Democratic septuagenarian White House candidates and President Trump provided skimpy details in recent months about their health, renewing questions about how much voters should know about the medical histories of politicians.

Presidential candidates since Ronald Reagan have released some medical records to the public, but no law demands their release, and no candidate has disclosed a full medical history. That has resulted in a huge amount of variability among candidates’ records and painted an incomplete picture of those vying for the White House.

“I find the whole state of affairs about the medical fitness of candidates for the presidency and vice presidency to be driven purely by politics, not making any medical sense, and then leaving us wondering all the time what’s going on,” said Arthur Caplan, founding head of the Division of Medical Ethics at NYU School of Medicine.

Last week, Vermont Sen. Bernie Sanders became the latest presidential candidate to release medical records. The details, in the form of four pages of doctors' notes, came three months after Sanders, 78, suffered a heart attack in Las Vegas. He told reporters afterward that he would “ probably not ” be releasing all of his medical records, despite promising otherwise a few months ago.

Three other Democratic presidential candidates have released doctor letters: Joe Biden , 77, Massachusetts Sen. Elizabeth Warren , 70, and Michael Bloomberg , 77. The letters were three pages, two pages, and one page, respectively. Trump, 73, recently took an unscheduled visit to Walter Reed National Military Medical Center, and the White House released a short memo saying he had an “interim checkup,” an uncommon occurrence for presidents, and didn’t provide any findings from the exam.

A short doctor letter is on par with what presidential candidates have provided over the years, though there have been exceptions. When Biden ran as Barack Obama’s running mate 11 years ago, he released 49 pages of medical history to reporters.

Republican Arizona Sen. John McCain made more than 1,500 pages of medical and psychiatric records available when he ran for president in 2008 because he had a history of cancer and had been a prisoner of war.

Some people believe it’s time to standardize medical exams for such a high office. Caplan has, for decades, said Congress should establish a law that would set up a medical panel to independently evaluate candidates and the president because otherwise, patients control what gets out. Under the status quo, he said, “We keep staggering from election to election with a mix of testimonials, censored statements, and a guy who is your personal doctor saying you’re wonderful.”

Proponents of evaluating politicians for physical and mental fitness are commonplace in other jobs. Large companies require their top executives to undergo a physical to ensure they don’t have a condition that would interfere with their ability to do a job. Members of the military who handle nuclear weapons are assessed for mental fitness. Airline pilots and truck drivers need to be cleared, too.

The job of commander in chief, however, has no such requirement.

Just as with private citizens, doctors are barred by confidentiality laws from releasing information without patient consent. Medical information is highly confidential, and people who access or share it without patient consent are likely to lose their licenses, their jobs, and to go to jail.

“When you hit a core set of medical issues, it’s hard to argue the public doesn’t have an interest in knowing about them when they’re casting their vote. At some level, it’s unarguable that they can’t disclose a certain base of facts,” said University of Wisconsin bioethicist Robert Streiffer. “There is an ethical dilemma for the doctor, or there could be, because they are acting as an agent of the candidate but also an obligation to the public with who they are sharing information with. If we could legally mandate a set of tests and a set of information that candidates are required to allow to be disclosed, as a condition of their candidacy, that would then sidestep that dilemma.”

Throughout American history, presidents have been far from forthcoming about their health. Woodrow Wilson's wife, for a time, decided which decision got brought to his attention because he was paralyzed following a stroke. Dwight D. Eisenhower’s White House said he was hospitalized because of an upset stomach, when in fact, he had a heart attack.

But in later years, candidates did disclose some information, partly because the public and media demanded it.

“In the 1960s and 1970s, there was a new sense of openness, with public officials needing to be more transparent, not just what they’re doing as president, but who they were as a person,” said Rutgers University presidential historian David Greenberg. “Ronald Reagan had a number of health scares as president, in a time when journalists were becoming increasingly inquisitive about all kinds of elements of a candidate — their graft record, their affairs, their recreational drug use in the past — this was another thing that people paid a lot of attention to.”

One of the more dramatic instances of questions about a candidate’s health in the modern era came during the 1992 Democratic presidential primary. That cycle, former Democratic Massachusetts Sen. Paul Tsongas staked a longshot bid for the White House by pitching himself as an honest broker willing to make politically unpopular choices such as cutting federal spending and raising taxes to curb the growing budget deficit, in contrast to questions about the integrity of Democratic Arkansas Gov. Bill Clinton.

Yet, questions about Tsongas’s previous battles with cancer plagued his campaign, even after the public received assurances from two doctors that a 1986 bone marrow transplant had been successful. Tsongas's campaign even filmed him swimming to prove his health and vitality.

But after Tsongas, 50, dropped out of the race, his doctors admitted that they had discovered a cancerous lymph node in his armpit years prior. Tsongas would later apologize for misleading the public. Tsongas died on Jan. 18, 1997, of complications from pneumonia and non-Hodgkin's lymphoma — two days before the end of the presidential term he had sought.

The Tsongas incident sparked public debate over the independence of a candidate’s doctors and their ethical obligations. Before he died, Tsongas called for a national commission on a universal standard for how much information presidential candidates must disclose as a condition for running.

“The issue is about privacy versus the public’s right to know,” said Dr. David Scheiner, the Chicago physician who wrote a letter about Obama, his longtime patient, when he ran for president in the 2008 cycle. “Does the right to know supersede privacy? I think the public has a right to know, but I don’t know if the public wants to know or cares to know.”

That question came to renewed attention this week when it was revealed that, despite suffering a heart attack, Sanders brought in a massive fundraising haul of $25.3 million in the third quarter of 2019. The Sanders campaign raised all of that campaign cash before his heart attack. In the next fundraising quarter, covering October through December 2019, and with contributors fully aware of Sanders's health condition, his campaign did even better. The Sanders campaign last week said it raised $34.5 million, the highest-reported quarter yet of a 2020 Democrat in the race so far.

All of the oldest candidates have also continued to poll at the top of the crowded Democratic field.

Aging candidates are more likely to face scrutiny about their health, given that as people get older, the probability of illness, disability, and death increases, as do the chances of cognitive impairment.

But age isn’t the only factor that determines good health. John F. Kennedy had Addison's disease, an endocrine disorder that can be life-threatening, and it only became more public after he was elected president at age 43.

And it’s not always clear which ailments could get in the way of people doing their jobs, or whether voters might perceive a diagnosis as debilitating when it’s not. Abraham Lincoln, for instance, had depression while in office. Reagan, who was 77 when he left office, disclosed five years later that he was diagnosed with Alzheimer’s disease, and questions over the extent to which the illness affected his judgment while he was in office have persisted.