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APOE4 gene test and polygenic risk scores

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An APOE test shows which variants of a single gene you carry, and this gene influences the risk of Alzheimer’s more strongly than any other common inherited trait. Polygenic risk scores, by contrast, bundle a very large number of small variants into one number for Alzheimer’s, heart attack or other diseases. The first is a well-supported risk marker, the second so far a crude tool for the individual.

In short

APOE4 is the strongest common genetic risk factor for Alzheimer’s: by age 85, 23 to 30 percent of people with one ε4 copy developed the disease, 51 to 60 percent of those with two copies, and 11 to 14 percent without regard to the gene. Since 2024, two copies have been regarded as a distinct genetic form of the disease. Clinically, the test has meanwhile become important before the new amyloid antibodies, which in the EU are approved only for people with at most one ε4 copy. Polygenic scores detect only about one in ten later cases at a low rate of false alarms and barely improve the prediction of heart disease. That healthy people stay healthy longer because of the knowledge has not been shown. In Germany, such a test is a predictive genetic examination: reserved for specialist physicians, written consent, genetic counseling before and after the result.

What the test measures

The APOE gene contains the blueprint for apolipoprotein E, a protein that transports fats and cholesterol, including in the brain. It occurs in three common variants, ε2, ε3 and ε4, and every person carries two copies, one from each parent. The test determines this combination from blood or saliva, for example ε3/ε4 or ε4/ε4. The result does not change over a lifetime; one measurement is enough.

A polygenic risk score works differently. It adds up the small effects of a very large number of variants that were linked to a disease in large genetic studies and places you within a distribution, for example among the top 5 percent. Such scores are offered, for example, for coronary heart disease or breast cancer. General basics on genetic tests, from pharmacogenetics to lifestyle panels, are on the page Genetic testing.

Why people take the test is easy to understand. Anyone who has seen a parent with Alzheimer’s wants to know where they themselves stand. In a survey of customers of US consumer tests, Alzheimer’s was, alongside heart disease and breast cancer, among the disease risks that interested them most.

What is well supported

The link between APOE4 and Alzheimer’s is among the best-confirmed findings in human genetics. It shows a clear dose effect: one copy markedly increases lifetime risk, two copies almost always lead to the typical Alzheimer’s changes in the brain, and symptoms begin earlier and within a narrower age window. What disclosure does to people is also well studied: in a randomized trial, it did not trigger additional anxiety or depression over one year. And there is an encouraging side: a program of diet, exercise, cognitive training and control of vascular risk factors worked in a large study in ε4 carriers too. In patients, the test has had a clear function since 2025: it helps decide whether antibody therapy is an option.

What the studies show

Genin 2011 – lifetime risk by APOE type

7,351 patients and 10,132 controls of European descent, extrapolated using incidence rates from Rochester in the USA. By the age of 85, the overall risk of Alzheimer’s was 11 percent for men and 14 percent for women. With ε3/ε4 it was 23 and 30 percent, with ε4/ε4 51 and 60 percent. With French incidence rates, the figures for women were even higher, at 35 and 68 percent. The authors compare the order of magnitude with genes such as BRCA1 in breast cancer.

Fortea 2024 – two copies as a distinct form of the disease

Analysis of 3,297 brains from the US National Alzheimer’s Coordinating Center and 10,039 people from five cohorts with biomarkers. Almost all people with ε4/ε4 had Alzheimer’s changes in the brain; from age 55, their biomarkers were markedly higher than in ε3/ε3. By 65, almost all had abnormal amyloid levels in the cerebrospinal fluid, and 75 percent had a positive amyloid scan. Symptoms began at a mean age of 65.1 years. The authors see this as a genetically determined form of Alzheimer’s, similar to the rare dominantly inherited forms and to the course in Down syndrome, and call for dedicated prevention strategies and studies.

REVEAL 2009 – what disclosure triggers

162 adults without symptoms whose mother or father had Alzheimer’s were randomly assigned: some learned their APOE type, the others did not. After 6 weeks, 6 months and 1 year, anxiety, depression and test-related distress did not differ between the groups. Those who were ε4-negative were less distressed afterwards than ε4 carriers. Those who were already highly distressed beforehand were also more likely to have difficulties afterwards. The result applies to children of patients in a study setting and over one year.

FINGER 2018 – lifestyle in ε4

Randomized trial in Finland with 60- to 77-year-olds at increased risk of dementia; 1,109 participants with known APOE type were analyzed, 362 of them ε4 carriers. Two years of diet, exercise, cognitive training and control of vascular risk factors improved performance in cognitive tests compared with general health advice, in the ε4 carriers too. No significant difference between carriers and non-carriers was found. The finding concerns cognitive tests, not the number of later dementia cases.

Hingorani 2023 – how well polygenic scores discriminate

Analysis of 926 scores for 310 diseases from the Polygenic Score Catalog. Allowing 5 percent false alarms, the scores detected a median of 11 percent of later cases, 12 percent for coronary heart disease. For a 50-year-old, the chance of developing coronary heart disease within ten years was 1 in 54 with a score at the 2.5th percentile and 1 in 8 at the 97.5th percentile. The authors’ conclusion: the strong promises bear no relation to the performance.

Elliott 2020 – heart score on top of the classic risk factors

352,660 participants in the UK Biobank, followed for a median of 8 years. The polygenic score alone separated later heart patients with a C-index of 0.61, the classic risk formula with age, cholesterol, blood pressure, diabetes and smoking with 0.76, and both together with 0.78. For classification above or below a 7.5 percent ten-year risk, net reclassification improved by 4 percent, almost only among those who later developed the disease. The authors advise further testing of the benefit before clinical use.

What users report

Published is a survey of 1,648 customers of two US providers before and after the result, conducted before the restrictions imposed by the US authorities in 2013. 66 percent were very interested in their Alzheimer’s risk beforehand. 38 percent had not considered before buying that they might learn something unwelcome. Afterwards, 59 percent said the results would influence how they deal with their own health; 2 percent regretted the test, 1 percent reported harm. These are self-reports without a comparison group.

Where the data stop

An APOE finding is a risk, not a diagnosis. Most people with one ε4 copy do not develop Alzheimer’s by 85, and even with two copies the timing is open. The risk figures come predominantly from people of European descent and depend on the underlying incidence rates.

The most important gap: no study shows that healthy people who know their APOE type live longer without dementia. The FINGER program was offered to everyone, regardless of APOE type. A dedicated preventive treatment for people with ε4 does not exist so far; the approved antibodies are intended for people with early-stage disease and are not approved precisely for those with two ε4 copies.

Polygenic scores are useful in population research, but imprecise as a personal health check. For the heart, age, blood pressure, blood lipids, diabetes and smoking say considerably more; there, it is worth looking at values such as ApoB and lipoprotein(a), measured once in a lifetime.

Status, approval and legal

In Germany, medical genetic tests are governed by the German Genetic Diagnostics Act (Gendiagnostikgesetz, GenDG). A test intended to clarify a disease that will only occur in the future is, under § 3, a predictive genetic examination, and that is exactly what an APOE test in healthy people is. The following applies:

  • Reserved for specialist physicians (§ 7): It may only be carried out by specialists in human genetics or other physicians who have qualified for genetic examinations within their specialty.
  • Written consent (§ 8): You decide explicitly on the scope and on whether, and which, results you learn or have destroyed; you can withdraw at any time.
  • Information and the right not to know (§ 9): Beforehand, you are informed about the purpose, the informative value and the options for prevention and treatment; afterwards, there is time to reflect.
  • Genetic counseling (§ 10): Genetic counseling is mandatory before the test and after the result, unless you waive it in writing after written information.
  • Prenatal (§ 15): Examinations for diseases that only break out after the age of 18 are prohibited before birth.
  • Insurance and employment (§§ 18, 19): Employers may neither require a test nor accept or use results. Neither may insurers, with one exception: for life, occupational disability, earning incapacity and long-term care annuity insurance with benefits of more than 300,000 euros or an annual pension of more than 30,000 euros, they may ask for results that are already known.

Tests that communicate health risks by post without medical information and counseling do not meet this framework. Anyone who orders such a test abroad receives the result without the support that the law provides for here. Without a medical indication, the test is a self-pay service.

Under medicines law, APOE becomes important with the amyloid antibodies. Lecanemab (Leqembi) has been approved in the EU since April 15, 2025, and donanemab (Kisunla) since September 24, 2025, both prescription-only and only for people with mild cognitive impairment or mild dementia due to Alzheimer’s who carry at most one ε4 copy. Before donanemab, the APOE test is explicitly mandatory. The reason is the risk of swelling and bleeding in the brain (ARIA), which is higher with two ε4 copies; for both, MRI checks are planned before and during treatment.

Safety

Physically, the test is harmless; a blood or saliva sample is enough. The risks lie in the result. In REVEAL, disclosure in the study setting did not trigger additional anxiety or depression, but ε4 carriers were more distressed than non-carriers, and those who were already highly distressed beforehand coped worse. Added to this are false reassurance from an unremarkable result and data that permanently also concern siblings and children. A conversation beforehand about what you would do with which result is exactly what genetic counseling is meant to provide. What can be done for the brain regardless of the gene is collected on the pages Prevention, Epigenetics & Genetics and Hearing & dementia.

BK-Score Supported, with caveats

Human evidence7
Mechanism6
Safety data6
Hype gap5
Track record of use6

Evidence 7, because APOE4 is among the best-confirmed findings in human genetics – lifetime risks from 7,351 patients and 10,132 controls (Genin 2011), Alzheimer’s changes in almost all people with two ε4 copies in 3,297 examined brains (Fortea 2024) – and disclosure of the result has been tested in a randomized trial (REVEAL, 162 participants), whereas polygenic scores detect a median of only 11 percent of later cases at 5 percent false alarms (Hingorani 2023) and no study shows that healthy people stay healthy longer because of the knowledge. Mechanism 6, because APOE is well described as a fat transport protein in the brain and ε4 makes amyloid deposition earlier and more frequent, but the path from gene to disease is not fully understood and polygenic scores are statistical sums without an explained mechanism. Safety 6, because the sample is harmless and the psychological consequences of disclosure have been studied in a randomized trial over 1 year and in a survey of 1,648 customers of consumer tests, but long-term consequences, false findings and the handling of data that also concern relatives barely at all. Hype 5, because the APOE finding itself is reliable, whereas polygenic scores are sold as precise prediction, although they improved the prediction of heart disease on top of the classic risk factors only from 0.76 to 0.78 (Elliott 2020). Use 6, because APOE has been determined in research since the 1990s and has been clinical routine before amyloid antibodies since 2025, whereas polygenic scores have been offered for only a few years. Direction mixed: as a risk marker, APOE4 holds up; a benefit of the test for healthy people and the informative value of polygenic scores for the individual are not supported. For comparison: Lipoprotein(a) (8/7/5/5/6) for a genetically determined risk marker, Epigenetic age test (5/4/6/3/5) for a consumer test with weak individual informative value, Cancer screening by blood test (8/6/7/7/4) for a well-studied test with open benefit.

The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)

Frequently asked questions about the APOE4 gene test

What does an APOE4 finding say about my Alzheimer’s risk?

It shifts the risk markedly, but decides nothing. In a large analysis, by age 85, 23 percent of men and 30 percent of women with one ε4 copy developed the disease, 51 and 60 percent with two copies, and 11 and 14 percent without regard to the gene. Most people with one copy therefore do not develop the disease by 85.

Will I definitely get Alzheimer’s with two ε4 copies?

Almost all people with two copies develop the typical Alzheimer’s changes in the brain with age; in a large study, symptoms began at a mean age of 65. When and how severely someone becomes ill can nevertheless not be predicted for the individual. Since 2024, this constellation has been discussed as a distinct genetic form of the disease.

Can I do anything despite APOE4?

Yes. In the randomized FINGER trial, a program of diet, exercise, cognitive training and control of blood pressure and blood lipids improved cognitive performance in ε4 carriers too. A dedicated drug for prevention in ε4 does not exist so far.

What do polygenic risk scores do for the heart?

Little beyond the classic risk factors. In the UK Biobank, a heart score together with age, cholesterol, blood pressure, diabetes and smoking improved prediction only from 0.76 to 0.78 in the C-index. Across all diseases, such scores detected a median of 11 percent of later cases at 5 percent false alarms.

Can I simply have an APOE test in Germany?

As a prediction of a future disease, it is a predictive genetic examination under the German Genetic Diagnostics Act. It may only be carried out by specialists in human genetics or appropriately qualified physicians, with written consent and genetic counseling before and after the test, unless you waive it in writing. You have a right not to know.

Do I have to tell my insurer or my employer the result?

Your employer never; they may neither require a test nor use results. Insurers, as a rule, not either. Only for life, occupational disability, earning incapacity and long-term care annuity insurance with benefits above 300,000 euros or an annual pension above 30,000 euros may they ask for results that are already known.

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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-11-07.