The DOI matches its Crossref record; 34 of the 35 references it cites were found in a registry or an index; none of the 10 sources its claims cite is checked for support yet.
Head Injury and Amyotrophic Lateral Sclerosis
Open accessAbstract
Recent data showed that soccer players in Italy had an unusually high risk of amyotrophic lateral sclerosis (ALS) and that repeated head trauma might have contributed to this increase. The authors examined whether head injury was related to ALS risk in a case-control study of 109 New England ALS cases diagnosed in 1993-1996 and 255 matched controls. They also conducted a meta-analysis of the published literature. Overall, ever having experienced a head injury was nonsignificantly associated with a higher ALS risk. When compared with persons without a head injury, a statistically significant ALS risk elevation was found for participants with more than one head injury (odds ratio (OR) = 3.1, 95 percent confidence interval (CI): 1.2, 8.1) and patients who had had a head injury during the past 10 years (OR = 3.2, 95 percent CI: 1.0, 10.2). For participants who had had multiple head injuries with the latest occurring in the past 10 years, risk was elevated more than 11-fold. The meta-analysis also indicated a moderately elevated risk of ALS among persons with previous head injuries (OR = 1.7, 95 percent CI: 1.3, 2.2). In this study population, physical injuries to other body parts, including the trunk, arms, or legs, were not related to ALS risk. These data support the notion that head injury may increase the risk of ALS.
Overview
AI snapshot
Written from the paper’s full text.
TL;DR
In a New England case-control study, head injury was not significantly associated with ALS overall, but repeated head injuries and recent head injuries were associated with higher ALS risk. A meta-analysis of published studies plus the current study found a pooled odds ratio of 1.7 for ALS among persons with previous head injury.
Key findings
- Ever having had a head injury was nonsignificantly associated with ALS (adjusted OR = 1.4, 95% CI: 0.8, 2.6).
- ALS risk was elevated for more than one head injury (adjusted OR = 3.1, 95% CI: 1.2, 8.1) and for head injury in the past 10 years (adjusted OR = 3.2, 95% CI: 1.0, 10.2); multiple head injuries with the latest in the past 10 years showed more than an 11-fold higher risk (adjusted OR = 11.3, 95% CI: 1.1, 114.3).
- The meta-analysis found a pooled OR of 1.7 (95% CI: 1.3, 2.2; p < 0.001) for ALS among persons with previous head injuries.
- Injuries to other body sites, including trunk, arms, or legs, were not related to higher ALS risk.
Methods
- Case-control study of 109 ALS cases diagnosed in 1993–1996 from two New England referral centers and 255 frequency-matched controls; structured questionnaire assessed injuries severe enough to require medical attention, with unconditional logistic regression adjusted for matching factors, smoking, and education.
- Meta-analysis of published studies since 1980 identified through MEDLINE and reference lists; one study was excluded because a risk estimate could not be calculated, and a fixed-effects model was used because no statistical heterogeneity was found (p for heterogeneity = 0.1).
Limitations
- The paper states that cases were interviewed in person and controls by telephone, raising concern about potential bias; analyses were limited by small sample sizes, so chance cannot be excluded; exposure assessment was not independently validated; the meaning of “severe injury” was open to interpretation; and defining head injury as requiring medical attention may limit generalizability.
- Evident from the text: the 11-fold estimate came from a post-hoc exploratory analysis based on small numbers, and in the meta-analysis, except for the current study, risk estimates were not adjusted for potential confounders and nearly all studies lacked sufficient details for further analysis.
Model-written summary. Check it against the paper before relying on it.
Integrity signals
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Verification
Claims the paper makes
12 Own result · 7 Sources not found · 7 Own method · 7 Own interpretation
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“For participants who had had multiple head injuries with the latest occurring in the past 10 years, risk was elevated more than 11-fold.”
- Also stated in: § Head Injury and ALS 811 · hedged
“A post-hoc exploratory analysis based on small numbers showed that persons who had experienced repeated head injuries with the latest occurring in the past 10 years had more than an 11-fold higher ALS risk than those without a head injury.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Abstract
plaincorrelationaln = 3- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Rests on an assumption: Self-reported severe head injury requiring medical attention accurately reflects true head injury exposure.
- Also stated in: § Head Injury and ALS 811 · hedged
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“and patients who had had a head injury during the past 10 years (OR ¼ 3.2, 95 percent CI: 1.0, 10.2).”
- Also stated in: § Head Injury and ALS 811 · hedged
“Detailed analyses (table 2) indicated that having experienced repeated head injuries or having been injured within the 10 years before diagnosis was associated with a more than threefold higher risk of ALS (OR ¼ 3.1 (95 percent CI: 1.2, 8.1) and OR ¼ 3.2 (95 percent CI: 1.0, 10.2), respectively).”
§ Head Injury and Amyotrophic Lateral Sclerosis > Abstract
plaincorrelationaln = 109 ·- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Rests on an assumption: Self-reported severe head injury requiring medical attention accurately reflects true head injury exposure.
- Also stated in: § Head Injury and ALS 811 · hedged
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Finally, cases with head injuries were more likely to have a bulbar onset (33.3 percent vs. 22.4 percent; p ¼ 0.3)”
- Also stated in: § DISCUSSION · plain
“Consistent with the recent reports on ALS among Italian soccer players (4, 5), ALS cases with a previous head injury were more likely to have an early and bulbar onset.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Head Injury and ALS 811
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Rests on an assumption: Self-reported severe head injury requiring medical attention accurately reflects true head injury exposure.
- Also stated in: § DISCUSSION · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“and an earlier age of diagnosis than cases without previous head injuries (54.0 years vs. 59.5 years; p ¼ 0.05).”
- Also stated in: § DISCUSSION · hedged
“Consistent with the recent reports on ALS among Italian soccer players (4, 5), ALS cases with a previous head injury were more likely to have an early and bulbar onset.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Head Injury and ALS 811
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Rests on an assumption: Self-reported severe head injury requiring medical attention accurately reflects true head injury exposure.
- Also stated in: § DISCUSSION · hedged
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Overall, ever having experienced a head injury was nonsignificantly associated with a higher ALS risk.”
- Also stated in: § Head Injury and ALS 811 · hedged
“Among individual body sites, only head injury tended to be associated with a higher risk of ALS (odds ratio (OR) ¼ 1.4, 95 percent confidence interval (CI): 0.8, 2.6), but the association was not statistically significant.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Abstract
plaincorrelationaln = 109- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Rests on an assumption: Self-reported severe head injury requiring medical attention accurately reflects true head injury exposure.
- Also stated in: § Head Injury and ALS 811 · hedged
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“When compared with persons without a head injury, a statistically significant ALS risk elevation was found for participants with more than one head injury (odds ratio (OR) ¼ 3.1, 95 percent confidence interval (CI): 1.2, 8.1)”
- Also stated in: § Head Injury and ALS 811 · hedged
“Detailed analyses (table 2) indicated that having experienced repeated head injuries or having been injured within the 10 years before diagnosis was associated with a more than threefold higher risk of ALS (OR ¼ 3.1 (95 percent CI: 1.2, 8.1) and OR ¼ 3.2 (95 percent CI: 1.0, 10.2), respectively).”
§ Head Injury and Amyotrophic Lateral Sclerosis > Abstract
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Rests on an assumption: Self-reported severe head injury requiring medical attention accurately reflects true head injury exposure.
- Also stated in: § Head Injury and ALS 811 · hedged
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The meta-analysis also indicated a moderately elevated risk of ALS among persons with previous head injuries (OR ¼ 1.7, 95 percent CI: 1.3, 2.2).”
- Also stated in: § Head Injury and ALS 811 · plain
“Nevertheless, the meta-analysis revealed a significant association between head injury and risk of ALS: Compared with persons without head injury, the risk of ALS was 1.7 times (95 percent CI: 1.3, 2.2; p < 0.001) higher among persons with head injuries.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Abstract
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Rests on an assumption: The unadjusted risk estimates from the published studies included in the meta-analysis are valid enough to combine into a summary estimate.
- Also stated in: § Head Injury and ALS 811 · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The only change was that the odds ratio for head injury within the past 10 years was even higher (OR ¼ 5.6, 95 percent CI: 1.3, 24.4) in the 3-year-lagged analysis.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Head Injury and ALS 811
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Rests on an assumption: Self-reported severe head injury requiring medical attention accurately reflects true head injury exposure.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Overall, ever having had an injury was not related to a higher risk of ALS (table 1).”
§ Head Injury and Amyotrophic Lateral Sclerosis > Head Injury and ALS 811
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Rests on an assumption: Self-reported severe head injury requiring medical attention accurately reflects true head injury exposure.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In this study population, physical injuries to other body parts, including the trunk, arms, or legs, were not related to ALS risk.”
- Also stated in: § Head Injury and ALS 811 · plain
“In contrast to head injury, no other injuries were related to a higher risk of ALS.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Abstract
plainn = 109- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Rests on an assumption: Self-reported severe head injury requiring medical attention accurately reflects true head injury exposure.
- Also stated in: § Head Injury and ALS 811 · plain
- It may state two separate claims as one. 11
- Probably not a substantial claim. 4
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Interestingly, three of the four cases (75 percent) with repeated head injuries with the latest occurring in the 10 years before diagnosis had a bulbar onset, and despite the small sample size, the proportion was significantly greater than that among cases without head injuries (Fisher's exact test: p < 0.05).”
§ Head Injury and Amyotrophic Lateral Sclerosis > Head Injury and ALS 811
plaincorrelationaln = 4 ·- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Rests on an assumption: Self-reported severe head injury requiring medical attention accurately reflects true head injury exposure.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“Controls were frequencymatched to cases by age (30-55, 56-65, and 66-80 years), gender, and telephone area code (as a surrogate for region within New England), at a ratio of 3:1 for the Boston area and 2:1 for other areas in New England.”
§ Head Injury and Amyotrophic Lateral Sclerosis > MATERIALS AND METHODS
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In this case-control study, head injury was associated with an elevated risk of ALS, particularly for recent repeated head injuries.”
§ Head Injury and Amyotrophic Lateral Sclerosis > DISCUSSION
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
In the paper
“The only prospective study included 821 patients with documented head injury, but only one ALS patient was identified during follow-up (17).”
§ Head Injury and Amyotrophic Lateral Sclerosis > Head Injury and ALS 813
What the sources say
- Not matchedcites [17]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Not matched
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“Finally, we conducted multivariate analyses to adjust for several potential confounders.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Head Injury and ALS 813
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
In the paper
“This finding was subsequently confirmed by an incidence study carried out among 7,325 Italian professional soccer players who had played between 1970 and 2001 (5).The incidence of ALS was 6.5 times higher than expected, and cases were clinically characterized by early onset and bulbar involvement at diagnosis.”
§ Head Injury and Amyotrophic Lateral Sclerosis > DISCUSSION
What the sources say
- Not matchedcites [5]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Not matched
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“As with many of the previous studies, the statistical analyses were limited by small sample sizes.Therefore, we cannot exclude chance as a potential explanation for the findings.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Head Injury and ALS 813
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
None of the sources cited for this claim could be matched to a paper in Crossref, so there is nothing to check it against.
In the paper
“Recent findings from both clinical observations of asymptomatic SOD1 mutant carriers (18) and experimental studies of SOD1 mutant mice (19) suggest that the preclinical motor neuron loss in ALS, like its postdiagnosis clinical course, may be dramatic and aggressive, indicating the importance of recent acute exposure or cumulative exposure as opposed to exposure in the distant past.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Head Injury and ALS 813
What the sources say
- Not matchedcites [18]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Not matchedcites [19]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Not matched
In the paper
“Recent data showed that ALS mortality among Italian professional soccer players was approximately 12-fold higher than expected (4), while mortality from other causes was generally lower than or comparable to that of the general population.”
§ Head Injury and Amyotrophic Lateral Sclerosis > DISCUSSION
What the sources say
- Not matchedcites [4]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Not matched
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Consistently, the detailed analyses from our study support this link and further suggest that recent repeated injuries may be more etiologically relevant.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Head Injury and ALS 813
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“Finally, exposure assessment in the current study was not independently validated, and the meaning of severe injury was, to some extent, open to individual interpretation.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Head Injury and ALS 813
hedged- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Furthermore, the definition of head injury as an injury requiring medical attention may limit the generalizability of our findings somewhat.”
§ Head Injury and Amyotrophic Lateral Sclerosis > Head Injury and ALS 813
hedged- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
None of the sources cited for this claim could be matched to a paper in Crossref, so there is nothing to check it against.
In the paper
“By the same token, significant recall bias is not a likely explanation for our results, since antecedent reports more frequently implicated injuries involving the shoulders and arms (12, 13)-findings which might have been more publicized among patients.”
§ Head Injury and Amyotrophic Lateral Sclerosis > DISCUSSION
What the sources say
- Not matchedcites [12]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Not matchedcites [13]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
hedged- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Not matched
In the paper
“Clinical observations and case-control studies have suggested that physical trauma may be associated with a higher risk of ALS, but the evidence is far from conclusive (3).”
§ Head Injury and Amyotrophic Lateral Sclerosis > Abstract
What the sources say
- Not matchedcites [3]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
hedgedcorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. It may state two separate claims as one.
- Not matched
The paper relies on this without support.
Self-reported severe head injury requiring medical attention accurately reflects true head injury exposure.
“Finally, exposure assessment in the current study was not independently validated, and the meaning of severe injury was, to some extent, open to individual interpretation.”
The paper relies on this without support.
The unadjusted risk estimates from the published studies included in the meta-analysis are valid enough to combine into a summary estimate.
“Except in the current study, risk estimates were not adjusted for potential confounders.”
The paper relies on this without support.
The New England case-control study population is representative enough to generalize the observed association to the American population.
“In summary, in line with the recent observations of higher ALS risk among Italian soccer players, we found that recent repeated head injury was related to a higher risk of ALS in an American population.”
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
The source backs part of the claim, not all of it — or backs it for a different population, condition or comparison.
In the citing paper
“Chen et al found that individuals were 11 times more likely to develop ALS if they reported multiple head injuries within the last 10 years prior to diagnosis (14), although other studies have not found a modifying effect of head injury on ALS (15).”
From Chronic Traumatic Encephalopathy Within an Amyotrophic Lateral Sclerosis Brain Bank Cohort (2018) · cites this paper as [14]
Experimental — accuracy not yet measuredThe source backs part of the claim, not all of it — or backs it for a different population, condition or comparison.
In the citing paper
“Chen et al. (10) reported a significant association for head injury overall in a meta-analysis of eight studies; however, some of the studies in the meta-analysis may have been influenced by recall bias.”
From Severe head injury and amyotrophic lateral sclerosis (2013) · cites this paper as [10]
Experimental — accuracy not yet measuredThe source backs part of the claim, not all of it — or backs it for a different population, condition or comparison.
In the citing paper
“Some studies have reported that multiple head injuries and age at first head injury were associated with ALS, which is also consistent with the findings we observed in our study [18,20,61,62].”
From Head Injury and Amyotrophic Lateral Sclerosis: Population-Based Study from the National ALS Registry (2025) · cites this paper as [20]
Experimental — accuracy not yet measuredThe cited source says what the claim attributes to it.
In the citing paper
“One such environmental risk factor may be traumatic brain injury (TBI).Chen et al found that individuals were 11 times more likely to develop ALS if they reported multiple head injuries within the last 10 years prior to diagnosis (14)”
From Chronic Traumatic Encephalopathy Within an Amyotrophic Lateral Sclerosis Brain Bank Cohort (2018) · cites this paper as [14]
The cited source says what the claim attributes to it.
In the citing paper
“and head injuries (14;20–22).”
From Association of ALS with head injury, cigarette smoking and APOE genotypes (2010) · cites this paper as [21]
The cited source says what the claim attributes to it.
In the citing paper
“As expected, the prevalence of both cigarette smoking and head injuries was higher in GENEVA controls than in population-based studies of civilian controls of similar age (ever vs. never smoking: 64.2% vs. 53.4% in (4); at least one head injury: 31.0% vs. 16.4% in (21)).”
From Association of ALS with head injury, cigarette smoking and APOE genotypes (2010) · cites this paper as [21]
The cited source says what the claim attributes to it.
In the citing paper
“In that study, the strongest association was observed for the interval “<=10 years between last injury and diagnosis” (OR 3.2, 95% CI 1.0–10.2), with a slightly elevated risk for the interval 11–30 years.”
From Association of ALS with head injury, cigarette smoking and APOE genotypes (2010) · cites this paper as [21]
The cited source says what the claim attributes to it.
In the citing paper
“Our results are consistent with a recently reported trend for an increasing ALS association with a decreasing number of years between the last head injury and ALS diagnosis, and with an increasing age at the last injury (21).”
From Association of ALS with head injury, cigarette smoking and APOE genotypes (2010) · cites this paper as [21]
The cited source says what the claim attributes to it.
In the citing paper
“Consistent with previous epidemiologic studies of head injury in PD (55;56) and ALS (21), our data also support the existence of a relatively long period of latency between injury and ALS onset, since head injuries up to 15 years before the reference date contributed to the observed increased odds of ALS.”
From Association of ALS with head injury, cigarette smoking and APOE genotypes (2010) · cites this paper as [21]
The cited source says what the claim attributes to it.
In the citing paper
“The same study also estimated a pooled OR of 1.7 (95% CI 1.3–2.2) for at least one previous head injury, based on a meta-analysis of eight ALS studies.”
From Association of ALS with head injury, cigarette smoking and APOE genotypes (2010) · cites this paper as [21]
In the citing paper
“In particular, repeated mTBI (rmTBI) has been identified as a major risk factor for neurodegenerative diseases including Alzheimer’s disease (AD) [100], Parkinson’s disease (PD) [68] amyotrophic lateral sclerosis (ALS) [21, 2], fronto-temporal dementia (FTD) [126, 124], and chronic traumatic encephalopathy (CTE) [95].”
From Early onset senescence and cognitive impairment in a murine model of repeated mTBI (2021) · cites this paper as [21]
In the citing paper
“Some data suggests that trauma and athletic exposure are risk factors for developing ALS [30, 31, 166], although there are conflicting reports regarding single versus repetitive head injury [24].”
From The neuropathology of sport (2014) · cites this paper as [24]
Citations
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Severely increased risk of amyotrophic lateral sclerosis among Italian professional football players
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Clinical limits of amyotrophic lateral sclerosis.
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Head injury and Parkinson's disease risk in twins
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A CASE-CONTROL STUDY OF AMYOTROPHIC LATERAL SCLEROSIS1
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Lead Exposure and Amyotrophic Lateral Sclerosis
Kamel, F., Umbach, D. M., Munsat, T. L., Shefner, J. M., Hu, H., & Sandler, D. P. (2002) · Epidemiology · doi:10.1097/00001648-200205000-00012 · Cited by 170
Self-citation
Research works printed but not linked: 1
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The neuropathology of traumatic brain injury
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Neuroimmunology of Traumatic Brain Injury: Time for a Paradigm Shift
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A comprehensive review of amyotrophic lateral sclerosis
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Metadata
- Authors
- Chen, H., Richard, M., Sandler, D. P., Umbach, D. M., & Kamel, F.
- Affiliations
- National Institutes of Health (US)
- Westat (United States) (US)
- National Institute of Environmental Health Sciences (US)
- Venue
- American Journal of Epidemiology
- Publisher
- Oxford University Press (OUP)
- Published
- 2007-06-27
- Volume
- 166
- Issue
- 7
- Pages
- 810-816
- ISSN
- 0002-9262 (ISSN-L)
- 1476-6256
- PMC
- PMC2239342
- OpenAlex
- W2152476219
- Cited by
- 279
- References
- 35
- Citations by year
- 2026: 8 · 2025: 11 · 2024: 12 · 2023: 15 · 2022: 11 · 2021: 19 · 2020: 19 · 2019: 16 · 2018: 19 · 2017: 19 · 2016: 24 · 2015: 25 · 2014: 18 · 2013: 12 · 2012: 13
- FWCI
- 5.76
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- American Journal of Epidemiology (publishedVersion)
- PubMed (publishedVersion)
- PubMed Central (acceptedVersion)
- Funders
- National Institutes of Health (Z01-ES049005)
- Topics
- Health Sciences › Medicine › Clinical Neurology › Amyotrophic Lateral Sclerosis Research
- Health Sciences › Medicine › Clinical Neurology › Traumatic Brain Injury Research
- Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports injuries and prevention
- Keywords
- amyotrophic lateral sclerosis, traumatic brain injury, repeated head trauma, ALS risk factors, soccer players, sports injuries
- MeSH terms
- Adult, Aged, Aged, 80 and over, Amyotrophic Lateral Sclerosis, Female, Craniocerebral Trauma, Humans, Life Style, Male, Middle Aged, New England, Risk Factors, Soccer, Confidence Intervals, Odds Ratio, Case-Control Studies, Risk Assessment
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
A language model drew the claims from the paper on 2026-11-07, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).
A second model labelled each claim on 2026-11-07 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
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