Alzheimer's Foundation of America

Foundation of America

Genetic Testing for Alzheimer’s Disease: To Test or Not to Test

Genetic testing for Alzheimer’s disease has become a hot topic following the recent controversy surrounding Australian actor Chris Hemsworth’s decision to go public with the results that his test revealed a high risk for Alzheimer’s.

The global genetic testing market was valued at $8 billion in 2021, according to Precedence Research. Ancestry tracing sites have spurred the growth of personal-information seeking so significantly that genealogy has become the second most popular hobby in the United States, Science News reports.

Nathaniel A. Chin, MD, an assistant professor (CHS) at the University of Wisconsin-Madison, department of medicine, geriatric division, says “probably the most important question” involving this interest is what people should consider before getting tested.

Things to consider regarding genetic testing for Alzheimer’s Disease

“It’s not just a test that affects one person, just as Alzheimer’s is not a disease that affects one person,” Chin says. “The key things to consider are: Why are they getting it? What are they hoping from the outcome? What is their motive?” Secondly, people need to consider what they will do with the information if they prove to be at risk. Will they behave differently and make changes? Will they see themselves differently or worry that others do? What are the psychological consequences of knowing this information?

“Are there specific treatments based on your genetic risk? The answer is no,” Chin says. But while no therapeutic interventions exist now, great support groups do and joining a research study is also possible.

“Who are you going to talk to? Will you tell family and friends? Will your insurance company learn about it? Will it change your medical care? These are some of the questions that come up. One test leads to so many other questions. It’s a ripple effect.”

Because of all these considerations, Chin advises against home tests, which don’t specifically test for Alzheimer’s but “can tell you a lot of interesting and emotionally charged things about yourself, including if you are at an increased risk through the gene APOE.”

What is the APOE gene and how does it affect risk?

APOE is apolipoprotein-E, a “susceptibility” gene for late-onset Alzheimer’s disease. It is designated into three risk levels—APOE 2, APOE 3 and APOE 4. APOE 3 is considered neutral and is the most common, with a 2 to 5 percent risk for Alzheimer’s. APOE 2 has a one to two percent risk. APOE 4 holds a 10 to 15 percent increase.

Chin emphasizes that a person can have the high-risk gene without ever developing Alzheimer’s and, conversely, may not have the gene and still develop the disease. “It’s a risk, not a guarantee.” What is most important for someone wishing to know their Alzheimer’s risk, Chin says, is that they find a healthcare provider who can discuss results and what they mean for that person. He said it is best to see a neurologist, psychiatrist, geriatrician or medical geneticist. In the seven years he has been in practice at an academic institution, he has never ordered a genetic test. He refers patients to a medical genetic clinic.

“I would advocate that people need to consider how they will handle the information. That is the value of good counseling, to know what is involved. Counseling plays a huge role and should be mandatory.” It is not currently mandatory. For initial exploration, Chin recommends the website, which helps people think through the whole process of getting tested.

Chin said counseling about risks, particularly genetic risks, should be part of medical education. Medical providers play a critical role in terms of explaining risk, helping the patient consider the psychological effect the information could have and what the consequences of telling family and friends could be.

A trained genetic counselor can spend between 45 minutes to two hours going over this with a patient, he said. Unfortunately, busy primary care doctors do not have that kind of time. That is why some may decline to do genetic testing. “They’re not prepared to handle what comes with it.”

Discrimination Following Genetic Testing for Alzheimer’s Disease

People shouldn’t have to worry that a test showing high risk will affect their health insurance because GINA, the Genetic Information Nondiscrimination Act, protects them, Chin says, but life and disability insurance are different. He advises that people get these types of insurance set up before they are tested.

Possible discrimination in employment for people testing at high risk is “tricky,” Chin says, because while laws prevent discrimination, “there is a lot of bias and stigma around Alzheimer’s.” If an employer were to learn of an employee’s risk factor, the employer might watch that person more closely, looking for mistakes that would lead to dismissal or demotion. “Information is readily accessible these days and one must be really careful.”

Chin points to the outcome of the 39-year old Hemsworth’s discovery and subsequent disclosure after a DNA test he took for his six part docuseries, Limitless, on the streaming service Disney+, revealed he has two copies of the APOE4 gene. He was supposed to learn the results on the show, but the producers told him privately because of what was revealed. He chose to be open to educating people about the importance of a healthy lifestyle in preventing or slowing Alzheimer’s and was criticized for going public with information his family didn’t ask for. “It’s sad to see them kicking a person while he’s down,” Chin said.

“There’s always value when a person in the spotlight headlights the power of prevention and emphasizes the importance of quality of life.” He reserves his concerns for the people who did the blood testing without potentially counseling Hemsworth about the consequences of knowing the results. “If he was blindsided then that is completely unacceptable. It’s high risk to drop something like that on a person who is not prepared. I’m impressed with the way he’s handling it. He’s letting people know this is serious information and must be treated as such. He’s having an impact.”

In addition to Dr. Nathaniel A. Chin’s professorship, he is the associate director of the Geriatric Memory Program at the University of Wisconsin Hospitals and Clinics, the medical director and clinical core co-leader at the Wisconsin Alzheimer’s Disease Research Center (ADRC) and the medical director of the Wisconsin Registry for Alzheimer’s Prevention (WRAP) study. He is also a member of AFA’s Medical, Scientific & Memory Screening Advisory Board.

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