Exploring the Relationship Between Mild Traumatic Brain Injury Exposure and the Presence and Severity of Postconcussive Symptoms Among Veterans Deployed to Iraq and Afghanistan.

OBJECTIVE: The aim of this study was to describe the association between mild traumatic brain injury (mTBI) and persisting postconcussive symptoms according to symptom category, number, and severity. DESIGN: The study design was observational. PARTICIPANTS: The study sample comprised veterans (≥18 years of age) deployed in Operation Enduring Freedom and Operation Iraqi Freedom (OEF/OIF) conflicts who had not received any treatment for mTBI in the 30 days preceding study enrollment. METHODS: Veterans were interviewed and completed testing in a single day. The Standard TBI Diagnostic Interview and the Clinician-Administered PTSD Scale were used. Testing included the Neurobehavioral Symptom Inventory and a full neuropsychological battery. Gold standard classification methods were utilized to determine presence/absence of mTBI. For each of the 5 symptom outcomes, an adjusted multiple linear regression model (negative binomial count models) accounting for effects of socio-demographic variables and behavioral health conditions was used. MAIN OUTCOME MEASURES: Self-report of neurobehavioral symptoms categorized as affective, cognitive, somatic, and vestibular symptoms, in addition to the instruments specified above. RESULTS: OEF/OIF veterans with mTBI, relative to veterans with no mTBI, were observed to have 30% more symptoms overall (P < .001), 34% more somatic symptoms (P < .001), 22% more cognitive symptoms (P = .008), 15% more affective symptoms (P = .017), and 59% more vestibular symptoms (P < .001). For adjusted models, variables significantly related to number of symptoms across all 4 symptom categories were anxiety (all P < .001) and insomnia (all P < .001). For the adjusted models, variables significantly related to symptom severity across all 4 symptom categories were insomnia (all P < .001), depression (P < .001-.05) and anxiety (all, P < .001). CONCLUSIONS: OEF/OIF veterans with mTBI, relative to veterans with no mTBI, have significantly more and significantly more severe persisting symptoms, with vestibular symptoms reported with the greatest frequency. After accounting for behavioral health conditions and socio-demographic factors, OEF/OIF veterans with mTBI compared to veterans without mTBI had significantly more cognitive, affective, vestibular, and somatic symptoms persisting 4.8 years after the mTBI event(s).