Chris Hemsworth just found out he has a high risk of Alzheimer's, and says watching his grandfather's dementia was 'heartbreaking'

• Chris Hemsworth said recent tests revealed he has a rare gene linked to higher Alzheimer's risk.
• He found out while filming a docuseries on longevity, and opted to share onscreen to raise awareness.

Chris Hemsworth discovered he has a higher genetic risk of Alzheimer's that may make him eight to 10 times more likely to develop the disease he said is his "biggest fear," according to an interview with Vanity Fair.

Hemsworth was alerted to the potential risk while doing extensive bloodwork for the National Geographic series,
"Limitless", which explores longevity through extreme feats of human endurance.

He told Vanity Fair that the discovery almost derailed the filming of the series. The show's longevity expert, Dr. Peter Attia, said he needed to alert Hemsworth off camera, and verify that he wanted to go through with filming, the "Thor" actor recalled.

"It was pretty shocking because he called me up and he told me," Hemsworth said to Vanity Fair.

The testing found he had two copies of the gene APOE4, a trait shared by just 2-3% of the population, according to the National Institutes of Health.

APOE4 may interfere with how brain cells handle cholesterol and other types of fat, increasing the odds of developing Alzheimer's and other forms of dementia, research suggests.

The gene is the strongest risk factor gene for Alzheimer's, although it doesn't guarantee a person will develop the disease — researchers don't yet fully understand how it works, according to a 2022 study.

Hemsworth said he was given the option not to discuss his personal risk in the final cut of the series, but he opted to share in the hopes that it might help other people.

He said in a clip of the show that his grandfather has experienced memory loss and cognitive decline from the disease, and it was "heartbreaking" to see him forget his children and grandchildren.

Hemsworth said the warning about his own risk was a blessing in some ways, because it allowed him to take steps to prevent Alzheimer's such as prioritizing sleep and stress management. It also prompted him to commit to working less and spending more time with his family.

"I just wasn't aware of any of it, so now I feel thankful that I have in my arsenal the sort of tools to best prepare myself and prevent things happening in that way," he told Vanity Fair.