Obama may be more gray these days, but presidents don’t age more quickly than most people, new research suggests. (Kevin Lamarque/Reuters)

In fact, the new analysis by S. Jay Olshanky, a demographer at the University of Illinois at Chicago, found that most U.S. presidents live longer than expected for men of their age and era.

Olshansky decided to examine the question of presidential aging and longevity when Obama turned 50 this summer, drawing attention to his graying hair, wrinkles and other supposed signs of aging. Some doctors have suggested that presidents tend to age at twice the normal rate.

But after excluding the four presidents who were assassinated, Olshanky using data from the United States and France, found that 23 of the 34 U.S. presidents who died from natural causes lived longer — and often significantly longer — than the average life expectancy of men of their same age when the presidents were inaugurated. The mean age of death for the presidents was 78; they would have been expected to live only to age 67 if they were aging twice as fast as normal while in office, Olshansky calculated.

The average lifespan of the first eight presidents was 79.8 years at a time when the average life expectancy for men was less than 40, Olshanky reported in a letter published in the Journal of the American Medical Association. The living ex-presidents have either already exceeded their predicted longevity at the time of their inauguration or are likely to do so.

“This study found no evidence that U.S. presidents die sooner, on average, than other U.S. men,” Olshanky wrote.

Olshanky speculated that U.S. presidents lived longer than expected in part because they tend to be better educated and wealthier than the average American male.

“Level of completed education and its related social and economic status correlates have documented powerful effects on longevity today and probably had even more powerful effects centuries ago,” he wrote.

“The graying of hair and wrinkling of skin seen in presidents while in office are normal elements of human aging; they occur for all men during this phase of life and can be accelerated by behavioral risk factors such as smoking and stress,” he wrote. “Whether these outward changes occur faster for presidents relative to other men of the same age is unknown. Even if these signs of aging did appear at a faster rate for presidents, this study shows that this does not mean that their lives are shortened.”

Want to listen to an interview with Olshansky?Click here.