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NIH scientists, studying Havana syndrome patients, find no physical trace of harm


We have an update this morning on Havana syndrome. That's the cluster of symptoms first reported by U.S. Embassy workers in Cuba. Two new government studies examined people who said they were affected, and NPR's Jon Hamilton reports they found what are called very real symptoms, but no evidence of physical injury.

JON HAMILTON, BYLINE: Since 2016, hundreds of U.S. diplomats and other government workers have reported the sudden onset of symptoms like vertigo, balance problems and pain. Some federal officials have speculated that these people were attacked by a foreign adversary using a new sort of weapon. But Louis French, a neuropsychologist at Walter Reed National Military Medical Center, says the new studies found no unusual pattern of injury or disease in people who had these symptoms.

LOUIS FRENCH: We did not find evidence of any permanent brain changes that would lead us to believe that a person is going to have some deteriorating course over time.

HAMILTON: The studies were done at the National Institutes of Health. The research included more than 80 people who had experienced what the government now calls anomalous health incidents, or AHIs. Dr. Leighton Chan of the NIH says a week of tests found that some of these people had severe symptoms, including headaches and dizziness.

LEIGHTON CHAN: What we didn't find when we looked at vision testing, vestibular testing, even blood biomarker testing - we didn't see differences when we compared individuals who'd had AHI to the control population.

HAMILTON: Brain scans also found no significant differences between people who'd experienced an anomalous health incident and similar people with no symptoms. Chan says the results are reassuring, even though they don't address the potential existence of a mystery weapon.

CHAN: I can't say for sure that there's not something out there that could do something like this, but your average person walking down the street probably shouldn't be worried about this.

HAMILTON: The new studies appear in the Journal of the American Medical Association.

Jon Hamilton, NPR News.

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Jon Hamilton is a correspondent for NPR's Science Desk. Currently he focuses on neuroscience and health risks.