02 Aug 2002

Humans who live longer display the same biomarkers found in laboratory animals who have restricted caloric intake. However, because these human subjects weren't actively restricting their caloric intake, there may be other ways to increase life span in humans, according to this short report in Science.

In laboratory mice and primates, write George Roth and colleagues at the National Institute on Aging in Baltimore, Maryland, "the most robust intervention for slowing aging and maintaining health and function in animals is dietary caloric restriction." And compared to animals fed a standard lab diet, animals on caloric restriction (CR) consistently have lower body temperatures and blood insulin levels, as well as higher blood levels of dehydroepiandrosterone sulfate (DHEAS), the adrenal steroid that gives rise to androgens like estrogen and testostserone.

Roth and colleagues examined data from 25 years of the ongoing Baltimore Longitudinal Study of Aging (BLSA), comparing the effects of high or low values body temperature, blood insulin, and blood DHEAS—on lifespan. Among their subjects (n = 700 men) men with lower temperature or insulin level, or with higher DHEAS level, had greater survival time than their counterparts.

The two biochemical markers are also of interest in the Alzheimer's research community, though there is no verdict on their connection to the disease. One well-known fact is that DHEAS levels decline with age, and some studies have hinted that AD patients have lower levels of DHEAS, though others have not found this to be the case.—Hakon Heimer