LOS ANGELES, Feb. 17, 2016 - Women experiencing worsening migraines while taking hormone replacement may face an increased risk of stroke, according to research presented at the American Stroke Association's International Stroke Conference 2016.

Researchers found that women who currently used hormone replacement and reported more severe migraines were 30 percent more likely to have an ischemic stroke (clot-caused), the most common type of stroke, than women who never took hormone replacement or women who did so in the past but were also coping with worsening migraines.

Researchers also found that women on hormone therapy were more likely to experience worsening migraines than women who never started or were on hormone replacement in the past.

"Many post-menopausal women use hormone replacement therapy, and a large number also experience migraines, although we're not sure if these put them at greater risk of stroke. The question we wanted to address was whether there is a greater risk of stroke if migraines are becoming more severe while taking hormone replacement," said Haseeb A. Rahman, M.D., lead author from the research team at the Zeenat Qureshi Stroke Institute in Minneapolis, Minnesota, and a neurology resident at Houston Methodist Hospital in Texas. "While earlier studies have looked at both as risk factors for stroke, they have sometimes come to different conclusions, and there are still 'gray areas' in our understanding."

Rahman added that this new study was the first to his knowledge to look at a change in migraine severity with hormone replacement as a risk factor for ischemic stroke.

Researchers analyzed data for 82,208 women aged 50 to 79 years old from the Women's Health Initiative Study, begun by the U.S. National Institutes of Health in the early 1990s. When they enrolled in the study, all of the women reported having some degree of migraines, and about 45 percent of them were using hormone replacement.

At a follow-up visit three years later, women completed a questionnaire to determine if their migraines had gotten better or worse. Altogether the women were followed for 12 years, and during that time 2,063 had an ischemic stroke, which is the most common type of stroke. Researchers adjusted their results for well-known risk factors for stroke, including age, high blood pressure, high cholesterol, diabetes and smoking.

Rahman said the findings suggest that women who have a history of migraines should talk to their doctor about the risks and benefits of hormone replacement, and if they choose to begin hormone replacement, they should monitor migraine severity.

"You should not simply ignore an increasingly bad migraine," he said. "You should also tell your doctor if you're getting migraines for the first time while on hormone replacement therapy."

Women, especially those on hormone replacement, should work with their doctor to identify all the other stroke risk factors they may have and create a plan "to improve and address these factors as best they can," Rahman said.

The Women's Health Initiative Study enrolled women at 40 clinical centers across 24 states. The ethnic and racial diversity of its participants gave researchers confidence that their results were relevant to women across the country.

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Co-authors are Ahmed Malik, M.D.; Omar Saeed, M.D.; Abraham Thomas, M.D., and Adnan Qureshi, M.D. Author disclosures are on the abstract.

Additional Resources:

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Video clips with researchers/authors of the studies will be added to the release link as available.

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