Women's Stroke Risk: In the Arteries

Scientists say a higher rate of strokes and stroke-related death among women than men may be linked to how aging affects arteries feeding blood to the brain -- and may be related to hormone levels.

Writing in the American Heart Association medical journal Stroke, German researchers say the clues may be in the difference in "cerebrovascular reactivity" between the sexes. That reactivity, measuring the degree to which the arteries provide that blood flow, drops significantly as women age "from the fourth to the fifth decades," without any similar reduction recorded for men.

"As reactivity decreases, one vessel's ability to compensate for a blockage or reduction in blood flow in another vessel suffers, setting the stage for a possible stroke," researchers say. The study also shows that postmenopausal women undergoing hormone replacement regimens tended to maintain better reactivity than those not using the therapy.

The reasons for those differences in hormone therapy remain unclear, but researchers say "increased cerebrovascular reactivity in younger women may provide us with reasons why they're somewhat more protected from strokes."