What is Havana syndrome, really?

In late 2016, diplomats and spies from the U.S. in Havana, Cuba began reporting symptoms of a “mysterious illness.” Pain and ringing in the ears, nausea, vertigo, and brain fog were all high on the list. The term “Havana Syndrome” quickly spread as did reported cases. While theories have ranged from sonic to microwave weapons and even pesticides, a CIA report released in January 2022 found that most Havana syndrome cases are “unlikely” to be caused by a foreign attack. A medical sociologist believes the controversy rests in a fundamental misunderstanding of how the brain works.

Here’s the background — After diplomats and spies reported symptoms in late 2016 and early 2017, U.S. and Canadian officials began calling the events “attacks;” soon after theories about sonic weapons by hostile foreign governments such as Russia, China, and Cuba hit the news. Some of the afflicted reported their symptoms were preceded by a loud noise coming from one direction.

But Robert Bartholomew, a medical sociologist and professor at Auckland University in New Zealand, tells Inverse that he believes we are at the “beginning of the end” of Havana Syndrome.

Initial studies, including a prominent one in the journal JAMA, suggested people with Havana Syndrome had brain anomalies, but there was no consistent damage pattern. A closer look at those foundational studies and an analysis of the various theories led Bartholomew and Robert Baloh, a neurologist at the University of California, Los Angeles, to believe everyone has been hearing hoofs and thinking zebras when the culprit is the much more commonplace horse.

“This is going to be taught in medical school for years to come,” Bartholomew tells Inverse. He and Baloh authored the 2020 book Havana Syndrome: Mass Psychogenic Illness and the Real Story Behind the Embassy Mystery and Hysteria.

Havana syndrome: Three leading theories

Since the first occurrences in late 2016, pundits have considered three primary theories about the cause — none of which are supported by quality evidence.

3. Sonic weapons

Sonic or acoustic weapons were one of the first theories of Havana syndrome, but it has been largely discredited. For one, not all people with Havana syndrome report hearing a noise before developing symptoms.

Conspiracy theories about “brown note” weapons — sonic weapons emitting a sound below an audible threshold with the ability to negatively affect the human body have existed since the Cold War. Mythbusters tested the claim and, well, busted it.

Further, “none of the attacks took place at the U.S. Embassy,” Bartholomew explains. “They were in large hotels, apartment complexes, and people’s homes.” To him, the notion that a sonic weapon could affect some people in an apartment complex and not others doesn’t add up.

2. Microwave weapons

If sound waves aren’t to blame, how about light waves? Microwave weapons were initially developed as a way to damage electronic equipment, and no damaged electronics have been found near supposed attacks.

In a 2021 story, chemist Cheryl Rofer explores the hypothesis for Foreign Policy and calculates that for such a portable weapon to damage humans, you would — at a minimum— need a 2,200-watt gasoline-powered generator weighing around 60 pounds.

“The evidence for microwave effects of the type categorized as Havana syndrome is exceedingly weak,” she writes. “No proponent of the idea has outlined how the weapon would actually work. No evidence has been offered that such a weapon has been developed by any nation. Extraordinary claims require extraordinary evidence, and no evidence has been offered to support the existence of this mystery weapon.”

A 2018 State Department report also concludes:

“No plausible single source of energy (neither radio/microwaves nor sonic) can produce both the recorded audio/video signals and the reported medical effects. We believe the recorded sounds are mechanical or biological in origin, rather than electronic. The most likely source is the Indies short-tailed cricket.”

1. Pesticides

One alternative theory to the hostile-government hypotheses is rooted in a different illness: the Zika virus. At the time of the initial reports, Cuba was fighting the Zika virus with cholinesterase inhibitor pesticides.

An obvious problem arises with that theory, Bartholomew says.

“There’s no neurotoxin in the world that only affects American and Canadian embassy staff and their families. Where are all the other people in Cuba reporting concussion-like symptoms? Also, they were spraying the stuff around the world, and no one else reported similar symptoms,” he says.

Further, a report by the National Academies of Sciences determines that the Havana incident was not consistent with acute poisoning by this specific type of insecticide (though it did not rule out chronic exposure as a possible contributing factor to people’s symptoms).

What the studies actually show about Havana Syndrome

Headlines (as well as politicians and other government officials) have suggested some external force must be responsible, given the documented brain changes.

But those studies fall apart on closer examination, Bartholomew argues, leading to a fundamental misunderstanding of Havana Syndrome.

“About a year before the first JAMA study came out in February of 2018, information was leaked to the press that there were white matter changes in many of the patients,” he says. “And then the study came out.”

Out of 21 patients, researchers found three people with white matter changes; two were mild, one was moderate.

“Well, if you went down to the streets of New York or Los Angeles this morning, you’re gonna randomly pick 21 people, you have basically the same thing because white matter track changes are common in migraine, depression, chronic stress, and in normal aging,” he explains.

The study authors allude to as much in their paper.

“The pattern of conventional imaging findings in these cases was nonspecific with regard to the exposure/insult experienced, and the findings could perhaps be attributed to other preexisting disease processes or risk factors,” they write.

A second study, published in JAMA in 2019, found “differences” in brain scans of 40 people who had worked at the Havana Embassy compared to controls but “no evidence of injury.”

“Twelve of the patients had a history of concussion compared to zero in the control group, which means that alone could explain the symptoms. The same anomalies that they found are consistent with anomalies you would expect from a group under long-term stress,” Bartholemew says.

Another study commissioned by the Canadian government found that Canadian diplomats had changes in the brain consistent with cholinesterase inhibitor pesticide exposure.

These findings weren’t persuasive to Bartholomew or Baloh, either.

“The anomalies they found in the patients are not very significant at all,” Bartholomew explains. He likens it to the researchers asserting that some people are a little taller than others, but all within normal range.

Havana Syndrome and how we treat psychological conditions

Bartholomew does not doubt that the symptoms people experience are genuine, and as an expert on mass psychogenic illness, he thinks he knows why.

“The diplomats went there right after the U.S. reopened the embassy. They’re in a hostile foreign country. They were told they’re going to be under surveillance 24/7 and that there’s a long history of Americans being harassed [in Cuba],” Bartholomew says.

“Then they’re told, ‘Oh, you might be the target of a sonic weapon. Don’t stand or sleep near windows.’ Some of these people have kids there. So for months, the pressure was ratcheted upon them, they were under serious stress. And [the symptoms and brain anomalies] are exactly what you would expect to find [from chronic stress].”

The common assumption that objectively real symptoms couldn’t have psychosomatic roots represents a fundamental misunderstanding about the brain. Consider Phantom Limb Syndrome. Between 80 and 100 percent of people who have had a limb amputated still experience sensations in a limb that no longer exists. While the pathophysiology behind the syndrome isn’t clear, it’s accepted as a legitimate condition; no one doubts the brain is generating sensory signals for a limb that isn’t there. Law enforcement officers are routinely hospitalized after fentanyl exposure because misinformation about the drug leads to such intense fear that they experience very real physical symptoms of a panic attack.

Indeed, a leaked FBI report on the Havana cases determines their conditions “psychologically-driven, most likely due to stress.”

Understandably, those affected find the “stress” conclusion unsatisfying and even offensive.

“But most people don’t understand or are unfamiliar with the literature on mass psychogenic illness,” Bartholomew says. “It actually causes changes in the brain. And [doctors and researchers] did these people no favors by telling them, ‘you have brain damage.’ Well, that’s not going to help them get better.” He says that only enhances people’s belief they experienced a physical attack.

The good news, he adds, is that with mass psychogenic illness, “the symptoms go away over time with a reduction in stress.”

Part of the hesitation from lawmakers and others to accept the increasing evidence suggesting mass psychogenic illness is responsible for Havana syndrome may rest in our societal attitudes towards conditions of the mind — especially mass psychogenic illness.

Brains are powerful, complex, and only partially understood. All the evidence points to Havana syndrome being a poorly named, well-documented stress response. That doesn’t make the symptoms any less real — and they should be treated appropriately.