SAN DIEGO— Coronary artery disease
continues to be a major cause of death in the US, killing hundreds of
thousands of people per year. However, this disease burden isn’t evenly divided
between the sexes; significantly more men than women are diagnosed with coronary
artery disease each year. The reasons behind this difference aren’t well
defined. Though some studies have shown that men’s hearts become more
constricted than women’s during exercise, letting less blood flow through, women
are more likely than men to have symptoms of heart trouble after emotional
upsets.
Searching for the reasons behind these disparities, Charity L.
Sauder, Alison E. Thompson, Terrell Myers, and Chester A. Ray, all of Penn State
College of Medicine, investigated the effects of mental stress on blood flow
through the heart. Their findings show that coronary blood flow actually
increases in men during mental stress, but shows no change in women. These
results may explain why women could be more susceptible to adverse cardiac
events when under stress.
An abstract of their study entitled, “Effect of
Mental Stress on Coronary Blood Flow in Humans,” will be discussed at the
meeting Experimental Biology 2012, being held April 21-25 at the San Diego
Convention Center. The abstract is sponsored by the American Physiological
Society (APS), one of six scientific societies sponsoring the conference which
last year attracted some 14,000 attendees.
The
researchers recruited 17 healthy adults, a near equal mix of men and women. Each
volunteer had his or her heart rate and blood pressure measured at rest, as well
as coronary vascular conductance, a Doppler ultrasound measure of blood flow
through the coronary blood vessels of the heart.
These volunteers then
underwent the same tests while participating in three minutes of mental
arithmetic, in which the researchers had them sequentially subtract 7 starting
with a random number. To increase the stress load, researchers lightly badgered
the volunteers during the task, urging them to hurry up or telling them they
were wrong even when they gave the correct number. At the end of the task, they
underwent the same three heart function tests again.
Results showed that
at rest, men and women showed little differences between the three tests. During
the mental arithmetic task, all the volunteers showed an increase in heart rate
and blood pressure, regardless of sex. However, while the men showed an increase
in coronary vascular conductance under stress, the women showed no
change.
This differing characteristic could
potentially predispose women to heart problems while under stress, says study
leader Chester Ray. He adds that the results came as a surprise, since previous
studies men have significantly less blood flow than women during the physical
stress of exercise, and could explain why women tend to have more heart troubles
after stressful events, such as losing a spouse. The findings also reemphasize
the importance of mental stress in affecting health.
“Stress reduction is
important for anyone, regardless of gender,” he explains, “but this study shines
a light on how stress differently affects the hearts of women, potentially
putting them at greater risk of a coronary event.”
Further research, he
says, could discern the mechanism behind this difference, leading to more
targeted treatments and prevention efforts for women at risk of coronary artery
disease.
This article was first published at www.newswise.com