Changes in personality after mild traumatic brain injury from primary blast vs. blunt forces

Introduction: Injuries from explosive devices can cause blast-force injuries, including mild traumatic brain injury (mTBI). Objective: This study investigated changes in personality from blast-force mTBI in comparison to blunt-force mTBI. Methods: Clinicians and significant others assessed US veterans who sustained pure blast-force mTBI (n = 12), as compared to those who sustained pure blunt-force mTBI (n = 12). Inclusion criteria included absence of any mixed blast-blunt trauma and absence of post-traumatic stress disorder. Measures included the Interpersonal Measure of Psychopathy (IMP), the Big Five Inventory (BFI), the Interpersonal Adjectives Scale (IAS) and the Frontal Systems Behaviour Scale (FrSBe). Results: There were no group differences on demographic or TBI-related variables. Compared to the Blunt Group, the Blast Group had more psychopathy on the IM-P, with anger, frustration, toughness and boundary violations and tended to more neuroticism on the BFI. When pre-TBI and post-TBI assessments were compared on the IAS and FrSBe, only the patients with blast force mTBI had become more cold-hearted, aloof-introverted and apathetic. Conclusion: These results suggest that blast forces alone can cause negativistic behavioural changes when evaluated with selected measures of personality. Further research on isolated blast-force mTBI should focus on these personality changes and their relationship to blast over-pressure.