Making healthy lifestyle choices in middle age may lead to a decreased risk of dementia later in life, research has shown.

The study of nearly 14,000 women in their 50s showed that following seven healthy habits and lifestyle factors may play a significant role in lowering the risk of dementia.

The seven cardiovascular and brain health factors, known as the American Heart Association's Life's Simple 7, are: being active, eating better, maintaining a healthy weight, not smoking, maintaining healthy blood pressure, controlling cholesterol, and having low blood sugar.

"Since we now know that dementia can begin in the brain decades before diagnosis, it's important that we learn more about how your habits in middle age can affect your risk of dementia in old age," said Pamela Rist, from Brigham and Women's Hospital in Massachusetts.

"The good news is that making healthy lifestyle choices in middle age may lead to a decreased risk of dementia later in life.

"It can be empowering for people to know that by taking steps such as exercising for half an hour a day or keeping their blood pressure under control, they can reduce their risk of dementia," Rist said. The study involved 13,720 female participants with an average age of 54 at the start of the study.

After 20 years of follow-up, 1,771, or 13 per cent, developed dementia. For each of the seven health factors, participants were given a score of zero for poor or intermediate health and one point for ideal health, for a total possible score of 7.

The researchers found that for every increase of one point in the score, a participant's risk of dementia decreased by 6 per cent. The study will be presented at the American Academy of Neurology's 75th Annual Meeting being held in Boston from April 22-27.