Cumulative and Contextual Effects of Low-Level Blast Exposure on Cognitive Function in Military Personnel: Interactions With PTSD and Mild TBI.

Objective: To examine the impact of low-level blast (LLB) exposure on cognitive functioning in combat-exposed service members and Veterans (SM/Vs), and its interaction with posttraumatic stress disorder (PTSD) and deployment-related mild traumatic brain injury (TBI).

Setting: Multi-site Department of Defense and Veterans Affairs research centers participating in the LIMBIC-CENC Prospective Longitudinal Study.

Participants: 1036 SM/Vs who deployed in support of combat operations and completed comprehensive baseline assessments between 2015 and 2023.

Design: Cross-sectional observational study using multivariate linear regression and interaction models to evaluate associations between LLB, PTSD, deployment-related mild TBI, and cognitive outcomes.

Main measures: LLB exposure was assessed using the generalized blast exposure value from the Blast Exposure Threshold Survey. Cognitive functioning was evaluated using neuropsychological tests assessing memory, attention, processing speed, executive function, and global performance. PTSD was assessed using the PTSD Checklist for DSM-5.

Results: LLB was not independently associated with poorer cognitive performance. However, LLB moderated the relationship between PTSD and memory outcomes, with significantly worse visual memory in those with PTSD and high LLB exposure. Significant interaction effects were also observed between PTSD and deployment-related TBI on verbal memory, working memory, and processing speed. PTSD demonstrated the most consistent independent associations across cognitive domains.

Conclusions: Although LLB exposure alone was not associated with cognitive deficits, it interacted with PTSD and TBI to influence cognitive performance. These findings support the need for integrated assessments of blast exposure, PTSD, and TBI history in evaluating cognitive health among SM/Vs.