Michael Tortorello is a writer in St. Paul, Minnesota.

If the polling numbers for the primaries have the voters’ blood pressure spiking, imagine what it’s doing to the presidential candidates themselves. Actually, we don’t need to imagine. Recently, a number of the leading presidential candidates, who are also the oldest candidates, released their doctor’s notes for public inspection. We learned from Bernie Sanders’ personal physician that the senator has experienced a bad back, laryngitis from acid reflux and gout. But his heart is good. Hillary Clinton suffers from seasonal allergies, her physician said. She also eats a diet rich in fruits and vegetables. Donald Trump’s gastroenterologist proclaimed, with Trumpian bravado, that Mr. Trump “will be the healthiest individual ever elected to the presidency.”

But the most interesting subject may be the one item the candidates’ physicians never mention: their brains. We learn about a presidential candidate’s appendectomy at age 10. But we’re left to guess about the likelihood that he or she will stay mentally acute in office. In this election, it’s a serious consideration: Sanders, Clinton and Trump would all be among the oldest ever sworn into office. Clinton is the baby of the group, at 69 and 3 months; Trump (70) or Sanders (75) would replace Ronald Reagan as the oldest president in history. (The non-candidate Michael Bloomberg would be 74.)


Some of the more partisan commentators, like Breitbart.com and Karl Rove, have insinuated that Clinton suffers cognitive impairments due to a fall she took in December 2012. The notable absence of an M.D. on the end of those sources makes us skeptical. Politico asked the candidates to discuss their brain health, but perhaps not surprisingly they declined. So we turned to the neuroscientists who have used advanced imaging techniques to study the structure and the function of the brain as it performs different tasks: learning a new language, memorizing strings of numbers and repeating them backwards, playing Go.

As it happens, the field of neuroscience has studied closely the trajectory of cognitive aging, and there is a fair amount of agreement about how our cognitive abilities—memory, learning, attention, reasoning—decline as we get older. Research shows that the decline, if it were a ski slope, would appear fairly flat until the age of 50 or 60. For the next decade or two, it would look like a bunny hill. Then somewhere around age 70, the slope would drop off like a black diamond run. Then a cliff. All three of those leading candidates are approaching, at least statistically speaking, the downhill-race-course portion of that decline.

But neuroscience also tells us that the difference between individuals is often much bigger than the changes in one person’s brain through the years. Anyone who is running for the presidency, weathering the demands of the campaign trail and lengthy debates, is probably an outlier on the cognitive scale already.

But they are, unquestionably, old. The comforting news here is that older brains aren’t necessarily incapable of handling a job as complex and stressful as the presidency—even something really surprising and fast-moving like the next financial meltdown, a coordinated global terrorist attack or a pandemic. We know the brain changes over time, losing a little speed on its fastball, but it also compensates in ways that might enable it to make even better, “wiser” choices than a fresh-packed 25-year-old brain.

“I think we should be thinking seriously about this issue,” said Mark Fisher, a professor of neurology and political science at the University of California. In a paper published last year, Fisher writes, “we should probably assume that a significant proportion of political leaders over the age of 65 have impairment of executive function.” These are the complex cognitive processes that guide “normal decision-making.” The onset of these changes can be sudden, as in a stroke, or slower, as a result of microbleeds or routine, age-related changes to brain structure.

Having watched the candidates speak spontaneously in the debates, “I think it is very likely many of these candidates are functioning fine in the area of executive function,” Fisher added. But “how we handle those who are below” is a historical riddle that the presidency has not solved. He concluded, “We can’t start to get anywhere unless the public is aware.”

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Science has yet to study the brains of politicians as a species. But Timothy Salthouse, a pioneering aging researcher at the University of Virginia, considered the brains of another group of aging executives—CEOs—in a 2012 paper called “Consequences of Age-Related Cognitive Declines.”

The study methodically establishes the correlation between intelligence and professional achievement. And then it documents a consistent, age-related decline in “fluid intelligence”—the ability to learn, reason and solve novel problems. (“Crystallized intelligence”—your accumulated skills and stuff you pull out of your hat during pub trivia—spikes later and holds up longer.)

What are the “consequences” of that brain slump? For Fortune 500 CEOs, who typically ascend to the top of their profession in high middle age, there don’t appear to be any.

Yet cognitive aging isn’t just something that shows up on the Wechsler Adult Intelligence Scale. The change originates in the structure and performance of the brain itself. There’s shrinkage of the pre-frontal cortex, an area important to thinking, decision-making, judgment and social relationships. At the same time, the aging brain experiences a back-to-front shift. Complex learning and memory tasks that used to be accomplished efficiently in the back of the brain now occupy the front, as well. In a processing change with the friendly name HAROLD—hemispheric asymmetry reduction of older adults—single-sided brain activities, like encoding (or tagging) and retrieving information, now recruit both hemispheres. It takes more brain to do the same job.

That description of physical transformation may leave you with a picture of the elderly brain as something like the rotting lung depicted on a pack of cigarettes. This comparison would be wrong. Broad differences would be visible if you examined a batch of brain scans for 20-year-olds and 80-year-olds. However, “If you are looking at the MRI of a person,” explained Dilip Jeste, a professor of psychiatry and neuroscience at the University of California, San Diego, “you may not be able to tell her age.”

“There are 40-year-old people whose brain is like an 80-year-old person’s,” Jeste said, “and there are 80-year-old people whose brain is like a 40-year-old person’s.”

In truth, there is no one ski slope that traces our cognitive path. It’s more like a resort, with a multitude of runs that correspond to separate skills. According to an ambitious study conducted by the neuroscientists Laura Germine and Joshua Hartshorne, peak cognitive performance spreads out across the decades of life. Tests of vocabulary show people maxing out around 50 and descending slowly afterward.

The areas of intelligence that show the greatest falloff would seem to be among the most important for a CEO—or a president. These would be the capacity to absorb large amounts of new information and data in a short time span and apply it to solve problems in unaccustomed fashion. Take the 2007 financial crisis. Even with an MBA, George W. Bush couldn’t have known beforehand about the different tranches of failing debt, asset-backed commercial paper, money markets breaking the buck, collateralized debt obligations and a mystery meat called “CDOs squared.”

Hartshorne, an assistant professor of psychology at Boston College, is willing to entertain the possibility that a younger person might be better suited to vacuuming up that mess of information. But it’s at best a parlor game to try splitting the job of governing into discrete, measurable tasks. “If I thought being smart was something important in being a president, then I would worry about how smart they were starting out instead of how old they are,” Hartshorne suggested.

An older president, Jeste believes, might depend more on wisdom: a complex human trait that includes empathy, resilience, emotional regulation and positive thought. (Running for office is almost the definition of optimism, he said. “Most of them are going to lose; only one will become president.”) His recent research has involved looking for the seat of wisdom in the prefrontal cortex and the limbic striatum—in evolution, the newest and oldest parts of the brain.

The most consistent rule about cognitive aging, it turns out, is heterogeneity. “As people become older, people become more different instead of more similar,” Jeste said.

The curves in cognition experiments don’t necessarily predict whether, say, Hillary Clinton will maintain her verbal dexterity in news conferences. A better measure would be to examine the news conferences she’s doing right now. That is likely to remain her trajectory. “We don’t have to rely on the mean to judge them,” Germine said of the candidates. “We have more data than that.”

A circular logic actually works in this case. One way you can tell if a presidential candidate has robust faculties is that the candidate is running for president. It is “a highly select group of people,” Jeste said. “Participating in these debates is no joke. There’s such a high level of scrutiny of these people—and appropriately so. They need to have skills, a group of supporters. They need to have raised millions”—try billions.

“A 90-year-old who runs a marathon,” he concluded, “is not like a normal 90-year-old.”

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The last American president who declined to seek a second term in office was Rutherford B. Hayes in 1880. Several presidents, after finishing a predecessor’s term, ran only once on their own, including Calvin Coolidge, Harry S. Truman and Lyndon Johnson. The lesson to take from this is that the 70-ish candidate we elect in November will likely hang around until he or she is close to 80.

The question, then, may not be whether the senior contingent is too old to be president now. It’s how we will know if (or when) they’ve become too old.

We may be able to discern quite a bit without demanding that the president submit to a yearly neurological workup, and release the results. What health cues point to cognitive decline?

“Pretty much everything,” said Julie Dumas, associate professor of psychiatry at the University of Vermont. “Cancer is a big one. Try to avoid that. Diabetes, obesity, smoking—I don’t know if anyone is doing that these days. Alcohol is funny: some is OK, but too much is not OK. Other studies show that walking through the door of the hospital, your cognition declines when you walk out.”

One way to predict failing cognitive health in the seventh, eighth or ninth decade would be to look for falls, strokes and hospitalizations. There is no such thing as a mind-body split. Where the body goes, the mind follows.

Dumas expressed special concern about dementia and, specifically, Alzheimer’s disease, which affects 15 percent of Americans between the ages of 66 and 74. In the next age group, 75-84, the incidence jumps to 44 percent. Inevitably, this is where the conversation turns to Ronald Reagan. Observers and critics have long seen the influence of Alzheimer’s disease in Reagan’s seemingly clouded judgment and his steady retreat from the Oval Office into the residence.

But what was suspected and what was known, or at least publicized, were two very different things. Robert E. Gilbert, a leading historian of presidential health and a professor emeritus at Northeastern University, spoke several times to Reagan’s personal physician about the onset of dementia. “He stated unequivocally, publicly and privately, that Ronald Reagan did not have Alzheimer’s when he was in the presidency,” Gilbert said. Reagan acknowledged publicly in 1994 that he had been diagnosed with Alzheimer’s. He died, a decade later, at age 93.

Short of dying midterm, once a president takes office, it would appear we’re stuck with him.

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The campaigns and their surrogates would be happy to edify the voting public on the broader points of brain science. Matt K. Lewis, author of Too Dumb to Fail, predicts that no general election candidate will fail to helpfully inform the voters about Clinton’s superannuation. “You tell me the last time Americans chose age and experience over youthful energy, optimism and vision.”

In some sense, this attention wouldn’t be ageism so much as electoral realism. “[Marco] Rubio won’t even really have to talk about it. It will be visceral.” Alternately, he said, “I know the way Donald Trump would do it: ‘I’m not saying she’s too old…’”

Or, like Jason Johnson, a professor of political science and political editor at The Root, the online commentary site, you could call it by a different name: sexism. “You don’t really hear anyone saying that about Bernie Sanders,” Johnson said, “and he’s old, too. Extremely old!”

In the end, Johnson doesn’t expect a lot of enlightened analysis about age, health, and the qualifications for office. “We’re not a society that associates age with wisdom—we say that sarcastically. Elder statesman is something we call someone right before we give them a gold watch and tell them to go away.”

What if there were a way to tell if a president was suffering from a global cognitive decline or a loss of executive function? We could stop dealing in hypotheticals about whether, say, the president is ducking news conferences to conceal an impairment.

Of course, such tests actually exist. You can take them yourself on Laura Germine’s crowd-sourced science site, TestMyBrain.org. Fisher, at the University of California, Irvine, identifies a series of common exams that neuropsychologists can use to identify losses of executive function: the Wisconsin Card Sorting Test, the Trail Making Part B, and the Stroop Color/Word Test. White matter disease—which affects executive function—can be observed through imaging. “If we were to do brain MRIs on all the candidates, it would be very interesting what changes are ongoing,” Fisher said. “As you know, that is never going to happen, at least in my lifetime.”

There’s a strong case to be made that it shouldn’t. Given medical privacy—and common sense—does anyone believe that the public should be able to demand the forced mental evaluation of a sitting president? And what would we do with the information? The realm of science and medicine has hardly been a neutral zone from political meddling and misinformation.

The debate is both complicated and high stakes—if, in fact, there were a debate. Fisher has written and lectured about the topic of aging (and faltering) leaders to his peers in medicine and political science. “When you do bring it to their attention, they say, ‘Wow, I hadn’t thought of it.’”

One doctor’s prescription to the body politic: Start thinking.