 years.
A most recent study on 10,000 people concludes that:
with two copies of APOE4, people start to show early symptoms of Alzheimer's by the age of 65 years (some even as early as 55); the onset of dementia from Alzheimer's in this group begins by the age of 74 years and they have a lower life span compared to others (of about 80 years instead of almost 90 without any APOE4 gene).
with one copy of APOE4, they start to show symptoms of Alzheimer's by the age of 70 years, onset of dementia by 79, and an approximate life span of 84 years.
with zero copies of APOE4, one does not show any symptoms of Alzheimer's until 74 years of age; the onset of dementia is not seen until mid-eighties and they have a longer life spans.
Graph showing the age at which symptoms of Alzheimer's first appear for different variants of APOE gene.
APOE4 is one of the several factors that affect cognitive health.
Other factors include life style, various genes, exercise, social connections, and mental, emotional and financial health.
Studies show that negative effects of APOE4 start much later in life and not everyone is affected equally.
You might enjoy a fulfilling life without worrying about APOE4 until you see any signs of cognitive decline.
Regular aerobic exercise, plant-based diets, adequate Omega 3 fatty acids, and certain supplements can lower the risks of cognitive decline.
You should consult a doctor if you suspect APOE4 genes and history of Alzheimer's in your family.
Onset of dementia from Alzheimer's disease occurs almost ten years early in those carrying two copies of APOE4 genes compared to others.
It depends on whether you have one copy or two copies.
Only about two-percent population carries both APOE4 alleles. And one-in-five people has at least one APOE4 mutation.
Those carrying APOE4/APOE4, one-in-three will get Alzheimer's in their lifetime. However, almost all of them will show some symptoms.
And one-in-five people with one APOE4 mutation will be diagnosed with Alzheimer's.
Even without APOE4, the risk of dementia is almost ten percent.
The overall risk of APOE4 is that is reduces 5-10 years of life span compared to those carrying zero APOE4 alleles.
Those carrying APOE4 might see their symptoms of Alzheimer's earlier than others.
They may become forgetful and suffer from memory loss faster with age, especially in their fifties.
They may see unexpected changes in mood, go through anxiety, depression and overall decline in emotional health, earlier than those without APOE4.
Presence of one APOE4 allele shortens the life span by 5 years and two APOE4 alleles by almost 10 years.
The 2024 study concludes that those carrying both APOE4 alleles are at higher risks of Alzheimer's.
The risk of APOE4/APOE4 is about reduction in lifespan by 10 years, as compared to those carrying zero APOE4 alleles.
With APOE4, signs of Alzheimer's, the onset of dementia, and death, all seem to occur about ten years earlier than carriers of APOE3 and APOE2.
A comparable risk for those carrying one copy of APOE4 is about 5 years.
There are hundreds of clinical trials running to study the impact of APOE genes on cognitive decline. You can check a trial near you at the AHEAD Study portal.
Also, https://www.clinicaltrials.gov is an excellent resource to track current or past clinical trials.
An APOE test can be performed with a simple cheek swab that you can collect at home.
You can order an at-home APOE test kit online, collect the sample at home, mail the kit to one of the CLIA-accredited labs, and receive your results in a few days.
The APOE test results can be downloaded from a secure web portal with the privacy of your home.
If you are at risk, please discuss the APOE4 test results with your doctor or a trained genetic councilor.
The cost of an APOE test is shown on this page.
The test includes a doctor's prescription, shipping to your address, and testing at a CLIA-certified lab.
If you are based in US, the APOE test kit also includes FREE return shipping.
The APOE test is performed using RT-PCR (real time polymerase chain reaction), which is a method similar to COVID-19 PCR tests.
This method of testing uses the TaqMan probes, which are the gold standard for genetic testing.
Your DNA sample is first 'extracted' and 'amplified', i.e., the useful genetic material unique to you is separated from the swab and analyzed.
However, certain rare mutations are not detected by these assays (e.g., APOE5, an extremely rare mutation in some African tribes).
We follow strict guidelines to protect your sample and genetic data.
The samples are incinerated after testing to completely destroy any usable genetic material.
The test results are only shared with you, using a secure website portal. WE DO NOT SELL YOUR INFORMATION TO ANY THIRD PARTIES.
The labs do not share your data with anyone else except as required by law.
Please note that certain state and federal healthcare agencies require the labs to keep records for auditing and accreditation, which means they may have to keep your test results for a certain required period to meet the legal requirements and licensing.
Order an at-home APOE gene test kit.
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