How much do voters need to know about a presidential candidate's health, and what information should politicians be obligated to share?

The New York Times takes an in-depth look at those questions today, concluding that candidates are sharing less medical information now than in some recent elections, despite candidates' previous health concerns. According to the article, the presidential and vice presidential candidates have only released limited and, in the case of GOP veep pick Sarah Palin, no medical records to date.

We know from a May review of some of John McCain's medical records and from previous reports that the Arizona senator has battled the most deadly form of skin cancer melanoma. His physician says McCain, who at 72 would be the oldest man ever sworn into a first term as president, has not  displayed any memory problems, but she has not said whether her patient has undergone cognitive tests.

Democrat Barack Obama in May released an undated one-page letter from his doctor to the media (based on regular exams since March 1987) stating that the Illinois senator, 47, was in "excellent health." The letter noted that Obama had used the nicotine gum Nicorette (to stem his nicotine craving) "with success," but it did not say whether Obama, a  longtime smoker, had kicked the habit. Obama said he stopped smoking last year when he launched his presidential campaign but admitted that he has "bummed" smokes since then.

Obama's running mate, Joe Biden, 65, suffered a near-fatal aneurysm—a brain bleed—20 years ago. But it's unknown whether he has had recent brain imaging scans or evaluations to detect possible new aneurysms; people who have suffered Biden's type of aneurysm are believed to have a 5 percent or less chance of developing another one. Biden today released 49 pages of medical records that indicated he did not have any aneurysm symptoms but did not reveal whether or not he had undergone recent brain scans, the Associated Press reports. The newly released documents show that he did not have any heart disease when checked two years ago, although he did suffer one or two episodes of an irregular heartbeat. The AP says that he takes a statin drug to keep his cholesterol in the healthy range, and that he has an enlarged prostate that isn't cancerous, a condition the Times noted this morning.

Palin's camp refused to release any medical information to the Times.

The author of today's Times article, Larry Altman, a physician who has been covering presidential health for 36 years, reported that he was denied access to the 1,200 pages of medical records that McCain released in May to a select group of other reporters; he said that he was shut out after an editorial critical of the senator appeared in his newspaper. 

Altman told the Columbia Journalism Review in June that the public has a right to know about the health of candidates they are electing to serve them. "In the past, White House physicians have been known to lie; candidates for president or nominees have been known to evade the truth, distort the facts, or lie," Altman told CJR.

"You’ve got Woodrow Wilson with a stroke and his wife allegedly running the affairs of the country; you’ve got Franklin Roosevelt who may or may not have been told how deathly ill he was in his last term, and certainly nothing was told to the country about it; you’ve got [John F.] Kennedy every which way not acknowledging that he had Addison’s disease (a disorder in which the adrenal glands do not produce enough cortisol or, in some cases, the hormone aldosterone; it can lead to life-threatening low blood glucose and high potassium levels); you had [Thomas] Eagleton who had to leave the [Democratic] ticket [as veep] in ‘72, because he didn’t tell [George] McGovern about his past history of electric-shock therapy and depression; and there was [Paul] Tsongas in [1992] and the fact that he had a recurrence after they had maintained that he was cured of cancer. I think all of those, collectively, led to the public to want to know more about the health of the people who were going to run their country."

(For more on those presidents' medical battles, see this September piece by NYU's Scienceline.)

The question of candidate health has gained currency in the past few weeks in the wake of a petition signed by more than 2,700 doctors demanding that McCain release all of his health records. Filmmaker Robert Greenwald, a Democratic contributor, was behind the petition.

Among candidates who have made themselves and their doctors available to the media include former President George H. Bush, Bob Dole, Al Gore and John Kerry.

Altman cites President Ronald Reagan – who is McCain's political idol – as an example of openness. He reports that during the 1980 election, Reagan, then 69, allowed his doctors to be interviewed and answered all of Altman's questions, including what he would do "if he became senile as president." His response, writes Altman: "Resign."

(Updated at 5:30 p.m. with AP report on release of Biden's medical records.)

(Image by iStockphoto/Oleg Prikhodko)