Home › Research › Getting a diagnosis
Association between recurrent concussion and late-life cognitive impairment in retired professional football players
Guskiewicz KM, Marshall SW, Bailes J, McCrea M, Cantu RC, Randolph C, Jordan BD.. Neurosurgery, 2005-10-01
Topic: Risk, prevention and care in population studies
Objective Cerebral concussion is common in collision sports such as football, yet the chronic neurological effects of recurrent concussion are not well understood. The purpose of our study was to investigate the association between previous head injury and the likelihood of developing mild cognitive impairment (MCI) and Alzheimer's disease in a unique group of retired professional football players with previous head injury exposure. Methods A general health questionnaire was completed by 2552 retired professional football players with an average age of 53.8 (+/-13.4) years and an average professional football playing career of 6.6 (+/- 3.6) years. A second questionnaire focusing on memory and issues related to MCI was then completed by a subset of 758 retired professional football players (> or = 50 yr of age). Results on MCI were then cross-tabulated with results from the original health questionnaire for this subset of older retirees. Results Of the former players, 61% sustained at least one concussion during their professional football career, and 24% sustained three or more concussions. Statistical analysis of the data identified an association between recurrent concussion and clinically diagnosed MCI (chi = 7.82, df = 2, P = 0.02) and self-reported significant memory impairments (chi = 19.75, df = 2, P = 0.001). Retired players with three or more reported concussions had a fivefold prevalence of MCI diagnosis and a threefold prevalence of reported significant memory problems compared with retirees without a history of concussion. Although there was not an association between recurrent concussion and Alzheimer's disease, we observed an earlier onset of Alzheimer's disease in the retirees than in the general American male population. Conclusion Our findings suggest that the onset of dementia-related syndromes may be initiated by repetitive cerebral concussions in professional football players.
Key findings
- Results on MCI were then cross-tabulated with results from the original health questionnaire for this subset of older retirees.
- Results Of the former players, 61% sustained at least one concussion during their professional football career, and 24% sustained three or more concussions.
- Statistical analysis of the data identified an association between recurrent concussion and clinically diagnosed MCI (chi = 7.82, df = 2, P = 0.02) and self-reported significant memory impairments (chi = 19.75, df = 2, P = 0.001).
- Retired players with three or more reported concussions had a fivefold prevalence of MCI diagnosis and a threefold prevalence of reported significant memory problems compared with retirees without a history of concussion.
- Although there was not an association between recurrent concussion and Alzheimer's disease, we observed an earlier onset of Alzheimer's disease in the retirees than in the general American male population.
Why it matters
In a survey of 2,552 retired professional football players, those reporting three or more concussions had a fivefold prevalence of diagnosed mild cognitive impairment and a threefold prevalence of significant memory problems compared with retirees reporting none. The study found no association between recurrent concussion and Alzheimer's disease itself, though Alzheimer's appeared earlier in these retirees than in the general American male population. These are survey-based associations and do not show that concussions cause cognitive decline.
New to this subject? Start with our plain-English guide: Getting a diagnosis →
Study details
- Evidence strengthLow
How this study scored 51/100
Published in a peer-reviewed journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Neurosurgery) |
| Journal's citation record | 3 / 4 | Neurosurgery: journal h-index 300 (OpenAlex, 2026-10-29) |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 2005 — older than 20 years, still counted |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 7 / 7 | Cited 1,013 times (OpenAlex, 2026-10-10) |
| Citations per year | 4 / 5 | 44.0 citations a year over 23 year(s) since 2005 |
| Impact for its field and year | 4 / 6 | Cited 8.7× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 3 / 6 | Cited by 14 other studies in this library |
| Still being cited | 2 / 4 | Cited 27 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 2 / 4 | Last-listed author Barry D. Jordan: h-index 43 (OpenAlex, whole career) |
| Institution's track record | 2 / 3 | Brigham and Women's Hospital: institution h-index 1,995 (OpenAlex) |
| Multi-centre collaboration | 3 / 3 | OpenAlex lists 10 institution(s) in 1 country |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 16239884) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 51 / 100 | — |
What each of these 20 components measures, and what this score is not →
Read the original
May need a subscription OpenAlex found no free copy of the full text (checked 6 Feb 1020), so the publisher may charge for it. The PubMed abstract is free.
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. The record names 7 authors; APA and Vancouver show the first six, BibTeX and the downloads carry all of them. Check the citation against the original before you use it.
APA 7th
Guskiewicz, K. M., Marshall, S. W., Bailes, J., McCrea, M., Cantu, R. C., Randolph, C., et al. (2005). Association between recurrent concussion and late-life cognitive impairment in retired professional football players. Neurosurgery. https://doi.org/10.1093/neurosurgery/57.4.719
Vancouver
Guskiewicz KM, Marshall SW, Bailes J, McCrea M, Cantu RC, Randolph C, et al. Association between recurrent concussion and late-life cognitive impairment in retired professional football players. Neurosurgery. 2005. doi:10.1093/neurosurgery/57.4.719. PMID: 16239884.
BibTeX
@article{guskiewicz2005-16239884,
author = {Guskiewicz, K. M. and Marshall, S. W. and Bailes, J. and McCrea, M. and Cantu, R. C. and Randolph, C. and Jordan, B. D.},
title = {{Association between recurrent concussion and late-life cognitive impairment in retired professional football players}},
journal = {Neurosurgery},
year = {2005},
doi = {10.1093/neurosurgery/57.4.719},
pmid = {16239884},
url = {https://doi.org/10.1093/neurosurgery/57.4.719}
}
Studies this one cites
Referenced by this study and also in the alzhub library, so you can read them here.
Later studies that cite this one
14 studies in the alzhub library list this one in their references. Showing the 8 highest-scoring.
Related studies in Getting a diagnosis
Also tagged “cognitive-function”
1,118 studies in the library carry the topic tag “cognitive-function”; these are this study's neighbours in a fixed, alphabetical-by-hash tour of them, not the closest in content. All 1,118 tagged studies.