P4‐216: Reduction in Hippocampal Volume is Associated With Age and Memory Deficits in Retired Professional Football Players
Bibliographic record
Abstract
Repeated concussions are associated with post-concussive symptoms including memory impairment. Professional athletes in contact sports seem to be at greater risk of persistent symptoms due to repeated concussions. We used volumetric analysis to test whether repeated concussions have delayed effects in terms of decreased hippocampal volume and poor memory performance in former professional football players. Participants were 38 retired Canadian Football League (ex-CFL) players (age=56.0+12.9 years) and 21 healthy male controls (age=48.3+10.7 years) without history of concussion. Controls from the Alzheimer’s Disease Neuroimaging Initiative database (ADNI) (N=179) were used for validation because of our small control sample size. The number of self-reported concussions in the ex-CFL group ranged from 0-48. Participants underwent a 3T T1-weighted structural MRI scan and a Rey Auditory Verbal Learning Test (RAVLT) to assess verbal memory. Scans were pre-processed using a standard pipeline: image intensity non-uniformity correction, intensity range normalization (0-100), stereotaxic registration and non-linear warping to an average template brain (Montreal Neurological Institute ICBM-152). Volumetric analysis was performed and hippocampal volumes were correlated with age, adjusting for intracranial volume, and with RAVLT word recall scores, adjusting for age. The ex-CFL players showed a significant association between age and left hippocampal (LH) (r=-.60,p<.001) and right hippocampal (RH) volume (r=-.57,p<.001), whereas in controls this trend was non-significant (LH r=-.32,p=.16; RH r=-.33,p=.14, respectively). A similar but significant association was found between age and both the LH and RH volumes (r=-.40,p<.001; r=-.36,p<.001, respectively) in controls from the ADNI database. In the ex-CFL group, we found a correlation between volume of the LH and RH and word recall performance on the RAVLT short delay (r=.45,p=.01; r=.42,p=.02 respectively) and long delay (r=.41,p=.02; r=.38,p=.04 respectively). No association was observed between LH and RH volumes and RAVLT short or long delay scores in our control group. Our data suggest a stronger effect of age on hippocampal volume in ex-CFL than in individuals without a history of concussion. The hippocampal volumes in the ex-CFL were related to performance on a verbal memory task. Multiple concussions may contribute to accelerated aging of the hippocampus that could explain some of the cognitive complaints reported by athletes.
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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 | 0.000 |
| 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".