Radiation-Associated Brain Dysfunction in Military and Occupational Settings: Neuroimmune Mechanisms and Functional...

Radiation-associated brain dysfunction is relevant to military and occupational health because low-dose, chronic, documented, suspected, or perceived radiation exposure can raise questions about cognition, fatigue, vigilance, effortful task engagement, and work-relevant function. This narrative review focuses on biomedical and occupational-health studies relevant to brain-related functional outcomes after documented, suspected, or perceived radiation exposure. Evidence from radiotherapy, occupational radiation cohorts, radiological events, and whole-body or extracranial irradiation models suggests that structural injury alone does not capture all functional concerns after exposure.

Targeted PubMed searches and reference-list screening primarily identified English-language biomedical and occupational-health literature published from 2020 through May 2026. Selected earlier studies were included when they provided foundational validation of representative assessment instruments or directly addressed irradiation models relevant to the review question. The synthesis prioritized radiation-induced brain injury, low-dose and low-dose-rate exposure, occupational and nuclear accident literature, neurovascular injury, glial responses, immunometabolism, gut-brain and systemic-to-brain signaling, and behavioral outcomes. This narrative review is not a systematic review or dose-reconstruction analysis.

Recent evidence indicates a shift from structural injury alone toward mechanisms involving the neurovascular unit, blood-brain barrier, microglia, astrocytes, redox stress, systemic inflammatory signaling, and functional readouts. Occupational and emergency-response settings require distinction among documented dose, suspected exposure, perceived exposure, and post-incident distress. Whole-brain irradiation, whole-body irradiation, and extracranial irradiation are not interchangeable models because systemic immune, gastrointestinal, endocrine, and autonomic pathways can modify brain-related outcomes. Rodent behavioral assays provide domain-level probes of working memory, anxiety-like behavior, effort, vigilance, and sustained attention, but they do not directly model occupational performance.

Radiation brain-health research is most useful for military and occupational medicine when it pairs exposure documentation and context with brief assessment of cognition, fatigue and sleep, affect or distress, vigilance, and duty- or work-relevant function. Persistent symptoms, abnormal findings, high or uncertain dose, or impaired safety-sensitive performance should guide follow-up and referral. Neurovascular, glial, inflammatory, metabolic, and systemic mechanisms are best used to guide biomarker development, recovery assessment, and countermeasure timing rather than as current clinical screening tests. This framework applies to documented, suspected, or perceived exposure while emphasizing the limits of cross-context extrapolation.