Havana Syndrome Among Canadian Diplomats: Brain Imaging Reveals Acquired Neurotoxicity
Bibliographic record
Abstract
Abstract BACKGROUND In late 2016, US diplomats stationed in Havana began presenting with a variety of neurological manifestations that proved difficult to diagnose. Though previous studies suggested a likely association with brain injury, the mechanism of injury, brain regions involved, and etiology remained unknown. METHODS We conducted a multimodal study examining 26 Canadian diplomats and their family members, the majority of whom presented with symptoms similar to their American counterparts while residing in Havana. Assessments included a medical history, self-reported symptom questionnaires, cognitive assessments, blood tests, and brain imaging assessments (magnetic resonance imaging (MRI) and magnetoencephalography (MEG)). Individuals showing signs of brain injury underwent further neurological, visual, and audio-vestibular assessments. Eight participants were tested both before and after living in Havana. RESULTS Our assessment documents multiple functional and structural impairments, including significant spatial memory impairment, abnormal brain-stem evoked potentials, degradation of fibre tracts in the fornix and posterior corpus callosum, blood-brain barrier injury to the right basal forebrain and anterior insula, and abnormal paroxysmal slowing events of cortical activity. Subsequent mass-spectrometry and blood analyses documented reduced serum cholinesterase activity and the presence of organophosphates (Temephos) and pyrethroid metabolites (3-phenoxybenzoic acid or 3-BPA). CONCLUSIONS Our findings confirm brain injury, specify the regions involved, and raise the hypothesis of overexposure to cholinesterase inhibitors as a plausible etiology. If correct, our hypothesis bears public health ramifications (see Discussion) and suggests a course of action for reducing exposure in the future. FUNDING Global Affairs Canada.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".