Relationships and Evidence-Based Theoretical Perspectives on Persisting Symptoms and Functional Impairment Among Mild Traumatic Brain Injury and Behavioral Health Conditions.

The purpose of this study is to characterize and describe the relationships between symptoms and functional impairment following mild traumatic brain injury (mTBI) and behavioral health conditions (BHCs) in order to inform evidence-based theories on why symptoms and functional impairments persist in some individuals but not others. This is a retrospective, multi-site, cross-sectional study utilizing data collected from a total of 289 Operation Iraqi Freedom/Operation Enduring Freedom Veterans who were classified into diagnostic groups using the symptom attribution and classification algorithm and the VA clinical reminder and comprehensive traumatic brain injury evaluation. The Neurobehavioral Symptom Inventory was used to assess mTBI symptom number and severity. The World Health Organization Disability Assessment Schedule 2.0 was used to assess functional impairment. Symptom profiles differed between diagnostic groups irrespective of symptom attribution method used. Veterans with both mTBI and BHCs and those with BHCs alone had consistently greater number of symptoms and more severe symptoms relative to no symptom and symptoms resolved groups. Symptom number and severity were significantly associated with functional impairment. Both symptom number and functional impairment were significantly associated with the number of mTBI exposures. Together, these results informed evidence-based theories on understanding why symptoms and functional impairment persist among some OEF/OIF Veterans.