Being exposed to more estrogen throughout life — or a longer reproductive life span — may be good for the brain, according to new research that found a lower risk of cerebral small vessel disease in women who had more cumulative exposure.
Cerebral small vessel disease happens from damage to small blood vessels in the brain. It can increase the risk of thinking impairments and dementia.
“Previous research has shown that rates of cerebrovascular disease increase after menopause, which is often attributed to the absence of hormones,” said study author Kevin Whittingstall, of the University of Sherbrooke in Quebec. “It remains unknown whether the amount of exposure to hormones before menopause extends that window of protection to after menopause.”
To study this, researchers included data from 9,000 postmenopausal women at an average age of 64 who didn’t have cerebral small vessel disease when the study began. The women all lived in the United Kingdom.
The researchers looked at the number of times women had been pregnant, their reproductive life span and white matter hyperintensities, a biomarker of vascular brain health.
Study participants answered questions on age at first menstruation and start of menopause, number of pregnancies, oral contraceptive use and hormone therapy.
Researchers also gave them brain scans to look for cerebral small vessel disease by estimating white matter hyperintensities, which indicate injury to the brain’s white matter.
The team then calculated lifetime hormone exposure by adding up the number of years participants were pregnant with the number of years from first menstruation to menopause. Among the participants, the average lifetime hormone exposure was 40 years.
They found that women with higher lifetime hormone exposure had lower volumes of white matter hyperintensity.
While the average total white matter hyperintensity volume was 0.0019 milliliters (ml), those with higher exposure had smaller volumes, a difference of 0.007 ml compared to people with lower lifetime hormone exposure.
The researchers also looked at numbers of years participants took oral contraceptives and hormone replacement therapy, but this didn’t alter the impact that the number of pregnancies and reproductive years had on white matter hyperintensities. A study limitation is that the information was based on participants’ recall of events, which may not have been accurate.
The findings were published Sept. 27 in the journal Neurology, the medical journal of the American Academy of Neurology. The study was supported by the Natural Sciences and Engineering Research Council of Canada and Quebec Research Fund.
“Our study highlights the critical role of reproductive history in shaping the female brain across the lifetime,” Whittingstall said in a journal news release. “These results emphasize the need to integrate reproductive history into managing brain health in postmenopausal women. Future research should investigate ways to develop better hormonal therapies.”
The American Brain Foundation has more on cerebral small vessel disease.
SOURCE: Neurology, news release, Sept. 27, 2023
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