Personality and neuroimaging measures differentiate PTSD from mTBI in veterans.

Mild traumatic brain injury (mTBI) is common among recent veterans and often is associated with chronic post-concussive symptoms (PCS). Elevated PCS may also be a consequence of post-traumatic stress disorder (PTSD) which shares symptoms with PCS. Identification of personality, biological, and psychopathology factors that contribute to the relationship between mTBI and PCS could help isolate the sources of chronic post concussive syndrome in veterans. Clinician rated diagnoses (PTSD, Major Depression, Alcohol Dependence), personality characteristics (Multidimensional Personality Questionnaire [MPQ] subscales), white matter brain imaging measures (Mean Diffusivity, Generalized Fractional Anisotropy), and diagnoses of mTBI were collected from 125 American military veterans of Iraq or Afghanistan. Linear and logistic regression models were tested to determine contributions to PCS and whether there were similar contributors to PTSD and mTBI. PCS score was associated with personality characteristics of high Stress Reaction and Traditionalism and low Control as well as mTBI. A diagnosis of PTSD was associated with low Social Closeness, PCS, Alcohol Dependence, and abnormal white matter mean diffusivity. Diagnosis of mTBI was associated with fewer white matter mean diffusivity abnormalities, PCS, and number of deployments. As commonly observed clinically, both PTSD and mTBI were associated with higher rates of PCS, though the contribution of PTSD appears to be secondary to personality traits, particularly Stress Reaction. Furthermore, the observation of factors that are uniquely associated with Blast mTBI (number of deployments) or with PTSD (Lifetime Alcohol Dependence and low Social Closeness), as well as a factor (region of abnormal MD) that had opposite effects on the likelihood of each diagnosis, indicates that the complex relationships between personality, psychopathology, and nature of mTBI need to be considered when interpreting chronic post-concussive symptoms.