NIH studies find severe symptoms of “Havana Syndrome,” but no evidence of MRI-detectable brain injury or biological abnormalities Compared to healthy volunteers, affected U.S. government personnel did not exhibit differences that would explain symptoms.

https://www.nih.gov/news-events/news-releases/nih-studies-find-severe-symptoms-havana-syndrome-no-evidence-mri-detectable-brain-injury-or-biological-abnormalities