‘Havana syndrome’ not correlated with results of MRI-based biomarkers, neuropsych tests

Key takeaways:

• Two studies examined U.S. government personnel and family members with anomalous health incidents.
• Those affected by “Havana syndrome” did not exhibit cognitive or neurological differences to explain their symptoms.

Two separate studies found no evidence to link anomalous health incidents with MRI-based biomarkers of disease or adverse results of neuropsychological testing among U.S. government staff, their families and matched controls.

“Our goal was to conduct thorough, objective and reproducible evaluations to see if we could identify structural brain or biological differences in people who reported [anomalous health incidents] AHIs,” Leighton Chan, MD, MPH, lead author, chief of rehabilitation medicine and acting chief scientific officer at NIH Clinical Center, said in a press release related to the studies, both published in JAMA.

Chan and fellow researchers conducted an exploratory study between June 2018 and July 2022 to assess whether the AHI experience — known as “Havana syndrome” — of 86 members of the U.S. government staff and family members (mean age 42.1 years) differed significantly from 30 vocationally matched control participants (mean age 43.8 years).

Havana syndrome was so named because it was first reported by U.S. government personnel stationed in Havana and included hearing noise, headache, head pressure, dizziness and other symptoms.

Participants were subjected to a battery of clinical, auditory, vestibular, neuropsychological and blood biomarker testing. Analysis was performed based on risk characteristics of the AHI within concerning cases and geographic locale.

Concurrently, the NIH conducted an exploratory study at its Clinical Center and MRI Research Facility in Maryland between June 2018 and November 2022 to assess the potential of imaging-detected brain lesions in those affected by AHI compared with a control group.

Carlo Pierpaoli, MD, PhD, senior investigator and chief of the Laboratory on Quantitative Medical Imaging at the National Institute of Biomedical Imaging and Bioengineering, and colleagues included 81 individuals who were either U.S. government staff or related family members (mean age 42 years) diagnosed with AHIs, paired with 48 age- and sex-matched controls, 29 of whom were in a similar line of work.

All participants underwent clinical, volumetric and functional MRI, then a high-quality diffusion MRI and second volumetric scan at a separate session. A total of 49 participants with AHI had at least one additional imaging session within a year from the index visit, with imaging performed as soon as 14 days post-AHI.

Chan and colleagues found no significant differences between the AHI group and controls over a mean evaluation period of 76 days with respect to the testing battery, but they observed significantly increased depression, fatigue, imbalance and neurobehavioral issues compared with controls. While 24 individuals with AHI presented with functional neurological disorders, no differences were found based on risk characteristics, incident or geographics of AHIs.

Pierpaoli and colleagues similarly found no significant differences between those with AHI and matched controls in any MRI-related point of analysis. They noted, despite instances of greater differences between groups regarding size of portions and regions of the brain, all participants appeared to register stable longitudinal MRI results, which suggests lack of telltale lesion development or evolution.

“A lack of evidence for an MRI-detectable difference between individuals with AHIs and controls does not exclude that an adverse event impacting the brain occurred at the time of the AHI,” Pierpaoli said in the release.

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