The research letter, by noted University of Illinois at Chicago demographer S. Jay Olshansky, is published in the Dec. 7 issue of JAMA, the Journal of the American Medical Association.
Olshansky became interested in the subject when, in the summer of 2011, President Obama celebrated his 50th birthday, and a flurry of news reports focused on his graying hair, pronounced wrinkles, and rapidly aging appearance.
“In the world of biology, we know that you can’t actually measure the aging of an individual,” says Olshansky, professor of epidemiology at the UIC School of Public Health. “There isn’t any single test to actually measure how long you’ve aged from point A to point B, nor is it possible to predict specifically how long an individual will live.”
Using the assumption that presidents age at twice the normal rate, Olshansky calculated how long U.S. presidents would have been expected to live based on their age and the year they were inaugurated — and compared it to how long they actually lived.
Aging at twice the normal rate was estimated by removing two days of life for every day in office (for example, a 4-year term led to a reduction in estimated remaining lifespan of 8 years).
Olshansky found that 23 of the 34 U.S. presidents who died from natural causes lived longer, and in many instances significantly longer, than predicted. Their average age at inauguration was 55.1 years.
Four presidents who were assassinated were excluded from the analysis.
Conventional wisdom suggests that the longevity of U.S. presidents is shortened due to the stresses of the office, but the average lifespan of the first eight presidents was 79.8 years — during a time when, for men, life expectancy at birth was less than 40.
“This is about how long females born in the U.S. today live,” Olshansky said.
The study also found that living ex-presidents have either already exceeded their predicted longevity at the time of their inauguration, or are likely to do so.
“We know that socioeconomic status has an extremely powerful effect on longevity now,” Olshansky said, “and it was likely to have been a factor in the past.” All but 10 U.S. presidents were college educated; all were wealthy; and all had access to health care.
“We don’t die from gray hair and wrinkled skin,” said Olshansky. “What we’re seeing in President Obama is really not inconsistent with what we see for any other man his age in the U.S. or elsewhere.”
Editorial note: An extended interview as MP3 audio file is available at http://bit.ly/vtQqBN