Brain training and doing what's good for your heart can reduce your probability of getting dementia, an expert says.

Making our brains healthier may reduce the chance of getting dementia, says an expert who's optimistic about a scientific breakthrough for preventing the disease.

"I know it sounds a bit cliched, but what's good for your heart is good for your head," says Professor Craig Ritchie from the Psychiatry of Ageing at the University of Edinburgh.

That includes exercise, keeping your weight down and having a Mediterranean Diet.

Prof Ritchie spoke to AAP before giving the Wicking Trust Public Lecture in Melbourne on Wednesday night.

He's also head of the new $A100 million European Prevention of Alzheimers Dementia Project (EPAD), aimed at preventing dementia in people with evidence of the disease but who still may have little or no complaints or clinical symptoms.

"I'm really optimistic we can actually do something," Prof Ritchie said.

The project wants to establish a risk score for dementia, such as applies to other conditions like cardiovascular disease.

"We are talking about looking at data which probably at the end of the project will relate to tens of thousands of individuals."

The project also involves a large clinical trial testing new treatments for the prevention of Alzheimer's disease.

Scientists have found that changes take place in the brain many decades before the disease actually develops, so making our brains healthier in mid-life can reduce the probability of getting dementia.

Brains need a good blood supply, so if people can maintain a healthy heart their brain will survive "more healthy for longer".

Another positive is "brain training", which involves doing new activities and not, as widely thought, continuing your long-term practice of doing a daily crossword.

"It's even better if you can do something novel in a social context," he said.

"What we are doing now (in the interview) is talking which is probably one of the most cognitively stimulating things you do."

He advises people to take up a hobby or interest they haven't pursued and do it in a social group - such as playing a musical instrument in a band or joining an art club.