Biden and Trump have questioned the other’s physical and mental fitness. Here’s what we know about their health.

WASHINGTON - President Trump and former Vice President Joe Biden both have battled life-threatening illnesses at Walter Reed National Military Medical Center, a facility they entered 32 years apart with uncertainty over whether they would return alive.

For Trump, his diagnosis with the novel coronavirus earlier this month was his most serious known brush with a fatal disease, and his rapidly dropping oxygen levels sparked grave concern among his top aides and doctors. For Biden, emergency surgery for two brain aneurysms in 1988 posed the risk of impaired cognitive capabilities, or worse. While he ultimately fully recovered, the situation was so dire at the time that a priest was brought in to deliver last rites.

Both episodes have become political fodder for opposing sides less than two weeks ahead of a presidential election in which the two septuagenarian candidates are competing for a chance to be the oldest sitting president in American history. More broadly, the health of each man has become a central component of an increasingly negative race in which questioning an opponent’s fitness for office has taken a personal turn.

Trump and his allies regularly have sought to raise doubts about Biden’s mental acuity, with the president telling Fox News in recent days that his rival could not complete his sentences.

“They said if you let him talk, he’ll lose his chain of thought because he’s gonzo,” Trump said during a 50-minute interview with the network in the lead-up to Thursday’s presidential debate. “There were a lot of people that say let him talk because he loses his train . . . He loses his mind, frankly.”

Trump’s opponents have openly questioned his mental wellness, with Biden campaign officials mocking him for musing about the medical efficacy of injecting disinfectant and for celebrating his ability to recite five simple words in order during a cognitive test.

Trump’s battle with the coronavirus highlighted his preexisting physical challenges. The Biden campaign has run ads showing Trump struggling to walk down a ramp.

Neither candidate has been fully transparent about their health status even as they claim to be in excellent shape. They have released information from doctors declaring them strong and energetic, while downplaying or concealing information that may undercut those descriptions. Neither has allowed access to their complete medical records.

Trump has been especially secretive, concealing information about his coronavirus infection and treatment, and providing contradictory answers about why he made a separate unplanned visit to Walter Reed last November.

For Trump, an overweight 74-year-old and recent survivor of covid-19, and Biden, a 77-year-old who today has a few minor medical conditions, proving to voters that they are fit for the job of president is a particularly critical task in the frantic final days of the race.

The challenge has been made more difficult as the two sides have traded barbs over health and mental ability, with false and misleading claims circulating among supporters of both candidates, according to Stuart Jay Olshansky, a professor of public health at the University of Illinois at Chicago who analyzes the longevity of presidents.

“Both candidates and their representatives are weaponizing age in a negative way,” said Olshansky, who published a paper last month reviewing the health status and projected life spans of Trump and Biden. “In fact, the very claims that they are making about the other candidate can equally apply to them.”

While Olshansky’s review found that both Biden and Trump would likely survive a four-year term, the information the candidates have allowed to be released shows that they each have a number of risk factors that could impact their ability to remain healthy.

At 244 pounds, Trump is medically obese with a body mass index above 30, according to a June report by White House physician Sean Conley. Despite advice from doctors to lose weight, Trump has eschewed exercise and continued to favor fatty foods and red meat. He has gained, rather than lost, weight during the course of his presidency and is at risk of cardiovascular disease, according to his annual medical reports.

Trump has said he takes a statin drug to manage his cholesterol, and the drug rosuvastatin is listed among those Conley said are prescribed for the president.

During his bout with covid-19, the disease caused by the coronavirus, Trump took an experimental cocktail of drugs aimed at stopping the progression of the disease that is particularly deadly for elderly people with obesity and other preexisting conditions.

While he was discharged from Walter Reed after four days and declared healthy by Conley, it is unclear whether he will suffer from long-term consequences of the disease that has killed at least 223,000 Americans. Trump had to be put on oxygen twice and has said that his lungs may have been infected, though Conley and White House aides have declined to describe in detail the seriousness of his condition earlier this month.

Even as Trump minimized his illness, and the virus that caused it, and rushed back to a heavy schedule of campaigning, his allies have increasingly raised questions about Biden’s health. During a call with reporters last week, former White House doctor Ronny Jackson repeatedly referred to Biden’s age and claimed with scant evidence that he suffered from mental decline.

“I’ve watched Joe Biden on the campaign trail, and I’m concerned and I’m convinced that he does not have the mental capacity, the cognitive ability to serve as our commander in chief,” said Jackson, who worked in the White House alongside Biden but never treated him.

A three-page summary of Biden’s medical history released by his doctor in December declared him “healthy, vigorous” and “fit to successfully execute the duties of the Presidency.” It also outlined a number of ailments he has faced over the years. The report, written by Kevin O’Connor, director of executive medicine at the GW Medical Faculty Associates, showed that he was being treated for an irregular heartbeat, gastroesophageal reflux and seasonal allergies.

While he has also been treated for orthopedic injuries and non-melanoma skin cancers, Biden’s most serious health challenge came while he was a senator in 1988. What he described as the worst headache of his life turned out to be the result of an aneurysm, a balloon-shaped bulge that forms on an artery wall.

His doctors explained that the aneurysm at the base of the brain had leaked, and that a further hemorrhage could be fatal. The 45-year-old senator needed surgery to permanently fix the problem, which doctors later learned involved two aneurysms. A Catholic priest was called to his hospital bedside to deliver the last rites, which are administered to those who face the possibility of imminent death.

As Biden lay on the operating table at Walter Reed, a two-inch wide circular hole was drilled in the top of his head, and the piece of skull was removed “like the top of a cookie jar,” Neal Kassell, one of the two surgeons who operated on him, said in an interview. Kassell peered into a microscope at an artery wall and saw a bulge ballooning dangerously.

As Kassell was preparing to put a clip on the aneurysm, it suddenly burst, filling Kassell’s field of vision with a mass of blood about the size of a quarter - a large amount in his microscope’s view.

The rupture was just the kind of complication that could turn the surgery into a particularly risky episode with grave outcomes. Kassell recalled that he uttered a four-letter expletive, but was quickly able to address the unexpected complication.

The way that Biden’s aneurysm erupted during surgery, as described by Kassell in the interview, was not widely known at the time, and Biden did not mention it in his autobiography. Weeks later, after experiencing a life-threatening blood clot, Biden had a second aneurysm surgery, which took place without incident.

Kassell, who has stayed in touch with Biden and supports his presidential bid, said the former vice president ultimately recovered fully.

“He had no brain damage whatsoever,” and the surgery had no impact on his cognitive capabilities, Kassell said. “He is as mentally sharp now as he was then.”

Cameron McDougall, director of endovascular neurosurgery at Johns Hopkins School of Medicine, who was not involved in Biden’s surgery, said he agreed with Kassell that aneurysm surgeries performed successfully can have no impact on a patient’s cognitive abilities.

McDougall said the letter from Biden’s physician, which stated that a 2014 screening showed no recurrence, demonstrated that the clips that treated the aneurysms have remained secure.

“If you have an effective clipping and complete closure of the aneurysm with the clip in a typical aneurysm, it is very unlikely to recur,” McDougall said. As a result, McDougall said, the average person is more likely to have an aneurysm than Biden.

That hasn’t stopped Biden’s opponents from raising questions about the operations in the heat of a political campaign in which unsubstantiated claims of mental disability have become common.

In an interview that aired Oct. 11, Fox Business Network host Maria Bartiromo told Trump that her “medical sources have told me that Joe Biden had two brain aneurysms, not one, but two. . . . Do you believe he should be disclosing that . . . and tell us exactly what is the issue in terms of any mental issues we need to know about?”

Trump responded that “he should certainly come clean, and he should - he should say something about that. Absolutely. If that’s the case.”

In fact, it was widely reported in 1988 that Biden had a second aneurysm surgery that year, and he wrote about it extensively in his 2007 autobiography. Bartiromo did not respond to a request for comment.

Biden, like Trump, has not released his medical records publicly during this campaign. Biden’s campaign pointed to O’Connor’s letter, which said that Biden “has never had any recurrences of any aneurysms.”

So far, Trump has been less than transparent about his own health. His doctors have withheld information about his medical history and declined to answer reporters' questions, citing privacy. While the Obama-Biden campaign released 49 pages of medical records ahead of the 2008 presidential election, Trump released a one-page letter from his doctor during the 2016 race.

According to Olshansky’s paper, Trump has more known medical risk factors than Biden. Despite being older, the former vice president is expected to outlive Trump, the paper found.

While Trump’s health profile suggests that he has been healthy in the past, “he now is aging at an accelerated pace,” Bradley Wilcox, who teaches geriatric medicine at the University of Hawaii’s medical school, wrote in the paper.

“He has clear evidence (on several Cardiac CT scans) for subclinical CAD (coronary artery disease), the leading cause of mortality in the U.S., that has been worsening over the past decade,” he wrote.

While neither man smokes or drinks, Trump’s “sedentary lifestyle” is a risk factor, wrote Nir Barzilai, director of the Institute for Aging Research at Albert Einstein College of Medicine.

While both candidates had parents who lived to be more than 80 years old, Trump’s father developed Alzheimer’s disease late in life. Doctors say that elevates the risk that the president may experience similar complications.

It remains to be seen whether Trump will have any lingering complications from contracting the coronavirus. His trip to Walter Reed was marked by several news conferences by doctors and aides providing contradictory and obfuscating information about his status.

It was not the first time Trump has visited Walter Reed and sparked fresh questions about his health.

Last November, Trump made an unexpected trip to the facility that the White House claimed was an attempt to begin the first portion of his annual physical. But a president’s annual physical is typically done in one visit, raising questions about whether the trip was sparked by more serious circumstances.

Adding to the mystery was that the trip was never on Trump’s regular schedule, Walter Reed officials had very limited notice that the president was coming, and the visit followed none of the standard protocols for a president’s planned medical visit.

White House staff required all members of the Walter Reed medical team who handled his care in November to sign nondisclosure agreements, according to two people familiar with the request. Some confided to friends they felt insulted at the suggestion they would violate patient confidentiality.

Last month, Trump took to Twitter to try to put those questions to rest.

“Now they are trying to say that your favorite President, me, went to Walter Reed Medical Center, having suffered a series of mini-strokes,” Trump wrote. “Never happened to THIS candidate - FAKE NEWS. Perhaps they are referring to another candidate from another Party!”

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The Washington Post’s Carol D. Leonnig and Lenny Bernstein contributed to this report.