The term Havana syndrome refers to a perplexing group of sometimes debilitating symptoms that can include difficulties with thinking, sight, and hearing. Researchers do not yet fully understand this phenomenon.

United States government officials first reported the symptoms while on assignments in Havana, Cuba. However, the exact origins and causes of Havana syndrome are still unknown.

Investigations into the syndrome are ongoing and involve multiple government agencies and scientific researchers.

This article looks at what we do and do not know about Havana syndrome, including theories on possible causes, investigations, treatment options, and more.

A street in Havana, Cuba, the namesake of Havana syndrome. -2Share on Pinterest
diegograndi/Getty Images

Havana syndrome refers to a set of idiopathic symptoms that have affected diplomats, intelligence officers, and other government officials primarily stationed in Cuba but also in other locations worldwide.

The term “Havana syndrome” originates from a cluster of cases reported among US and Canadian embassy staff in Havana, Cuba, in late 2016.

However, similar incidents have been reported in other countries, including China, Russia, and, most recently, India.

The US Department of State and other federal agencies refer to Havana syndrome occurrences as Anomalous Health Incidents (AHI).

For most people with Havana syndrome, initial symptoms included hearing a loud, high-pitched noise or buzzing and then experiencing pressure in either the head, ears, or both.

Additional symptoms of Havana syndrome can vary among individuals and cover a range of cognitive, visual, auditory, behavioral, and emotional areas.

Examples include:

Some individuals experience mild symptoms that resolve quickly, while others may experience more severe and persistent symptoms lasting for months or even years.

The duration and severity of symptoms vary depending on factors such as the individual’s proximity to the perceived source of the phenomenon and their overall health.

Despite extensive investigations by various government agencies and independent researchers, the exact cause of Havana syndrome remains unknown.

Some theories include exposure to some form of directed energy, such as microwaves or sonic waves, as well as chemical or environmental factors.

Some experts believe that the syndrome may be the result of a targeted attack by a foreign government using sophisticated technology. In 2018, the US Department of State issued a Level 3 travel advisory for Cuba due to “health attacks directed at U.S. Embassy Havana employees.”

Others suggest that it could be a psychological or psychosomatic response to stress or other factors.

There have been numerous investigations into possible causes of Havana syndrome.

These investigations have involved experts from multiple fields, including medicine, neuroscience, engineering, and intelligence.

However, progress has been slow, with no definitive conclusions. Some experts have criticized the lack of transparency and cooperation among government agencies and international partners.

Most recently, the US House Intelligence Committee has been investigating the ways in which US intelligence agencies examined Havana syndrome cases. The committee is potentially challenging those agencies’ conclusions that Havana syndrome was most likely due to environmental or undiagnosed medical conditions.

This section answers some frequently asked questions about Havana syndrome.

Can Havana syndrome be cured?

There is no specific cure or treatment for Havana syndrome because the underlying cause remains unknown.

Treatment typically focuses on managing individual symptoms, such as pain relief for headaches and therapy for cognitive and emotional difficulties.

Symptom improvement or resolution can vary from person to person.

What were the MRI findings of Havana syndrome?

Advanced brain magnetic resonance imaging (MRI) studies of individuals experiencing symptoms of Havana syndrome have shown abnormalities in the brain, including changes in:

Additionally, researchers found changes in functional connectivity in certain brain networks, including those related to vision and hearing.

These findings imply that the syndrome might involve structural and functional changes in the brain. However, the clinical importance of these differences remains uncertain and may require further investigation.

Despite multiple investigations and theories, Havana syndrome — the array of cognitive, visual, auditory, and other symptoms US government officials first experienced in Cuba — remains a mystery.

Research into what causes Havana syndrome is ongoing. Because of this, treatment options focus on individual symptoms rather than the syndrome as a whole.