Chris Hemsworth describes 'gear shift' after learning he's 10 times more likely to get Alzheimer's

Chris Hemsworth has told Sky News that finding out he had a greater chance of developing Alzheimer's disease was a "gear shift" in his life motivations.

During a genetic test in season one of Limitless: Live Better Now, the Australian actor discovered that he is, biologically, eight to 10 times more likely than others to have the brain disorder during his lifetime as he carries two copies of the APOE4 gene. He had first taken part in the National Geographic show to be its "guinea pig" and face new experiences that challenge the body and mind.

But after having the test, the 41-year-old Thor, Furiosa and Transformers star was faced with an unexpected truth. One in every 50 people inherit two copies of the APOE4 gene and research has found that nearly all double carriers showed key early signs of the disease which causes dementia by the age of 55.

Everyone's risk is different, and evidence suggests there are things you can do to reduce your risk whether you're a carrier of the gene or not, including not smoking, reducing alcohol intake, daily exercise, monitoring cholesterol and blood pressure and eating a balanced diet. Speaking of when he found out he was a double carrier, Hemsworth told Sky News: "It was just kind of this point in my life where up until your 40s, you're kind of gathering data and information and it's all reactionary and then you get to a point where you think, oh some of this sort of identity that I've sort of built doesn't hold true anymore.

"There's some inner sort of protest or inner voice that has a deeper need to understand and there's deeper questions and what is the purpose and the why behind what I'm doing ... and what am I seeking, what am I contributing, as opposed to just what I am collecting." Reacting on screen, he said it made him shift his focus to living better and increase the chances of him spending as much time as possible with his family and friends.

What's changed in the second series? The change in mindset is evident in season two. "This time around, I was very involved in the orchestration and the sort of production and bringing together spaces that I was interested in or there was a deep curiosity or were deeply personal to me.

And it was more sort of experiential journalism as opposed to a contestant in a challenging kind of fun, reality show. He adds: "I was much more committed or invested in the experience.

"And I was a bit more educated on the topics too. I had to research, I had a deeper point of view, I suppose, personally, but also sort of the education I was given prior and I enjoyed that more, to be honest, I didn't like that I felt very uncomfortable in the first season because I was standing around all these experts and I knew nothing about these topics, yet I was kind of asked to speak on them and so I felt like an imposter the entire time." Limitless: Live Better Now looks at the ways in which you can improve your brain and body's health through endurance challenges and learning a new instrument.

Read more entertainment and arts news:Actor settles lawsuit with Disney - and thanks Musk for funding itEddie Murphy: I'll get an Oscar eventually Teaming up with Sheeran Hemsworth chose the drums and, taking it to the extreme, was set the task of joining his friend Ed Sheeran on stage to play Thinking Out Loud. "That fear and that anxiety was incredibly overwhelming," Hemsworth says, detailing how he felt "underwater" in the weeks leading up to the event.

"It's weird the way intense situations actually cause a hyper focus; it's a survival mechanism of the brain. "Some of the other challenges where if I did the training it was beneficial, but I could kind of muscle my way through it.

You can't do that with a musical instrument and then the realisation that the entire band is relying on you to keep time. And then 70,000 people are sitting there going, 'please don't wreck our favourite song'." Reflecting on the moment, he says it's one of the most magical feelings he's ever had.

"The joy was unlike anything I've ever experienced. You know, if you could bottle that and have it in a healthy way and not have all the negatives that someone may have for it, it was amazing.

It was a true kind of one of my first probably proper out of body experiences, I suppose. "It was like, I kind of remember being in the out, looking down at myself almost, kind of going, wow, I'm kind of floating along with this thing that's so much bigger than me and I'm in true sort of flow state with it." National Geographic's Limitless: Live Better Now is available to stream on Disney+ from 15 August..