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Health Information Under the Microscope:
Of Estrogen and Aneurysms

Results from a first-of-its-kind study at Rush University Medical Center suggest that oral contraceptives and hormone replacement therapy may yield the additional benefit of protecting against the formation and rupture of brain aneurysms in women.

The study, led by neurointerventionalist Michael Chen, MD, was initiated based on the observation, in the two largest brain aneurysm trials to date, that 70 percent of these deadly aneurysms occurred in postmenopausal women. The mean age (52 years) of study participants coincided with a severe drop in estrogen, which is usually associated with the menopausal transition.

Menopause and Effect
During the two-year trial, Chen and his team studied a group of 60 women, ages 31 to 80, with both unruptured and ruptured aneurysms. The team compared a variety of factors in this study group to a control group of 4,682 random females who represented national population averages.

A comparison of the two groups revealed that the rate of oral contraceptive and hormone replacement therapy use was significantly lower among study participants than among the women from the control group. Women in the study also spent less time on oral contraceptives (2.6 years on average) than the women in the control group (5.2 years on average).

"What these numbers tell us is that women with brain aneurysms use oral contraceptives and hormone replacement therapy less frequently than the general population," says Chen. "It is reasonable to conclude that drops in estrogen that occur in menstruation and at menopause may explain why cerebral aneurysms are more frequently found in women, particularly those who are postmenopausal."

The Missing Link
For neurointerventional specialists, this study provides another piece of evidence that addressing loss of estrogen help protect women who are at risk of aneurysms — those who have had a previous aneurysm or have a family history of aneurysms.

Of course, hormone replacement therapy isn’t right for everyone. A prior large-scale study funded by the National Institutes of Health, the Women's Health Initiative, found that it may increase the risk of several health problems, including breast cancer, heart attacks and stroke, in some women. When it comes to hormone replacement therapy, there are risks and benefits each woman must consider in light of her own family history and health.

Chen and his team at Rush, meanwhile, will continue studying the effects of estrogen on the blood vessels of the brain. "By understanding the potential link between low levels of estrogen and aneurysms," he says, "we can focus our areas of study with the hope of providing preventive therapies for women who are at risk for brain aneurysms."

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Please note: All physicians featured in Discover Rush Online are on the medical faculty of Rush University Medical Center. Some of the physicians featured are in private practice and, as independent practitioners, are not agents or employees of Rush University Medical Center.

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Under the Microscope:
Of Estrogen and Aneurysms

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