Havana Syndrome: a primer for skeptics in an age of alternative facts


Robert Bartholomewhttps://link.springer.com/book/10.1007/978-3-030-40746-9
Robert Bartholomew is an Honorary Senior Lecturer in the Department of Psychological Medicine at the University of Auckland in New Zealand. He is one of the co-authors of Havana Syndrome: Mass Psychogenic Illness and the Real Story Behind the Embassy Mystery and Hysteria (Copernicus Books, 2020).

Robert W. Balohhttps://link.springer.com/book/10.1007/978-3-030-40746-9
Robert Baloh is an Emeritus Professor of Neurology at the David Geffen School of Medicine, UCLA and the former director of the Neurotology Testing Laboratory at the Ronald Reagan UCLA Medical Center. He is one of the co-authors of Havana Syndrome: Mass Psychogenic Illness and the Real Story Behind the Embassy Mystery and Hysteria (Copernicus Books, 2020).

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Things are seldom what they seem, skim milk masquerades as cream.

William S. Gilbert

In late 2016, an American intelligence officer walked into the US Embassy medical clinic in Cuba complaining of headache and ear pain. He reported that the symptoms began after hearing a strange noise, like a beam of sound had been directed at his home. Soon after, other intelligence operatives in the same unit described a similar experience and a folk theory emerged – they had been attacked by a secret weapon that used sound waves.

Before long, news of the ‘sonic attacks’ spread like wildfire through the embassy, and not long after to the Canadian embassy with which the US routinely shared information. During 2017, American and Canadian diplomats stationed in Havana were on the lookout for strange sounds and an array of health complaints. Dozens were affected. Because it was first identified in Havana, it was dubbed ‘Havana Syndrome.’ Technically, it does not fit the definition of a syndrome since the symptoms and course were so variable but to avoid confusion, we have retained the term and placed quotation marks around it.

To date ‘attacks’ have been reported on more than 200 US officials on every continent other than Antarctica, including reports from Australia (Sydney), Austria (Vienna), China, Colombia, England, Georgia, Germany, Kyrgyzstan, Poland, Russia (Moscow), Serbia, Taiwan, United States (Washington DC & Virginia), Uzbekistan, and Vietnam.

In 2018, after ‘attacks’ were reported by several American diplomats stationed in China, the State Department warned its foreign corps to be vigilant. However, by warning diplomats and intelligence officers to be vigilant for “anomalous health incidents” that may be accompanied by strange sounds, the American government created a global experiment in what psychologists refer to as the nocebo effect whereby negative expectations produce negative symptoms.

To complicate the situation, in September 2021, Defence Secretary Lloyd Austin sent an alert to nearly 2.9 million military personnel, civilian officials and contractors, asking them to report any unusual health incidents. He wrote:

Over the course of the last several years, and predominantly overseas, some DOD (Department of Defence) personnel have reported a series of sudden and troubling sensory events such as sounds, pressure, or heat concurrently or immediately preceding the sudden onset of symptoms such as headaches, pain, nausea, or disequilibrium (unsteadiness or vertigo).

He told them it was their duty to report such incidents. The problem is – the symptoms are so common that it would be unusual if someone did not experience at least one of them in any given week.

Lawyers are now involved, as some victims have filed lawsuits arguing the government knew of the threat but failed to protect them; others are filing claims for compensation after experiencing health problems within the past five years.

Alleged Havana Syndrome symptoms

Victims of Havana Syndrome have reported a broad range of symptoms, including:

  • headache
  • tinnitus
  • nausea
  • vision problems
  • dizziness
  • trouble sleeping
  • fatigue 
  • balance problems
  • difficulty concentrating
  • head pressure
  • disorientation   
  • ear pain and pressure
  • difficulty focusing eyes
  • forgetfulness
  • confusion
  • white matter tract changes (normal for population)
  • hearing loss (never documented)
  • brain damage (never documented)

However, in 2018, the results of a soon to be released study on 25 diplomats were leaked to the media and it was claimed that one-third had hearing loss. When the study was eventually published it found hearing loss in only two subjects (Hoffer et al., 2018). In both cases, the loss had occurred before they were posted to Cuba.

Havana Syndrome theories

Multiple theories have been put forward to explain the symptoms of Havana Syndrome, some less plausible than others:

Sonic/acoustical weapon:

The idea that the symptoms were caused by some kind of sonic or acoustical weapon seems highly implausible, not least because such a device would necessarily defy the laws of physics: the energy in sound waves would quickly dissipate and could not selectively damage the brain. A very loud noise could damage hearing, but no one developed objective hearing loss.


The microwave explanation was assessed by the 2018 ‘Jason panel’ of expert scientists, who found it to be far-fetched. Microwaves can produce vague clicking sounds by directly stimulating nerves (in what is known as the Frey effect), but not the type of sounds reported by the victims. Eight of the first twenty-one victims recorded sounds they heard accompanying their ‘attacks’, but microwaves do not create recordable sound waves. Analysis of the recorded sounds concluded they were crickets.

What’s more, any microwaves deployed on the victims would also interfere with electronics, knock out WiFi, shut down computers, etc – yet none of these other effects were reported in Cuba or globally.

Within the past decade, Nature published a review on the progress with microwave weapons, concluding that “despite 50 years of research on high-powered microwaves, the US military has yet to produce a usable weapon”, describing such research as “wasted energy”.


A tractor spraying a field with pesticide

While pesticides have been offered as a potential explanation for the Havana Syndrome symptoms, such an explanation could not account for why non-diplomats working in the embassies were not similarly affected. There is no known neurotoxin in the world which only affects US and Canadian diplomats and their families, so if pesticides were the answer, why wasn’t there an epidemic of concussion-like symptoms across Cuba? Suffice to say, the symptoms reported by the victims were also not consistent with acute insecticide poisoning

Mass Psychogenic Illness:

If you remove the claims of brain damage and hearing loss (which were never documented), you are left with a classic outbreak of mass psychogenic illness. Of course, not all of the affected diplomats in Cuba were suffering from psychogenic illnesses. Some victims were simply redefining a laundry list of vague symptoms under a new label – ‘Havana Syndrome.’ Some may even have had other illnesses.

Brain changes reported in the Havana patients are consistent with findings one would expect to find in people exposed to prolonged stress. Importantly, brain dysfunction is not the same as brain damage – the latter of which has never been demonstrated.

There are numerous parallel cases of ‘Havana Syndrome” in the annals of the ‘mass hysteria’ literature. The involvement of four people from the same CIA station is a defining feature of mass psychogenic illness, which is known to follow social networks. Outbreaks commonly begin in a small, cohesive unit and spread outward, starting with people of higher status. Those affected belonged to a common work environment and social network who were under stress in a foreign country where they were under constant surveillance and told they were being targeted with a secret weapon.

Common misconceptions about Havana Syndrome

Discussions around Havana Syndrome have been mired in misconceptions. For example, it is commonly reported that the ‘attacks’ occurred at the US Embassy in Havana, Cuba. This is false: episodes were not reported at the US Embassy, but instead in two large hotels (the Hotel Capri and Hotel Nacional de Cuba), an apartment complex, and at diplomats’ own homes.

Some of the reporting claims the National Academy of Sciences (NAS) panel concluded that microwaves were the cause. This is not quite the case. The NAS panel wrote that microwaves were the most probable explanation, but after their report was released in December 2020, a classified report produced by elite scientists who examined the microwave theory dismissed it as “highly unlikely” (Vergano, 2021), prompting NAS Chair David Relman to tell National Public Radio in October 2021:

“We were not confident (in microwaves). And I have to be clear…we didn’t have any direct evidence that this could explain the entire story for sure or even parts of it”.

McCammon, 2021

It is also commonly claimed that the NAS panel eliminated psychogenic illness as a possible cause. This is completely false. The panel never assessed the ‘mass hysteria’ hypothesis, saying there was no data on the early spread (ignoring our book, which documented the early transmission starting with ‘patient zero’). Furthermore, the NAS panel conspicuously failed to interview any prominent ‘Havana Syndrome’ skeptics, such as neurologists Sergio Della Sala and Jon Stone of the University of Edinburgh, microwave expert Ken Foster at the University of Pennsylvania or ourselves, and no one on their panel was a specialist on mass psychogenic illness or microwaves.

Reports often claim that, early on, some US Embassy staff who fell sick were unaware that other employees were unwell, eliminating the possibility of mass psychogenic illness. Again, this is false. This claim has been contested by an Embassy staffer who told us that once the ‘attack’ news got out it spread like wildfire and “we all knew intimate details about each others’ issues.”

The dismissal of psychogenic illness as a possibility may well result from another common misconception: that victims of psychogenic illness are crazy, mentally ill or weak-minded. In reality, mass psychogenic illness is a collective stress response that can happen to anyone because it is caused by a stress-generating belief – and we all have beliefs. The symptoms are as real as symptoms from any illness.

Another common misconception stems from the claim that, from 1953 to 1976, the US Embassy in Moscow was targeted with a microwave beam that was believed to be triggering listening devices in the embassy (known as ‘the Moscow Signal’). While this is true a State Department study found that microwaves produced no threat to human health (Lilienfeld et al., 1978).

Finally, it has been claimed that there must be something to the attack claims, because of more than 200 cases reported around the world since 2017, the State Department says that about half involve intelligence officers. This is not the case: in Havana, intelligence agents were viewed as the first targets, and intelligence officers around the world were warned that they might be the next, thus resulting in agents being hyperaware of their health and creating a self-fulfilling prophecy.

Key Studies

There have been two key studies into the alleged phenomenon known as Havana Syndrome. The Journal of the American Medical Association’s 2018 study found that, for the 21 patients tested, most findings were normal. While three showed white matter changes on MRI studies (two were mild and one was moderate), the changes were within the range of normal. White matter tract changes are common in everything from migraine to depression to normal ageing. However, the study used a threshold for impairment of 40% – a level at which 4 in 10 people would have been classified as impaired! The real threshold should have been 5%, and as a result of this flaw, the study should never have been published.

The following year, the Journal of the American Medical Association published a second study, this time finding minor brain anomalies in the patients studied. This is not uncommon when looking at small cohorts, and the anomalies were so minor that study authors admitted they could have been caused by individual variation – after all, brain anomalies do not equate to brain damage. The anomalies were said to be consistent with people exposed to prolonged stress, and 12 of those affected had pre-existing histories of concussion, compared to none in the healthy controls. This alone could explain the differences between the two groups.

Common Sense

What is the more likely, that the diplomats were the target of a mysterious new weapon for which there is no evidence and the use of which defies the laws of physics, or that they were suffering from mass psychogenic illness – a well-documented condition that has been described in the scientific literature for millennia? Common sense and the evidence dictate the latter.


  • Baloh, Robert W., and Bartholomew, Robert E. (2020). Havana Syndrome. Cham, Switzerland: Copernicus Books.
  • Bartholomew, Robert E., and Baloh, Robert W. (2019). “Challenging the Diagnosis of ‘Havana Syndrome’ as a Novel Clinical Entity.” Journal of the Royal Society of Medicine 113(1):7-11
  • Hoffer ME, Levin BE, Snapp H, Buskirk J, Balaban C. Acute findings in an acquired neurosensory dysfunction. Laryngoscope Investigative Otolaryngology 2018;1–8 (12 December).
  • Lilienfeld, Abraham, et al. (1978). Evaluation of Health Status of Foreign Service and other Employees from Selected Eastern European Posts. Baltimore: Department of Epidemiology, School of Hygiene and Public Health, The Johns Hopkins University, July 31. DOS-6025-619073
  • McCammon, Sarah (2021). “New Cases of ‘Havana Syndrome’ Grow while cause Remains a Mystery.” National Public Radio (Washington, DC), October 15, accessed at: https://www.npr.org/2021/10/15/1046519741/new-cases-of-havana-syndrome-grow-as-cause-remains-a-mystery.
  • Vergano, Dan. 2021. “A Declassified State Department Report says Microwaves didn’t cause ‘Havana Syndrome.’” BuzzFeed News, September 30: https://www.buzzfeednews.com/article/danvergano/havana-syndrome-jason-crickets
  • Weinberger, Sharon (2012). “Wasted Energy.” Nature 489:198-200. (13 September).
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