What's my risk of dementia?

While just one in 1,000 people between 40 and 65 has dementia, that jumps to one in 50 between 65 and 70 and one in five over 80. Women are slightly more likely than men to develop Alzheimer’s, even if you discount the fact that they live longer. Men are more likely to suffer vascular dementia caused by clots blocking small blood vessels in the brain.

If a parent had dementia, you are only slightly more at risk than you would have been anyway. You have a higher risk with high blood pressure, heart disease or if you were obese in mid-life. Smoking increases the risk, as does excessive alcohol intake over many years (although “moderate” amounts of wine protect the brain). Fewer highly educated people get dementia.

Is dementia preventable?

As age is the biggest risk factor, dementia is not completely preventable. But you can radically cut the risk.

“We know that maintaining a normal body weight in your forties and fifties is important in lowering your risk of getting dementia in your sixties, seventies and eighties,” says Dr Susanne Sorensen, head of research at the Alzheimer’s Society. “It’s also well documented that eating a varied diet with five to seven portions of fruit and vegetables a day decreases the risk – boring, I’m afraid, but true.”

One startling study in September 2006 claimed that three glasses of fruit or vegetable juice a week lowered the risk of getting Alzheimer’s by 76%. Many were sceptical, but Dr Sorensen believes the research is valid.

“It’s probably because juice contains the skin of the fruit, which contains polyphenols. It would explain why those taking vitamins don’t see the same effect,” she says.

Other nutrients may offer protective benefits. Omega 3 and 6 (in oily fish) and folic acid (in broccoli and breakfast cereals) are the top two “probables”; research is ongoing. Research also shows that people with a wide social network and many hobbies may lower their risk, as do those who keep their brains active with puzzles.

What are the signs of dementia?

Not all sufferers will have all these signs, and people who do have some of them won’t have dementia (depression is often the explanation).

The most common signs are: recent memory loss, forgetting words or using them in the wrong context, time and place disorientation, difficulty performing familiar tasks, problems with abstract thinking, changes in mood or personality and loss of initiative. Balance problems and a weakened hand grip could be an early sign.