Menopause, reproductive factors affect dementia risk

Women who have gone through menopause may have more of a brain biomarker called white matter hyperintensities than premenopausal women or men of the same age, according to a study published in the journal Neurology. White matter hyperintensities are tiny lesions visible on brain scans that become more common with age or with uncontrolled high blood pressure, and have been linked to an increased risk of stroke, Alzheimer’s disease and cognitive decline.

The study involved 3410 people with an average age of 54, all of whom were given MRI brain scans. After adjusting for age and vascular risk factors such as high blood pressure and diabetes, researchers found that postmenopausal women had more white matter hyperintensities when compared to men of similar age. In people 45 and older, postmenopausal women had an average total white matter hyperintensities volume of 0.94 mL compared to 0.72 mL for men. Researchers also found that the increase in brain biomarkers accelerated with age and at a faster rate in women than in men.

Premenopausal women and men of a similar age did not have a difference in the average amount of white matter hyperintensities. The researchers also found that postmenopausal women had more white matter hyperintensities than premenopausal women of similar age. In participants aged 45 to 59, postmenopausal women had an average total volume of white matter hyperintensities of 0.51 mL, compared to 0.33 mL for premenopausal women.

There was no difference between postmenopausal and premenopausal women using hormone therapy, suggesting that such therapy may not have a protective effect on the brain. Unrelated to menopausal status, women with uncontrolled high blood pressure had higher amounts of the brain biomarker compared to men.

“Our results imply that white matter hyperintensities evolve differently for men and women, where menopause or factors that determine when menopause starts, such as variations in the aging process, are defining factors,” said study author Dr Monique MB Breteler, of the German Center of Neurodegenerative Diseases (DZNE).

“The results of our study not only show more research is needed to investigate how menopause may be related to the vascular health of the brain, they also demonstrate the necessity to account for different health trajectories for men and women, and menopausal status.”

The news comes after a separate study, published in PLOS Medicine, suggested that reproductive and hormonal factors may be involved in women’s dementia risk. The study authors used data from the UK Biobank to examine the risk of all-cause dementia and reproductive factors in 273,240 women, as well as the number of children of those women and of 228,965 men.

After controlling for age, socioeconomic status, smoking, BMI and other elements, certain events related to shorter cumulative exposure to internally produced oestrogen — such as older than average age at first period, younger than average age at menopause and having a hysterectomy — were associated with higher dementia risk. Pregnancy (even aborted pregnancy), longer reproductive span, older age at menopause and use of contraceptive pills were associated with a lower risk of all-cause dementia.

For both men and women, compared with having two children, having no children or four or more was apparently associated with greater risk of dementia. The researchers said the similar association between the number of children and dementia risk observed for women and men indicates that the risk variation in women may be more related to social and behavioural factors in parenthood, rather than biological factors involved in childbearing.

Image credit: ©stock.adobe.com/au/missty

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