NEEDED SYNTHESIS IN AN EMERGING NEUROSCIENCE AREA: REPEATED LOW-LEVEL BLAST EXPOSURE, A NONCONCUSSIVE INJURY

Studying nonconcussive repeated low-level blast exposure (rLLBE) can be challenging due to its unique neuropathophysiology and subclinical nature; synthesized guidance for effective outcome metrics is lacking, thus, we aimed to review current and promising neurological outcome metrics including symptomatology, and cognitive and sensory (ocular, auditory, balance) function post-rLLBE.
We identified cognitive, symptom, and sensory (ocular, auditory, balance) outcome metrics post-rLLBE from peer-reviewed literature through October 2025, compiled key results (subtests, effect estimates, significance) and study characteristics (design, exposure status, sample size), then summarized field applicability, implementation lessons, and participant and administrative burden. We formulated recommended outcome metrics in future research to decrease divergent strategies and increase study efficiency.
We present 30+ cognitive tests, 20+ self-reports, 12 ocular assessments, 8 auditory evaluation, and 11 balance assessments. The Defense Automated Neurobehavioral Assessment showed effect and significance while 25+ other cognitive tests did not. Questions probing for neurological symptoms (headaches), cognitive function (forgetfulness), and mood (irritability) showed effect and significance, while those for diagnosable mental health conditions (post-traumatic stress disorder) did not. Self-reported hearing outcomes (tinnitus) showed effect and significance while most objective hearing assessments (75%) did not. All balance assessments were null except AccWalker and Limits-of-Stability test/SMART Balance Master, which showed effect and significance. Six ocular tests showed effect while 11 assessments did not.
Multiple assessments were promising for studying cognitive, balance, and symptomatology outcomes. Focused efforts on ocular and auditory assessments are needed. Informed rLLBE outcome metrics enable integration of results, support scientific consensus, and increase efficiency in research.