After two decades of acting, Chris Hemsworth revealed he will take a break from his career, after learning he has a much higher-than-average chance of developing Alzheimer’s disease. 

The Australian actor learned the news while he was filming a new National Geographic docuseries for Disney+, Limitless, which explores the impacts of time and age.

Throughout the series, Hemsworth undergoes multiple genetic tests to see what his future might have waiting for him.

He is confronted by his own mortality in episode five.

Hemsworth eight to 10 times more likely to develop Alzheimer’s

The Marvel actor was filmed as his doctor informed him he was eight to 10 times more likely to develop the disease. 

“His makeup includes two copies of the gene ApoE4, one from his mother,” said Peter Attia, the longevity doctor in the docuseries. The other he inherited from his father.

More on that below. 

In a recent interview with Vanity Fair, Hemsworth emphasised that it’s not a hard diagnosis of Alzheimer’s.

However, he told the tabloid magazine that the double occurrence of the gene places him in a category of much higher risk of being impacted by the condition.

“My concern was I just didn’t want to manipulate it and overdramatise it, and make it into some sort of hokey grab at empathy, or whatever, for entertainment,” he said. 

“It’s not like I’ve been handed my resignation.” 

Chris Hemsworth said his makeup includes two copies of the gene, one from his mother, the other from his father. (Reuters: Evgenia Novozhenina)

When asked if acting “still excites” him, Hemsworth said it does, but that he is “going to recharge now”.

“I’m going to just not be so focused on the future — and what’s next?” he said in the interview.

“I don’t mean that in a sort of apathetic way, but there’s a stillness to my thinking about it all now.”

What is Alzheimer’s disease? 

Alzheimer’s disease is the most common type of irreversible dementia that causes the brain to shrink and brain cells to die, slowly destroying memory and thinking skills, according to the US National Institute on Aging (NIA).

Dementia and Alzheimer’s — what’s the difference?

Dementia:

Is a broad term used to describe the gradual loss of someone’s memory, intellect and ability to think rationally.

Dementia is not one specific disease, but a collection of symptoms.

Alzheimer’s:

Is a specific disease that affects the brain and causes dementia. 

Healthdirect says it affects up to 1-in-10 Australians over 65 years of age.

Up to 3-in-10 Australians aged over 85 years are affected. 

It was the second leading cause of death in Australia in 2020, according to the Australian Institute of Health and Welfare (AIHW). 

The AIHW says survival time is affected by age, sex, dementia type and severity at diagnosis, among other factors.

What is the ApoE4 gene? 

Certain genes can increase the risk of developing Alzheimer’s disease. 

ApoE4, or the apolipoprotein E gene, is the strongest risk factor gene for Alzheimer’s disease. 

Having one or two copies of this gene increases the risk of developing Alzheimer’s, according to the NIA.

It says about 25 per cent of people carry one copy of ApoE4.

Just 2 to 3 per cent carry two copies, making Hemsworth a rare case. 

However, even if a person has two copies of the gene, this does not mean they will definitely develop Alzheimer’s. 

Survival time is affected by age, sex, dementia type and severity at diagnosis.(AP Photo: Matt York)

A look inside the human brain:

The brain contains millions of brain cells (neurons) that organise how the brain stores memories, learns habits and shapes our personality.

Signals pass along the connections between brain cells in the form of chemicals called neurotransmitters.

Alzheimer’s disease affects these cells and chemicals.

It disturbs memory, impairs thinking and causes behaviour changes over time.