Normative Data for the Neurobehavioral Symptom Inventory (NSI) and post-concussion symptom profiles among TBI, PTSD, and nonclinical samples.

The Neurobehavioral Symptom Inventory (NSI) is a self-report measure of symptoms commonly associated with Post-Concussion Syndrome (PCS) that may emerge after mild traumatic brain injury (mTBI). Despite frequent clinical use, no NSI norms have been developed. Thus, the main objective of this study was to establish NSI normative data using the four NSI factors (i.e., vestibular, somatic, cognitive, and affective) identified by Vanderploeg, Silva, et al. ( 2014 ) among nonclinical epidemiological samples of deployed and non-deployed Florida National Guard members as well as a reference sample of Guard members with combat-related mTBI. In addition, NSI subscale profile patterns were compared across four distinct subgroups (i.e., non-deployed-nonclinical, deployed-nonclinical, deployed-mTBI, and deployed-PTSD). The deployed-nonclinical group endorsed greater PCS symptom severity than the non-deployed group, and the mTBI group uniformly endorsed more symptoms than both nonclinical groups. However, the PTSD group endorsed higher symptom severity relative to the other three subgroups. As such, this highlights the non-specificity of PCS symptoms and suggests that PTSD is associated with higher symptom endorsement than mTBI.