Neurocognitive performance and prior injury among U.S. Department of Defense military personnel.

This study examined the neurocognitive performance of U.S. military personnel completing the Automated Neuropsychological Assessment Metrics (version 4) TBI Military (ANAM4 TBI-MIL) battery as part of the Department of Defense Neurocognitive Functional Assessment Program. Descriptive analyses utilizing the ANAM4TBI Military Performance Database were performed. We examined ANAM Composite Score (ACS) differences between five injury subgroups (no injury, brain injury with current symptoms, brain injury without current symptoms, nonbrain injury with current symptoms, and nonbrain injury without current symptoms) using general linear mixed modeling. Almost 11% (70,472/641,285) reported brain injury in the 4 years before assessment. The ACS differed significantly by injury group (p < 0.0001). In comparison to the no injury group, those reporting brain injury with current symptoms (d = -0.44) and nonbrain injury with current symptoms (d = -0.24) demonstrated significantly reduced ACS scores (p < 0.0001) indicative of reduced neurocognitive proficiency. In this population-based study of U.S. military personnel, neurocognitive performance was significantly associated with reported injury within the past 4 years among those experiencing current symptoms. Occupational programs focusing on prospective brain health of injured population groups are warranted.

Evidence for added value of baseline testing in computer-based cognitive assessment.

CONTEXT: Large-scale baseline cognitive assessment for individuals at risk for concussion is a common part of the protocol for concussion-surveillance programs, particularly in sports. Baseline cognitive testing is also being conducted in US military service members before deployment. Recently, the incremental validity of large-scale baseline cognitive assessment has been questioned. OBJECTIVE: To examine the added value of baseline cognitive testing in computer-based neuropsychological assessment by comparing 2 methods of classifying atypical performance in a presumed healthy sample. DESIGN: Cross-sectional study. SETTING: Military base. PATIENTS OR OTHER PARTICIPANTS: Military service members who took the Automated Neuropsychological Assessment Matrix (ANAM) before and after deployment (n = 8002). MAIN OUTCOME MEASURE(S): Rates of atypical performance in this healthy, active-duty sample were determined first by comparing postdeployment scores with a military normative database and then with each individual's personal baseline performance using a reliable change index. RESULTS: Overall rates of atypical performance were comparable across these 2 methods. However, these methods were highly discordant in terms of which individuals were classified as atypical. When norm-referenced methods were used, 2.6% of individuals classified as normal actually demonstrated declines from baseline. Further, 65.7% of individuals classified as atypical using norm-referenced scores showed no change from baseline (ie, potential false-positive findings). CONCLUSIONS: Knowing an individual's baseline performance is important for minimizing potential false-positive errors and reducing the risks and stresses of misdiagnosis.

Effects of military deployment on cognitive functioning.

Military deployment poses many risks for cognitive functioning. When deployed individuals are compared to a nondeployed control group, there is some evidence that deployment may be associated with declines in cognitive functioning. The current study examined cognitive performance before and following deployment in a large sample of active duty military personnel (N = 8002) who reported no traumatic brain injury (TBI). Cognition was assessed using the Automated Neuropsychological Assessment Metrics version 4 TBI Military (ANAM4 TBI-MIL) battery, a computer-based battery of tests measuring attention, processing speed, and general cognitive efficiency. Pre- and postdeployment scores were compared using repeated measures analyses. Although statistically significant differences were observed for all tests (with 5 of 7 tests demonstrating performance improvement), effect sizes were very small for all but 1 test, indicating that performance differences had minimal clinical significance. Likewise, determination of change for individuals using reliable change indices revealed that a very small percentage (<3%) of this presumed healthy sample showed meaningful decline in cognition following deployment. Analyses indicated that despite risks for cognitive decline while in theater, deployment had minimal to no lasting effect on cognition as measured by ANAM4 TBI-Mil upon return from deployment.

Cognitive change associated with self-reported mild traumatic brain injury sustained during the OEF/OIF conflicts.

Traumatic brain injury (TBI) has received much attention due to high rates of this injury in Service Members returning from the Iraq/Afghanistan conflicts. This study examined cognitive performance in Service Members tested with ANAM prior to and following deployment. The sample was divided into a control group (n=400) reporting no TBI injury prior to or during most recent deployment, and a group who self-reported a TBI injury (n=502) during most recent deployment. This latter group was divided further based on self-report of post-concussion symptoms at post-deployment testing. All three groups performed similarly at pre-deployment. The group reporting TBI with active symptoms performed worst at post-deployment and included the highest percentage of individuals showing significant decline in cognitive performance over time (30.5%). A small sample of symptomatic individuals with a non-TBI reported injury did not demonstrate similar declines in performance, suggesting that active symptoms alone cannot account for these findings. Of those reporting a TBI injury during deployment, 70% demonstrated no significant change in cognitive performance compared with baseline. Although the exact etiology of observed declines is uncertain, findings indicate that individuals who self-report TBI during deployment with active symptomatology at post-deployment are at greatest risk for declines in cognitive performance. These individuals can be identified using self-report and brief computer-based testing. Importantly, the majority of active-duty individuals reporting TBI during deployment do not present with lasting significant cognitive impairment, a finding consistent with the civilian literature on mild TBI.

Case report: Treatment of mild traumatic brain injury with hyperbaric oxygen.

Two United States Air Force Airmen were injured in a roadside improvised explosive device (IED) blast in Iraq in January 2008. Both airmen suffered concussive injuries and developed irritability, sleep disturbances, headaches, memory difficulties and cognitive difficulties as symptoms of mild traumatic brain injury (mTBI). Six months after injury, repeat Automated Neuropsychological Assessment Metrics (ANAM) testing showed deterioration, when compared to pre-injury baseline ANAM assessment, in all measured areas (simple reaction time, procedural reaction time, code substitution learning, code substitution delayed, mathematical processing, and matching to sample). The airmen were treated with hyperbaric oxygen in treatments of 100% oxygen for one hour at 1.5 atmospheres absolute, resulting in rapid improvement of headaches and sleep disturbances, improvement in all symptoms and resolution of most symptoms. Repeat ANAM testing after completion of the hyperbaric treatments - nine months after initial injury - showed improvement in all areas, with most measures improving to pre-injury baseline levels. The airmen received no other treatment besides medical monitoring. Repeat neuropsychologic testing confirmed the improvement. We conclude that the improvement in symptoms and ANAM performance is most likely attributable to HBO treatment.

Reliability and construct validity of the Automated Neuropsychological Assessment Metrics (ANAM) mood scale.

The reliability and construct validity of the Automated Neuropsychological Assessment Metrics (ANAM) mood scale (AMS) were examined using concurrent, well-validated measures of mood and confirmatory factor analysis (CFA) with a sample of 210 volunteer college students. The AMS was given in computerized format with multiple adjectives using a visual analog Likert scale yielding seven dimensions of mood including vigor, restlessness, depression, anger, fatigue, anxiety, and happiness. All seven mood dimensions of the AMS demonstrated excellent test-retest reliability and internal consistency. Also, the AMS anxiety dimension correlated strongly with the Spielberger's State Anxiety Inventory (r=0.67) and the AMS depression dimension correlated strongly with the Beck Depression Inventory-II (r=0.71). CFA revealed that the AMS 7-factor mood model fit the data well and significantly better than an alternative, theoretically plausible model. When concurrent measures of mood were incorporated in the CFA model, the AMS demonstrated both convergent and discriminant validity. The AMS 7-factor model explained 55.12% of the total variance in the items. It was concluded that the AMS provides a brief yet reasonably complete and valid assessment of mood.

Development and quality assurance of computer-based assessment batteries.

The purpose of this article is to outline critical elements in the development and quality assurance (QA) assessment of a computer-based assessment battery (CAB). The first section of the article provides an overview of the life cycle of a representative CAB, typical evolutionary stages, and many of the essential considerations for designing and developing a CAB. The second section of the article presents a model for conducting a quality assurance assessment of a CAB. A general narrative of several steps in the QA process is supported by a table of recommended QA assessment elements. Although this QA process model may not be definitive for all cases, it provides a general framework within which a systematic assessment of any CAB can be conducted.

An investigation of heat stress effects on time-sharing performance.

A study was conducted to investigate the effects of heat stress on time-sharing performance. Twelve participants performed three dual-task scenarios and a multiple-task scenario for 2 h in each of six climates. The climates were obtained by generating each of three wet bulb globe temperatures (WBGT; 22, 28 and 34 degrees C) with two relative humidity levels (30 and 70%). The dual tasks selected from the Criterion Task Set (CTS) were: (1) display monitoring with mathematical processing; (2) memory search with mathematical processing; and (3) unstable tracking with memory search. The multiple task scenario was generated using the SYNTASK software. The results indicated a significant heat stress effect on CTS display monitoring and unstable tracking performance and on the SYNTASK visual monitoring and auditory discrimination tasks. Additionally, at 34 degrees C WBGT, 70% relative humidity was more detrimental to performance than 30% relative humidity. Results were interpreted using the Maximal Adaptability Model and Shingledecker's information processing stage/resource framework. To describe the results in an orderly manner, the authors propose the concept of heat stress selectivity effects. In addition, the results were used to evaluate whether the most recent NIOSH recommended heat stress standard, which is based solely on physiological and medical criteria, protects time-sharing performance. It was concluded that the NIOSH criterion does offer protection up to 28 degrees C WBGT.