The brains of US diplomats who were struck down with a mysterious illness while stationed in Cuba appear to have undergone changes that are unlike any known disorder. The findings are tentative, but if borne out they would undermine the theory that “mass hysteria”, otherwise known as mass psychogenic illness, is to blame.
The diplomats first began reporting strange, unexplained health problems in 2016. These symptoms typically followed loud and unusual sounds, often described as like grinding metal, buzzing, or piercing squeals. Some also reported feelings of pressure or vibrations in the air. Afterwards the staff reported symptoms including nausea, headaches, sleep problems, vertigo, hearing loss and memory and cognitive issues – some of which lasted for months. In 2017, the US government concluded that its staff had been targeted by “an advanced device that operated outside the range of audible sound”.
The symptoms seemed to suggest some kind of brain injury. But last year a team of researchers at the University of Pennsylvania analysed the brains of 21 of the diplomatic staff with magnetic resonance imaging (MRI) and found that all but three of them looked normal.
Ragini Verma at the University of Pennsylvania and her colleagues have now used more advanced imaging techniques to study 40 of the diplomats, and compared the results to a control group.
Verma’s team used functional and structural MRI to get a more detailed picture of the diplomats’ brain volume, connections and tissue health. They found significant differences compared to the controls. The diplomats had less white matter across their whole brains, as well as in the frontal, occipital, and parietal lobes. They also had fewer connections in the regions of the brain responsible for hearing and visuospatial abilities.
“The fact that there were brain differences between patients and controls seems to suggest that there is a neurological basis to the symptoms they are experiencing,” says Lindsey Collins-Praino at the University of Adelaide, Australia.
It remains difficult, however, to determine what that neurological basis is. There was a long delay — between four days and 400 days — between the onset of the symptoms and the scanning of their brains. Plus, some of the diplomats were referred for clinical rehabilitation treatments, which could have itself cause changes, says Collins-Praino.
Interestingly, the diplomats showed the opposite changes in their white matter to what neurologists expect to see after a traumatic injury, says Collins-Praino. That tends to be associated with an increase in the volume of free water in the brain. But the diplomats’ water readings came out lower.
Bryce Vissel at University of Technology Sydney, Australia, says it is difficult to attribute the symptoms the diplomats report to the changes seen with brain imaging because the study was small and we don’t yet know enough about how the brain works. Still, Vissel says it is unlikely the reported illness was caused by ‘mass hysteria’ as some have suggested, given the similar neurological changes seen in this group.
“It’s intriguing that [the diplomats] all had a consistent description of what was going on, and a shared set of experiences, symptoms and cognitive changes, as well as these changes in brain matter imaging.”
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