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Old age, said the ancient Greek philosopher Bion of Borysthenes, is “the harbour of all ills; at least they all take refuge there.” While the quotation is obviously nothing new, some things do change, among these society’s pace of life and its knowledge of aging. In the past two centuries we’ve seen more change in these areas than in the law designed to protect America from the dangers of elderly presidents. Given the current crop of presidential contenders, the law’s failure to keep up may very well erupt into both a political and a constitutional crisis in the not-so-distant future.

The original Constitution did provide for presidents who grew unable to carry out the duties of the office. Under Article II, Section 1, in the event of a president’s “inability to discharge the powers and duties” of the presidency, the vice president would take over. But this short passage skirts over several pitfalls. One of the biggest was first raised in the 1787 Constitutional Convention by John Dickinson, a delegate from Delaware. Addressing an early draft of the provision, which had slightly different wording, he asked two questions that still plague the country today: “What is the extent of the term ‘disability,’” he asked, “& who is to be the judge of it?” So far as anyone knows, his questions went unanswered by his fellow delegates.

Presidential inability hasn’t exactly been a rarity. Beginning with George Washington, who nearly died of a monthlong bout of pneumonia a few months into his presidency, a number of chief executives have been incapacitated, from periods ranging from a few hours to several weeks. In 1881, President James A. Garfield, mortally wounded by an assassin, lingered for two and a half months before dying. In 1919, Woodrow Wilson suffered a major stroke, which permanently altered his cognitive functioning. During his final years, Franklin D. Roosevelt was suffering badly enough from cardiovascular disease to cause his top subordinates severe worry before his death, from a cerebral hemorrhage, and in 1981 Ronald Reagan was under general anesthesia for a time following John Hinckley’s assassination attempt. There are many more examples.

Many episodes of disability, such as Wilson’s stroke, FDR’s illness, Dwight D. Eisenhower’s 1955 heart attack and 1957 stroke, and Reagan’s 1985 cancer surgery, relate to infirmities that are more likely to occur in older populations. But nearly all of these instances were sudden occurrences, unlike dementia, Alzheimer’s, and the generally reduced cognitive functioning that are an almost inescapable consequence of growing older. Presidential advisers have often worried about a chief executive’s deteriorating condition, as in the case of Reagan and even Richard Nixon (though the latter was more a case of depression than age), but no official statement of inability or disability from individual advisers, the Cabinet, or even Congress has ever resulted from such concerns. Yet senescence, the creeping incapacity of an aging presidential brain, is something that could very well lead to a crisis in the coming years.

The Founders, of course, knew that age could affect capacity. Anyone who has dealt with either young children or elderly relatives has learned this from personal experience. But in discussing age qualifications for federal office, the delegates to the Philadelphia Convention never expressly connected advancing age with the Constitution’s standard of “inability.” Instead they limited their age concerns to the dangers of having officeholders who were too young. Representatives must be 25; senators, 30; presidents, 35. (Interestingly, there’s no minimum age for judges, who are supposed to be the repositories of disinterested reason born of mature wisdom.) The convention’s longest discussion of age came in the context of debating requirements for representatives. The Pennsylvania delegate James Wilson argued that minimum-age requirements were undemocratic and could deprive the country of the services of youthful geniuses, citing England’s William Pitt the Younger as an example. In the end he was overruled; George Mason retorted that while people claimed that the Confederation Congress “had proved a good school for our young men,” he himself preferred those youngsters to “bear the expense of their own education.”

At least part of the reason for the delegates’ silence on the cognitive decline of senior decision making is that their society was far younger than ours. Since the early 1800s, the average American life expectancy has increased by a remarkable 40 years, from around 35 to a mean of 78. The Philadelphia delegates’ own average age was 42. Given their classical educations, the delegates likely recalled and approved of Plutarch’s admonition to welcome the elderly into public life; Benjamin Franklin was an object lesson for them in this regard. At the age of 81 he was the oldest delegate—and apparently still pretty sharp.

But today, aging brains are all over the nation’s capital, and their infirmities have a big impact on national affairs. The problem isn’t limited to the presidency, of course; members of Congress are obviously subject to the slings and arrows of aging. But Congress consists of hundreds of people, and its decisions tend to be more deliberative and—even in this age of hyperpartisanship—collegial, at least within the party caucuses. The Supreme Court is a special case. It has only nine members, not hundreds; unlike both Congress and the president, its members effectively sit for life, if they wish, without regard to the electorate; and its decisions are often controversial ones on matters of great import, and cannot be easily changed by either higher courts or  the usual political processes. In fact, the Supreme Court’s history is rife with episodes of judges incapacitated by age and other maladies who continued to sit and vote. Even so, the presidency is the spot of the greatest—one might say the most acute, as opposed to chronic—danger. The president is a single individual, the single preeminent voice in American foreign policy and American media, the individual with a finger on the nuclear button. Presidential decisions, moreover, are the ones most likely to be urgent ones in the face of potential crises.

Since we’ve been willing to restrict the public’s freedom to elect immature leaders, we should be equally willing to bar them from the presidency when sufficient ills of advancing age compromise their judgment. Modern neuroscience dates almost entirely from the period after the Founders’ time, and what we know about the science of the aging brain should serve as an incentive to establish age-based limitations on public, and particularly presidential, service.

This modern science tells us that the human brain is the most complex form of organic matter in the known universe. It consists of nearly 100 billion intricately interconnected neurons and reaches its apogee in the third decade of life. Thereafter, according to both common observation and varying scientific assessments, its intellectual functionality declines. Age-associated wasting structural changes can be quantified by a number of methodologies, including autopsy data that goes back at least to the 19th century. More recently, a variety of volumetric radiographic studies, particularly functional and volumetric MRI appraisal, have confirmed this earlier autopsy data.

What do the data say? A number of studies have shown an association between age and cerebral atrophy, including substantial accelerating decreases in brain mass. One such study revealed that brain mass generally begins declining around the age of 50; another showed that the average cerebral-cortex volume in patients over 90 had a loss of 14 percent compared to a younger population.

A growing number of rigorous psychological tests provide another important methodology to assess age-associated cognitive decline. The measure of intellectual decline obtained from such tests is somewhat subjective; nevertheless, one meta-analysis showed an increase in dementia prevalence in the United States from 3.4 percent in the 70–74 age cohort compared to a prevalence of 47.5 percent in a study population of 90 and above. No serving president has ever been 90, but President Trump is 73, Joe Biden is 77, and Bernie Sanders is 78. Even if they don’t have dementia, their brains are likely considerably smaller and less agile than those of politicians 10 to 20 years younger. Compare this to Ronald Reagan, who faced serious concerns about his age when he ran for president in 1980 yet was only 69 when he was first inaugurated. And this isn’t even considering the sheer physical and mental stamina required of a president.

The presidency has always been hard work. That work, according to Lyndon Johnson, “is demanding and unrelenting. It is always there to be done. Of all the 1,886 nights I was President, there were not many when I got to sleep before 1 or 2 A.M., and there were few mornings when I didn’t wake up by 6 or 6:30. It became a question of how much the physical constitution could take.” Barack Obama, a relatively youthful 55 when he left office in 2017, routinely got only about six hours of sleep a night. Recently, Jimmy Carter, in what could be taken as a criticism of Trump (as well as perhaps certain Democratic presidential contenders), stated, “If I were just 80 years old, if I was 15 years younger, I don’t believe I could undertake the duties I experienced when I was president.”

This isn’t new. Woodrow Wilson reportedly called his workload “preposterous,” and even George Washington complained that the ceremonies involved with his job meant that there weren’t enough hours in the day for him to see to all of the other duties.

But Washington, and even Wilson, lived in simpler times. Since the mid-19th century, and especially since the mid-20th, America has had light-speed communication within itself and with the rest of the world, permitting and necessitating quick and stressful government decision making. For decades, the country has been in the cross hairs of potential nuclear, chemical, or cyberattacks that could be delivered in minutes. Washington’s complaints were aimed at his ceremonial duties; he wasn’t the leader of a globe-spanning empire and economic powerhouse with an interventionist foreign policy and massive control over its own citizens’ lives. The decisions today involve far higher stakes than people in an earlier age could have imagined.

John F. Kennedy’s assassination brought the potential danger of an incapacitated president home to Americans and their leaders in 1963. There had been serious talk of modernizing presidential-disability and -succession law for some time by then, prompted in part by Wilson’s stroke and Eisenhower’s health problems. But Kennedy’s heart kept beating for as long as half an hour after the shooting despite the fact that most of his brain had been destroyed. America was vulnerable in that moment to an all-out attack, with no one clearly empowered to lead a response. The problem didn’t fully abate even after Johnson had assumed power; his own potential successors were House Speaker John McCormack, age 71, and the Senate president pro tempore, Carl Hayden, who was 86. All of this finally prompted the drafting and ratification of the Twenty-Fifth Amendment.

This amendment, among other things, provides for both a president’s own voluntary declaration of inability and a means for him to be declared incapacitated even when he might want otherwise. The former provisions have been both implicitly and explicitly used on occasion. Reagan, for instance, relied on it in 1985 to transfer power to Vice President George H. W. Bush in advance of cancer surgery, and George W. Bush, facing the bane of middle-age existence—colonoscopy and polyp removal—twice ceded power to Vice President Dick Cheney for a few hours. The amendment’s most famous moment came in September 2018, when an anonymous White House source claimed that he and other Trump advisers had contemplated invoking the “involuntary” provisions to have Congress declare Trump incapacitated. Because of this as well as his impeachment, Trump has thus been the president who has faced the most sustained and varied efforts to strip him of his power by extraordinary, if not unconstitutional, means. (A declaration of presidential incapacity based simply on bad judgment or policy differences is by no means clearly legitimated by the amendment’s provisions.)

Nevertheless, even the Twenty-Fifth Amendment doesn’t expressly discuss the incapacitating dangers of age. Yet we know those dangers exist. And we can’t trust presidents to keep Americans informed even when they’ve experienced undeniable incapacitation or threats to their capacity. During George Washington’s 1790 illness, abortive efforts were made to keep word from the public about his condition. (“It was thought prudent to say very little upon the Subject,” Abigail Adams wrote, “as a general allarm [sic] might have proved injurious to the present state of the Government.”) Wilson’s wife and doctor engaged in a conspiracy that kept the country in the dark about the president’s condition for months. Ross McIntire, Franklin Roosevelt’s doctor, publicly insisted that Roosevelt’s condition was excellent for years after he’d told his patient otherwise. Decades after Roosevelt’s death, another one of his physicians, Howard G. Bruenn, arguably violated his patient’s confidence by publishing an article divulging his medical history. The publication was abetted by Roosevelt’s family and was possibly doctored, or at least biased, in favor of showing that the president’s judgment hadn’t been impaired during the critical Yalta Conference of 1945.

In light of this pattern, in the struggle for one of the most powerful positions in human history, can we really accept at face value the declarations of presidents and presidential hopefuls in their 70s that they’re up to the job? Should we uncritically accept the evaluations of their medical attendants? The answer is no. We should take such claims with a grain of salt, especially when we see videos of a 68-year-old Hillary Clinton collapsing and being bundled into a car, or watch as Joe Biden’s eye fills with blood during a town hall meeting last September. Stuart Jay Olshansky, a professor of public health at the University of Illinois at Chicago, has observed that Biden hasn’t undergone any recent tests for cognitive functioning. But Olshansky claimed that being “on the campaign trail and meeting a rigorous travel and meeting schedule probably would suffice as a replacement” for formal cognitive tests. While Olshansky is a noted specialist in gerontology, his degree is in sociology, not medicine or politics, so this assessment isn’t exactly reassuring.

As for Trump, he’s predictably dismissive of the possible consequences of his age. “I met with a man the other day who was 85 years old, the sharpest guy you’ll ever meet,” he said, when confronted with Jimmy Carter’s implied criticism. “I’ve dealt with people that were 92, 93, 94, and they were totally sharp.” Maybe he has; and maybe William Pitt the Younger had sufficiently mature judgment at age 24 to be prime minister. But, as in Pitt’s case, the odds are against it.

The basic question is simple: Should an age restriction exist for those seeking the presidency? There would certainly be downsides to such a restriction. First, while affording society a degree of protection, the restriction would doubtless exclude some meritorious individuals whose cognitive abilities have been happily preserved—who, in short, have beaten the odds. Next, when substantial supportive mechanisms exist they can reduce the burden on the aging brain somewhat, and the president likely has more staff and technical support than nearly anyone else imaginable. This assistance might allow easier navigation for those with only minor cognitive dysfunction. But given the responsibilities of the president, are we willing to take this gamble?

If not, we still face the question of how to set up the age limitation. The clearest way would be a constitutional amendment that imposes a bright-line upper age limit to bookend the current minimum age. Or instead of a bright line, the amendment could require cognitive tests—a more tailored, if somewhat more difficult to design, approach. We already have some such tests, and better ones than merely being on the campaign trail. Improved radiographic evidence and psychological testing will likely make objective assessment more possible in the future. The downside would be that the designing, choice, and interpretation of such tests might all be open to charges of partisan manipulation for tactical advantage in an election. After all, in the cases of Wilson and FDR, there did seem to be some collusion from the medical community to help a president hold on to power when perhaps he shouldn’t have. Could America trust that community not to play politics in presidential campaigns? In light of this almost-certain danger, a bright-line approach would probably be best.

Amending the Constitution is notoriously difficult, but when the goal is truly nonpartisan, it should be somewhat easier. The fact of the Twenty-Fifth Amendment’s eventual ratification attests to that. Yet even that amendment was years, even decades, in the making, and it took the crisis of a presidential assassination to get it to the finish line. The danger of creeping incapacity due to old age may or may not precipitate such a crisis, but the issue is bipartisan—both Democrats and Republicans have been known to get old on occasion—and the danger is not only increasing but probably inevitable. Prompted by the number of gray hairs on the campaign trail this year, we should resolve to deal with the problem now before catastrophe forces us to deal with it later.

This story is part of the project “The Battle for the Constitution,” in partnership with the National Constitution Center.

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