Widespread cortical morphological alterations are associated with repetitive blast exposure independent of concussion history
Bibliographic record
Abstract
Abstract Background Concussion is a public health crisis, but mounting evidence indicates that repetitive subconcussive head impacts can also lead to lasting structural and functional brain changes. Subconcussive exposures are common in military environments where personnel are routinely subjected to occupational blast overpressure. While functional consequences of blast exposure are increasingly recognized, corresponding structural alterations remain less consistently reported. Here, we investigated how cumulative subconcussive exposure relates to cortical and subcortical brain structure in a military cohort. Methods Using FreeSurfer, we analyzed high-resolution T1-weighted images from 80 participants (n = 41 high blast, n = 39 low blast; 4 and 8 females, respectively), grouped by lifetime blast exposure history using the generalized blast exposure value. Vertex-wise general linear models tested for cortical differences in cortical volume, thickness, surface area, and curvature, adjusting for age, trauma exposure, and diagnosed concussion count. ANCOVAs evaluated subcortical volume differences. Results Compared to the low blast group, individuals with high blast exposure demonstrated widespread cortical alterations. Across metrics, higher values were predominantly observed in frontal and central regions, including the precentral and superior frontal gyri, whereas lower metrics mainly appeared in temporal, parietal, and occipital cortices. Specifically, high blast participants showed greater cortical volume, thickness, and surface area in precentral and superior frontal regions, higher curvature in frontoparietal and temporal areas, and reduced volume, surface area, and thickness in lateral temporal, parietal, and occipital cortices (e.g., supramarginal, inferior parietal, and lingual gyri) and the entorhinal cortex. Subcortically, high blast participants showed no volumetric differences from the low blast group. Conclusion These findings provide evidence that repetitive subconcussive blast exposure alters cortical morphometry, independent of concussion history, suggesting complex, spatially heterogenous structural changes and highlighting the need for proactive monitoring and mitigation strategies in operational populations.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".