Dimensions of Military Neurotrauma: Factor Structure and Clinical Correlates of the Boston Assessment of Traumatic Brain Injury-Lifetime.

OBJECTIVE: To examine the dimensional structure of the Boston Assessment of Traumatic Brain Injury-Lifetime (BAT-L) and evaluate whether derived injury dimensions are associated with neurobehavioral symptoms and functional disability in post-9/11 US military veterans and service members. SETTING: VA Medical Centers in Boston, MA and Houston, TX, within the Translational Research Center for traumatic brain injury (TBI) and Stress Disorders study. PARTICIPANTS: A total of 752 post-9/11 veterans and service members with deployment history were included: 570 in the Boston exploratory sample and 182 in the Houston confirmatory sample. DESIGN: This observational, cross-sectional analysis of baseline cohort data used exploratory factor analysis in the Boston sample followed by confirmatory factor analysis in the independent Houston sample. Confirmatory factor analysis-derived factor scores from the combined sample were examined in relation to clinical outcomes. MAIN MEASURES: Boston Assessment of Traumatic Brain Injury-Lifetime (lifetime history of TBI and blast exposures); Neurobehavioral Symptom Inventory; World Health Organization Disability Assessment Schedule II. Adjusted models controlled for post-traumatic stress disorder and depressive symptom severity. RESULTS: Exploratory factor analysis identified 4 clinically interpretable factors: Blast Exposure (Blast-Exp), Military Blast TBI (MBlast-TBI), Military Blunt TBI (MBlunt-TBI), and Civilian TBI (Civilian-TBI). The confirmatory factor analysis supported this structure in the Houston sample. After adjustment, MBlast-TBI showed the broadest associations with Neurobehavioral Symptom Inventory symptom burden and functional disability. MBlunt-TBI was associated with somatic symptoms and functional disability, whereas Civilian-TBI was associated only with affective symptoms. Blast-Exp was not significantly associated with either outcome. CONCLUSION: The BAT-L demonstrates a replicable and clinically meaningful factor structure that distinguishes blast exposure frequency from blast-related TBI severity and separates military and civilian injury contexts. These findings support the BAT-L's utility for dimensional characterization of lifetime neurotrauma and for future studies examining clinical and biological correlates of distinct TBI profiles.