Cited by 117Amyotrophic Lateral Sclerosis ResearchTraumatic Brain Injury ResearchAlzheimer's disease research and treatments

The DOI matches its Crossref record; 74 of the 76 references it cites were found in a registry or an index; 12 of the 62 sources its claims cite were checked for support.

Association of ALS with head injury, cigarette smoking and APOE genotypes

Open access
Schmidt, Silke, Kwee, Lydia Coulter, Allen, Kelli D., Oddone, Eugene Z.·2010·Journal of the Neurological Sciences

Abstract

Objective An increased risk of ALS has been reported for US veterans, but the cause is unknown. Since head injury and cigarette smoking are two previously implicated environmental risk factors that are more common in military than civilian study populations, we tested their association with ALS in a US veteran study population.Methods We used logistic regression to examine the association of ALS with head injury and cigarette smoking in 241 incident cases and 597 controls. Since APOE is a plausible ALS candidate gene, we also tested its main effect and its statistical interaction with these environmental exposures.Results Cigarette smoking was not associated with ALS in this predominantly male and Caucasian population. Veterans who had experienced head injuries during the last 15years before the reference date had an adjusted odds ratio of 2.33 (95% confidence interval 1.18-4.61), relative to veterans without any head injuries. This association was strongest in APOE-4 carriers.Conclusions Our results add to the body of evidence suggesting that head injuries may be a risk factor for multiple neurodegenerative diseases, including ALS. We hypothesize that the strength of association between head injuries and ALS may depend upon APOE genotype.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

In a US veteran case-control study, cigarette smoking was not associated with ALS, but head injury within the 15 years before the reference date was associated with higher ALS odds. The head-injury association appeared strongest among APOE-4 carriers, though the authors call for replication.

Key findings

  • Among 241 incident ALS cases and 597 controls, cigarette smoking was not associated with ALS, including analyses by never/former/current status, smoking duration, and pack-years.
  • Veterans with head injury in the last 15 years before the reference date had adjusted OR 2.33 (95% CI 1.18–4.61) for ALS relative to no head injuries.
  • The head-injury association was strongest in APOE-4 carriers: genotype-specific OR for injury within ≤15 years was 7.5 (95% CI 1.4–41.3) in APOE-4 carriers, versus 1.9 (0.8–4.4) in APOE 3/3 and 2.2 (0.8–5.6) in APOE-2 carriers.
  • APOE-2 carriage showed a non-significant elevated ALS risk (OR 1.32, 95% CI 0.88–1.98); APOE-4 carriage was not associated with ALS risk.

Methods

  • Case-control study within the GENEVA study of US veterans: 241 incident sporadic ALS cases with interviews and 597 veteran controls; APOE genotypes were available for 417 cases and 482 controls.
  • Structured telephone interviews assessed head injury and cigarette smoking; APOE genotypes were determined from rs7412 and rs429358.
  • Unconditional logistic regression estimated ALS associations adjusted for age, sex, race/ethnicity, and education, with gene-environment interaction tests between APOE, smoking, and head-injury interval.

Limitations

  • The authors state the study is not population-based, case and control enrollment methods were not identical, and case enrollment may have increased the proportion of more slowly progressing individuals.
  • The authors note control participation was 41%, they lacked detailed context/severity of head injuries, and genotype-specific categories were limited with wide confidence intervals requiring replication.
  • Evident from the text: the sample was predominantly male and Caucasian veterans, so generalizability to other populations is limited; exposure and injury data were self-reported, and the observational design cannot establish causality.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1016/j.jns.2010.01.011

Cites

74 of 74 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

31 Own result · 28 Own method · 20 No full text of the sources · 13 Own interpretation · 6 Supported so far · 4 Supported · 2 Partly supported · 1 No basis given · accuracy not yet measured

Show all 51 claims

  • Probably not a substantial claim. 41
  • It may state two separate claims as one. 26
  • The quote only partly states this claim. 1
54 of 54
  • The paper relies on this without support.

    Excluding head injuries reported within two years of the reference date is sufficient to remove injuries caused by early ALS symptoms.

    “To reduce recall bias, and to account for the fact that injuries reported by ALS cases may be due to early signs of muscle weakness, any head injuries reported within two years of the reference date were excluded.”
  • The paper relies on this without support.

    The association between head injury and ALS is not due to unmeasured confounding.

    “All results were adjusted for age, sex, race/ethnicity and education.”
  • The paper relies on this without support.

    Excluding smoking data reported within the last two years before the reference date is sufficient to remove smoking changes caused by early ALS symptoms.

    “to account for the fact that ALS cases may stop smoking due to early signs of the disease, smoking data (duration, dose) reported within the last two years before the reference date were excluded”
  • The paper relies on this without support.

    Most previous studies of ALS and head injury did not include a more detailed analysis of the injury-to-onset interval or the age at which head injuries occurred.

    “Most previous studies of ALS and head injury did not include a more detailed analysis of the injury-to-onset interval or the age at which head injuries occurred.”
  • The paper relies on this without support.

    None of the studies conducted to date examined APOE genotypes jointly with head injuries.

    “None of the studies conducted to date examined APOE genotypes jointly with head injuries.”
  • The paper relies on this without support.

    The success of GWAS in ALS has been much more limited than for other complex human diseases.

    “the success of GWAS in ALS has been much more limited than for other complex human diseases.”
  • The paper relies on this without support.

    Environmental risk factors have been completely ignored in all of the ALS GWAS studies published to date.

    “environmental risk factors, which have been completely ignored in all of the ALS GWAS studies published to date.”
  • The paper relies on this without support.

    Recall bias would lead to under-reporting of milder injuries by controls.

    “which would be expected to lead to under-reporting of milder injuries by controls.”
8 of 8

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Metadata

Authors
Schmidt, S., Kwee, L. C., Allen, K. D., & Oddone, E. Z.
Affiliations
Duke Medical Center (US)
Corresponding author
Schmidt, Silke
Venue
Journal of the Neurological Sciences
Publisher
Elsevier BV
Published
2010-04
Volume
291
Issue
1-2
Pages
22-29
ISSN
0022-510X (ISSN-L)
OpenAlex
W1988832005
Cited by
117
References
76
Citations by year
2026: 2 · 2025: 4 · 2024: 2 · 2023: 3 · 2022: 4 · 2021: 5 · 2020: 4 · 2019: 7 · 2018: 7 · 2017: 7 · 2016: 10 · 2015: 13 · 2014: 14 · 2013: 6 · 2012: 15
FWCI
6.67
Type
journal article
Language
en
Open access
Locations
  • Journal of the Neurological Sciences (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
National Institute of Environmental Health Sciences (R01ES013244)
Topics
  • Health Sciences › Medicine › Clinical Neurology › Amyotrophic Lateral Sclerosis Research
  • Health Sciences › Medicine › Clinical Neurology › Traumatic Brain Injury Research
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Alzheimer's disease research and treatments
Keywords
amyotrophic lateral sclerosis, traumatic brain injury, cigarette smoking, APOE genotype, APOE ε4, veterans, environmental risk factors, gene-environment interaction, neurodegenerative diseases
MeSH terms
Amyotrophic Lateral Sclerosis, Apolipoproteins E, Environmental Exposure, Female, Genotype, Craniocerebral Trauma, Heterozygote, Humans, Male, Middle Aged, Risk Factors, Smoking, United States, Veterans, Logistic Models, Odds Ratio, Genetic Predisposition to Disease, White People, Apolipoprotein E4

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