ALSO SEE: RFK Jr. Says He Suffered From a Parasitic Brain Worm and Mercury Poisoning

Everything you need to know about the most horrifying diagnosis you can imagine

Robert F. Kennedy Jr. has sold himself as the younger, healthier alternative to Joe Biden and Donald Trump in the 2024 presidential election, but he once suffered a medical ailment so bizarre it has become an internet shorthand for delusional and disordered thinking: a brain worm.

On Wednesday, The New York Times reported details of a 2012 deposition Kennedy gave while divorcing his second wife, Mary Richardson Kennedy. In that interview, he detailed a litany of health concerns that he argued would diminish his future earnings potential, and recounted an incident in which Kennedy’s doctors identified a dark spot in one of his brain scans after he complained of memory fog and impaired cognitive ability.

At first, this discoloration was taken for a tumor. But Kennedy said a doctor told him it was a worm that “got into my brain and ate a portion of it and then died.” Doctors did indeed find a dead worm in his brain, according to Kennedy.

Worms in the brain. The symptom-Googling hypochondriac within each of us shudders at the thought. Kennedy doesn’t seem too bothered, though. He tweeted about it later on Wednesday, writing that he’ll “eat 5 more brain worms and still beat” Trump and Biden in a debate, and that he’s confident he can beat them “even with a six-worm handicap.”

I feel confident of the result even with a six-worm handicap.

— Robert F. Kennedy Jr (@RobertKennedyJr) May 8, 2024

Kennedy should know that this is now how brain worms work, though. We reached out to a neurologist specializing in infectious disease to learn everything you need to know about this upsetting phenomenon.

What is a brain worm?

Broadly speaking, “brain worm” is a colloquial term for several parasitic infections affecting the brain and central nervous system. While Kennedy did not name the species of parasite he had been diagnosed with, conditions commonly caused by these organisms include neurocysticercosis, an infection caused by larva of pork tapeworm; and neuroschistosomiasis, caused by the presence of parasitic eggs in the brain or spine.

One usually imagines worms as the pink, fleshy, wriggly tubers found in gardens or classroom science projects. However, parasitic brain “worms” are usually not worms at all, but larvae, enclosed in a small, fluid-filled cyst. They don’t typically travel around the brain — although extremely rare instances of this have been documented — and they are usually treatable with readily available anti-parasitic medication, or, far less often, surgery.

Do they actually eat your brain?

No. According to Dr. Michael Wilson, a neurology professor at the University of California, San Francisco’s Weill Institute for Neurosciences who specializes in infectious disease, the worms are typically contained in the cysts that form around them.

“That’s a dramatic way to put it,” Wilson says of Kennedy’s claim that the worm found in his brain ate away a pocket for itself to chill in. “It’s not that they’re chewing up the brain and causing extensive damage. They tend to just sit there in their cyst.”

“For reasons we don’t understand, oftentimes, the worm will just kind of live in its cyst for a number of years and not cause any symptoms,” Wilson adds. “No seizures, nothing. And then finally, the immune system will recognize that it’s there, and then it’ll attack it and kill it.”

Once the worm is dead, the remains will often calcify, leaving a small spot — often only millimeters long — that is visible on brain scans. But the most common forms of neurological parasites don’t tunnel through your brain like a prospector looking to strike gold.

What are the symptoms?

Depending on where the cyst from a parasite actually is — whether in the brain tissue, the fluid-filled ventricles that support it, or the spinal cord — a patient may experience unexplained dizziness or headaches. It’s possible, Wilson says, that they will also experience a loss of cognitive function, though this is uncommon and, again, contingent on the area affected.

“The brain’s like real estate: it’s all about location,” he says. “If the worm sits in a part of the brain that has nothing particularly to do with cognition, then you’ll have no cognitive problems.” (A doctor interviewed by the Times said that Kennedy’s brain fog and memory issues were more likely a result of another medical condition he explained in the 2012 deposition: mercury poisoning from a fish-heavy diet.)

However, Wilson says, “if that cyst is near the surface of the brain, if it gets inflamed, it can cause a seizure. And that’s what brings people into the hospital initially.” In fact, in parts of the developing world where neurocysticercosis is far more prevalent due to poor sanitation, the infection is cited as a leading cause of acquired epilepsy in adults.

How does one get infected?

Kennedy speculated that he might have picked up the brain worm during his extensive travels, perhaps in South Asia. Neurocysticercosis caused by pork tapeworm larvae is endemic there, as well as in Latin America and Sub-Saharan Africa, due to sanitary conditions, animal husbandry practices, and lack of suitable drinking water.

“This this infection is incredibly rare in the U.S.,” Wilson says, “not because we’re administering massive amounts of anti-parasitic drugs, just because we have clean waters.”

This particular tapeworm can infect humans at two different stages of its life cycle. First, you can get a gastrointestinal infection from consuming raw or uncooked pork contaminated with the larval cysts, which develop into adult worms in the small intestine that then lay microscopic eggs which are shed in feces. In poor sanitary conditions, these eggs can be directly transferred to other people, or they may contaminate the local water supply. Once the eggs are consumed by a host, they hatch into larvae that Wilson says are more “neuro-invasive,” but they may also form cysts in muscle tissue.

How common are they?

If you feel nauseated or have a headache after reading this far, don’t assume the worst: you probably don’t have a brain worm.

Although the World Health Organization has estimated tens of millions of cases of neurocysticercosis worldwide, these are overwhelmingly from endemic regions of the developing world. “It’s quite unusual in native-born folks in the U.S.,” Wilson says. To the extent that we do see cases in the west, they tend to be in urban areas with large populations of immigrants from those places, he says.

As for becoming infected while abroad, some basic precautions will go a long way. “It’s not just traveling to different parts of the world,” Wilson explains. “It’s actually getting exposed to contaminated water or something like that. A lot of people, if they’re going to a resort, there are not particular risks.”

Are they treatable?

Yes, thank god. “There are anti-parasitic oral medications, and they can they work quite well,” Wilson assures us. In an interview with the Times, Kennedy said his brain worm had not required any treatment whatsoever — it was already dead, after all — and that he had recovered from the mental fog and memory loss that plagued him around the time it was diagnosed.

Not many of these parasites call for surgical intervention, Wilson says, though there are exceptions. A cyst in the brain’s ventricles, for instance, can block the flow of spinal fluid in a way that drastically increases pressure inside the skull, which “in the extreme cases can be fatal,” he says. Those parasites have to be removed.

In other cases, a worm may be removed from brain tissue surgically because it was misdiagnosed as a tumor. Kennedy had in fact been preparing for a procedure based on his doctors’ belief that he had a tumor when he received the second opinion that it could be a parasite. Some of Wilson’s research is focused on “better diagnostics for neurologic infections,” which would of course improve treatment outcomes and, ideally, help to prevent unnecessary surgeries.

So, there you go. Brain worms: unfortunately real, definitely gross, but not as much cause for alarm as you feared. The threat they pose certainly don’t compare to the medical hysteria Kennedy has cooked up with his anti-vax activism and conspiracy theories about antidepressants causing school shootings. And lastly, no, we can’t blame those comments on the worm that got into his head. But it sure makes a striking metaphor.