Chris Hemsworth doesn’t give in to fear—or at least it seems that way. The action star spent his childhood adventuring around the Australian outback, and now, he even does some of his own stunts in his movies. He’s climbed the vertical surface of a dam, trained with elite military teams, and watched his kids take death-defying jumps on their dirt bikes, channeling any anxiety he might feel along the way into a little extra grit.
But true bravery lies in vulnerability and confronting our deepest fears, which are often more mental than anything else. Hemsworth is now leaning deep into that vulnerability, facing the fear that many people have of losing memory—their own, or that of their loved ones.
During the first season of his National Geographic docuseries, Limitless, Hemsworth learned that he inherited two copies of the gene variant APOE4. There are three naturally occurring versions of the gene APOE, but about 20 percent of the human population has one copy of APOE4, which increases the risk of Alzheimer’s disease by two to three times. Two to three percent of people have a double dose of the gene variant, according to Stanford Medicine, which increases the likelihood of developing the disease by eight to 10 times. Hemsworth has also revealed that one of his grandparents suffered from Alzheimer’s.
