To study the natural recovery from sports concussion, 12 concussed high school football athletes and 12 matched uninjured teammates were evaluated with symptom rating scales, tests of postural balance and cognition, and an event-related fMRI study during performance of a load-dependent working memory task at 13 h and 7 weeks following injury. Injured athletes showed the expected postconcussive symptoms and cognitive decline with decreased reaction time (RT) and increased RT variability on a working memory task during the acute period and an apparent full recovery 7 weeks later. Brain activation patterns showed decreased activation of right hemisphere attentional networks in injured athletes relative to controls during the acute period with a reversed pattern of activation (injured > controls) in the same networks at 7 weeks following injury. These changes coincided with a decrease in self-reported postconcussive symptoms and improved cognitive test performance in the injured athletes. Results from this exploratory study suggest that decreased activation of right hemisphere attentional networks mediate the cognitive changes and postconcussion symptoms observed during the acute period following concussion. Conversely, improvement in cognitive functioning and postconcussive symptoms during the subacute period may be mediated by compensatory increases in activation of this same attentional network. (JINS, 2013, 19, 1–10)

Comprehensive reviews of neurocognitive outcomes following mild, uncomplicated traumatic brain injury (TBI) in children have shown minimal effects on neurocognition, especially in methodologically rigorous studies. In this study, we report longitudinal (1, 6, and 12 months post injury) results in four domains of neurocognitive functioning in a large sample of children with mild TBI (n = 124, ages 8–17 at injury) relative to two demographically matched control groups (other injury: n = 94 and non-injury: n = 106). After accounting for age and parental education, significant main effects of group were observed on 7 of the 10 neurocognitive tests. However, these differences were not unique to the TBI sample but were found between both the TBI and other injury groups relative to the non-injured group, suggesting a general injury effect. Effects were primarily within the domains measuring memory, psychomotor processing speed, and language. This is the largest longitudinal study to date of neurocognitive outcomes at discrete time points in pediatric mild TBI. When controlling for pre-injury factors, there is no evidence of long-term neurocognitive impairment in this group relative to another injury control group. The importance of longitudinal analyses and use of appropriate control groups are discussed in the context of evaluating the effects of mild TBI on cognition. (JINS, 2011, 17, 886–895)

Patients with a history of mild (n = 134) or moderate-to-severe (n = 91) TBI were asked to complete the Neurobehavioral Symptom Inventory (NSI) and the Posttraumatic Stress Disorder Checklist. Consistent with prior research, significantly more postconcussion symptoms were endorsed by the mild group. After controlling for age, time since injury, and mechanism of injury, TBI severity continued to be significantly related to postconcussion complaints on the NSI. However, after controlling for these same variables, along with posttraumatic stress disorder symptom severity, there no longer were differences between the TBI severity groups. That is, patients with mild TBI did not endorse significantly more complaints (adjusted mean = 22.4) than the moderate-to-severe group (adjusted mean = 21.8). These findings suggest that much of the symptom complaints in mildly injured patients may be due to emotional distress. (JINS, 2010, 16, 194–199.)

The use of improvised explosive devices has become the hallmark of modern warfare and has resulted in an ever-increasing number of blast-related traumatic brain injuries (TBIs). Despite this fact, very little is actually known about the cognitive sequelae of blast-related TBIs. The purpose of the current study was to compare patterns of performance on neuropsychological measures in subjects who have sustained TBIs as a result of blast (or explosion) with those who have sustained TBIs from non-blast or blunt force trauma (motor vehicle accident, fall, assault, etc.). Participants were categorized as blast-related TBI or non-blast-related TBI and according to severity of injury (mild or moderate-to-severe). No main effects were observed in analysis of covariance between blast-related TBI participants and non-blast-related TBI participants across any of the neuropsychological variables, although an interaction was observed on a visual memory test showing stronger performance for mild blast-related and poorer performance for moderate-to-severe blast-related participants compared with both non-blast groups. Overall, the results do not provide any strong evidence that blast is categorically different from other TBI mechanisms, at least with regard to cognitive sequelae on select measures. Additional findings included a marginally increased incidence of reported posttraumatic stress disorder symptoms among blast-injured participants. (JINS, 2009, 15, 1–8.)

On the mild end of the acquired brain injury spectrum, the terms concussion and mild traumatic brain injury (mTBI) have been used interchangeably, where persistent post-concussive syndrome (PPCS) has been a label given when symptoms persist for more than three months post-concussion. Whereas a brief history of concussion research is overviewed, the focus of this review is on the current status of PPCS as a clinical entity from the perspective of recent advances in the biomechanical modeling of concussion in human and animal studies, particularly directed at a better understanding of the neuropathology associated with concussion. These studies implicate common regions of injury, including the upper brainstem, base of the frontal lobe, hypothalamic-pituitary axis, medial temporal lobe, fornix, and corpus callosum. Limitations of current neuropsychological techniques for the clinical assessment of memory and executive function are explored and recommendations for improved research designs offered, that may enhance the study of long-term neuropsychological sequelae of concussion. (JINS, 2008, 14, 1–22.)