How Reproductive Lifespan And Brain Health Are Related

Not only do hormones play an essential role in reproductive function, they can also potentially protect the brain as we age. Previous research has already shown that estrogen has a protective effect on the female brain, limiting the loss of gray matter that normally accompanies menopause and thereby could reduce the risk of Alzheimer’s disease.

Women with higher cumulative estrogen exposure over their lifetime may also be at lower risk of small cerebral vessel disease, according to a new study published online in the online edition of Neurology®, the medical journal of the American Academy of Neurology.

Hormones And Their Influence on the Brain

Cerebral small vessel disease, a form of cerebrovascular disease, results from damage to small blood vessels in the brain. It increases the risk of cognitive impairment and dementia. Previous research has shown that the incidence of cerebrovascular disease increases after menopause, which is often attributed to the lack of hormones. It remains unclear whether the amount of hormone exposure before menopause extends this window of protection into the postmenopausal period.

Researchers at the University of Sherbrooke in Quebec, Canada, examined the connection between lifetime hormone exposure, i.e. H. the number of pregnancies and reproductive lifespan, and white matter hyperintensity, a common biomarker of brain vascular health that develops with age.

Women With Higher Hormonal Exposure Have Lower White Matter Hyperintensity Volume

The study involved 9,000 postmenopausal women with an average age of 64 years living in the UK. They did not have cerebral small vessel disease at the start of the study. Subjects answered questions about reproductive health, including their age at first menstruation and onset of menopause, number of pregnancies they had, and use of oral contraceptives and hormone therapy. The participants also had brain scans performed to look for small cerebral vessel disease by measuring white matter hyperintensity, which indicates injury to the brain’s white matter. Researchers calculated lifetime hormone exposure by adding the number of years participants were pregnant to the length of their reproductive lifespan, i.e. H. the number of years from the first menstruation to menopause. The average lifetime hormone exposure was 40 years.

After accounting for factors such as age, high blood pressure and nicotine consumption, the researchers found that women with higher hormone exposure had lower white matter hyperintensity volume over their lifetime. The average total volume of white matter hyperintensity was 0.0019 milliliters (mL). They found that individuals with higher lifetime hormone exposure had lower volumes of white matter hyperintensities, with a difference of 0.007 ml, compared to those with lower lifetime hormone exposure. Researchers also calculated lifetime hormone exposure by adding up the number of years participants used oral contraceptives and received hormone replacement therapy. These factors did not change the effect that the number of pregnancies and the number of reproductive years had on white matter hyperintensity. The number of participants’ pregnancies and the number of reproductive years independently affected the volume of white matter hyperintensity.

These results highlight the need to integrate reproductive history into the management of brain health in postmenopausal women. Future research should investigate ways to develop better hormonal therapies. A limitation of the study was that information on reproductive factors was collected primarily based on the participants’ ability to recall events and that the women may not have accurately recalled such events. The study does not prove that lower estrogen exposure causes small cerebral vessel disease, it simply shows a connection.