Alzheimer's test may miss over half of cases among those with a traumatic brain injury

Embargoed until: Publicly released: 2026-06-30 01:00

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Israeli and US scientists say an Alzheimer's test called the plasma phosphorylated tau 217 (p-tau217)/amyloid-β 42 (Aβ42) ratio - which looks at the ratio of two Alzheimer's-linked proteins, tau and beta amyloid - appears to be less accurate among patients who have experienced traumatic brain injuries (TBI) in the past. To determine the test's accuracy, they looked at 272 US veterans, and found the test was highly accurate among people with no history of TBI, but markedly less accurate in those who had experienced TBI. They calculated that, among people with a TBI, the test might miss over half of cases. The findings suggest TBI may modify the chemical signals in the body that the test measures, affecting its accuracy, the authors conclude.