Prior Traumatic Brain Injury and Alzheimer Disease Blood Biomarkers.

Cross-sectionalJAMA neurology· Aug 2026

Prior Traumatic Brain Injury and Alzheimer Disease Blood Biomarkers.

Yael Rosen-Lang, Agathe Vrillon, Shlomit Pasternak … Department of Defense Alzheimer’s Disease Neuroimaging Initiative (DOD ADNI) Investigators and the Department of Defense Alzheimer’s Disease Blood-Testing Initiative (DOD ADBI)

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Nuclear MedicineCross-sectionalDiagnosisQ1IF 10.8

Alzheimer blood test is far less accurate in veterans with prior head injury.

Prior Traumatic Brain Injury and Alzheimer Disease Blood Biomarkers.

Yael Rosen-Lang … Department of Defense Alzheimer’s Disease Neuroimaging Initiative (DOD ADNI) Investigators and the Department of Defense Alzheimer’s Disease Blood-Testing Initiative (DOD ADBI)

JAMA neurology · Aug 2026

Background

IMPORTANCE: Traumatic brain injury (traumatic brain injury) is a risk factor for dementia and is known to impact levels of several Alzheimer disease (alzheimer disease) blood biomarkers.

Purpose

To evaluate the accuracy of emerging alzheimer disease blood biomarkers in veterans with and without a traumatic brain injury history.

Methods

DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional cohort study of a diagnostic test assessed the performance of the US Food and Drug Administration-approved plasma p-tau217/Aβ42 ratio and plasma levels of p-tau217 and Aβ42/40 ratio for detecting brain Aβ positivity (eg, amyloid-positron emission tomography [PET] consensus visual read).

n = 272 participants

Results

test misses over half of brain amyloid cases after longer blackout tbi

No TBI

90%

TBI, LOC 0-5 min

78%

TBI, LOC >5 min

63%

More results

In 272 participants, mean (SD) age was 70 (4.5) years, 270 were male (99.3%), and 83 (30.5%) were amyloid-PET positive.

Results were similar for plasma p-tau217 alone and plasma Aβ42/40 ratio.

“

Conclusion · 1 of 2

Results of this cross-sectional cohort study of a diagnostic test suggest that among individuals who are cognitively unimpaired or have mild cognitive impairment and a traumatic brain injury history, the p-tau217/Aβ42 ratio test may miss over half of amyloid-PET-positive cases.

Conclusion · 2 of 2

Caution is advised in interpreting alzheimer disease blood test results in this context.

Prior Traumatic Brain Injury and Alzheimer Disease Blood Biomarkers.

Prior Traumatic Brain Injury and Alzheimer Disease Blood Biomarkers.

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