By Deena Beasley
(Reuters) -A U.S. government research team found no significant physical evidence of brain injury in a group of federal employees suffering symptoms of the "Havana syndrome" ailment that emerged in 2016, according to studies published in a medical journal on Monday.
The National Institutes of Health (NIH) researchers also found no differences in most clinical measures between a group of 86 employees and their adult family members reporting unusual health incidents and a group of healthy volunteers with similar work assignments.
Symptoms of the mysterious ailment, first reported by U.S. embassy officials in the Cuban capital Havana and later afflicting diplomats, spies and other personnel worldwide, have included hearing noise and experiencing head pressure followed by headache, migraines, dizziness, and memory lapses.
"These individuals have symptoms that are real, distressing and very difficult to treat," Dr. Leighton Chan, NIH Clinical Center acting chief scientific officer and lead study author, said on a call to discuss the findings published in JAMA.
Study participants, including personnel who had been stationed in Cuba, China, Vienna and the United States, underwent a battery of clinical, auditory, balance, visual, neuropsychological and blood testing. They also received different types of MRI scans aimed at investigating volume, structure and function of the brain.
Mark Zaid, a Washington-based lawyer who has represented Havana sufferers, said the findings of no significant medical differences between the two populations after time had passed "do nothing to undermine the theory that a foreign adversary is harming U.S. personnel and their families with a form of directed energy."
An NIH spokesperson said the studies sought to identify structural brain or biological differences and did not seek to determine whether some external phenomenon was the cause of symptoms, nor could they rule that out.
"We understand that some patients may be disappointed that researchers were unable to identify clear markers of injury," the spokesperson said.
EARLIER STUDY HAD DIFFERENT FINDING
The NIH studies, conducted from 2018-2022, do not match results from a study done at the University of Pennsylvania in 2019, which showed subtle brain changes in those affected.
Chan said the NIH used more rigorous MRI imaging protocols and a control group more closely matched in terms of work activities and location.
The researchers in a statement later said if the symptoms were caused by some external phenomenon, there is no persistent physical evidence, but acknowledged the possibility that such evidence is no longer detectible by methods they used.
An accompanying JAMA editorial from Dr. David Relman, professor at Stanford University School of Medicine, noted that earlier studies concluded that some of the cases could be plausibly explained by exposure to radiofrequency energy.
NIH researchers did find that more than a quarter of patients reporting symptoms developed a chronic condition called persistent postural-perceptual dizziness. They also reported significantly increased symptoms of fatigue, post-traumatic stress and depression, compared to the control group.
The MRI brain imaging results "should be some reassurance for patients," since researchers did not find a link between unusual symptoms and neurodegenerative changes, said Louis French, study investigator from Walter Reed National Military Medical Center.
“The post-traumatic stress and mood symptoms reported are not surprising given the ongoing concerns of many of the participants,” he said.
The U.S. State Department on Monday said it was reviewing the NIH report on what the department calls anomalous health incidents (AHI).
A spokesman said Secretary of State Antony Blinken was determined the department would do "everything possible to ensure employees and family members who report an AHI are treated with respect and compassion and receive timely access to medical care and all benefits to which they are entitled."
U.S. intelligence agencies last year concluded that it was "very unlikely" a foreign adversary was responsible for the Havana syndrome cases.
Dr. Mitchell Valdes, who spearheaded a Cuban task force that investigated the incidents from Havana, said the U.S. intelligence conclusion and NIH studies, were "devastating blows to the entire story that was put together that there was an attack with a mysterious energy weapon that had caused damage to (the diplomats') brain."