Women who have had multiple children may have a lower risk of dementia owing to a higher exposure of oestrogen, research suggests

Women who have had several children could be at a reduced risk of dementia, research suggests.

Experts have discovered that higher exposure to oestrogen throughout a woman’s life could lead to a healthier brain.

Those with a longer ‘reproductive lifespan’, or who have had several children, accumulate a higher exposure to the hormone.

This appears to lead to a lower risk of cerebral small vessel disease – a condition that results from damage to small blood vessels in the brain and is linked to cognitive impairment and dementia.

Researchers analysed 9,000 postmenopausal women with an average age of 64 living in the UK.

Participants answered questions on reproductive health including their age at their first period, when they started the menopause and their number of pregnancies.

They also had brain scans to look for cerebral small vessel disease.

The scientists calculated lifetime hormone exposure by adding the number of years women were pregnant to the duration of their reproductive lifespan, which is the number of years between first menstruation and menopause.

The average lifetime hormone exposure was 40 years. Analysis revealed those with a higher lifetime hormone exposure had lower white matter hyperintensity volumes – an indicator of cerebral small vessel disease.

The team also discovered that taking oral contraceptives, or HRT, did not appear to alter the beneficial effects of pregnancies or reproductive lifespan.

Study author Kevin Whittingstall, of the University of Sherbrooke in Quebec, Canada, said: ‘Our study highlights the critical role of reproductive history in shaping the female brain across the lifetime.’

Writing in the journal Neurology, he added the results ’emphasise the need to integrate reproductive history into managing brain health in postmenopausal women’.

Previous studies have shown that rates of certain diseases – for example cerebral small vessel disease – increase after the menopause, which is often linked to the absence of hormones.

Experts have discovered that higher exposure to oestrogen throughout a woman’s life could lead to a healthier brain

Until now, it remained unknown whether the amount of exposure to hormones before menopause extends the window of protection afterwards. A separate study, published in 2021, found that women who had been exposed to larger amounts of oestrogen throughout their life had larger volumes of grey matter in their brains.

Grey matter is a major component of the nervous system and is involved in sensory perception such as seeing and hearing, memory, speech and decision-making.

The researchers, from Weill Cornell Medicine in New York, found that for every extra year a woman was exposed to oestrogen in her life, average grey matter volume in certain areas of the brain increased by 1 per cent. 

For each additional child a woman had, grey matter volume rose by an average of 2 per cent.