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Cited by 398Traumatic Brain Injury ResearchTraumatic Brain Injury and Neurovascular DisturbancesDementia and Cognitive Impairment Research

Association of Mild Traumatic Brain Injury With and Without Loss of Consciousness With Dementia in US Military Veterans

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Barnes, Deborah E., Byers, Amy L., Gardner, Raquel C., Seal, Karen H., Boscardin, W. John, Yaffe, Kristine·2018·JAMA Neurology
DOI 10.1001/jamaneurol.2018.0815PMC PMC6143113
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Abstract

Importance: Traumatic brain injury (TBI) is common in both veteran and civilian populations. Prior studies have linked moderate and severe TBI with increased dementia risk, but the association between dementia and mild TBI, particularly mild TBI without loss of consciousness (LOC), remains unclear. Objective: To examine the association between TBI severity, LOC, and dementia diagnosis in veterans. Design, Setting, and Participants: This cohort study of all patients diagnosed with a TBI in the Veterans Health Administration health care system from October 1, 2001, to September 30, 2014, and a propensity-matched comparison group. Patients with dementia at baseline were excluded. Researchers identified TBIs through the Comprehensive TBI Evaluation database, which is restricted to Iraq and Afghanistan veterans, and the National Patient Care Database, which includes veterans of all eras. The severity of each TBI was based on the most severe injury recorded and classified as mild without LOC, mild with LOC, mild with LOC status unknown, or moderate or severe using Department of Defense or Defense and Veterans Brain Injury Center criteria. International Classification of Diseases, Ninth Revision codes were used to identify dementia diagnoses during follow-up and medical and psychiatric comorbidities in the 2 years prior to the index date. Main Outcomes and Measures: Dementia diagnosis in veterans who had experienced TBI with or without LOC and control participants without TBI exposure. Results: The study included 178 779 patients diagnosed with a TBI in the Veterans Health Administration health care system and 178 779 patients in a propensity-matched comparison group. Veterans had a mean (SD) age of nearly 49.5 (18.2) years at baseline; 33 250 (9.3%) were women, and 259 136 (72.5%) were non-Hispanic white individuals. Differences between veterans with and without TBI were small. A total of 4698 veterans (2.6%) without TBI developed dementia compared with 10 835 (6.1%) of those with TBI. After adjustment for demographics and medical and psychiatric comobidities, adjusted hazard ratios for dementia were 2.36 (95% CI, 2.10-2.66) for mild TBI without LOC, 2.51 (95% CI, 2.29-2.76) for mild TBI with LOC, 3.19 (95% CI, 3.05-3.33) for mild TBI with LOC status unknown, and 3.77 (95% CI, 3.63-3.91) for moderate to severe TBI. Conclusions and Relevance: In this cohort study of more than 350 000 veterans, even mild TBI without LOC was associated with more than a 2-fold increase in the risk of dementia diagnosis. Studies of strategies to determine mechanisms, prevention, and treatment of TBI-related dementia in veterans are urgently needed.

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  • A study of 178,779 veterans with TBI with propensity-matched veterans without TBI found dementia risk was associated with TBI severity (HR 2.4, 95% CI 2.1-2.7 for mild TBI without loss of consciousness; 2.5, 2.3-2.8 for mild TBI with loss of consciousness; and 3.8, 3.6-3.9 for moderate to severe TBI).

    “A study of 178 779 veterans with TBI with propensity-matched veterans without TBI found dementia risk was associated with TBI severity (HR 2·4, 95% CI 2·1–2·7 for mild TBI without loss of consciousness; 2·5, 2·3–2·8 for mild TBI with loss of consciousness; and 3·8, 3·6–3·9 for moderate to severe TBI).70”

    From Dementia prevention, intervention, and care: 2020 report of the Lancet Commission (2020) · cites this paper as [70]

  • Mild traumatic brain injury is associated with about a twofold higher risk of receiving a dementia diagnosis.

    “A study found that mild TBI is associated with a two-fold increase in the risk of dementia diagnosis.185”

    From 2023 Alzheimer's disease facts and figures (2023) · cites this paper as [185]

  • People who have had a mild traumatic brain injury have a higher dementia risk than people who have not had such an injury.

    “Even those who experience mild TBI are at increased risk of dementia compared with those who have not had a TBI.”

    From 2023 Alzheimer's disease facts and figures (2023) · cites this paper as [185]

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Authors
Barnes, D. E., Byers, A. L., Gardner, R. C., Seal, K. H., Boscardin, W. J., & Yaffe, K.
Affiliations
San Francisco VA Medical Center (US)
ORCID
Venue
JAMA Neurology
Publisher
American Medical Association (AMA)
Published
2018-09-01
Volume
75
Issue
9
Pages
1055
ISSN
2168-6149 (ISSN-L)
DOI
10.1001/jamaneurol.2018.0815
PMC
PMC6143113
OpenAlex
W2802173280
Cited by
398
References
49
Citations by year
2026: 37 · 2025: 38 · 2024: 58 · 2023: 50 · 2022: 61 · 2021: 65 · 2020: 38 · 2019: 28 · 2018: 23
FWCI
30.23
Type
journal article
Language
en
Open access
Locations
  • JAMA Neurology (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • eScholarship (California Digital Library) (submittedVersion)
Funders
U.S. Department of Veterans Affairs
Topics
  • Health Sciences › Medicine › Epidemiology › Traumatic Brain Injury Research
  • Health Sciences › Medicine › Neurology › Traumatic Brain Injury and Neurovascular Disturbances
  • Health Sciences › Medicine › Psychiatry and Mental health › Dementia and Cognitive Impairment Research
Keywords
mild traumatic brain injury, dementia, loss of consciousness, military veterans, TBI severity, Iraq and Afghanistan veterans, dementia risk, psychiatric comorbidity, cognitive impairment, war injuries, neurodegeneration, depression, alcoholism, substance use disorders
MeSH terms
Adult, Brain Concussion, Dementia, Female, Humans, Male, Middle Aged, Risk Factors, Severity of Illness Index, Unconsciousness, United States, Veterans, Cohort Studies

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