This information is for people with dementia and their carers. It tells you about HRT, a treatment that's been tried for dementia. It's based on the best and most up-to-date research.
Does it work?
No. There's no evidence that taking hormone replacement therapy (HRT) can help women with dementia to remember things better and think more clearly. And taking HRT can increase your risk of some other conditions, including breast cancer and heart disease.
What is it?
Many women take hormone replacement therapy when they reach the menopause. HRT includes a hormone called oestrogen. Oestrogen is one of a group of hormones that control a woman's reproductive system (the parts of the body that enable a woman to get pregnant and give birth).
Women's bodies make less oestrogen when they reach the menopause. So, many women take HRT to restore some of the oestrogen they've lost.
If you would like to read more about the different kinds of hormone replacement therapy, see HRT or What treatments work for the menopause?
Some studies have found that women who take HRT are less likely to get dementia.  Out of nearly 6,000 women studied, 15 in 100 taking HRT got dementia compared with 21 in 100 not taking it.
For this reason, doctors started looking at whether women should take HRT to reduce the symptoms of dementia. However, there is no evidence that HRT can help in this way. Doctors think that there may be something else about women who take HRT that protects them against dementia. For example, something in their lifestyle, such as taking exercise, could help keep them from getting dementia.
How can it help?
There's no evidence that taking HRT can help improve symptoms for women with dementia.  And it could cause serious side effects (see below).
How does it work?
In theory, researchers thought HRT might: 
Improve blood flow in the brain by widening blood vessels
Increase the amount of chemical messengers in the brain, helping signals travel through the brain
Help keep brain cells alive in a part of the brain that's linked with memory and problem solving
Prevent amyloid plaques. (These small lumps in the brain are one of the telltale signs of Alzheimer's disease.) 
But studies haven't shown that HRT improves memory and thinking for women with dementia.
Can it be harmful?
Yes. There are several serious risks with taking HRT.
One large study on HRT was stopped early because researchers found the risks of taking HRT, especially the risk of breast cancer, outweighed the benefits. 
HRT can also increase the risk of heart disease, blood clots, and strokes.
To learn more, see HRT in our section on the menopause.