In 2010, Robert F. Kennedy Jr. he was experiencing memory loss and mental fog so severe that a friend worried he might have a brain tumor. Mr. Kennedy said he consulted several of the nation’s leading neurologists, many of whom had either treated or spoken to his uncle, Senator Edward M. Kennedy, before his death the previous year from brain cancer.
Several doctors noticed a dark spot on the younger Mr. Kennedy’s brain scans and concluded he had a tumor, he said in a 2012 deposition reviewed by The New York Times. Mr. Kennedy was immediately scheduled for an operation at Duke University Medical Center by the same surgeon who had operated on his uncle, he said.
While packing for the trip, he said, he received a call from a doctor at NewYork-Presbyterian Hospital who had a different opinion: Mr. Kennedy, he believed, had a dead parasite in his head.
The doctor believed the abnormality seen in his scans “was caused by a worm that got into my brain and ate part of it and then died,” Mr. Kennedy said in the deposition.
Now an independent presidential candidate, the 70-year-old Mr. Kennedy portrayed his athleticism and relative youth as an advantage over the two oldest people ever to seek the White House: President Biden, 81, and former President Donald J. 77. Mr. Kennedy has secured a spot on the ballot in Utah, Michigan, Hawaii and, his campaign says, California and Delaware. His strong efforts to gain access to more states could put him in a position to swing the election.
He has gone out of his way to appear hale, skiing with one professional snowboarder and with Olympic gold who called him “the ripper” as they ran down the mountain. A camera crew was on his side while lifting weights, shirtless, at an outdoor gym in Venice Beach.
However, over the years, he has faced serious health problems, some previously unknown, including the apparent parasite.
For decades, Mr. Kennedy suffered from atrial fibrillation, a common heart beat abnormality that increases the risk of stroke or heart failure. He has been hospitalized at least four times for episodes, though in an interview with The Times this winter, he said he hadn’t had an episode in more than a decade and believed the condition was gone.
Around the same time he learned about the parasite, he said, he was also diagnosed with mercury poisoning, likely from ingesting too many fish containing the dangerous heavy metal, which can cause serious neurological problems.
“I have cognitive issues, clearly,” he said in the 2012 deposition. “I have short-term memory loss and I have long-term memory loss that affects me.”
In his interview with the Times, he said he had recovered from the memory loss and fog and had no side effects from the parasite, which he said required no treatment. Asked last week whether any of Mr. Kennedy’s health problems could jeopardize his eligibility for the presidency, Stephanie Spear, a spokeswoman for the Kennedy campaign, told the Times: “That’s a ridiculous suggestion, given the competition. ».
The campaign declined to provide his medical records to the Times. Neither President Biden nor Mr. Trump have released medical records this election cycle.
Doctors who have treated parasitic infections and mercury poisoning said both conditions can sometimes permanently damage brain function, but patients can also have temporary symptoms and make a full recovery.
Some of Mr. Kennedy’s health problems were revealed in a 2012 deposition he gave during divorce proceedings from his second wife, Mary Richardson Kennedy. At the time, Mr. Kennedy argued that his earning power had been diminished by his cognitive struggles.
Mr. Kennedy gave more details, including about the apparent parasite, in the telephone interview with The Times, conducted on the eve of his first vote in the state. His campaign declined to answer follow-up questions.
In the days after the 2010 call from NewYork-Presbyterian, Mr. Kennedy said in the interview, he underwent a series of tests. Scans over several weeks showed no change in the spot on his brain, he said.
Doctors concluded that the cyst seen on the scans contained the remains of a parasite. Mr Kennedy said he did not know the type of parasite or where he might have contracted it, although he suspected it might have been during a trip to South Asia.
Several infectious disease specialists and neurosurgeons said in separate interviews with The Times that, based on what Mr. Kennedy described, they believed it was likely a pork tapeworm. Doctors have not treated Mr. Kennedy and were speaking in general terms.
Dr. Clinton White, a professor of infectious diseases at the University of Texas Medical Branch in Galveston, said the tiny tapeworm eggs are sticky and easily spread from one person to another. Once hatched, the larvae can travel through the bloodstream, he said, “and end up in all kinds of tissues.”
Although it is impossible to know, he added that it is unlikely that a parasite would eat part of the brain, as Mr. Kennedy described. Instead, Dr. White said, it survives on nutrients from the body. Unlike the tapeworm larvae in the intestines, those in the brain remain relatively small, about a third of an inch.
Some tapeworm larvae can live in the human brain for years without causing problems. Others can wreak havoc, often when they start to die, which causes inflammation. The most common symptoms are seizures, headaches and dizziness.
There are about 2,000 hospitalizations for the condition, known as neurocysticercosis, each year in the United States, according to the journal Emerging Infectious Diseases.
Scott Gardner, curator of the Manter Laboratory for Parasitology at the University of Nebraska-Lincoln, said that once any worm is in a brain, cells calcify around it. “And basically you’ll have almost like a tumor that’s going to be there forever. It’s not going anywhere.”
Dr. Gardner said it is possible for a worm to cause memory loss. But the severe memory loss is more often linked to another health scare Mr. Kennedy said he had at the time: mercury poisoning.
Mr Kennedy said he then maintained a diet high in predatory fish, mainly tuna and perch, both of which are known to have elevated levels of mercury. In the Times interview, he said he had experienced “severe brain fog” and had trouble retrieving words. Mr. Kennedy, an environmental lawyer who has railed against the dangers of mercury contamination in fish from coal-fired power plantshe did blood tests.
He said tests showed his mercury levels were 10 times what the Environmental Protection Agency considers safe.
At the time, Mr. Kennedy was also a few years into his crusade against thimerosal, a mercury-containing preservative used in some vaccines. He is a longtime vaccine skeptic who has falsely linked childhood vaccinations to an increase in autism, as well as other medical conditions.
In the interview, Mr Kennedy said he was sure his diet had caused the poisoning. “I liked the tuna sandwiches. I ate them all the time,” he said.
The Times described Mr. Kennedy’s symptoms to Elsie Sunderland, an environmental chemist at Harvard who has not spoken to Mr. Kennedy and responded generally about the condition.
He said the mercury levels Mr Kennedy described were high, but not surprising for someone consuming that amount and type of seafood.
Mr Kennedy said he made changes after those two health scares, including sleeping more, traveling less and reducing his fish intake.
He also underwent chelation therapy, a treatment that binds to minerals in the body so they can be expelled. It is generally given to people contaminated by metals, such as lead and zinc, in industrial accidents. Dr Sunderland said that when mercury poisoning is clearly related to diet, she would simply recommend that the person stop eating fish. But another doctor who spoke to The Times said she would advise chelation treatment for the levels Mr Kennedy said.
Mr. Kennedy’s heart problem began in college, he said, when he began to beat out of sync.
In 2001, he was hospitalized in Seattle while in town to give a speech, according to news reports. He was treated and released the next day. He was hospitalized at least three additional times between September 2011 and early 2012, including once in Los Angeles, he said in the filing. At that visit, he said, doctors used a defibrillator to shock his heart to restore rhythm.
He said in the deposition that stress, caffeine and lack of sleep triggered the condition. “I feel like I have a bag of worms in my chest. I can feel it immediately when it goes off,” he said.
He also said in the deposition and interview that he contracted hepatitis C through intravenous drug use in his youth. He said he had been treated and had no lingering effects from the infection.
Mr. Kennedy has spoken publicly about another major health condition – spasmodic dysphonia, a neurological disorder that causes his vocal cords to squeeze too close together and accounts for his hoarse, sometimes strained voice.
He first noticed it when he was 42, he said in the deposition. Mr. Kennedy for years made a substantial amount of money giving speeches and that business fell off as the situation worsened, he said.
He said an interviewer last year that he had recently undergone a procedure available in Japan to implant titanium between his vocal cords to prevent them from contracting involuntarily.