Toward the end of his time in office, President Barack Obama joked about his graying hair.
"The first thing I want from young people is to stop calling me old," Obama said in 2015. "When I came into office, I had no gray hair, and now I have a lot. I don't dye my hair, and a lot of my fellow leaders do. I won't say who, but their barbers know, their hairdressers."
Indeed, despite his close-cut hairstyle, it was impossible not to notice the trademark presidential graying, as the president's short black hair had become more of a salt-and-pepper color.
And though some dermatologists maintain that Obama was the latest victim of an expedited aging process in which presidents appear to age faster because of the stress of the office, others say that it's more attributable to natural aging than stress.
Other studies, including a comprehensive analysis of elections dating back to the 1700s, have found that heading a nation can take years off a leader's life. The analysis, from the Harvard Medical School, found that elected heads of government, on average, had lives almost three years shorter than those of the candidates they defeated.