OAK BROOK, Ill. (April 1, 2025) — In military service members with a history of repetitive blast exposure, researchers found that higher blast exposure correlated with changes in the functional connectivity between brain regions, according to a new study published today in Radiology, a journal of the Radiological Society of North America (RSNA). Even when standard MRI exams appeared normal, the researchers found clear abnormalities using more advanced MRI techniques.

"We found that service members with more blast exposure had more severe symptoms—including memory problems, emotional difficulties and signs of post-traumatic stress disorder—and that their brains showed weaker connectivity in key areas," said lead author Andrea Diociasi, M.D., neuroradiologist and past research fellow in the Department of Radiology at Massachusetts General Hospital and Harvard Medical School in Boston. "In short, repeated trauma seems to weaken the brain's internal communication."

Traumatic brain injury has diverse negative consequences for military personnel, affecting both the brain's structure and function. These effects are especially alarming for Special Operations Forces members who often face multiple blast injuries. Understanding the long-term neuroimaging implications of repeated blast injuries is challenging due to the variability of injuries in intensity, force and recurrence, underscoring the multiscale neurological implications of repeated trauma.
The research team analyzed structural and resting-state functional MRI data of Special Operations Forces members and the relationship between the frequency of blast injuries, persistent clinical symptoms and related changes to volume measurements in the cerebral cortex—the layer of the brain responsible for higher-level cognitive function—as well as functional connectivity changes. Functional connectivity refers to the activity between different brain regions, reflecting how they interact and exchange information to support various cognitive and behavioral processes.

Included in the study were 212 service members with a history of repetitive blast exposure who underwent psychodiagnostics and a comprehensive neuroimaging evaluation. The group of service members were split into two datasets for model development and validation, and each dataset was divided into high and low exposure groups based on participants' exposure to various explosives. An external age and gender-matched healthy control group of 212 participants was included in the volumetric analysis.

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