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Explosions can injure the human brain primarily through blast overpressure waves, which transmit shock forces that disrupt brain tissue even without direct head impact. These primary blast injuries often lead to mild traumatic brain injury (TBI), affecting veterans and civilians exposed to improvised explosive devices (IEDs) or similar events. The cerebellum and frontal regions show particular vulnerability, resulting in cognitive, motor, and emotional deficits.

Blast Mechanisms

Blast waves cause brain damage via multiple pathways: direct transmission through the skull, compression of thoracic blood vessels leading to cerebral surges, or disruption of the blood-brain barrier (BBB). Shockwaves generate shear strains, cavitation bubbles, and rapid pressure changes, harming neurons, axons, and glia. Repeated low-level exposures, common in military training, exacerbate inflammation and tau protein buildup, mimicking early neurodegenerative changes.[healthcare.utah +1]

Neurological Effects

Common outcomes include neuroinflammation, axonal swelling, and microglial activation, impairing memory, anxiety regulation, and motor control. Symptoms mimic concussion: headaches, sleep issues, PTSD-like responses, and cognitive fog. Mild blasts alter anterior cingulate cortex activity, increasing anxiety and reducing object recognition in models.[news.virginia +1]

Long-Term Risks

Chronic effects involve reduced brain volume, BBB leaks, and elevated oxidative stress, raising risks for dementia or chronic traumatic encephalopathy (CTE). Veterans report average 21 blast exposures, correlating with structural thinning in key areas like the hippocampus.[americanbrainfoundation +1]

Protective Insights

Helmets reduce secondary/tertiary injuries but less so primary blasts; strategies focus on blast-mitigating gear and limiting exposures. Research emphasizes early imaging like MRI/DTI to detect subtle changes.[news.mit +1]