The NIH has stopped its study of U.S. government personnel who experienced the anomalous health incidents (AHIs) known as Havana syndrome, the agency said.
The decision was made after investigating concerns that arose about the NIH study that was published in JAMA in March 2024.
The investigation found that regulatory and NIH policy requirements for informed consent were not met due to coercion, the agency said in an email to 麻豆传媒. The coercion was not on the part of NIH researchers, the agency clarified.
"In March 2024, the National Institutes of Health initiated an investigation in response to concerns from participants who were evaluated as part of a study on anomalous health incidents, the results of which were published in the journal JAMA," the agency wrote in its email.
"The investigation was conducted by the NIH Office of Intramural Research and the NIH Research Compliance Review Committee, an institutional review board within the NIH," the email continued. "Given the role of voluntary consent as a fundamental pillar of the ethical conduct of research, NIH has stopped the study out of an abundance of caution."
The study, one of several conducted about AHIs and government personnel, reported that despite severe symptoms, no significant evidence of brain injury and no abnormalities in most clinical measures were found.
The investigation's findings did not affect the study's conclusions, the NIH said.
The agency began studying AHIs in early 2018, engaging experts and enrolling individuals in an exploratory natural history study, noted Leighton Chan, MD, MPH, of the NIH Clinical Center in Bethesda, Maryland, and colleagues in their .
Before the findings were published, Tim Bergreen, JD, of the Bethesda law firm Hogan Lovells, sent an email to JAMA editors and the NIH with a document listing concerns from some study participants. The document, which Bergreen shared with 麻豆传媒, included allegations about ethical issues involving participant recruitment and how medical information was handled, among other things.
AHIs have been referred to as Havana syndrome because the first cases involved American officials and their families living and working at the U.S. Embassy in Cuba. Since then, AHI symptoms have emerged in other countries.
Symptoms usually followed a loud noise and intense pain in the ears and head and included severe headaches, dizziness, blurred vision, tinnitus, or vertigo. In some cases, they led to persistent cognitive, sensory, and balance problems.
Two of the most comprehensive studies on AHIs involved the Havana cases in 2018 and 2019, in their JAMA paper earlier this year.
, researchers at the University of Pennsylvania in Philadelphia documented that some Havana embassy personnel experienced visual and balance problems, headaches, sleep problems, and deficits in working memory, sustained attention, and concentration.
, the Penn team showed that Havana personnel with AHI symptoms had imaging differences in whole brain white matter volume, regional gray and white matter volume, cerebellar tissue microstructural integrity, and functional connectivity compared with healthy individuals.
The overall picture was one of "concussion without concussion," Penn researcher Douglas Smith, MD, who led the Havana clinical studies, previously told 麻豆传媒.
The NIH study published in 2024 was not a replication study, he pointed out. The populations and exposures were different: "It is like trying to compare apples with artichokes," Smith told 麻豆传媒 when the study was published.
"The patients who overlapped were seen in NIH after they had rehab, so there is no comparison to their brains when they were seen at Penn, prior to any kind of treatment," Penn researcher Ragini Verma, PhD, said previously.
A number of other institutions, including the and the , have studied AHIs. To date, the etiology of AHIs remains unknown. Last month, the FBI released a that said AHI symptoms were the result of social contagion.
The total number of people with AHIs also is unknown. At least 334 Americans, mostly intelligence community employees, have qualified for medical AHI care through a federal program run by the Department of Defense (DOD), according to the (GAO).
Of these, only 33 people were entered in the DOD's AHI Registry as of May 2024, GAO said. Key agencies have not signed agreements with DOD, which has contributed to the slow inclusion of AHI patients, the GAO report noted.