Thomas McAllister, Michael McCrea (2017), Journal of Athletic Training (vol. 52, no. 3, pp. 309–317) — DOI-10.4085/1062-6050-52.1.14
Key takeaways
From the reading, NOTE-858.
- Short term is known. “The overwhelming majority of athletes achieve a complete recovery in self-reported symptoms and performance-based measures … by 1 to 2 weeks”. Recurrent concussion is rarer than a first one (3.1 against 22.2 per 100,000 athlete-exposures in high school) and worse acutely.
- Exposure without effect, mostly. Football players take hundreds of head impacts a season (median 257–438 per college team), and season-long studies mostly find no cognitive effect of impact counts. One study found 24% of contact athletes against 3.6% of non-contact athletes below prediction on verbal learning.
- Long term is unmeasured. “To date, no prospective, longitudinal studies of well-defined cohorts over longer periods … have been conducted”. The evidence is surveys of retired players (5 times the MCI prevalence with three or more reported concussions), brain-bank autopsies and case series.
- CTE is uncertain. Its pathology may mark exposure rather than the clinical syndrome, and some critics doubt it is a distinct disease.
- What would settle it. Prospective cohorts of concussed, exposed-but-unconcussed and unexposed athletes with baselines and long follow-up.
Standing in the record
Filed by the reading-time triage of 2026-09-25 (775 seconds of active reading over 1 session), and read in full on 2026-10-14 in NOTE-858. No THEORY, QUESTION or CLAIM cites it, and nothing in the record reads concussion. Its one conclusion is epistemic and dated: as of 2017 the long-term risk of repetitive concussion had not been measured by any design able to measure it. The reading files no THEORY: a narrative review whose claims are other studies’, and a dated statement of ignorance, are not accounts the record should hold. Anyone wanting the current state needs the later prospective studies. No ML connection.