What to know about Chris Hemsworth’s increased Alzheimer’s risk

While filming his new docuseries, “Limitless,” Chris Hemsworth underwent a series of trials centered around pushing the limits of the human body and learning how to live better for longer.

But the journey also led the 39-year-old actor to a profound discovery about his own genetic makeup: He has two copies of the ApoE4 gene, which may put him at a heightened risk for Alzheimer’s disease.

“ApoE4 is a susceptibility gene, which means it increases the risk of getting Alzheimer’s but does not guarantee it,” says Dr. Darren Gitelman, behavioral neurologist and senior medical director of the Advocate Memory Center at Advocate Lutheran General Hospital in Park Ridge, Ill. “Having the gene also can shift the disease onset to an earlier age.”

Each person has two copies of the ApoE gene, of which there are three common forms: E2, E3 and E4. For people with one copy of the E4 variant, the odds of developing Alzheimer’s increase two- to threefold, Dr. Gitelman says. Those with two copies of E4 are eight to 12 times more likely to get the disorder compared to noncarriers.

It’s not entirely known why E4 confers a greater Alzheimer’s risk than E2 or E3 , though a review in 2019 noted ApoE4 may affect multiple brain cellular functions including those related to lipid transport, synaptic function, glucose metabolism and cerebrovascular function. About one in four people carry one copy of the APOE4 gene, while 2% to 3% carry two copies like Hemsworth.

While inheriting two copies of ApoE4 may not mean you will definitely get Alzheimer’s disease, not having the gene reduces the risk but doesn’t guarantee you won’t develop the disease. More than 40% of Alzheimer’s patients don’t carry the E4 variant, Dr. Gitelman says.

That uncertainty is one reason why Dr. Gitelman advises against testing for genetic predispositions to Alzheimer’s unless it’s important for family planning or research purposes.

“There’s no surefire way to prevent Alzheimer’s disease, so knowing whether you have ApoE4 won’t lead to better treatment at this time,” he says. “We encourage everyone, regardless of their E4 status, to lead a healthy lifestyle to reduce their risk of dementia.”

Dr. Gitelman’s recommendations include:

• Getting regular exercise
• Eating a healthy diet, such as Mediterranean, DASH (Diet Approaches to Stop Hypertension), or the hybrid MIND (Mediterranean-DASH Intervention for Neurogenerative Delay) diet
• Engaging in intellectual stimulation and social connections
• Getting 7-8 hours of sleep per night
• Avoiding smoking
• Avoiding head injuries
• Diagnosing and treating sensory deficits, such as hearing or vision problems

Patients also should maintain regular follow-ups with their physicians to monitor and manage their dementia risk, Dr. Gitelman says. In fact, he is involved with a project aimed at increasing cognitive testing in patients over the age of 65.

“This will help alert patients and physicians if cognition is starting to change and allow them to look for modifiable risk factors, such as vascular disease or sleep disorders,” Dr. Gitelman says.

Do you have trouble sleeping? Learn more about sleep apnea by taking a free online quiz.