Apolipoprotein E epsilon4 associated with chronic traumatic brain injury in boxing
Jordan BD, Relkin NR, Ravdin LD, Jacobs AR, Bennett A, Gandy S.. JAMA, 1997-07-01
Topic: Brain proteins, microglia and lab models
Context Given the similarities between Alzheimer disease and dementia pugilistica, we evaluated the relationship between apolipoprotein E (APOE) genotype and chronic traumatic brain injury (CTBI) in boxers to determine whether there is a genetic susceptibility to the effects of head trauma. Objective To assess the relationship between CTBI and APOE genotype in boxers. Design and setting Clinical characterization of 24 volunteer and 6 referred boxers in an outpatient setting. Participants Thirty professional boxers aged 23 to 76 years underwent neurologic and behavioral assessment in conjunction with APOE genotyping. Main outcome measures Apolipoprotein E genotype was examined in relationship to measures of CTBI. A 10-point clinical rating scale (0-9), the Chronic Brain Injury (CBI) scale, was devised to assess the severity of traumatic encephalopathy associated with boxing. Boxers with abnormal CTBI scores were further classified on the basis of whether their impairments were possibly or probably related to boxing. Scores were analyzed in relation to boxing exposure (number of bouts) and APOE genotype. Results Among the 30 boxers, 11 were found to be normal (CBI score=0), 12 showed mild deficits (CBI score=1-2), 4 were moderately impaired (CBI score=3-4), and 3 showed signs of severe impairment (CBI score > 4). High-exposure boxers (ie, those with > or = 12 professional bouts) had significantly higher CBI scores (mean [SD], 2.6 [1.9]) than low-exposure boxers (mean [SD], 0.3 [0.7]) (P Conclusions These preliminary findings suggest that possession of an APOE epsilon4 allele may be associated with increased severity of chronic neurologic deficits in high-exposure boxers.
Key findings
- A 10-point clinical rating scale (0-9), the Chronic Brain Injury (CBI) scale, was devised to assess the severity of traumatic encephalopathy associated with boxing.
- Results Among the 30 boxers, 11 were found to be normal (CBI score=0), 12 showed mild deficits (CBI score=1-2), 4 were moderately impaired (CBI score=3-4), and 3 showed signs of severe impairment (CBI score > 4).
- High-exposure boxers (ie, those with > or = 12 professional bouts) had significantly higher CBI scores (mean [SD], 2.6 [1.9]) than low-exposure boxers (mean [SD], 0.3 [0.7]) (P<.001), indicating that neurologic impairment as measured by the CBI scale seems related to boxing exposure.
Why it matters
In this study of 30 professional boxers, high-exposure boxers had significantly higher scores on a chronic brain injury scale, and APOE genotype was examined in relation to these measures. It is a small study and does not report a treatment, cure, or prevention for Alzheimer's disease.
New to this subject? Start with our plain-English guide: Genetics →
Study details
- Evidence strengthLow
How this study scored 48/100
Published in a top-tier journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it. We have no data on institution's track record, so that was left out: it earned 47 of the 97 points we could judge it on, which is 48 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 10 / 10 | Tier 1 — top-tier general journal (JAMA) |
| Journal's citation record | 4 / 4 | JAMA: journal h-index 1,011 (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 | 1997 — 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 | 6 / 7 | Cited 428 times (OpenAlex, 2026-10-10) |
| Citations per year | 3 / 5 | 13.8 citations a year over 31 year(s) since 1997 |
| Impact for its field and year | 4 / 6 | Cited 13.3× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 3 / 6 | Cited by 12 other studies in this library |
| Still being cited | 1 / 4 | Cited 14 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 | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | 0 / 3 | OpenAlex lists 0 institution(s) in 0 countries — scores zero (affiliation lists can be incomplete) |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 9214529) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 47 / 97 | Scored on 19 of 20 parts. We have no data for the rest, so they are left out: 47 of the 97 points we could judge it on is 48 out of 100. |
| Total | 48 / 100 | — |
What each of these 20 components measures, and what this score is not →
Read the original
May need a subscription Unpaywall, Europe PMC and OpenAlex found no free copy of the full text (checked 10 Oct 2026), 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. Check the citation against the original before you use it.
APA 7th
Jordan, B. D., Relkin, N. R., Ravdin, L. D., Jacobs, A. R., Bennett, A., & Gandy, S. (1997). Apolipoprotein E epsilon4 associated with chronic traumatic brain injury in boxing. JAMA. https://doi.org/10.1001/jama.1997.03550020068040
Vancouver
Jordan BD, Relkin NR, Ravdin LD, Jacobs AR, Bennett A, Gandy S. Apolipoprotein E epsilon4 associated with chronic traumatic brain injury in boxing. JAMA. 1997. doi:10.1001/jama.1997.03550020068040. PMID: 9214529.
BibTeX
@article{jordan1997-9214529,
author = {Jordan, B. D. and Relkin, N. R. and Ravdin, L. D. and Jacobs, A. R. and Bennett, A. and Gandy, S.},
title = {{Apolipoprotein E epsilon4 associated with chronic traumatic brain injury in boxing}},
journal = {JAMA},
year = {1997},
doi = {10.1001/jama.1997.03550020068040},
pmid = {9214529},
url = {https://doi.org/10.1001/jama.1997.03550020068040}
}
Later studies that cite this one
12 studies in the alzhub library list this one in their references. Showing the 8 highest-scoring.
Related studies in Genetics
Also tagged “mice”
1,150 studies in the library carry the topic tag “mice”; these are this study's neighbours in a fixed, alphabetical-by-hash tour of them, not the closest in content. All 1,150 tagged studies.