Verbal Memory Deficits in OEF/OIF/OND Veterans Exposed to Blasts at Close Range

Objectives: This study investigated the relationship between close proximity to detonated blast munitions and cognitive functioning in OEF/OIF/OND Veterans. Methods: A total of 333 participants completed a comprehensive evaluation that included assessment of neuropsychological functions, psychiatric diagnoses and history of military and non-military brain injury. Participants were assigned to a Close-Range Blast Exposure (CBE) or Non-Close-Range Blast Exposure (nonCBE) group based on whether they had reported being exposed to at least one blast within 10 meters. Results: Groups were compared on principal component scores representing the domains of memory, verbal fluency, and complex attention (empirically derived from a battery of standardized cognitive tests), after adjusting for age, education, PTSD diagnosis, sleep quality, substance abuse disorder, and pain. The CBE group showed poorer performance on the memory component. Rates of clinical impairment were significantly higher in the CBE group on select CVLT-II indices. Exploratory analyses examined the effects of concussion and multiple blasts on test performance and revealed that number of lifetime concussions did not contribute to memory performance. However, accumulating blast exposures at distances greater than 10 meters did contribute to poorer performance. Conclusions: Close proximity to detonated blast munitions may impact memory, and Veterans exposed to close-range blast are more likely to demonstrate clinically meaningful deficits. These findings were observed after statistically adjusting for comorbid factors. Results suggest that proximity to blast should be considered when assessing for memory deficits in returning Veterans. Comorbid psychiatric factors may not entirely account for cognitive difficulties.