Effects of Deployment Traumatic Brain Injury on the Functional Connectome

Research ObjectivesTo determine if the context in which a mild TBI is acquired (deployment or non-deployment) affects complex brain function, as indicated by changes to the functional connectome.DesignCross-sectional observational cohort.SettingVeterans Affairs Medical Center.Participants181 Iraq/Afghanistan combat Veterans (n = 74 with deployment-related mild TBI; M years since injury = 11.0, SD = 4.1). Moderate to severe TBI was exclusionary.InterventionsNone.Main Outcome MeasuresThe Mid-Atlantic MIRECC Assessment of Traumatic Brain Injury (MMA-TBI) assessed lifetime history and severity of TBI. The Clinician Administered PTSD Scale – 5 (CAPS-5) evaluated current and lifetime PTSD diagnosis and severity. Functional connectomes were created from brain activity measured using magnetoencephalography (MEG), a non-invasive functional neuroimaging method.ResultsLinear regression adjusting for relevant covariates demonstrated a significant (FDR corrected p < .05) association between deployment mild TBI with reduced Global Efficiency and degree of the K-Core. Non-deployment mild TBI was significantly associated with a reduced number of modules. The interaction between deployment and non-deployment mild TBI was significantly associated with increased mean and mode frequency at which connections occur.ConclusionsResults demonstrate distinct effects of mild TBI sustained in a deployment versus non-deployment context on the functional brain connectome. This is consistent with prior findings demonstrating differential effects in other areas including psychiatric diagnosis/severity, pain, sleep, and cognitive function. Participants were an average of 11 years post-injury, suggesting these represent chronic effects of mild TBI, rather than changes associated with acute effects of the injury. Overall, these findings add to the growing body of evidence suggesting the effects of mild TBI acquired during deployment are different and longer lasting than injuries acquired in a non-deployment context.Author(s) DisclosuresNo competing financial or conflicts of interest exist.