A study published May 30, 2026, in the Journal of Alzheimer’s Disease is reshaping how researchers understand cognitive decline in combat veterans. Using data from the Department of Defense’s Alzheimer’s Disease Neuroimaging Initiative, USC researchers examined how TBI and PTSD affect brain imaging markers and cognition in a U.S. veteran population.

The study found that greater PTSD symptom severity was linked to poorer performance across all three cognitive tests used, and higher TBI severity correlated with lower scores on the Mini-Mental State Examination. What is striking about these findings is that they did not show that TBI severity nor PTSD symptoms were associated with neuroimaging biomarkers of neurodegeneration or vascular damage.

This discovery suggests that cognitive impairment in veterans may not stem directly from the accumulation of Alzheimer’s pathologies or vascular injuries. This matters enormously for treatment. It suggests veterans’ cognitive struggles may require targeted interventions beyond standard dementia pathways – a finding directly relevant to legislative reauthorizing of funding for federal TBI surveillance and research programs.