( Health.com ) -- Earlier this year , sociologist Jay Olshansky , Ph.D. , watched President Barack Obama return to his hometown of Chicago to celebrate his 50th birthday . In the days that followed , Olshansky was struck by the amount of media coverage dedicated to a single question : When did Obama 's hair get so gray ? Being president is a demanding job -- especially in times like this -- and it seems plausible that the stress of juggling politics , the economy , and the military could literally take years off a person 's life . Michael Roizen , M.D. , a doctor at the Cleveland Clinic , in Ohio , even suggested on Obama 's birthday that presidents age twice as fast as normal while in office . But Olshansky , a professor of public health at the University of Illinois-Chicago , was n't buying it . Wealth , access to healthcare , and education are all closely linked to longer lifespans , and presidents have all three resources in abundance , he reasoned ; if anything , presidents should age slower than the average person . Health.com : 30 stay-healthy tips for men . To test his hunch , Olshansky collected the birth , death , and inauguration dates of every American president that died of natural causes . ( He also included living presidents . ) Then , based on their time in office , he estimated their projected lifespans under Dr. Roizen 's `` accelerated aging '' theory . Two-thirds of presidents lived ( or are living ) longer than their projected lifespans , Olshansky found . What 's more , two-thirds also made it past the average lifespan of men in their age group . `` The first eight presidents lived an average of 79.8 years during a time when life expectancy for men was under 40 , '' says Olshansky , whose findings were published today in the Journal of the American Medical Association . `` It seems like most presidents live exceptionally long lives . '' Health.com : How to live to 100 . If that 's the case , what explains the rapidly graying hair and premature wrinkles that seem to beset presidents ? ( Obama is n't the only president whose visible aging has attracted attention : In years past , the media has n't failed to note that Bill Clinton was white-haired by the time he left office , that Jimmy Carter had baggier eyes , and that George W. Bush developed new lines across his forehead . ) The obvious answer is that U.S. presidents are simply older when they leave the White House as when they enter . They also take office in their mid-50s , on average -- a stage in life when the external signs of aging tend to become more pronounced in men . In addition , Olshansky suspects , high levels of stress may indeed contribute to superficial aging , even if they do n't shorten lifespan . `` There is good , strong literature to suggest that stress can lead to accelerated graying of hair , '' he says . `` There 's no question that stress has a powerful effect , but at least with regard to the presidents , it does n't appear to be making them die sooner . '' Health.com : Job killing you ? 8 types of work-related stress . Olshanksy plans to study people in other high-stress jobs -- like CEOs of insurance companies -- to test whether stress really does influence how old they look . Either way , he says , Obama and other stressed-out workers should n't fret over their appearance . `` No one dies from gray hair and wrinkles , '' he says . Copyright Health Magazine 2011 .
Wealth , access to healthcare , and education are all closely linked to longer lifespans . Comment: Two-thirds of presidents lived ( or are living ) longer than their projected lifespans .