Alison J. Donnell

Screening for postdeployment conditions: development and cross-validation of an embedded validity scale in the neurobehavioral symptom inventory.

Objective:To develop and cross-validate internal validity scales for the Neurobehavioral Symptom Inventory (NSI). Participants:Four existing data sets were used: (1) outpatient clinical traumatic brain injury (TBI)/neurorehabilitation database from a military site (n = 403), (2) National Department of Veterans Affairs TBI evaluation database (n = 48 175), (3) Florida National Guard nonclinical TBI survey database (n = 3098), and (4) a cross-validation outpatient clinical TBI/neurorehabilitation database combined across 2 military medical centers (n = 206). Research Design:Secondary analysis of existing cohort data to develop (study 1) and cross-validate (study 2) internal validity scales for the NSI. Main Measures:The NSI, Mild Brain Injury Atypical Symptoms, and Personality Assessment Inventory scores. Results:Study 1: Three NSI validity scales were developed, composed of 5 unusual items (Negative Impression Management [NIM5]), 6 low-frequency items (LOW6), and the combination of 10 nonoverlapping items (Validity-10). Cut scores maximizing sensitivity and specificity on these measures were determined, using a Mild Brain Injury Atypical Symptoms score of 8 or more as the criterion for invalidity. Study 2: The same validity scale cut scores again resulted in the highest classification accuracy and optimal balance between sensitivity and specificity in the cross-validation sample, using a Personality Assessment Inventory Negative Impression Management scale with a T score of 75 or higher as the criterion for invalidity. Conclusions:The NSI is widely used in the Department of Defense and Veterans Affairs as a symptom-severity assessment following TBI, but is subject to symptom overreporting or exaggeration. This study developed embedded NSI validity scales to facilitate the detection of invalid response styles. The NSI Validity-10 scale appears to hold considerable promise for validity assessment when the NSI is used as a population-screening tool.

Incidence of Postconcussion Symptoms in Psychiatric Diagnostic Groups, Mild Traumatic Brain Injury, and Comorbid Conditions

The constellation of physical, cognitive, and emotional symptoms, collectively known as postconcussion syndrome (PCS), is not uniquely associated with concussion, making the etiology of chronic postconcussion symptoms controversial. The current study compared percentages of individuals meeting symptom-based criteria for PCS in a population-based sample of veterans composed of subgroups with various psychiatric diagnoses, a history of mild traumatic brain injury (MTBI), and healthy controls. Participants were identified from 4462 randomly sampled male U.S. Army veterans who served during the Vietnam era. Only 32% of veterans with a history of MTBI met DSM-IV symptom criteria for PCS as compared to 40% of those diagnosed with post-traumatic stress disorder (PTSD), 50% with generalized anxiety disorder (GAD), 57% with major depressive disorder (MDD), and 91% with somatization disorder. Results were consistent with existing literature showing that the PCS symptoms are not unique to concussion, and also provide important base-rate information for neuropsychologists practicing in both clinical and personal injury forensic settings.

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.

The structure of postconcussion symptoms on the Neurobehavioral Symptom Inventory: a comparison of alternative models.

Objective:To evaluate and compare the existing Neurobehavioral Symptom Inventory factor structure models to determine which model provides the best overall fit for postconcussion symptoms and determine which model is useful across different samples (eg, with and without mild traumatic brain injury [TBI] history). Setting:N/A. Participants:A Florida National Guard sample (N = 3098) and a national Department of Veterans Affairs sample (N = 48 175). Design:Retrospective structural equation modeling was used to compare 16 alternative factor structure models. First, these 16 possible models were examined separately in both samples. Then, to determine whether the same factor structures applied across subsamples within these samples, the models were compared for those deployed and those not deployed in the Florida National Guard sample and between those with TBI confirmed on clinical evaluation and those who were determined not to have sustained a TBI within the Department of Veterans Affairs sample. Main Measures:Neurobehavioral Symptom Inventory. Results:A 4-factor model—vestibular, somatic, cognitive, and affective—had the best overall fit, after elimination of 2 items (ie, hearing problems and appetite disturbance), and was most applicable across samples. Conclusions:These findings extend the findings of Meterko et al to other samples. Because findings were consistent across sample and subsamples, the current findings are applicable to both Department of Veteran Affairs and Department of Defense postdeployment medical evaluation settings.

Consolidation deficits in traumatic brain injury: the core and residual verbal memory defect.

While memory deficits are consistently found to be a salient problem in individuals with moderate to severe traumatic brain injury (TBI), the specific memory processes (i.e., encoding, consolidation, and retrieval) underlying the verbal memory deficit are disputed in the literature. The current study evaluated the recovery of these verbal memory processes over time. A TBI patient group evaluated acutely after the injury (baseline) and again at 6 months and 1 year post injury was compared to a demographically similar control group evaluated only once. The current results replicated previous findings in support of an impaired consolidation hypothesis as the primary deficit underlying memory impairment in TBI. These deficits are reflected in relatively more rapid forgetting through 1 year post injury and relatively less proactive interference up to 6 months post injury.

Implications of Psychometric Measurement for Neuropsychological Interpretation

The purpose of this study is to examine the implications of various less-examined psychometric issues in the interpretation of neuropsychological data. Using a dataset of 4371 independent functioning and community-dwelling individuals who underwent neuropsychological evaluations, it was demonstrated that many common measures are not normally distributed. Non-normalized data can lead to erroneously pathological conclusions, particularly on the lower end of negatively skewed distributions. Another issue involves scatter. In line with previous studies, the current study found that approximately 67% of the 4371 participants showed discrepancies of three or more standard deviations between their highest and lowest test scores on 21 measures. However, in contradiction to the existing literature, in the current study mean scatter levels were relatively stable across increasing levels of intelligence. It is argued that this is due to regression to the mean. As an individual moves away from the population average in either direction, scores on other measures will regress from that persons IQ score toward the population mean. The lower a test correlates with IQ, the greater will be the regression toward the mean. Therefore the test battery in question must be considered during the interpretation process, in addition to the individuals premorbid IQ.

Abnormal Neurological Exam Findings in Individuals with Mild Traumatic Brain Injury (mTBI) Versus Psychiatric and Healthy Controls

In those with a history of mild traumatic brain injury (mTBI), cognitive and emotional disturbances are often misattributed to that preexisting injury. However, causal determinations of current symptoms cannot be conclusively determined because symptoms are often nonspecific to etiology and offer virtually no differential diagnostic value in postacute or chronic phases. This population-based study examined whether the presence of abnormalities during neurological examination would distinguish between mTBI (in the chronic phase), healthy controls, and selected psychiatric conditions. Retrospective analysis of data from 4462 community-dwelling Army veterans was conducted. Diagnostically unique groups were compared on examination of cranial nerve function and other neurological signs. Results demonstrated that individuals with mTBI were no more likely than those with a major depressive disorder, generalized anxiety disorder, posttraumatic stress disorder, or somatoform disorder to show any abnormality. Thus, like self-reported cognitive and emotional symptoms, the presence of cranial nerve or other neurological abnormalities offers no differential diagnostic value. Clinical implications and study limitations are presented.

Development and Initial Validation of Military Deployment-Related TBI Quality-of-Life Item Banks.

Objective:To investigate unique factors that affect health-related quality of life (QOL) in individuals with military deployment–related traumatic brain injury (MDR-TBI) and to develop appropriate assessment tools, consistent with the TBI-QOL/PROMIS/Neuro-QOL systems. Participants:Three focus groups from each of the 4 Veterans Administration (VA) Polytrauma Rehabilitation Centers, consisting of 20 veterans with mild to severe MDR-TBI, and 36 VA providers were involved in early stage of new item banks development. The item banks were field tested in a sample (N = 485) of veterans enrolled in VA and diagnosed with an MDR-TBI. Design:Focus groups and survey. Outcome Measures:Developed item banks and short forms for Guilt, Posttraumatic Stress Disorder/Trauma, and Military-Related Loss. Results:Three new item banks representing unique domains of MDR-TBI health outcomes were created: 15 new Posttraumatic Stress Disorder items plus 16 SCI-QOL legacy Trauma items, 37 new Military-Related Loss items plus 18 TBI-QOL legacy Grief/Loss items, and 33 new Guilt items. Exploratory and confirmatory factor analyses plus bifactor analysis of the items supported sufficient unidimensionality of the new item pools. Convergent and discriminant analyses results, as well as known group comparisons, provided initial support for the validity and clinical utility of the new item response theory–calibrated item banks and their short forms. Conclusion:This work provides a unique opportunity to identify issues specific to individuals with MDR-TBI and ensure that they are captured in QOL assessment, thus extending the existing TBI-QOL measurement system.

TBI and Nonverbal Executive Functioning: Examination of a Modified Design Fluency Test's Psychometric Properties and Sensitivity to Focal Frontal Injury

The purpose of this study was to investigate a modified version of the Design Fluency Test (DFT; Jones-Gotman & Milner, 1977) to establish its psychometric properties and clinical sensitivity to frontal traumatic brain injury (TBI). Twenty-five participants with moderate-to-severe TBI and focal frontal injury confirmed on magnetic resonance imaging or computed tomography, and 25 participants with TBI and nonfrontal focal injury were administered a modified fixed version of the DFT (Russell & Starkey, 1993). Analyses revealed that this modified DFT demonstrated excellent interrater agreement and consistency. This measure also demonstrated modest convergent validity with established measures of executive function abilities and discriminant validity with measures of other cognitive domains. Lastly, participants with frontal TBI generated significantly fewer novel designs compared with participants with nonfrontal focal injury. However, no significant differences were detected with regard to the total number of errors committed. Collectively, these results suggest that this fixed version of the DFT is a reliable measure of nonverbal executive functioning sensitive to frontal TBI.

Utility of the Neurobehavioral Symptom Inventory As an Outcome Measure: A VA TBI Model Systems Study.

Objective: To examine the utility of the Neurobehavioral Symptom Inventory (NSI)—a measure of postconcussion symptoms used within the Veterans Health Administration—as an index of rehabilitation outcome. Setting: Veterans Administration Polytrauma Rehabilitation Centers Traumatic Brain Injury (TBI) Model Systems program. Participants: A total of 159 Veterans (14% with mild TBI; 86% with moderate-severe TBI). Main Measures: Disability Rating Scale; Functional Independence Measure; Glasgow Outcome Scale–Extended; NSI; Participation Assessment with Recombined Tools–Objective; Posttraumatic Stress Disorder Checklist–Civilian Version; Satisfaction With Life Scale; Supervision Rating Scale. Analyses: Correlations and exploratory factor analyses examined the interrelations among outcome measures. Hierarchical regression analyses were utilized to determine if the NSI predicted rehabilitation outcome measures after controlling for demographic variables, TBI severity, and time since injury. NSI reliable changes from pretreatment to 1-year follow-up were examined. Receiver operating characteristics curve analyses were conducted to evaluate the ability of changes in the NSI to predict meaningful change in functioning and employment status. Results: The NSI correlated with psychological distress measures. The NSI administered prior to brain injury rehabilitation had limited predictive utility beyond satisfaction with life. A minority of patients (32%) demonstrated reliable changes on the NSI from baseline to 1-year follow-up. Changes on the NSI were not predictive of meaningful change in employment or functioning. Conclusion: The NSI was not useful for assessing meaningful change in a sample of mixed severity TBI patients.