Sir Jackie Stewart says finding a cure for dementia would be his "greatest legacy".

The three time Formula One world champion's wife Lady Helen was diagnosed with the condition around six years ago.

"There are an awful lot of people who are in the same problem as we are, to care for someone they love," explains Sir Jackie.

"I'm fortunate that motor racing has allowed me to have nurses and people to help Helen 24 hours a day. And that's what dementia requires.

"It's a very cruel disease because people can't remember anything. My wife will not remember that she was at Silverstone a few days ago."

Sir Jackie has set up the Race Against Dementia charity, aiming to combine the cutting edge technology and speed of Formula One with the research and medical wizardry of the world's top neuroscientists.

One element of the charity's work will see the top PhD students in medical research embedded to observe the work done by F1 teams - particularly focussing on their efficiency and speed in bringing new developments to the track.

"There are 50 million people in the world with this illness that's not yet been found a cure for and I want to do that," Sir Jackie explains.

"We are driving as fast as we can to find new young PhDs who are using the young Formula One McLaren team, the Red Bull Formula One team to vitalise those PhDs that are starting their lives, the young ones, to be able to get things done faster, like in motor sport."

Last week Sir Jackie shared a touching moment with his wife at the Goodwood Festival of Speed, stopping to pass her a rose on the famous hillclimb.

Yet the 80-year-old fears, such is his wife's condition, that even that recent moment will have been lost.

"I fear that might already be forgotten. And that was a precious moment for both of us," he adds.

While Sir Jackie is best known for being one of Scotland's greatest ever sportsmen, he says attempting to find a cure for dementia is the biggest challenge of his life.

"I think in the case of the medical profession, it's not a question of breaking down a brick wall, it's just enthusing things to be done in a faster way," he said.

"We have to find new ways of doing business because if we keep doing it the same way as we have for the last 30 years, we won't break down that terrific wall that exists and that's terribly expensive and terribly tear-making for families.

"[Finding a cure] would be my biggest legacy."