Until recently, the title of politician who generates the most mortifying headlines was indisputably held by South Carolina Governor Kristi Noem, who in recent weeks has given us such marvels as “Trump VP contender Krist Noem writes of killing dog,” “Kristi Noem suggests Biden’s dog Commander should be killed too,” and “Kristi Noem has admitted the Kim Jong Un part of her book isn’t true but she read it for her audiobook anyway.”

You might think it’s impossible to top news stories about killing a dog and lying about meeting a dictator. But insurgent candidate Robert F. Kennedy Jr. inspired a headline on Wednesday that was even more disquieting: R.F.K. Jr. Says Doctors Found a Dead Worm in His Brain. Almost equally troubling was the sub headline in The New York Times: “Presidential candidate has faced previously undisclosed health issues, including a parasite that he said ate part of his brain.”

Apparently, in 2010 Kennedy was experiencing symptoms of cognitive decline. His memory was becoming hazy and he was walking around in a state of confusion. Brain scans revealed a mysterious patch—possibly a tumor. At first, doctors feared that he, like his uncle Edward Kennedy, was suffering from brain cancer. But then a doctor at New York Presbyterian offered another diagnosis, that the blotch on the scans was, in Kennedy’s words, “caused by a worm that got into my brain and ate a portion of it and then died.”

Kennedy said these words as part of a deposition made in 2012 during divorce proceedings with his second wife, Mary Richardson Kennedy. In that deposition, Kennedy gave great salience to his poor health and diminished cognitive capacity, which he claimed resulted in a lower income—hence justification for a smaller alimony payment.

Aside from the dead parasite nestled inside his brain, Kennedy claimed that as a result of mercury poisoning (which he blamed on his love of eating fish), “I have cognitive problems, clearly. I have short-term memory loss, and I have longer-term memory loss that affects me.” The presidential hopeful ruefully acknowledged, “I loved tuna fish sandwiches. I ate them all the time.” To find someone else as in love with tuna as Kennedy, you have to turn to a movie: In the 2002 black comedy Matchstick Men, the addled and creepy Roy Waller (played by Nicholas Cage) is a tuna junkie on par with Kennedy.

Since college, Kennedy has also struggled with atrial fibrillation—an irregular heartbeat—which has led to repeated hospitalization. In a striking metaphor, he says of this condition, “It feels like there’s a bag of worms in my chest.”

Kennedy’s litany of health problems casts a shadow on his presidential aspirations for two distinct reasons. First, as The New York Times notes, Kennedy has made his personal fitness a key argument, contending that as a vigorous 70-year-old he is superior to his rivals Joe Biden (age 81) and Donald Trump (age 77), both of whom have arguably given signs of physical and cognitive decline. Kennedy’s campaign ads and videos show him skiing and lifting weights. He’s clearly meant to be someone in the same sporting league as his father (Robert F. Kennedy Sr.) and uncle John F. Kennedy, both of whom were famous for their fiercely competitive game of touch football. But of course the Kennedy legend always benefited from more than a bit of media trickery: Posthumously, it was revealed that John suffered from a longtime back injury that led to a heavy reliance on painkillers.

Is Robert Kennedy following in his uncle’s footsteps, presenting himself as an emblem of vigor while hiding a medical history that many voters might regard as disqualifying? Kennedy’s campaign claims he has fully recovered from his ailments and compares favorably to his political rivals. That may be the case, although even Biden and Trump do not have, as far as we know, missing brain parts.

In truth, while voters do seem to like robust politicians, cognitive decline should be a far bigger cause for concern than any other physical ailment. After all, the polio-stricken Franklin Roosevelt—wheelchair bound for most of his political career—was one of America’s greatest presidents. Jesse Jackson drew great applause at the 1984 Democratic National Convention when he thundered, “I would rather have Roosevelt in a wheelchair than Reagan on a horse.”