The US government told makers of hormone replacement therapies today to add yet another warning to their labels – that hormones may increase older women’s risk of Alzheimer’s or other types of dementia.

Since last year, products containing oestrogen and progestin have had to bear warnings that the hormone combination increases the risk of breast cancer, heart attacks and strokes.

Those risks were discovered in a landmark study in 2002 that overturned years of conventional thinking that postmenopausal hormones were generally beneficial.

Oestrogen remains an effective treatment for menopausal symptoms such as hot flashes, night sweats and vaginal dryness, but the Food and Drug Administration-written labels urge women to use the lowest possible dose for the shortest amount of time to minimise the risks.

Today, FDA asked manufacturers to add to those labels the results of another study that found hormone supplements don’t keep women’s brains sharp, as was long believed – long-term users over age 64 actually had a higher risk of dementia.

It isn’t known if using oestrogen alone causes similar risks studies are under way to tell.

But since 2002, FDA has seen a trend by manufacturers toward lower doses of hormone products, said agency medical officer Dr Theresa Van Der Vlugt.