It tends to emerge in people older than 65, but it can occur earlier too.
Estimates from NHS England suggest around 850,00 people in the UK have dementia at the moment.
In 2020, there were more than 55 million people around the world who live with dementia.
Is it possible to reduce your risk of developing dementia?
Yes, according to a new two-decade long study of 13,720 women who were mostly aged 54 at the start.
It has been supported by the US National Institute of Health (although it is yet to be peer-reviewed).
So after 20 years, researchers found some 1,771 women or 13% of study participants had developed dementia.
The researchers gave each participant a score on each of the healthy habits which may help decrease the risk of dementia to see if there was any correlation with this lifestyle and the disease.
With each new habit rewarding the participant one point, the maximum available was seven – the average score ended up being 4.3 at the start of the study and 4.2 ten years later.
But even after factoring in age and education, they found that for every increase of one point in the score, the risk of dementia fell by 6%.
However, there were limits to the study such as understanding how quitting smoking can affect risk of dementia.
Pamela Rist, assistant professor and from Brigham and Women’s Hospital said: “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.”
She said that making these changes in middle age can decrease your risk of developing dementia later on.
So, what habits do the scientists think you need to adopt?
1. Stay active
2. Eat a better diet
3. Maintain a healthy weight
4. Don’t smoke
5. Keep blood pressure at a normal level
6. Watch and control cholesterol
7. Have a low blood sugar
How have other experts reacted?
Susan Mitchell, head of policy at Alzheimer’s Research UK, said the entire study showed “overwhelming evidence” that women can change their chances of developing dementia in later life.
She told news agency PA that women “are far more likely to develop it than men” and it is currently the leading cause of death among British women.
“Whatever our gender, we can all take simple steps to reduce our risk of dementia,” she urged.
She added that getting a good night’s sleep, challenging our brain and staying connected to people can help too.
These latest findings are similar to a study from University College London last week, which found that staying active is effective to reduce dementia risks as it keeps the brain in good health.