Early menopause may raise the risk of dementia according to new research by the American Heart Association.
Entering very early menopause - that is, before 40 - was linked to a 35 percent higher chance of developing dementia later in life compared to those entering menopause aged 50.
The study found people starting menopause before age 45 were 1.3 times more to develop dementia before 65.
People who enter menopause at an average age (about 50 or 51) or later had similar dementia risks.
Researchers said low oestrogen levels could be a factor in the possible link between early menopause and dementia.
The findings could help women and people assigned female at birth to keep an eye on their mental abilities as they age and start to reduce their risk of dementia.
The researchers went on to advise ways to lower your dementia risk.
What is dementia?
Dementia is a term that describes serious changes in the brain.
The condition affects the ability to remember, make decisions and use language.
Alzheimer's disease is the most common form of dementia, followed by vascular dementia which is caused by reduced blood flow to the brain.
Both forms of dementia are more common as we age.
Some risk factors for dementia are unchangeable, like getting older and family history.
The menopause and dementia study
Researchers analysed the possible relationship between age at the start of menopause and dementia diagnosis arising from any cause.
The study examined data from 153,291 women who were on average 60 years old when they became participants in the UK Biobank between 2006 and 2010.
UK Biobank is a large medical database that includes genetic and health information for half a million people in the UK.
Experts advise ways to prevent dementia
There's no set way to prevent all types of dementia, the NHS says, but a healthy lifestyle can help reduce your risk.
"Dementia can be prevented, and there are a number of ways women who experience early menopause may be able to reduce their risk of dementia," said Wenting Hao, MD, a PhD candidate at Shandong University in Jinan, China.
"This includes routine exercise, participation in leisure and educational activities, not smoking and not drinking alcohol, maintaining a healthy weight, getting enough vitamin D and, if recommended by their physician, possibly taking calcium supplements."
Researchers suggested that lowered oestrogen levels could be a factor in the possible connection between early menopause and dementia.
"We know that the lack of estrogen over the long term enhances oxidative stress, which may increase brain aging and lead to cognitive impairment," Dr Hao noted.
The study recommended healthcare professionals should be aware of the age people begin menopause and closely monitor those who reach menopause before 45 for cognitive decline.
