The 'Chasing Cars' hitmaker fears he could be struck down by the disease, which causes memory loss, after his father suffered the same fate.
Speaking to The Sun newspaper's Bizarre column, he said: "My dad has dementia and I've always had memory problems. That's been a lifetime problem. I'm sure that it will run to me and that's why I'm trying to get on top of it in my forties, rather than leave it any later. Hopefully I've got a few years yet before that affects me. Memory is close to my heart and on my mind. I've been trying to do memory exercises."
Meanwhile, Gary previously credited his acupuncturist pal with saving his life after he got seriously ill in 2016, which turned out to be a serious infection.
He said: "I had my tickets and flights booked for all the matches and was going to France with four friends. I woke up one morning and wasn't feeling very well - physically unwell. I was doing my exercises and I bent down to touch my toes and when I came up, it was like it was an earthquake. I was dizzy and everything was moving. I phoned a friend who lived nearby and went to see a doctor. I had tests and basically my whole head, eyes, ears, nose and sinuses were infected. I was told I needed an operation and there was no way I could get on a plane. She also asked me to calm down on the drinking. So I stopped. That was two years ago and I credit my friend with saving my life. The song 'Heal Me' is written all about the experience."