Cardiologist Annabelle Volgman, MD, asks some of her patients to make this decision.
"It comes down to: What are you going to do about it?" says Volgman, director of the Rush Heart Center for Women. "If you can make changes because you know your risk, it might be worth finding out. If it's just going to cause anxiety and stress, it's not worth it."
This common-sense advice might sound familiar. Doctors tend to say the same thing to women deciding whether they should get tested for the BRCA gene mutations closely linked to breast and ovarian cancer risk.
Volgman's patients face a similar choice. Tests she offers can show whether their genes put them at risk for heart disease, heart attack or stroke. One of these tests reveals whether the patient has APOE E4 — a type of the apolipoprotein E (APOE) gene linked not only to heart problems but also to Alzheimer's disease.
APOE and heart health
Volgman tests for APOE E4 because it puts people at risk for atherosclerosis. (Atherosclerosis, or hardened arteries, is a common problem that can lead to heart attack, peripheral vascular disease and stroke.)
But she doesn't think everyone should get tested.
In most cases, she explains, treatment for atherosclerosis risk factors such as high cholesterol or high blood pressure would be the same no matter what form of APOE a patient had. Sometimes, though, the test can help decide the best course of action.
"For example, if a patient has been eating well and exercising and her cholesterol levels still haven't changed, it could help to know whether she has a higher risk," Volgman says. "If she does, we might want to start medication earlier."
Of course, treatment is not the only thing that can change in the lives of people who test positive for APOE E4. From then on, they know they have a high risk of Alzheimer's disease.
APOE and Alzheimer's disease
Research has shown that your risk of getting Alzheimer's disease depends partly on which form of APOE you have.
Everyone has two copies of the gene, one from each parent. The roughly 25 percent of people with a copy of the E4 form have a higher risk, compared with the average person. People with the uncommon E2 form have a lower risk. About 75 percent of people have the E3 form, which has no effect on Alzheimer's risk.
Having APOE E4, though, does not mean you will definitely get Alzheimer's (or atherosclerosis, for that matter). And having another form of APOE does not mean that you won't get it.
Because there are no treatments proven to prevent or delay Alzheimer's, finding out you have APOE E4 has no proven medical benefit. For this reason, doctors do not generally recommend getting tested just to learn more about your Alzheimer’s risk.
If you can make changes because you know your risk, it might be worth finding out. If it's just going to cause anxiety and stress, it's not worth it.
Knowing your Alzheimer’s risk
But people who know they have a high risk can make choices that might help lower it.
"I talk with them about current research on heart and brain diseases, as well as lifestyle changes that we think could lower their risk of Alzheimer's," Aggarwal says. "Things like eating a healthy diet, getting exercise and staying mentally active."
Aggarwal also screens these patients for mild cognitive impairment (which can lead to Alzheimer's) and talks with them about upcoming clinical trials. She will soon begin recruiting patients at high risk of Alzheimer's for prevention trials.
"These patients tend to be glad they know their risk and feel better knowing that we're following them and that we are working together," Aggarwal says.