ARI SHAPIRO, HOST:
Two new government studies found no unusual pattern of injury or illness in people with the mysterious cluster of symptoms known as Havana syndrome. The findings are the latest to challenge the idea that diplomats and intelligence service workers have been attacked and injured by foreign adversaries. NPR's Jon Hamilton reports.
JON HAMILTON, BYLINE: Havana syndrome refers to symptoms like dizziness, balance problems and pain that were first reported in 2016 by embassy workers in Cuba. Since then, hundreds of reports have come from U.S. government workers and family members in countries including China, Austria and the U.S. The new studies represent the latest attempt to explain those reports. During a press conference, Dr. Leighton Chan explained how the research was carried out at the National Institutes of Health in Bethesda.
LEIGHTON CHAN: Participants spent about a week with us and received extensive evaluations including cognitive, auditory, vision, ocular motor, vestibular, balance and blood biomarker testing.
HAMILTON: They also got two separate brain scans. The studies compared more than 80 people thought to have Havana syndrome with dozens of similar people who did not have symptoms. In an interview, Chan says neither study found an explanation.
CHAN: We didn't see differences in brain volumes or other metrics that look at the structure of the brain or even in the functional connectivity of the brain.
HAMILTON: That finding stands in contrast to the result of a smaller imaging study done at the University of Pennsylvania in 2019. It found subtle changes in the brains of affected people. Dr. Carlo Pierpaoli is an imaging expert at the NIH. He says he's confident that the new study got it right.
CARLO PIERPAOLI: We were very careful about designing the imaging study as a research study with very high reproducibility.
HAMILTON: NIH scientists say the new studies also chose control groups that closely match the age, profession and location of people thought to have Havana syndrome. One difference the NIH researchers did find was that people with symptoms were more likely to report high levels of fatigue, depression and post-traumatic stress. Louis French is a neuropsychologist at Walter Reed National Military Medical Center who has been treating affected government workers. He says it's important to remember that they have devoted their lives to government service and that their symptoms are real.
LOUIS FRENCH: Some of these people are in distress. Many people are sad and feel overwhelmed, and so we are doing our best to try to address some of that distress that's associated with them feeling sick.
HAMILTON: The new studies are unlikely to settle ongoing debates about Havana syndrome, which the government now calls anomalous health incidents. Dr. David Relman of Stanford University wrote an editorial accompanying the new research. He says both studies have problems.
DAVID RELMAN: And one of the problems is the inadequacy of currently available methods for detecting the kind of brain disruption that may be involved in some of these cases.
HAMILTON: Relman says the NIH studies also may have lumped together people who actually sustained a brain injury with people whose symptoms have a psychological explanation. He says that would make it harder to detect a difference. Relman would like to see more studies that try to address these problems. But Leighton Chan of the NIH says that's unlikely to find the cause if there is one.
CHAN: Medical research may not be the answer to this if what you're looking for is attribution. The answer to this is counterintelligence - somebody taking a photo of somebody doing this, somebody actually getting whatever it is.
HAMILTON: In other words, finding a source that would explain Havana syndrome. Jon Hamilton, NPR News.
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