Render of a human brain with representation of activity

Marvel star goes public on his APOE genetic link to Alzheimer’s

Chris Hemsworth recently revealed his APOE4 status, which he discovered while filming a documentary on living better for longer

Australian actor Chris Hemsworth, most known for his role of Marvel’s Thor, discovered he has two copies of the APOE4 gene variant during filming for Disney+’s Limitless, a documentary series about trying to live better for longer.

Speaking to Vanity Fair magazine, the 39-year-old actor spoke of his APOE4 variant and its connection to Alzheimer’s disease: “It’s not a pre-deterministic gene, but it is a strong indication.” He added that Alzheimer’s is “8 to 10 times more likely” in those who, like him, have two copies of the APOE4 variant.

Risk factors for Alzheimer’s

Age is the biggest risk factor for developing Alzheimer’s disease, which is a type of dementia. According to the NHS, about 1-in-14 people over 65 years are affected by the disease, with prevalence increasing to 1-in-6 people over 80 years.

Controlling certain lifestyle factors may reduce the chance of developing Alzheimer’s disease and related dementias. The NHS recommends keeping to a healthy weight, lowering high blood pressure, lowering high cholesterol, exercising regularly and not smoking.

There is a genetic component to Alzheimer’s, with many gene variants at play. So even if a person’s relative had the disease – Hemsworth spoke of his grandfather having the disease, for instance – that person may not necessarily develop it. Some gene variants have a larger effect, with the most significant among these being found at the APOE gene.

Everyone has two copies of the APOE gene, which can further be divided into different variants. The APOE3 and APOE2 variants don’t affect the risk of developing Alzheimer’s – indeed, APOE2 may decrease the risk. Yet with the APOE4 variant, having one copy gives a slight increase in risk, and two copies – which Hemsworth noted he has – gives a significant increase in risk.

How does APOE4 contribute to Alzheimer’s?

Recently, researchers have shown for the first time how APOE4 affects the brain, and it seems to be related to myelin.

Myelin is a fatty substance that insulates some nerve cells and increases their effectiveness at transmitting nerve signals. Cells called oligodendrocytes make myelin using lipids, like cholesterol, and the APOE protein is involved in this process.

Comparing brain samples from Alzheimer’s patients with and without APOE4, the researchers found that individuals with APOE4 had accumulated cholesterol in the oligodendrocytes, rather than in the myelin. They also showed that the drug cyclodextrin, which helps transport cholesterol, could reduce cholesterol accumulation and increase myelin production. This offers a potential treatment of APOE4 carriers in the future, but for now prevention remains the best advice for those in a similar position to Hemsworth and his family.

The human impact

Speaking of his three children and their risk, he added: “One day I’m sure I’ll bring [my APOE4 status] up. They probably want to test themselves and [find out]: ‘Are you in the category that’s going to be sensitive to this or not?’”

Hope for Alzheimer’s patients and their families rest in research efforts into treatments that intervene in the disease’s progression. Indeed, a recent landmark study showed the drug lecanemab can slow down Alzheimer’s disease progression. UK Dementia Research Institute director Professor Bart De Strooper said in a statement: “This is the first drug that provides a real treatment option for Alzheimer patients.”

While a promising breakthrough, lifestyle factors remain an important aspect for those with an increased chance of developing the disease. Hemsworth remains positive about his genetic result: “I feel thankful that I have in my arsenal the sort of tools to best prepare myself.”

Please note: This article is for informational or educational purposes, and does not substitute professional medical advice.