Traumatic brain injury, environmental exposures, and subjective cognition in post-9/11 veterans enrolled in the VA Million Veteran Program

Abstract

Using data from the VA Million Veteran Program (MVP), this study aimed to (1) examine rates of environmental exposures as a function of traumatic brain injury (TBI) history in post-9/11 veterans and (2) examine the independent and interactive effects of TBI and exposures on subjective cognition. Participants included 6707 MVP-enrolled veterans (78 % male; age: M = 44.66, SD = 10.91) who were deployed in support of the Iraq/Afghanistan-era conflicts, completed MVP surveys, and participated in the VA TBI Screening and Evaluation Program (TBI-SEP). Veterans were classified into three groups based on the results of the TBI-SEP: (1) negative TBI screen; (2) positive TBI screen but no TBI diagnosis; or (3) positive TBI screen and confirmed TBI diagnosis. Environmental exposures were extracted from MVP surveys and included solvents/fuels; pesticides; lead; other metals; combustion products; open-air burn pits; and chemical/biological warfare (CBW) agents. The Medical Outcomes Study Cognitive Functioning-Revised (MOS-Cog-R) scale was used to assess subjective cognition. Chi-square tests showed that exposure rates were highest among veterans screening positive for TBI. The most commonly reported exposure types were combustion products, burn pits, and solvents/fuels. Adjusted linear regressions showed that both TBI and environmental exposures independently contributed to worse subjective cognition, but there were no synergistic effects between TBI and exposures on cognition, except for CBW agents. Our findings emphasize the importance of considering environmental exposures as independent risk factors for subjective cognitive difficulties in post-9/11 veterans and support the use of toxic exposure screenings to connect veterans with appropriate resources and clinical care.