Post-Concussion Brain Changes Relative to Pre-Injury White Matter and Cerebral Blood Flow
Bibliographic record
Abstract
BACKGROUND AND OBJECTIVES: Medical clearance for return to play (RTP) after sports-related concussion is based on clinical assessment. It is unknown whether brain physiology has entirely returned to preinjury baseline at the time of clearance. In this longitudinal study, we assessed whether concussed individuals show functional and structural MRI brain changes relative to preinjury levels that persist beyond medical clearance. Secondary objectives were to test whether postconcussion changes exceed uninjured brain variability and to correlate MRI findings with clinical recovery time. METHODS: For this prospective observational study, healthy athletes without a history of psychiatric, neurologic, or sensory-motor conditions were recruited from a single university sport medicine clinic. Clinical and MRI data were collected at preseason baseline, and those who were later concussed were reassessed at 1-7 days after injury, RTP, 1-3 months after RTP, and 1 year after RTP. A demographically matched control cohort of uninjured athletes was also reassessed at their subsequent preseason baseline. Primary outcomes were postconcussion changes in MRI measures of cerebral blood flow (CBF), white matter mean diffusivity (MD), and fractional anisotropy (FA), evaluated using mixed models. Secondary outcomes were group differences in MRI change scores and correlations of change scores with days to RTP. RESULTS: , z = -6.07) in the corona radiata and internal capsule. Effects persisted beyond RTP, although only CBF changes exceeded longitudinal variability in controls. For participants with longer recovery periods, significantly greater changes in medial temporal CBF were also seen (ρ = 0.64 [0.44, 0.81], z = 6.80). DISCUSSION: This study provides direct evidence of persistent postconcussion changes in CBF and white matter at RTP and up to 1 year later. These results support incomplete recovery of brain physiology at medical clearance, with secondary analyses emphasizing the sensitivity of CBF to clinical recovery.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".