Blast Exposure Linked to Cognitive Effects in Military Personnel With PTSD, Mild TBI

Low-level blast (LLB) exposure alone is not linked to poorer cognition in military personnel, but when combined with posttraumatic stress disorder (PTSD) and mild traumatic brain injury (TBI), it is associated with worse memory and processing outcomes, according to study results published in the Journal of Head Trauma Rehabilitation.

Although the effects of high-level blasts that cause TBI have been widely studied, less is known about the cumulative and potentially subtle impact of lower-intensity blasts that often occur during training exercises. To address this gap, researchers analyzed data from the Long-term Impact of Military-relevant Brain Injury Consortium–Chronic Effects of Neurotrauma Consortium Prospective Longitudinal Study, which tracks neurological, psychological, and cognitive outcomes in service members and veterans over time. The Blast Exposure Threshold Survey was used to measure LLB exposure. Cognitive outcomes were assessed through neuropsychological tests measuring verbal and visual memory, attention, executive function, and processing speed.

A cross-sectional analysis was conducted using baseline data collected between 2015 and 2023. The final sample included 1036 combat-deployed service members and veterans (mean [SD] age, 43.93 [10.65] years; 87.1% men; 76.8% White). Nearly half (47.3%) reported deployment-related mild TBI, 51.8% reported high cumulative LLB exposure, and 26.7% met criteria for probable PTSD.

Although LLB was not independently associated with cognitive performance, its interaction with PTSD and deployment TBI underscores the importance of considering cumulative exposures in both research and clinical settings.

Exposure to LLB alone was not significantly associated with cognitive performance (P = .116), but it interacted with PTSD to predict poorer visual memory. Specifically, individuals with PTSD and high LLB exposure performed worse on the visuospatial learning and memory test, showing deficits in both immediate and delayed recall (both P < .001). PTSD also interacted with blunt TBI to negatively affect verbal memory, with stronger impairment in short-delay free recall when blunt TBI was present (P < .001) compared with when absent (P = .043).

PTSD showed the strongest independent associations across cognitive domains, including visual memory, verbal memory, and processing speed. Blunt TBI was independently associated with reduced processing speed, while blast-related TBI alone was not linked to poorer cognitive outcomes. Notably, PTSD was associated with slower processing speed only when blast TBI was absent, suggesting a complex, non-additive interaction between PTSD and blast exposure.

Study limitations include reliance on self-reported estimates of blast exposure, a cross-sectional design, and the potential influence of occupational variability on exposure levels.

“Although LLB was not independently associated with cognitive performance, its interaction with PTSD and deployment TBI underscores the importance of considering cumulative exposures in both research and clinical settings,” the study authors concluded.

Disclosures: This research was supported by the Assistant Secretary of Defense for Health Affairs, the US Department of Defense, the US Department of Veterans Affairs, the US Army Medical Research Acquisition Activity, and VA Health Services Research and Development.