Women, long assumed to be the "weaker sex," carry within them the secrets of longevity that, if better understood, could prolong the lives of millions of men.
Until recently, no one has studied what it is about women's behavior, biochemistry and genetic makeup that helps them live an average of seven years longer than men, Dr. Bernadine Healy, director of the National Institutes of Health, told a meeting of the International Women's Media Foundation in Cleveland recently.But biology is destiny, scientists are learning. And men and women are not created equal.
"It is important to understand the differences - not deny them - and learn from them," said cardiologist Steven Nissen of The Cleveland Clinic Foundation in Cleveland.
According to physiologist Estelle Ramey of Georgetown University School of Medicine in Washington, D.C., "such research will help keep men alive longer and extend the viable life of men and women so that they can squeeze through the door of life together, rather than apart."
The gap between the life spans of the sexes already has begun to shrink, narrowing from 7.8 years in 1970 to seven years.
Part of the change is behavioral: Men are acting like women, drinking less and smoking fewer cigarettes. Some are better managing the stresses that trigger hormone-fueled Type A behaviors.
Men are also beginning to benefit from innovations in medical treatments, some first suggested by studies in women. For instance, one recent landmark study found that estrogen therapy can help ward off heart disease in men.
Another soon-to-be-published NIH study has found that post-menopausal women on hormone replacement-therapy suffer from lower rates of Alzheimer's disease. That suggests estrogen may also prolong the survival of certain brain cells.
Among other applications of lessons learned in women, doctors have observed that they are less likely than the average man to be helped by a common operation for atherosclerosis, called balloon angioplasty, perhaps because their vessels tend to be narrower then men's. This might explain why men of smaller stature - say, those of Asian descent - also are less likely to be saved by the procedure.
Men begin life far ahead of women, at least in sheer numbers. At conception, male fetuses outnumber females 115 to 100; at birth, the ratio has fallen to about 105 boys to 100 girls. But by age 80, there are twice as many women as men.
Much of the success of women's longevity can be credited to one hormone: estrogen. It helps remove harmful blood fats and prevents blood clots that lead to heart and blood-vessel disease. The male sex hormone, testosterone, has the opposite effect.
Another advantage is that women have two X chromosomes. The extra X can offset one that is defective. Males, who have an X and Y chromosome, lack this advantage. In the future, gene therapy could help correct these defects.
Men's physiological traits, once essential to survival, are now life-threatening. For instance, men secrete testosterone and high levels of stress hormones that cause them to react to stress more intensely than women, said Ramey. The hormones cause "flight or fight" responses that bring about faster clotting, a more forcible heart beat and increased blood pressure.
Distributed by Scripps Howard News Service.