An Investigation of Neurological soft signs as a discriminating factor between Veterans with Post-traumatic Stress Disorder, mild Traumatic Brain Injury, and co-occurring Post-traumatic Stress Disorder and mild Traumatic Brain Injury

Abstract

AN INVESTIGATION OF NEUROLOGICAL SOFT SIGNS AS A DISCRIMINATING FACTOR BETWEEN VETERANS WITH POST-TRAUMATIC STRESS DISORDER, MILD TRAUMATIC BRAIN INJURY, AND CO-OCCURING POST-TRAUMATIC STRESS DISORDER AND MILD TRAUMATIC BRAIN INJURY By David J. Rothman, MS A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University. Virginia Commonwealth University, 2019 Major Director: Scott R. Vrana Professor, Departments of Psychology and Psychiatry While multiple Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn veterans suffer from mild Traumatic Brain Injury (mTBI), Post-traumatic Stress Disorder (PTSD), and co-morbid mTBI and PTSD, there remains difficulty disentangling the specific symptoms associated with each disorder using self-report and neurocognitive assessments. We propose that neurological soft signs (NSS), which are tasks associated with general neurologic compromise, may prove useful in this regard. Based on our review of the literature we hypothesized that individuals with PTSD would present with a greater number of NSS than controls or individuals with mTBI. Further, we hypothesized a synergistic effect, such that individuals with mTBI + PTSD would present with the greatest number of NSS. To test these hypotheses, we analyzed a subset of individuals (N=238) taken from a larger study of neurocognitive functioning in veterans. Participants completed a battery of neuropsychological measures, which included the Behavioral Dyscontrol Scale (BDS), the current study’s measure of NSS. A subset of other neuropsychological measures were also included to examine the utility of NSS over and above traditional neuropsychological measures. Individuals were removed from the study if they sustained a moderate/severe TBI or did not meet validity criteria on the Green’s Word Memory Test or the Negative Impression Management subscale of the Personality Assessment Inventory. Binomial logistic and multinomial logistic regression were used to examine the ability of NSS to discriminate between the study groups, first by themselves and then after the variance explained by the traditional neuropsychological measures was accounted for. Exploratory cluster analyses were performed on neuropsychological measures and NSS to identify profiles of cognitive performance in the data set. Results indicated that individuals in the mTBI and/or PTSD group had more NSS compared to controls. Of the individual NSS items only a go/no-go task of the BDS discriminated between groups, with worse performance among individuals in the mTBI, PTSD, and mTBI + PTSD group compared to controls. In contrast, the overall BDS score and individual NSS, in general, did not discriminate between the mTBI, PTSD, and mTBI + PTSD group. Overall, the current study suggests that, when eliminating participants who do not meet validity criteria, NSS do not aid in discriminating between individuals with mTBI, PTSD, and mTBI + PTSD.