Is A Longer Reproductive Lifespan Good For Your Brain?

"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, PhD, of the University of Sherbrooke in Quebec, Canada. "It remains unknown whether the amount of exposure to hormones before menopause extends that window of protection to after menopause."

This study involved 9,000 postmenopausal women with an average age of 64 years old without CSVD at the beginning of the study, who provided answers to questions related to reproductive health and had brain scans to look for the disease by estimating white matter hyperintensities (a common biomarker of vascular brain health that develops with age). 

Participant lifetime hormone exposure was calculated by adding the number of years that the women were pregnant with the duration of their reproductive lifespan (the number of years from the first menstruation to menopause). Analysis revealed the average total white matter hyperintensity volume was 0.0019 ml. and the average lifetime hormone exposure was 40 years. According to the researchers, after adjusting for a variety of factors, participants with higher lifetime hormone exposure had lower white hyperintensity volumes. Those with higher lifetime hormone exposure had a smaller volume difference of 0.007 ml compared to those with lower lifetime hormone exposure. 

The lifetime hormone exposure was also calculated by adding the number of years participants took oral contraceptives and hormone replacement therapy, but these factors did not alter the effect the number of pregnancies and the number of reproductive years had on white matter hyperintensities. The number of pregnancies and the number of reproductive years both affect white matter hyperintensity volumes independently.

"Our study highlights the critical role of reproductive history in shaping the female brain across the lifetime," said Whittingstall. "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 researchers noted several limitations to the study and stressed that this study does not prove that lower estrogen exposure causes cerebral small vessel disease, it only shows an association.