DALLAS, July 3 -- More women than men die of strokes each year and new research from German scientists may provide a clue as to why this occurs.
In a study in this month's Stroke: Journal of the American Heart Association, researchers found that cerebrovascular reactivity -- the ability of vessels in the brain to maintain optimal blood flow -- decreases in women as they get older, with the most significant decrease coming in their 40s and 50s. The researchers found no changes in cerebrovascular reactivity in men as they aged.
A high level of cerebrovascular reactivity means blood and oxygen are being transferred to the brain in an optimal manner and that carbon dioxide is being carried away. 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.
"Increased velocity of blood flow in the brain and increased cerebrovascular reactivity in younger women may provide us with reasons why they're somewhat more protected from strokes," says Andreas Kastrup, M.D., of the Department of Neurology, University of Tubingen, Germany. "As cerebrovascular reactivity decreases, the result may be a higher incidence of strokes."
In 1995, the latest year for which statistics are available, 96,428 women died of stroke compared to 61,563 men. Stroke incidence and death in women tends to increase as women get older. The scientists say the reduction in blood vessel reactivity may help explain why.
In a study of 100 healthy people between the ages of 20 and 70, researchers found a decline in reactivity in women in their 50s, 60s and 70s, especially compared to their 30 to 40-year old counterparts. Women on hormone replacement therapy (HRT) after menopause enhanced their reactivity when compared to those who did not receive HRT.
The senior author of the article is Martin Schabet, M.D. Co-authors are Andreas Kastrup, M.D., Johannes Dichgans, M.D., and Matthias Niemeier, M.D.
For copies of the study, please telephone: 214-706-1173
NR 98-4919 (Stroke/Kastrup)
Media advisory: Dr. Kastrup can be reached by phone at 650-723-5754 or
by fax at 650-723-5795 or by email at andreas@s-word.stanford.edu. Dr. Schabet
can be reached by phone at 49 7071-29-2051 or by fax at 49 7071-29-6507 or by
e-mail at Schabet@uni-tuebingen.de. (Please do not publish numbers.)