Study Suggests Estrogen May Regulate Blood Pressure In Women, But Only Until Menopause

BUFFALO, N.Y. -- The results of a study by researchers at the University at Buffalo looking at how mental stress affects blood pressure of women versus men suggest that estrogen may help regulate women's blood pressure during mental stress, and that the protective effect disappears after menopause.

Women's lower rates of cardiovascular disease during their reproductive years, as well as a reversal of that trend after menopause, have been noted for many years. Scientists have theorized that estrogen plays a protective role in that phenomenon, but the way estrogen protects is still not fully understood.

Bong Hee Sung, Ph.D., UB research associate professor of medicine, and colleagues working at Millard Fillmore Hospital may have filled in one piece of that puzzle.

They found that blood pressure increased more in post-menopausal women in response to mental stress than in a group of men or in two groups of pre-menopausal women.

"Increased blood pressure is a risk factor for cardiovascular disease," said Sung, "and mental stress is one factor that is known to cause blood pressure to rise. If blood pressure rises in response to mental stress, we would expect it to rise in similar fashion in response to other stress.

"The blood pressure of the post-menopausal women in our study rose significantly higher than the other study groups," Sung said.

"This leads us to conclude that hormones, particularly estrogen, can influence the body's response to stress, and that the higher blood pressure rise among post-menopausal women when subjected to stress may be a factor in this group's increased risk of developing cardiovascular disease."

The research results were reported in Circulation and presented at the American Heart Association meeting in November.

To measure blood-pressure response to stress, the researchers gave a standard mental arithmetic test to 10 pre-menopausal women, 10 pre-menopausal women taking oral contraceptives, 10 post-menopausal women and 10 young men. All had normal blood pressure at rest, although the men had significantly higher readings. The average age of the post-menopausal group was 53, while the other three groups had an average age of 31. Heart rates were similar in all groups at baseline and during stress.

The blood pressure of the post-menopausal women rose 21 percent, nearly twice the increase of that of the men and the other women, in response to the test, Sung said.

• Pre-menopausal women had the smallest increase in systolic pressure -- 5 percent -- compared to 11 percent in men, but the diastolic increase in these two groups was similar -- 13 percent versus 14 percent, respectively.

• Pre-menopausal women taking oral contraceptives had a blood-pressure increase similar to that of the males.

• Post-menopausal women experienced a 21 percent increase in both systolic and diastolic pressure.

Working with Sung were UB researchers Lawrence H. Golden, M.D.; Wendy Orlowski; Paresh Dandona, M.D.; Joseph L. Izzo, M.D., and Michael F. Wilson, M.D.