In late 2022, actor Chris Hemsworth, best known for his role as Thor in the Marvel Cinematic Universe, revealed a personal health discovery. While filming the National Geographic docuseries “Limitless With Chris Hemsworth,” the actor, then 39, learned that he has a genetic predisposition to Alzheimer’s disease. This news made headlines and started conversations about genetics, Alzheimer’s, and what people with a family history or genetic risk of the disease can do to support their brain health.

Hemsworth explained that he has two copies of a variation of the apolipoprotein (APOE) gene, APOE4. This genetic variant is linked to an increased risk of Alzheimer’s. His announcement sparked interest and concern about what having this gene means for Hemsworth and for anyone with a family history of the disease.

Does having the APOE4 gene mean you’ll definitely get Alzheimer’s, or does it just increase your chances? More importantly, what can you do if you, like Hemsworth, have a family history or genetic risk of Alzheimer’s disease?

Understanding Alzheimer’s Disease and Genetics

Alzheimer’s disease is a progressive brain disorder that leads to memory loss, cognitive decline (problems with mental processes like thinking and memory), and, eventually, the inability to carry out daily tasks. It’s the most common cause of dementia, affecting about 6.5 million people in the U.S. aged 65 and up. Certain factors, including genetics, lifestyle, and environment, can influence a person’s risk of Alzheimer’s.

APOE is a gene that helps regulate cholesterol and is important for brain health. There are three versions: APOE2, APOE3, and APOE4. Each person inherits one copy of the APOE gene from each parent. If you have the APOE4 variant, your risk of Alzheimer’s is higher, and you may be more likely to have a severe form of the disease. This is especially true if you inherit two copies of APOE4, as Hemsworth did.

What We Know About the APOE4 Gene

The APOE4 gene is one of the strongest genetic risk factors for late-onset Alzheimer’s, which is the most common form of the disease — it usually begins after age 65. According to researchers, people with one copy of APOE4 have up to 4 times the risk of developing Alzheimer’s, while those with two copies (like Hemsworth) have up to 12 times the risk.

It’s important to understand that having the APOE4 gene increases your risk, but it doesn’t mean you’ll definitely get the disease. Many people with the gene never develop Alzheimer’s, and some people without the gene may be diagnosed. The gene just raises your chances.

Genetic Testing and Alzheimer’s Disease

Genetic testing can help you understand your risk of Alzheimer’s, but it also comes with emotional and practical challenges. Hemsworth shared how his test results made him face the realities of his genetic risk.

If you’re thinking about genetic testing, be sure to consider whether knowing you have a genetic predisposition would help you or cause more anxiety. Some people find that learning about their risk encourages them to take steps to protect their brain health, but others may feel overwhelmed by the information.

Supporting Brain Health: What You Can Do

If you have a family history of Alzheimer’s disease or know you carry a genetic variant like APOE4, you may wonder what you can do to support your brain health. Although there’s no cure for Alzheimer’s, researchers believe that certain lifestyle changes may help lower your risk or delay the start of symptoms.

Exercise Regularly

Exercise is one of the most powerful tools for brain health. Studies show that regular physical activity can reduce the risk of developing Alzheimer’s by up to 50 percent. A study published in Medicine & Science in Sports & Exercise suggests that exercise is especially effective in lowering the risk for those with the APOE4 gene. Each week, aim to get at least 150 minutes of moderate exercise, such as walking or swimming.

Eat a Brain-Healthy Diet

Diet is key to protecting your brain. The Mediterranean diet, which is rich in fruits, vegetables, whole grains, fish, and healthy fats, has been associated with a lower risk of Alzheimer’s. Hemsworth has mentioned his commitment to following a balanced diet to support his brain health.

Omega-3 fatty acids, found in algal oil and in fish like salmon, are especially good for the brain. Antioxidants, found in berries, leafy greens, and nuts, help protect the brain from damage caused by oxidative stress (an imbalance between harmful molecules called free radicals and the body's defense mechanisms).

Stay Mentally Active

Keeping your brain engaged is another important way to reduce your risk of Alzheimer’s. Activities like reading, solving puzzles, learning a new language, or playing a musical instrument can help strengthen cognitive function. The goal is to keep challenging your brain with new tasks and information to keep it sharp.

Prioritize Sleep

Good sleep is essential for brain health. Chronic sleep deprivation has been linked to an increased risk of dementia. Try to log seven to eight hours of quality sleep each night. If you have trouble sleeping, talk to your health care provider, because solving sleep issues is an important part of keeping your brain healthy.

Manage Stress

High levels of stress can contribute to cognitive decline and may increase your risk of Alzheimer’s. Adding a stress-reducing practice such as mindfulness, meditation, or deep breathing to your daily routine can support brain health. Hemsworth has described how mindfulness helps him manage stress and stay focused.

Stay Socially Connected

Social interaction is also important for brain health. Spending time with friends and family, participating in group activities, or volunteering can help lower your risk of cognitive decline. Isolation, on the other hand, has been shown to increase the risk of dementia, so staying connected to others is crucial.

Hemsworth’s Approach to Brain Health

After learning about his genetic risk of Alzheimer’s, Hemsworth made his physical and mental health a priority. He has talked about making lifestyle changes, such as improving his diet, practicing mindfulness, and staying physically active. While he acknowledges that there’s no way to predict his Alzheimer’s outcome, these habits give him peace of mind — he knows he’s doing everything he can to lower his risk.

For those with a family history or genetic predisposition, following similar habits may help reduce chances of developing Alzheimer’s. There’s no one-size-fits-all solution, but being proactive about your health can make a big difference in your future well-being.

Talk With Others Who Understand

On myALZteam, the social network for people with Alzheimer’s and their loved ones, more than 86,000 members come together to ask questions, give advice, and share their stories with others who understand life with Alzheimer’s disease.

Are you living with Alzheimer’s or concerned about your risk? Do you take steps to protect your brain health? Share your experience in the comments below, or start a conversation by posting on your Activities page.