Male Hormone Linked to Predicting Longevity
Researchers have discovered that a little-understood hormone in the blood of middle-aged and elderly men is a significant predictor of heart disease and longevity, possibly offering a useful tool for predicting life expectancy.
Doctors at UC San Diego announced Wednesday that a 12-year study of 242 older men found that those who died during that period had low levels of the hormone DHEAS. Those who survived had consistently higher levels.
The reason for the correlation is not known, the researchers said. They said additional studies will be needed to confirm the results and to explore the possibility of using such measurements to predict longevity.
“There is no way known to either raise or lower DHEAS levels with medication or behavior,” said Dr. Elizabeth Barrett-Conner, the study’s principal author. But she said it is conceivable that therapy might be developed to alter levels of the hormone.
DHEAS, which stands for dehydroepiandrosterone sulfate, is secreted by the adrenal gland. Its precise functions are unclear. Previous studies, however, have linked low levels with cardiovascular disease and have traced a decrease in DHEAS levels with age.
The UCSD study, reported Wednesday in the New England Journal of Medicine, is the first to show that DHEAS levels can predict longevity independent of well-known risk factors such as age, smoking, obesity, cholesterol and family history of heart disease.
Blood plasma samples were taken between 1972 and 1974, as part of a broader, long-range population study of the community of Rancho Bernardo. The samples were frozen for 12 years, then thawed. The researchers then compared the DHEAS levels with participants’ mortality.
Among other things, they found significantly lower DHEAS levels among the 76 men who had died in the intervening years. The difference was most striking among the younger men, age 50 to 54; the levels in those who died were one-third the levels in those who lived.
While levels of the hormone dropped with age, men with higher levels in each age group had lower death rates and less heart disease, the researchers found. The study included white men age 50 through 79.
“We simply looked at whether or not having a high level of that hormone was related to life and death,” Barrett-Conner told a wire-service reporter earlier this week. “We found that, indeed, people with a high level appear to be protected.”
Barrett-Conner was traveling Wednesday and could not be reached for comment.
The researchers said it is unclear why some people have high levels of DHEAS. They noted that previous studies have linked weight loss and a low-fat diet with increased levels but said that did not explain the levels in the Rancho Bernardo group.
Also unexplained is why smokers in the study had high levels of DHEAS and nonsmokers had low levels. Although the smokers in the study were leaner than the nonsmokers, that did not appear to explain the higher levels, the study found.
According to the study, even after taking into account risk factors such as age, blood pressure, smoking and a history of heart disease, each increase in DHEAS levels of 100 micrograms per deciliter correlated with a 36% reduction in mortality.
The same increase was associated with a 48% reduction in death from heart disease.
Barrett-Conner observed earlier this week that, when the team excluded men with a history of heart disease, the link between DHEAS levels and survival was “as strong as or stronger than” the link between age and survival.
The authors concluded that while DHEAS could simply be a “marker” for another attribute that determines longevity more directly, “it is also plausible that DHEAS confers protection against death in general and against cardiovascular disease in particular.”
They pointed to studies in which DHEAS and a related hormone, DHEA, were given to laboratory animals. In those studies, the hormone appeared to delay aging, prevent obesity and lower cholesterol.
In a statement released by the university, Barrett-Conner stressed that her findings do not necessarily apply to women or younger men. She has said additional studies must be done to further explore the link.
