Is Joe Biden too old to run again?

President Joe Biden turned 80 on Nov. 20, and so far, he has given every indication he plans to run for re-election in 2024. If he were to win, his second term would conclude not long after his 86th birthday.

Too old?

One of Biden's would-be opponents has previously said he thinks not. Former President Donald Trump, 76, who has announced he will run again, once declared, "I would never say anyone is too old," adding at the time that Biden and other rival candidates were making him "look very young."

America is being led by a president well into what most people would describe as old age. But as Trump pointed out, there's old and then there's "old."

Most people associate "old" with changes that go beyond a few gray hairs. As people grow old, inevitably, the heart works harder, the skin feels different, sight and hearing weaken and energy declines. Yet we all know people who seem to defy old age, working effectively and energetically well into their 80s.

The Constitution requires presidents to be at least 35 years old, but it sets no upper limit, and clearly some octogenarians are more capable than others.

Without directly addressing Biden's age, Vice Adm. Vivek Murthy, America's surgeon general, acknowledged as much to the Chicago Tribune Editorial Board earlier this month. "There is such a wide range between your actual age and how you perform and function and show up in the world," Murthy observed.

Research supports Murthy's perspective. But try telling a youngster that 80 isn't "old." Much depends on who is making the assessment of what age is "old," and the range can vary dramatically from person to person. In one 2021 study, researchers interviewing 300 adults at a Montreal hospital elicited answers ranging from 45 to 100.

A recent survey of 2,000 Americans pinpointed the age at which people consider themselves old at a surprisingly low 57. The World Health Organization states that in most of the developed world, old age is considered to begin at a still-surprisingly low 60. In the U.S., early retirees can begin collecting Social Security at 62, and Medicare typically kicks in at 65.

It should be noted that some predictable health risks correspond with age. At 65, for instance, the risks from COVID-19 become more pronounced, Murthy noted. Korean researchers who studied more than 64,000 emergency-room visits determined that older patients were more likely to be admitted for hospital stays, but the odds were considerably less for the "youngest-old," aged 65 to 74, than for the "oldest-old" group of 85-plus.

Republican President Ronald Reagan, 73 at the time, gave a famous answer to the "too-old" question at a 1984 debate against Democratic nominee Walter Mondale, who was 56. "I will not make age an issue of this campaign," Reagan said. "I am not going to exploit, for political purposes, my opponent's youth and inexperience." Even Mondale laughed.

Leading up to the midterm elections, most Democratic candidates carefully avoided stating that Biden is too old to run again, even if they were thinking it. Should the GOP nominate a much younger candidate than Trump, the contrast with Biden would be impossible to miss, and potentially put a greater focus on Biden's running mate. For his part, the president has said he will discuss running for re-election with his family over the holidays and announce a decision early next year.

Reagan used humor to defuse the focus on his age, but questions about his mental capacity continued to dog him. He was diagnosed with Alzheimer's disease five years after he left the presidency, though there's no evidence that he had the debilitating illness while in office.